Boll Weevil Information Exchange Group
February 20 – 21, 2001
Little Rock, Arkansas
Meeting Minutes
Gus M. Lorenz, Secretary
Welcome, Overview and Introduction – Roy Parker
Roy Parker, Chairman, welcomed participants and called the meeting to order. He acknowledged Gus Lorenz and thanked him for the organization of this year’s meeting. He passed out the minutes from last year’s meeting in Fort Worth and asked everyone to review them for any changes that needed to be made. Gus discussed the program and asked for a head count of attendance for that night’s Social and Mixer. Each person in the room then introduced themselves.
Jim Harper, Administrative Representative, gave the administrative comments. He requested time that everyone was spending on the activity and would like to have an accountability of effort and time being spent. He encouraged everyone to look out for funding of resources. Acknowledged that Roy had worked diligently to extend the depth of the SERA group and would like to bring in other activities other than boll weevil problems.
FUNDING PROSPECTS FOR BOLL WEEVIL ERADICATION
Bill Grefenstette, Moderator, showed the 30 different zones currently involved in active eradication, the projected costs for reach zone, and prospects for program completion in the future. He also showed the new expansion areas, scheduled to join the program in 2001.
Questions were asked about funding and at what point the money begins to decline. Dick Hardee asked about the $73M in cost-share cash, and how much is likely to be appropriated in the future, and at what point it would begin to decline. Grefenstette said that there is a good chance of getting another sizeable appropriation in 2002, but that program costs should begin to decrease significantly thereafter. The program would require less each year, while still maintaining the same percentage of cost-sharing. Phil Tugwell asked what the total expenditures were so far. Phil Haney, has been collecting historical records since the beginning, is a good source for that kind of information. Dick Hardee asked when we would be weevil freeweevil-free in the United States. The answer was that by 2005-2006, the boll weevil should be eradicated.essentially eradicated, with only a few "hot spots" remaining.
MALATHION ISSUES
Grefenstette then showed, by states and program areas, the projected need for malathion in 2001. He cautioned to not get too excited about projected winter kill and to stay the course and be prepared in case the trap counts are a little higher than we would like. There are currently two suppliers of malathion ULV licensed by EPA, Cheminova (Denmark) and Griffin (Mexico). Following an accident last summer, Griffin’s plant has been retrofitted and tested. It is reported to have received the final permits from Mexican officials last week, though nothing has been finalized since there are still some kinks in the production facility which need to be worked out.
Malathion rates being used now are 10-12 oz/acre instead of 16 because of improvements in application equipment. There doesn’t seem to be any problems with coverage, although a few folks are still a little anxious about the 10 oz/acre rate. Airports and schools near cotton have been a problem in Texas. Doug Ladner said using helicopters can be better because they can get in areas where fixed-wing aircraft cannot go. We have to keep making progress in this area. He said that radio-controlled para-foils are being used for various purposes, but there are questions about regulations governing the use of such equipment.
Risk Assessment for Malathion Summary – A brief update was given on the status of EPA’s risk assessment
Issues were discussed as to dietary risks, carcinogens, drinking water, non-dietary risks, and residential risks. Diet risks are low and of no concern. Cancer – some have speculated that there is possible carcinogenicity, but not sufficient to assess cancer potential. Classification is based on occurrences of tumors in rats given excessive doses; nothing resulted from more typical doses. Drinking water risks are low and of no concern. Residential – home and garden uses, as well as turf, are not of concern. Aggregate dietary risk – also no concern as well as food and water. Worker risks – no concern. Ecological – risks to birds and mammals are low but should be of concern if rates and shortest application intervals are used. Drift – Environmental Protection Agency (suggestive mitigation) – (1) Reduced application rate, (2) Increased application intervals, (3) Impose a buffer zone near water (125 – 700 ft), (4) Limiting maximum number of applications—all of these would significantly reduce program effectiveness and likely prevent the program from accomplishing its objective.
Question was asked as to when the risk assessment would be completed. Chris Bowley of Cheminova said it could be by the end of April and June before measures would be put into effect, and that Malathion has come through this process relatively unscathed.
Also a question was raised as to the new administration and if there would be any changes. Not very likely to get the attention of the new EPA Administrator. Charles Allen asked if it would affect mosquito control (notably in TX). Chris said that any buffer zones would affect spraying.
Quarantine was discussed at state and federal levels. ARS has looked at weevil survival at gins and experiments have been performed to see what would happen to them. Can they survive the bale process? Need to look at the potential for weevils to move from the field and escape. Charles Allen asked about the risks of livestock feeding on gin trash. Remote plants are not a big risk. Long-term monitoring plan – Met in December and invited the Technical Advisory Committee. Chairmen to join program directors and discuss the general long-term strategy for weevil-free areas. It was stated that a replacement for methyl bromide is being looked into, regarding regulatory use under state and federal quarantines.
Doug Ladner said that Missouri is asking what is going to happen. There will be some kind of regulations and Arkansas and Missouri need to get together and work out the details.
Bill Grefenstette stated that we need to hang on to methyl bromide as long as we can.
Jim Leser – Introduced by Roy Parker – He presented Boll Weevil Overwintering in the High Plains and Rolling Plains Regions of Texas in association with Stan Carroll, Don Rummel, Mark Arnold and Jim Leser from Texas A & M.
Stan Carroll gave a historical overview of boll weevil overwintering studies conducted in the Texas High and Rolling Plains regions of Texas. Twenty years of overwintering studies (D. R. Rummel-project leader) yielded an average survival of 6.6% (range 0.1-24.5%) for the first ten years (winters of 78-79 to 88-89) while the second 10-year period showed an average survival of 21.1% (range 1.6-61.9%). The occurrence of an extended series of extremely mild winters beginning in 1990-91 is believed to be the primary factor causing the increased survival rates observed during the second period. Beginning in the late 1980’s and early 1990’s, the boll weevil became firmly established in the cotton producing counties of the southern Texas High Plains. Following mild winters, High Plains weevil populations exhibit high winter survival rates with significant numbers emerging from more marginal types of habitats such as the vast acreages of Conservation Reserve Program grasses.
Current Winter Observations: Dig-up cage overwintering studies indicate much higher mortality rates this winter when compared to the three preceding winters. The observed steady rate of weevil mortality cannot be attributed to a specific weather event, but to numerous repeated cold spells that may have played a role in creating detrimental conditions for diapausing weevil survival. Results of previous studies establish a correlation between extended, severe artic fronts and immediate (or direct) boll weevil mortality, but little is know about the chronic effects of repeated cold exposure at non-lethal temperatures. In addition, above average moisture accompanying this winter’s repeated cold periods raises unanswered questions about possible detrimental effects of excessive habitat moisture on boll weevil winter survival.
Lanny Brashear gave a presentation for the Tennessee BWEP which stated that TN is divided into three boll weevil eradication program areas: Middle, Southwest and Northwest with the middle portion of the state consisting of those counties adjacent and directly north of the TN River Valley cotton growing area in north Alabama. This area consisted of 17,677 acres in 2000 and has been considered part of the eradicated area in the southeastern BWEP since about 1996. The southwestern portion of TN contains 173,765 acres of cotton and entered into the SEBWEP when a fall diapause spray program was initiated there in 1998. In 1999 and 2000 the boll weevil trapping levels for the total season has remained about the same as this area is really a buffer zone with migrating boll weevils being received from northwest TN, southeast MO and NE AR. With the entrance of NW TN into the program in 2000, along with cold temps, much lower boll weevil levels are expected in 2001. Almost 6M weevils were trapped there during 2000 and an average of 12 sprays were applied.
The NW program area entered in August, 2000. Historically known for low BW populations, trapping efforts indicated extremely high populations during the 2001 season. This is expected to change due to the 2000 fall diapause spraying plus the cold weather.
Tina Teague, AR, commented on the boll weevil situation in the northeast Arkansas. The Buffalo Ditch on Crowley’s Ridge offers some of the only overwintering habitat in the area known as Buffalo Island where weevils historically are at very low levels. The temperature data reflected differential insulative capacities of the overwintering sites. The greater the insulation, the greater the probability that weevils survive the winter. Cumulative hours under 230F for the overwintering habitat types were approximately 60 hours for grassy habitats, 40 for kudzu, 20 for shallow (< 1 inch) deciduous leaf litter and 0 hours for deep leaf litter (> 4 inches). The deep litter was on Crowley’s Ridge and the other readings were from Buffalo Ditch.
Michael Boyd, MO, announced that there were three different referendums last year and in November they passed it with 70% approval. Will start its BWE program in mid-August. He also stated that 99% of cotton grown in Missouri is in the bootheel.
Danny Kiser, gave the financial status of the AR BWE program. Treatments – 74%; salaries and benefits – 9%; vehicle and equipment - 8%; trapping – 8% and Other – 1%. Projected budget for 2001 is $35M. He also reported that all zones except the northeast Delta have passed referenda. The northeast Delta zone is scheduled to vote in the fall of 2001. Cotton acreage in the southwest zone totaled 6,886 and was initiated in 1997. In the southeast zone, initiated in 1999 cotton acreage totaled 298,258 and the spring average trapping was 13 and 3.3 for the fall. A total of 250,000 acres were sprayed from June to November, 2000, with treatments consisting of ULV malathion. The central zone initiated in 2000 consisted of 212,000 acres and the spring average trapping was 29 and 16 for the fall, with weekly diapause treatments consisting of ULV malathion.
The northeast ridge of eradication passed by 74% in 2001 and consists of 122,000 acres. They will start mistblower applications on all fields on August 1 and aerial applications August 15. Will spray fields every seven days until there is no hostable material. The northeast Delta zone is the only zone in Arkansas which has not voted to begin boll weevil eradication. The northeast Delta zone is expected to hold a referendum in the fall of 2001. Secondary pests are always a concern when eradication programs are spraying large acreages. In 2000 the Arkansas program was very fortunate that damaging secondary insect pest problems were minimal and in most situations insecticide controls were very effective against these pests.
Ralph Bagwell, LA, reported that the northeast zone has had five applications. The Red River zone votes in March and anticipates that it will pass. Reports relatively high numbers of weevils in a portion of the Red River zone – 0.37 weevils per trap. Starting with the northeast zone the fall count is higher than spring count. By fall, however, got significant reductions in boll weevil counts. They averaged 11 applications in each field in northern Louisiana. Danny Kiser reported that the producers are doing a good job.
Charles Allen, TX, reports 100% reduction in the Southern Rolling Plains of TX and that because of perserverance in the program it has been a success. The Texas Commissioner of Agriculture declared 365,000 acres in the zone functionally eradicated in 2000. South TX with 393,000 acres lost ground here because of a hurricane in 1999 and have access issues where growers are not cooperating. Windy weather conditions hamper effectiveness and are considering using helicopters for spraying near urban areas in the zone. Weevil numbers have been reduced 91% in the zone. Rolling Plains Central is making good progress with 99.8% reduction in the zone and the Permian Basin with 769,000 acres is now at 98% reduction in weevil numbers from diapause initiation in the fall of 1999. The program in the Permian Basin zone got help from hot/dry weather conditions of 2000. NW Plains with 586,000 acres – migration from surrounding areas not in eradication is a problem. Weevil numbers were reduced 78%. Beet armyworm populations were high late in the season. El Paso/Trans Pecos with 46,000 acres has had a 96% reduction in boll weevil numbers. Growers voted on a pink bollworm project which will be initiated in 2001. On the 338,000 acres in the Northern Rolling Plains wet weather kept traps from being read during the critical pinhead square stage, but an 88% reduction in the boll weevil population was achieved. West High Plains experienced a 96% boll weevil reduction. Beet armyworm populations were first seen in this zone.
Charles presented a graph on the distribution of money. All zones of TX are 6.7% over budget, $292M budgeted with $313M spent. Average income 2000 - $3.7M budgeted, $4M actual and a 10.5% increase. He reported that there was good momentum in the Blacklands and lots of publicity to get BWE initiated. Personnel requirements – 1,500 in 2000 and 2,150 in 2001. He also thanked good producer involvement, APHIS-USDA, Texas A & M personnel, National Cotton Council, Growers Association, BWE Foundation Board, aerial applicators and the 2,000 TX BWE employees for the success that Texas has experienced in eradicating the boll weevil.
February 21
General Discussion
Roy Parker welcomed the group for the continuation of the meeting. He again asked if everyone had received copies of last year’s minutes and if there were any changes to be made. No one offered any and he asked for a motion that they be approved. Dick Hardee made the motion, it was seconded and the motion was passed. He announced that Gus Lorenz would be the Program Chair and discussion followed as to a location for next year’s meeting and it was decided that it would be left to Gus to designate a location. Gus Lorenz took a minute to recognize and thank Cheminova, Griffin and Plato Industries who helped sponsor the Little Rock meeting.
Jerry Coakley presented the OK program’s financial budget. Northern Oklahoma now has a big cotton acreage and is in a new area of the panhandle and are going about it in a big way. As a result of their tenacity, should see no weevils there.
Dale Spurgeon, Moderator - 2001 ARS Research Plans - Because of the short time allotted for reporting research plans, detailed discussions were not possible. Instead, the research objectives of respective ARS scientists were enumerated and briefly discussed. Constructive criticism, suggestions, encouragement, and offers for collaboration were solicited from meeting participants. Participants were informed that the overall ARS research program in Texas is highly integrated, and objectives reported by individual scientists often represented collaborative efforts. Reports of objectives by individual scientists followed.
Dale Spurgeon -Evaluation of boll weevil pheromone lure component ratios. Problem: Although influence of pheromone component ratios on trap capture have been studied, recent results from studies to improve estimation of pheromone production by individual weevils have indicated that pheromone released by males differs substantially from that released by commercial lures. These differences may be substantial enough to influence capture, and further evaluations of lure component ratios may result in improved lures providing increased capture efficiency and/or decreased trapping costs. Objectives: Compare trap capture of boll weevils in response to the traditional Grandlure pheromone formulation to that of a new formulation derived from pheromone production monitoring studies.
Influence of boll weevil age and physiological condition on pheromone production. Problem: Recent research has identified important weaknesses in traditional methods of estimating boll weevil pheromone production. As a consequence, previous estimates of pheromone production and the influences of age and physiological parameters must be reexamined. More accurate estimates of pheromone production, especially for individual weevils, would improve our understanding of the ecology and physiology of pheromone production and result in better estimates of release rate requirements for effective pheromone lures. Objectives: Determine the influence of square size on pheromone production (5-7 mm vs 7-9 mm), and determine the influence of food type on pheromone production (squares vs small bolls). In both of these objectives, association between accessory gland condition and pheromone production will be examined by dissection.
Temperature-dependence of boll weevil host-free survival.Problem: The influence of temperature on duration of host-free survival of diapausing boll weevils has not been adequately investigated. Quantitation of the impacts of winter temperatures on weevil survival patterns during the non-cropping season would facilitate efforts to reduce management program costs through better timing of the initiation of fall diapause sprays, and improve understanding and prediction of boll weevil overwinter survival. Objectives: Examine the temperature dependence of host-free survival of diapausing boll weevils and calculate corresponding temperature coefficients for use in predictive models to estimate overwintering survival and earliest date at which diapausing weevils can be expected to survive to the following cropping season.
Correlation of host-free survival with boll weevil diapause characters. Problem: Although the morphological characters of boll weevil reproductive diapause have been described and used in various combinations to assess the factors controlling diapause induction, adequate data defining the relative importance of the respective characters and their consequences to weevil overwintering survival are lacking. Because these characters have been used inconsistently and without demonstrable evidence of their meaning, the criteria for diapause reported in many studies may be arbitrary and lack biological meaning. Confirming evidence as to the biological consequences of the diapause characters would be useful in more accurate evaluation of the regulation of diapause, and in assessing the ecological and control implications of the seasonality of diapause. Objectives: Define relationships between morphological characters of boll weevil diapause and duration of host-free survival.
Examination of factors controlling diapause/reproductive dormancy in temperate boll weevils. Problem: Insecticide applications to reduce populations of diapausing boll weevils are considered the cornerstone of current eradication efforts and are also used in other regional suppression programs. Yet, controlling factors and dynamics of diapause are poorly understood. Improved understanding of boll weevil adult diapause/reproductive dormancy should result in improved economics and effectiveness of diapause control efforts. Objectives: Examine impacts of host parameters (specifically boll size) on control and dynamics of diapause/reproductive dormancy of temperate zone boll weevils with emphasis on induction of the reproductive dormancy, and examine the influence of feeding regime on diet-mediated termination of diapause.
Influence of flight activity on fat body condition and diapause termination of boll weevils. Problem: Recent trapping and emergence studies of overwintering boll weevils indicate weevils collected from cages shortly after emergence tend to have more developed fat bodies than do weevils collected from traps during the same period. At least two factors may be involved in these differences: 1) weevils collected from traps represent weevils entering overwintering quarters with poorly developed fat bodies, or 2) upon emergence, fat bodies are rapidly diminished in response to flight activity. Elucidation of these differences would be useful in interpreting spring trap captures where weevils are dissected, and may play a critical role in studies of diapause termination because very fat weevils tend to feed reluctantly. Objectives: Determine the role or influence of sustained flight activity on fat body consumption and diapause termination through alterations in the propensity to feed.
Charles Suh presented Season-dependent characterization of boll weevils responding to pheromone traps. Problem: Pheromone trapping is a key component of boll weevil management and eradication programs, but trap data are difficult to interpret because of day-to-day variability in captures and the inability to identify the source(s) of captured weevils. Of particular importance, but unknown, is the proportion of the weevil population responding to traps during different times of the season. Morphological or physiological characterization of trapped weevils, in comparison to weevil populations infesting the cotton crop at different times of the season, would provide insight into potential source(s) of trapped weevils and improve our ability to interpret capture data. Objective: Characterize the season-dependent morphological/physiological status of trapped boll weevils in comparison to that of weevils infesting the standing cotton crop.
Evaluation of host-free longevity of fat, reproductive weevils. Problem: It is traditionally accepted that female weevils possessing eggs are unable to successfully overwinter. Recent trapping studies in the Brazos Valley area revealed that boll weevils were overwintering with eggs. The impact of overwintering with eggs on survival, however, is unknown. Increased knowledge of boll weevil overwintering ecology and survival should lead to improved control strategies. Objective: Define relationship between reproductive development of weevils with well-developed hypertrophied fat bodies and duration of host-free survival.
Evaluation of reproductive development of overwintered and newly-enclosed weevils on presquaring cotton. Problem: Prior literature indicated that boll weevils fed vegetative stages of cotton were unable to produce mature eggs. Circumstantial evidence from recent trapping studies indicated that overwintered boll weevils could produce mature eggs in the absence of fruiting cotton. Confirmation of this evidence is needed, and results should prove useful in designing more efficient and effective control tactics. Objective: Determine if overwintered and newly enclosed adults can produce mature eggs on presquaring cotton.
Color-based identification of adult weevil prior food source. Problem: Boll weevil eradication programs rely almost exclusively on pheromone trap captures for population assessments and treatment decisions. Despite this reliance, there is little assurance that trap-captured weevils arrived from adjacent cotton fields, and evidence or methods linking captured weevils to their origin is generally lacking. Our observations in past studies indicated that coloration and texture of gut contents varied with food type. Examination of gut content may provide a means for accurately determining the recent food source of captured weevils, and should provide insight into the recent origin of trap-captured weevils. Objective: Examine color changes of gut contents associated with known dietary histories and evaluate the use of gut content color and texture for identification of recent weevil source.
Diet-mediated termination of reproductive development:Problem: Recent studies conducted by Unit scientists indicated that expression of "diapause" characteristics was significantly influenced by diet. However, the influence of diet on reproductive termination/dormancy in fully reproductive weevils is unknown. Improved understanding of reproductive termination/diapause induction should result in improved timing of diapause treatments and lead to improved control tactics. Objective: Examine impact of diet switching (squares to bolls) on termination of reproductive development in fully reproductive weevils.
Influence of physiological condition and feeding status on supercooling points of adult weevils. Problem: Winter-kill is an important mortality factor of adult boll weevils and plays an important role in the seasonal population dynamics of weevils. Because adult boll weevils are freeze-intolerant, it is generally assumed that many overwintering adults are killed as a result of freezing. The temperature at which an insect freezes is commonly referred to as its supercooling point. Very little is known about the supercooling capabilities of adult weevils and impact of sub-freezing temperatures on adult survival. A better understanding of factors influencing adult supercooling points and survival should lead to improved control strategies. Objective: Examine the influences of physiological condition and feeding status on supercooling points of adult weevils.
Influence of age, sex, and physiological condition on boll weevil response to pheromone and host-plant volatiles.Problem: Intrinsic biological factors influencing the responsiveness of boll weevils to pheromone and host-plant odors are poor studied, and previous reports are equivocal or incompatible with field observations. Improved understanding of the age- and physiological-dependent response of the boll weevil to its chemical environment could improve interpretation of trap data and facilitate design of efficient trapping plans. Objectives: 1) Test a newly designed olfactometer and modified existing two-choice olfactometer for consistency and reproducibility of results; and 2) examine the influences of selected biological and physiological parameters on response to pheromone and host plant volatiles.
Jesus Esquivel - Boll weevil feeding and longevity on pre-squaring cotton. Problem: Many boll weevils emerge from overwintering before the availability of fruiting cotton. Survival of these early emerging weevils has been studied and is considered to be of short duration. However, longevity of overwintered weevils on pre-fruiting cotton has not been studied under controlled conditions. Knowledge of the value of pre-fruiting cotton for weevil survival would be useful in devising early-season cultural control strategies. Objective: Determine the comparative survival rates of boll weevils feeding on different stages of pre-squaring cotton.
Collection efficiency of the Keep It Simple Sampler (KISS) in early-season cotton. Problem: The KISS has particular utility in sampling early-season boll weevil populations when population levels are typically low. However, detailed estimates of collection efficiency and changes in efficiency in response to plant development are not available. Objective: Determine the collection efficiency of the KISS during early-season cotton using mark-recapture techniques.
Evaluate the use of puncture characteristics for estimating oviposition. Problem: Oviposition punctures, indicated by the presence of oviposition plugs, are traditionally used to determine boll weevil infestation rates, make treatment decisions, and estimate fecundity. Preliminary data by Unit scientists indicate that this methodology may not be a reliable indicator for estimating oviposition. Objective: Examine the accuracy of selected puncture characteristics for detecting and estimating oviposition.
John Westbrook presented outlines of his research and research by four colleagues who were unable to attend the meeting.
Clint Hoffmann - Influence of Crop Canopy on Spray Movement. Problem: Millions of dollars have been spent by the Spray Drift Task Force to generate a computer model (AgDrift) for predicting spray movement. AgDrift does not include a definitive parameter for predicting the role that crop canopy has on spray deposition and drift. If crop canopies can be shown to reduce the downwind movement of sprays, the usability of some crop protection chemicals may be increased through a decrease in buffer zones. Objective: To quantify the role of a crop canopy on spray movement.
Control of Thrips with Aerial Application: Problem: The research literature is split on whether or not thrips are of economic importance in cotton. Cotton producers routinely use a systemic, restricted use insecticide for early season thrips control. Objective: To evaluate the efficacy of conventional and electrostatic aerial spray systems on control early season thrips in cotton.
UV Protectants for ULV Malathion. Problem: ULV malathion degrades rapidly under field conditions and this degradation is enhanced in the presence of sunlight. Techniques that decrease the degradation rate of malathion would improve the effectiveness of each application and could permit a decrease in the number of applications and associated costs needed to provide effective boll weevil control. Objective: Determine if UV protectant materials will decrease the rate of degradation of ULV malathion under field conditions.
Buddy Kirk - Droplet spectra classification handbook for commonly used aerial spray nozzles. Problem: EPA has begun to include application criteria on product labels that will require aerial applicators to apply a given product in a specific spray droplet classification. Many nozzle manufacturers publish atomization data for ground application conditions but not for the more complex aerial application situation. Most applicators do not have information to determine droplet spectra for a given spray nozzle orifice size, nozzle angle, operating pressure, and airspeed. NAAA has requested ARS to develop predictive models and a spray nozzle manual to assist aerial applicators with droplet spectra classification for their operating conditions. Objective: Develop a manual for aerial applicators based on previously developed fixed and rotary wing spray nozzle models.
Boom length for helicopters vs. spray drift. Problem: Research has shown that spray boom length for fixed-wing aircraft should be no more that 75 percent of wingspan to reduce spray droplet entrainment in wing-tip vortices. This guideline has been applied to helicopters even though research has not confirmed the principle for rotary-wing aircraft. The configuration geometry of the spray boom relative to the wing-tip and rotor-tip vortices is considerably different for the two types of aircraft. Objective: Determine the influence of 75 percent and 100 percent boom length for helicopters on swath width and spray drift.
Electrostatics for reduction of driftable fine droplets:Problem: Conventional hydraulic spray nozzles produce a range of spray droplet sizes. Previous research has shown that alternate charging of adjacent spray nozzles can cause fine droplets to merge with each other or with larger droplets. Objective: The objective of this research is to assess the potential for using electrostatic spray charging to reduce the number and volume-content of driftable fine droplets in conventional-volume aerial sprays.
Parafoil Sprayer for spraying problem areas of boll weevil eradication program. Problem: Small and difficult to spray (because of size, obstructions, proximity to sensitive areas, etc.) cotton fields in the eradication program have often been sprayed with mist blowers or ground rigs. These approaches present various difficulties to eradication program managers and field personnel. Remote controlled helicopters have been evaluated for this use but have not been satisfactory. Objectives: Assess the performance and practical utility of a para-foil sprayer to apply ULV malathion in small difficult-to-spray areas encompassed in the boll weevil eradication program.
Aerial distribution of unrefined sugar syrup-based attracticides for adult pest control. Problem: Recently developed attracticide formulations for insect control have unique physical properties that are incompatible with widely available conventional pesticide application equipment. Continued development and refinement of novel application equipment would facilitate efficient evaluation and transfer of attracticide technologies. Objectives: Provide cooperation and engineering support for attracticide protocols developed by Dr. Lopez, et al. in APMRU.
Juan D. Lopez, Jr. - Operational Aspects of Corn Earworm/Bollworm Adult Control with Aerially-applied Feeding Stimulant/Insecticide Mixtures in Corn and Cotton. Problem: It is time to move toward a practical application of adult control technology for corn earworm/bollworm on corn and cotton. In these crops, the only application method that will be practical for adult control is aerial application and to aerially apply feeding stimulant/insecticide mixtures, we need to know optimal application parameters for killing the adults. Objective: Evaluate operational aspects for aerial application of feeding stimulant/insecticide mixtures such as swath width of treated strips, strip spacing, strip orientation relative to row and wind direction, spray volume per acre, etc. for maximizing adult kill in corn and cotton.
Use of Pheromone and Feeding Stimulant/Insecticide Mixtures for Killing Adult Boll Weevils during the Spring and Fall. Problem: In active and post eradication programs, major concerns are the widespread applications of insecticide and movement of boll weevils from infested areas to areas under active or post eradication programs. Pheromone has to be recognized as the most effective attractant for boll weevils during the spring and fall. Use of pheromone in traps is a major component of active and post eradication programs; however, this use for control purposes is limited by the logistics of trapping. Combining the use of pheromone to attract boll weevils to an area treated with a feeding stimulant/insecticide mixture to kill the adults has merits for use in active eradication programs to enhance early season mortality of overwintered boll weevils and reduce numbers of boll weevils entering diapause in the fall. In active or post eradication programs, treatments could serve as barriers to prevent or reduce movement from infested areas and possibly to control an incipient infestation in an eradicated area. Objective: Evaluate use of pheromone in combination with a feeding stimulant/insecticide mixture applied on various vegetation types to kill adult boll weevils.
Gretchen D. Jones - Development of a Lepidopteran model for the risk-assessment of genetically modified plants. Problem: Pollen from genetically modified corn is known to adversely effect the larvae of non-target lepidoptera. Rearing of monarch butterflies is difficult because of the necessity of obtaining or growing milkweeds for larval development. An easily reared lepidopteran species that is sensitive to genetically modified corn is needed to assess impact on non-target species. Objective: Evaluate and develop a Lepidopteran model for assessing the effect of pollen from genetically modified plants on non-target insects.
Evaluate pollen as an indicator of nursery habitats of secondary pests. Problem: Flea hoppers and green stinkbugs are secondary insect pests on cotton, that periodically become major pests. Numbers of these insects increase rapidly and seemingly "come out of the blue." Improved understanding of "nursery" habitats for these pests would increase the possibility of preventing future infestations. Objective: Evaluate the use of pollen as an indicator of "nursery" habitats.
Effect of non-cotton feeding on adult boll weevil longevity. Problem: Adult boll weevils are considered polyphagous pollen feeders and numerous taxa have been reported as foraging resources regardless of the presence or absence of cotton. The life expectancy of adult boll weevils feeding only on pollen from many of the reported foraging resources and the effect of temperature on pollen feeding and longevity is unknown. Objectives: Examine the effect of non-cotton pollen feeding on the longevity of adult boll weevils. Determine any differences in longevity due to variation of pollen taxa.
Determination of sterol composition of pollen from cotton and other plant species. Problem: Insects are unable to biosynthesize the steroid nucleus for structural and physiological purposes, therefore, they must convert phytosterols to cholesterol or other sterols. Objective: Determine the amount of sterols and lipids present in the pollen of Gossypium hirsutum C. Linnaeus (cotton) and other plant species.
John K. Westbrook - Bat Predation of Bollworms. Problem: Mexican free-tailed bats feed on adult bollworms and other noctuid pests, but their contribution to crop pest management has not been adequately quantified. Objectives: Quantify the suppression of bollworm and other noctuid pests by Mexican free-tailed bats.
Local Dispersal of Bollworm Moths. Problem: Available information regarding bollworm dispersal between corn, cotton and other habitats is insufficient to facilitate improvements in current population suppression tactics. Improved understanding of bollworm dispersal would supply additional insight necessary for assessing attract-and-kill strategies and establishing refuge plots used in resistance management schemes. Objectives: Determine the dispersal of adult bollworms within and between corn, cotton, and uncultivated habitats, with respect to climatic factors and crop growth stages.
Emergence of Overwintered Boll Weevils. Problem: Mechanisms controlling boll weevil emergence from overwintering, including influences of habitat temperature and moisture conditions, are poorly understood. Improved understanding of these mechanisms would facilitate more accurate prediction of emergence patterns and would be useful in devising improved early-season control strategies. Objectives: Determine the effects of temperature, precipitation, and other climatic factors on the daily pattern of emergence of overwintered boll weevils.
Seasonal Distribution of Boll Weevil Captures Relative to Landscape. Problem: Spatial and temporal patterns of trap-monitored boll weevil populations in non-cotton habitats and mechanisms influencing these patterns are poorly understood. Consequently, such data are difficult to interpret in a meaningful fashion. Relation of trap capture patterns in non-cotton habitats, both during and between cotton production seasons, to spatial biogeographical features and synoptic weather patterns would provide an improved framework for interpreting ecological management implications of these populations. Objectives: Develop a geographic information system to examine seasonal changes in the spatial distribution of boll weevils relative to biotic and abiotic factors.
Atmospheric Diffusion of Grandlure Volatiles. Problem: Information is lacking about ambient concentrations of boll weevil pheromone produced in infested cotton fields and of grandlure dispensed from pheromone trap baits. Results of this study will contribute to universal improvements in the placement and density of pheromone traps and other monitoring and management technologies. Objectives: Determine physical characteristics of plumes of grandlure volatiles for varying microclimatic conditions.
Tom Sappington - Effects of microclimate and pheromone trap position on boll weevil captures. Problem: The pheromone trap is an indispensable component of boll weevil monitoring, management, and suppression programs, but environmentally induced fluctuations in trap captures make interpretation of trapping data difficult. Improved understanding of interactions between wind speed, wind direction, temperature, and trap position within trap lines will lead to increased effectiveness, economy, and quality of information from trapping programs. Objectives: Examine effects of temperature, wind speed, and wind direction on trap captures within narrow time frames, relative to distance from a brush line. Examine effects of position within a trap line to trap captures.
Molecular marker profiles of boll weevil populations.Problem: Knowledge of boll weevil dispersal patterns and population interchange is critical to organized suppression programs, but direct evidence of such movements using mark-recapture or natural marker techniques is difficult to obtain and to interpret. If polymorphic molecular markers were available for populations across various geographic regions, these genetic patterns could be used to estimate the extent of gene flow between these populations and to validate other movement studies. Objectives: Examine the usefulness of RAPD’s (Randomly Amplified Polymorphic DNA) and possibly AFLP’s (Amplified Fragment Length Polymorphisms) for distinguishing weevils collected in the Lower Rio Grande Valley (LRGV), College Station, and Tampico. Molecular marker profiles will subsequently be obtained for additional populations and used to estimate gene flow as a function of geographic distance between populations. Retrieve and store reintroduced weevils collected in eradicated zones for DNA extraction.
Determine precision of boll weevil age-estimates based on current cuticular hydrocarbon profile data, and begin examination of potential sources of age-independent variation. Problem: Information obtained from boll weevil trapping programs would be more useful if ages of trapped weevils could be determined, but current methods of age estimation are subjective, imprecise, and of questionable accuracy. Our recent work has shown that cuticular hydrocarbon profiles change with age of the boll weevil under controlled conditions, but other factors (such as diet, temperature, reproductive status) may superimpose interindividual variation in the field. If we can estimate the precision of age predictions based on our current data, and identify and quantify factors that may introduce hydrocarbon variation independent of age, we will be able to determine the approximate age of individual weevils captured in the field with a known level of confidence. Objectives: To estimate precision of the current predictive equation using an independent data set, and to quantify any systematic variation generated by adult diet, duration of exposure to heat and sunlight in a pheromone trap, and sex.
Suppression of boll weevil populations by fall trap cropping. Problem: Area-wide diapause control programs rely on conventional synthetic pesticides, and although these programs can be effective, they are expensive and incompatible with environmentally sensitive areas. An effective fall trap-cropping system would concentrate potentially overwintering weevil populations where they could be controlled with minimal cost and environmental contamination. Objectives: Estimate the percentage of boll weevils evicted from the main crop that are arrested by trap crop, and the length of time they remain there. Determine the effectiveness of an experimental photoactive dye bait applied in the trap crop as the killing agent for attracted boll weevils.
Identify biochemical markers to distinguish diapausing and reproductive boll weevils. Problem: Efficient implementation of late-season diapause controls requires thorough knowledge of the seasonality and controlling mechanisms of boll weevil diapause, but current dissection methods for determining diapause status are subjective and labor intensive. Identification of biochemical correlates of boll weevil diapause and the development of efficient assays would facilitate efforts to both monitor and study the diapause phenomenon. Objectives: In cooperation with Dr. L. Keeley (TAMU) and Dr. D. Spurgeon (ARS, College Station), we will confirm the diagnostic capacity of a recently discovered hemolymph protein for populations in both the Lower Rio Grande Valley and the Brazos Valley of Texas, and further examine aspects of endocrine control of the protein. Monoclonal antibodies will be raised to a synthetic peptide based on the partial amino acid sequence recently deduced, and we will continue immunological characterization of the polyclonal antibodies to determine the feasibility of developing a diagnostic kit.
Evaluate potential for boll weevil transport to and survival in cotton gins. Problem: The potential for reinfestation of an eradicated or nearly-eradicated area is particularly acute for zones that border an infested zone or a zone that is not far advanced in the eradication process. This situation is particularly common in Texas where blocks of counties have entered the program in a patchwork fashion in both time and space based on timing of referenda passage, rather than on a plan of systematic progression. If data were available on the risks of transport of weevils to gins and the ability of weevils to survive the ginning process, informed decisions could be made regarding whether gins in weevil-suppressed areas can safely continue to service customers from infested areas. Objectives: A series of laboratory and field experiments will be conducted to generate hard data on the survivability of boll weevils in harvested fields, moduled seed cotton, ginned lint, cottonseed, and ginning waste. Ginning equipment specifications and operating procedures will be established to insure that weevils brought to the gin are killed during processing. The potential for post-harvest weevil survival in the field under different tillage regimes will be assessed as well.
Allan Showler - Effects of late-season/post-harvest field operations on flying boll weevil populations. Problem: Late-season boll weevil populations and flight peaks resulting from field operations have long been recognized anecdotally but have not been empirically characterized. It is possible that control tactics, including non-chemical means, aimed at these vulnerable populations might significantly reduce the size of the population that eventually emerges from the winter crop-free period. Other modes of suppressing boll weevil populations such as fallow tillage practices and early season insecticide applications also have not been adequately researched. Objectives: Conduct the second year of a study using large capacity traps to measure flying boll weevil populations resulting from defoliant application, defoliation, harvest, shredding, and tillage in grower fields. A large plot trial to determine the effects of automatic pre-emptive insecticide applications on square damage and yield, and a study on tillage practice impacts on the capacity of fields harbor overwintering boll weevils are both in their second years. Follow up studies are planned in 2002 for quantifying late-season and post-harvest flying boll weevil population peaks in relation to selected late-season and post-harvest control tactics. Modifications to the trap for enhancing its rate of capture will continue to be assessed.
Alternate food sources of the boll weevil. Problem: Pilot experiments indicated that certain wild plants are food sources for the boll weevil. Objectives: A series of lab and field studies will commence in 2001 with the aim of identifying plants that might provide boll weevils with adequate nutrition for periods during which cotton growth is scarce. In 2002, the study will be expanded to include selected crop plants.
Kaolin particle film for protection of cotton from selected pests. Problem: Kaolin is a highly reflective white mineral that is available in a wettable powder formulation; it has been shown to suppress injury to some crops caused by important arthropod and plant pathogens. It’s potential for reduction of damage to cotton has not been assessed. Objectives: Kaolin’s effect on boll weevil injury to small plot cotton, and other arthropod groups, will be tested for a second year. Lab and cage assays have been completed for the boll weevil component; the beet armyworm component requires one lab study to be completed in 2001.
Effect of vegetative diversity in the cotton agroecosystem on cotton production and on nontarget arthropod populations. Problem: Some aspects cotton field ecology have not been explored, including the interaction of weeds with the cotton plant on pest and natural enemy populations. Objectives: For a second season, weedy and weed-free cotton plots will be examined for their capacities to harbor predatory and parasitic arthropods. Impacts of vegetative diversification with weeds on boll weevil injury to cotton, and on growth and yield, are measured. The likelihood of promoting natural vegetative diversity with the aim of enhancing natural enemies will be assessed.
Stress and the accumulation of free amino acids in cotton foliage. Problem: Insect associations with stressed plants are well documented, but the physiochemical mechanisms responsible for them are poorly understood. Results might relate to increasing plant resistance to pests. Objectives: Using an HPLC, 16 free amino acid concentrations are being measured in cotton plants in relation to water deficit, weed competition, kaolin application, and shade. The effect of water-deficit stressed cotton plants on beet armyworm oviposition behavior and larval development will continue into 2001. Studies on the effects of cotton stress to cotton aphid populations will be initiated this year.
Shoil M. Greenberg - Combining reduced rates of insecticides with defoliants for diapause control of boll weevil. Problem: The best opportunity for reducing populations of potentially overwintering boll weevils is just before dispersal from the field at or before harvest. Such "diapause treatments" are generally successful, but if an insecticide treatment could be combined with a normal defoliant treatment, savings from one less application would be realized. If certain combinations of insecticide with defoliant show synergistic effects (as preliminary tests suggest is the case) then it might be possible to apply the latter at a reduced rate at even greater savings to the grower. Objectives: To determine the efficacy of combinations of insecticides at reduced rates with defoliants (or combinations of defoliants) on boll weevil mortality in large-plot field trials.
Effects of tillage and cultural practices on population dynamics of cotton insect pests and beneficial organisms. Problems: The IFNRRU SARC ARS-USDA continues to study the effects of conservation tillage, soil types, irrigation, crop rotation on abiotic and biotic conditions for cotton growing, cotton productivity, and associated environmental problems. Conservation tillage is increasingly finding acceptance among farmers in the USA because of its advantages over conventional systems in preventing soil erosion and in conserving soil moisture. However, there is limited information about its impact on boll weevil and other cotton insect pests and beneficial insect populations. Objectives: Complete a second year of comparative evaluations of effects of conservation tillage and conventional tillage systems in dry land cotton on population dynamics of boll weevil and other insect pests and beneficial organisms. Similar experiments will be initiated comparing tillage systems in irrigated cotton.
Effects of plant age, geographic origin, and multi-generation dietary conditioning on host-plant oviposition preference of beet armyworm. Problem: Beet armyworm oviposits and feeds on a wide variety of plants including cotton, but not all plants are equally favored. Development of novel and efficient strategies for controlling beet armyworm (such as trap-cropping) will require more thorough knowledge of the biological relationships between the host plants and the insect. Although experiments indicate that pigweed is preferred over cotton, the effects of host-plant phenology and dietary history of the moths on oviposition preference could be substantial but are unknown. Objectives: Determine the influence of cotton and pigweed age on beet armyworm oviposition under both no choice and choice conditions. Cross beet armyworms from different geographic populations and compare their preferences to cotton and pigweed. Rear beet armyworms for up to three generations on a single host and compare host-plant preferences among strains and crosses.
Aubrey Harris demonstrated how aerial images with GPS benefits bug counts.
Ralph Bagwell – Spatially Variable Insect Control in Louisiana. Said that LSU is working with five different fields at 850/A. Divide fields – red is the broadcast treatment and green areas are based on aerial images.
Eric Villavaso, MS State - Tarnished Plant Bug (TPB) were irradiated with 5 krad gamma irradiation. Hatch of eggs from matings between normal females and irradiated males was half that of matings between normal females and males. (Greater reduction with higher dosages is anticipated). Hatch of eggs from matings between irradiated females irradiated and normal males was 2% that of matings between normal females and males. Hatch from matings when both parents were irradiated was 0.2% that of matings between norml females and males. Hatch of eggs from matings between F1 male progeny of irradiated TPB males and normal females was only 15% that of eggs from matings between normal parents. Hatch from matings between F1 female progeny and normal females was 68% that of normal parents. (Greater reduction with higher dosages is anticipated). Treatment with 5 krad gamma-radiation did not affect longevity of TPB. Irradiated bugs lived just as long as normal bugs suggesting that reasonable levels of competiveness might be expected. TPB research on sterility with greater dosages of radiation is in progress. We plan to conduct more laboratory tests and possibly field cage tests later in the year.
Jeff Willers gave a presentation on remote sensing which is a new area for scientists. Discussed the current and future capabilities in satellite acquisition, commercial remote sensing satellites and the different companies and the quality of image resolution. The use of remotely sensed images maximizes the efficiency of scouting for insects in large or highly variable cotton fields. Just as the sensors used to acquire the images detect differences in crop status, many cotton insects have the sensory and behavioral capabilities to respond to differences in cotton growth. Information from both the image and the scouting data can be combined to create a pest density map that represents the spatial pattern of the pests. Spatial data from spray planes can also be utilized to build better maps. The maps are geo-referenced and converted into a prescription that is uploaded into the computerized controller of a real-time GPS equipped ground sprayer. The controller uses the prescription to electronically control valves on the spray boom to permit or restrict the application of insecticides at different locations in the cotton field. The approach was implemented on more than 1000 acres of cotton in the Mississippi Delta. Numerous benefits exist with spatially variable insecticide applications and include reduction in the amount of pesticide applied, decreased cost of insect control, reduced selection for insecticide resistance, lessening of adverse impacts upon the environment, conservation of natural enemies, and greater stability in yield potential. Comments were also offered about imagery. Affordable, high resolution imagery via satellite should be available in the near future from several companies. Air-borne image acquisition companies are available. Some difficulties remain, however, chief of which is near real time availability.
Jeremy Greene gave a report on Management Decisions for Stinkbug – Because of the success of the BWE program, they no longer have a major problem in the southeast, but need to educate consultants, scouts, etc. in the identification of immature stink bugs and be able to identify stink bug egg masses. Reported that in many areas of the cotton belt, successful eradication of the BW, expanding use of transgenic Bt cotton, and advances in lepidopteran-specific chemistry have all contributed to a changing pest complex in cotton. The bottom line concerning these changes and the increased importance of stink bugs, is the reduction of broad-spectrum insecticide use for other pests and the opportunity for stink bugs to avoid coincidental control.
In many areas of the cotton belt, successful eradication of the boll weevil, expanding use of transgenic Bt cotton, and advances in lepidopteran-specific insecticide chemistry have all contributed to a changing pest complex in cotton. The bottom line, concerning these changes and the increased importance of stink bugs, is the reduction of broad-spectrum insecticide use for other pests and the opportunity for stink bugs to avoid coincidental control.
Several important species of Pentatomidae that we observe in cotton are the green stink bug, Acrosternum hilare (Say), the southern green stink bug, Nezara viridula (L.), and the brown stink bug, Euschistus servus (Say). Organophosphorus insecticides such as dicrotophos (Bidrin) and methyl parathion provide excellent control of stink bugs in cotton. Pyrethroid insecticides will also offer control (apparently differing between species) and are useful when populations of lepidopterous pests and stink bugs are present concurrently. Several new insecticides that target worm pests (Tracer, Denim, Steward) were examined and compared with existing materials for efficacy in controlling stink bugs. In general, the selective materials provided little or no control of stink bugs.
In order to understand how we can better manage these pests, we must have an understanding of their biology and how they relate with their environment. We know that as stink bugs age, they can cause increasing damage to bolls in terms of visible symptoms of feeding and yield loss. Late instars (4th and 5th) of the southern green stink bug can cause damage comparable to that caused by adults. Also, we have found that bolls younger than 3 wk from white bloom remain susceptible to damage from stink bugs, but decrease in susceptibility with age.
Many states have adopted the same treatment recommendations for stink bugs in cotton. Insecticide application is commonly recommended at 1 bug per 6 feet (2 m) of row. Because bugs are frequently difficult to detect, some states now recommend a threshold for treatment based on a percentage (10 - 20%) of bolls internally damaged by stink bugs. For example, in Georgia, Extension recommends intervention with insecticide at the 1 bug per 6 ft threshold and/or when 20% of medium-sized (ca. 2-wk-old) bolls have at least one internal feeding symptom (wart-like growth or stained lint/seed associated with puncture) per boll.
Trapping of stink bugs in pheromone traps has potential as a monitoring tool for stink bugs in cotton. Stink bugs can be caught successfully using the combination of a commercially available lure for the brown stink bug complex (Euschistus spp.) and a trap designed to visually attract stink bugs. However, effectiveness of the trap is currently hindered by the unavailability of effective lures for other species, such as green and southern green stink bugs. Trap captures could have some predictive value in terms of population development in the crop, but additional research into this area is necessary. As a result of these studies, alternative monitoring and management recommendations are available for stink bugs in cotton.
The last presentation of the 2001 SERA-IEG 23 meeting was from Tom Sparks of Dow AgroSciences entitled "Insect Control Agents of the 21st Century – The Shape of Things to Come" which is listed as an attachment to this transmission.
Jim Plato was asked to describe the new kill strips.
The meeting was adjourned.