Welcome, Overview and Introduction, Gus Lorenz (Chairman) welcomed participants and called the meeting to order. He acknowledged Scott Stewart and thanked him for the organization of this year’s meeting. He passed out the minutes from last year’s meeting in Little Rock, AR and asked everyone to review them for any changes that needed to be made. An agenda (above) was also distributed. Everyone was asked to sign the registration form in the back and to get a nametag. People in the room were asked to introduce themselves.

Jim Harper (Administrative Representative) gave the administrative comments. He welcomed the group from the directors. He said that the program looks real good and good work done. Thanks to sponsors. Dennis Coop—CREES—list of all projects ($68M+ in funding). Number of programs and points of interest, such as the President’s Homeland Security ($34M+) to protect agriculture and food from insects. He wished the members a successful meeting.

El-Lissy introduced Bowley (Cheminova) who gave a presentation about the risk assessment/review package for malathion. Highlight are below.

E. A. P. released its revised risk assessment in December 2000. The target date for release of the interim IRED is July 2002. Some E. P. A. conclusions on Malathion are as follows:

1. Dietary risk from food treated with Malathion low and not of concern. There is no potential impact on BWEP.
2. Acute and Chronic exposure from surface and ground drinking water sources are low and of no concern. There is no potential impact on BWEP.
3. Risks to mixers/loader/applicators are not of concern, with provision of adding PPE or engineering controls. Impact on BWEP is to have mixers/loaders should wear gloves and coveralls when mixing and loading ULV material for aerial application. Closed cockpits may be required for aerial applicators.
4. Re-entry intervals: EPA concluded some REI’s may have to e revised, however the impact will be minimal (e.g. Cotton: hand picking will require 2 day REI, all other activities require ZERO days.).
5. There is concern for acute and chronic risk to fish and aquatic invertebrates and EPA noted that possible mitigation measures include buffer zones adjacent to water and changes in application rates and frequency.
6. Current EPA classification on Carcinogenicity is "suggestive evidence for carcinogenicity, but not sufficient to assess human carcinogenic potential".
7. Assessment of non-occupational bystanders exposure. EPA conclusions are "Of-target drift from aerial ULV use results in Margin of Exposure (MOE) of 900 for toddlers and 1,800 for adults, well outside the "Threshold for Concern" of 100. Therefore, not of risk concern. Also MOE’s form incidental oral ingestion for toddler’s hand to mouth activities are > 36,000 and are therefore not of risk concern.

The following are Cheminova’s response to EPA

1. Mixer/loader assessment over-estimates exposure and a more accurate assessment leads to the conclusion that coveralls are not necessary.
2. EPA’s conclusions about risk to aquatic species are based on an overly conservative model with "worst case" assumptions as the norm. A more realistic and scientifically valid assessment shows much less risk concern for aquatic species.
3. The most appropriate carcinogenetic classification for malathion is "not likely to be carcinogenic to humans."
4. Cumulative risk assessment—The eventual outcome of EPA’s cumulative risk assessment for OP’s is uncertain and largely dependent on what degree of additional safety factors are deemed necessary. However, EPA has acknowledged that malathion is a relatively small contributor to the OP risk cup. EPA recently evaluated the relative potencies of all OP’s and determined malathion to be "the least toxicologically potent of the organophosphates".

Westbrook gave a detail summary of ARS boll weevil research being condicted, primarily in TX. Highlights of this research are presented below.

1. Integrated Farming & Natural Resources Research Unit, Weslaco, TX

Kaolin particle film for protection of cotton from boll weevils. A possible organic tactic to conventional insecticides for protection of cotton squares against boll weevils, wettable powder formulation kaolin particle film can be sprayed directly onto foliage using a tractor-mounted sprayer. Kaolin, a mineral, coats plant surfaces with a fine white mineral dust that was shown in lab and cage tests to deter boll weevil oviposition and feeding on squares, and untreated squares on plants with treated foliage. The boll weevil, however, will increasingly utilize treated squares or squares on treated plants as untreated squares or whole plants become more scarce. Two years of small plot field trials have shown that boll weevil damage to squares is lower in plots where kaolin has been applied, and that yields in the small plots, even if they were untreated controls, have significantly higher yields than large adjacent plots that were not treated with kaolin. This, and corroborating lab assays, suggest that boll weevils can choose between host plant material at both the scale of a Petri dish, and at the field scale, based to some extent on color differences imparted to the plant by kaolin. Future research will seek ways to lengthen the time which kaolin is retained on the plant surfaces so that repeated applications can be reduced, and possibly combining kaolin with repellent plant extracts. (Showler)

Effect of vegetative diversity in the cotton agroecosystem on cotton production and on non-target arthropod populations. In some agroecosystems, including sugarcane, key pest populations can be reduced as a result of weed growth and its support of higher numbers of natural enemies of those pests. A field study has shown that weed growth in Rio Grande Valley cotton does increase numbers of some predators, but none that appear to affect boll weevil populations. On the other hand, weed growth was associated with lower numbers of aphids and whiteflies which might be influenced so some extent by the higher numbers of certain predators. Examination of boll weevil infested squares indicated that most boll weevil eggs and larvae are killed by heat, not predators. In other parts of Texas, where wetter conditions favor imported fire ant colonization of cotton fields, weed growth could possibly play a bigger role in suppressing boll weevils by supporting denser colonization of imported fire ants. (Showler)

Large capacity boll weevil traps. We have developed a large capacity boll weevil trap that use a pheromone lure and a sticky surface. These traps can potentially collect an estimated 27,800 boll weevils before it reaches capacity, as compared to 500 – 1,000 in the conventional boll weevil trap. This trap has been shown to capture up to 10,000 boll weevils over a two day span. A series of field tests have shown that the large capacity trap collects boll weevils at a higher rate than the conventional trap and other, cylindrical, sticky traps. This trap has been useful in studying relative numbers of adult boll weevils when populations are very large. The ability of the large capacity trap for reducing boll weevil populations is not known, but this aspect might be examined at some later time. (Showler)

Late season field disturbances and boll weevil movement at the field scale. Using large capacity boll weevils traps, adult boll weevil populations were measured during late season field operations – defoliation, harvest, shredding, and tillage or stalk pulling. Significant increases in trap captures are found following each operation. This demonstrates that boll weevils can be captured in large numbers after their cotton habitat is disturbed in various ways. The high populations captured after tillage demonstrated that boll weevils are present in large numbers within cotton fields after harvest, and even after stalks have been shredded. It is possible that these large exposed boll weevil populations might be a vulnerable stage at which to impose control measures, particularly when much of the boll weevil’s habitat is being systematically destroyed in a series of routine late season operations. Future research using large capacity traps will also aim at determining the effect of mixing insecticides with defoliant on late season boll weevil populations. (Showler)

Plume spreaders and pheromone dose. Increasing the quantity of boll weevil aggregation pheromone resulted in significantly higher boll weevil captures on the large capacity traps than the standard quantity. Also, various contraptions were tested for their ability to spread the pheromone plume from its point of origin. Plume spreading was shown to increase the numbers of boll weevils caught in the traps. These studies are ongoing. (Showler)

Malathion+cottonseed oil. A large plot field study was conducted to assess the efficacy of reduced rates of ulv malathion mixed with cottonseed oil as compared to the standard 16 oz/acre undiluted ulv malathion. Both the 10 oz and 12 oz per acre ulv malathion mixed with cottonseed oil caused mortality of boll weevils that was not statistically different than the standard rate of malathion alone in both field and laboratory assays. No pronounced differences as regards non-target arthropods were observed. (Showler)

Overwintering biology of boll weevil. Cages placed over fallow cotton plots that were subject to conventional tillage or minimum tillage collected adult boll weevils as they emerged throughout the winter and early spring. In one year of data collection, approximately 9 times more boll weevils were collected from minimum tillage plots than the conventional mold-boarded and bedded plots. A second winter of data has just been collected for later statistical analysis. (Showler)

Stress and the accumulation of free amino acids in cotton foliage. Accumulations of selected free amino acids in variously stressed cotton plants were measured. Water deficit, shade, weed competition, and foliar coverage with kaolin particle film all resulted in significantly altered accumulations of free amino acids, and it was determined that free proline could be used as an indicator for water deficit stress, and increased free arginine – in the absence of higher levels of free proline – was indicative of light reduction stress. Using those two free amino acid indicators, it was shown that cotton in weed-infested plots were not being stressed by water deficit, but by shade from the uncontrolled weed growth. The kaolin was associated with a reduction in free arginine and no change in free proline, so the particle film appeared to be enhancing light reception, possibly because of it’s reflectivity, while it did not affect water-related stress. (Showler)

Host choice: Pigweed vs cotton. Female beet armyworms preferred to oviposit on pigweed than on cotton, and use of an olfactometer indicated that at least part of the preference is related to host plant volatiles. Although first instars did not show a preference, the more mobile third instar moved mostly to pigweed leaves over cotton. Free amino acids, readily available for protein synthesis, were more abundant and more diverse – including those amino acids essential for insect growth and development – in the pigweed leaves than the cotton leaves. In combination with other cues, including deterrent and toxic compounds in cotton leaves, nutritional value might play a role in the selection of other plant hosts over cotton. (Showler)

Kaolin particle film for protection of cotton from beet armyworm. In a series of laboratory and cage assays, kaolin particle film on cotton foliage was shown to be a deterrent to beet armyworm oviposition, it was completely lethal to first instars, significantly lethal to third instars, and significantly protected cotton foliage from feeding by third instars. The combination of these effects of kaolin on the beet armyworm make it a potentially useful tool for reducing damage caused by this pest. (Showler)

Effects of cotton plant stress. Ongoing laboratory and greenhouse assays show that beet armyworm females are attracted to water deficit stressed cotton plants, but water deficit stressed leaves are not favorable for beet armyworm larval survival and development, whether first or third instars. It appears that the benefits of higher foliar abundances of readily available amino acids caused by the water stress is offset by a presumably reduced intake of water in the leaf matter ingested. (Showler)

Effects of defoliants alone and in combination with insecticides on boll weevil. We examined selected defoliants and reduced rate insecticides alone and combined for their ability to control boll weevils and to achieve adequate and cost effective defoliation. Both laboratory and field plot experiments were conducted. The results indicated that Def, 1.0x or 0.5x (defoliant) alone exhibited only a slight toxic effect to boll weevil, while Def, 1.0x+Karate, 0.5x (insecticide); Def,1.0x+Guthion, 0.5x (Insecticide); Def, 0.5x+Dropp, 0.5x (defoliant)+Guthion, 0.5 performed as well or better than full rates of Karate or Guthion alone. Adequate defoliation can be attained when Def, 0.5x and Dropp, 0.5x are mixed. In 2002, we plan to examine the effects of defoliants in combination with lower rates of insecticides on boll weevil, whitefly, and aphid mortality in large field trials, as well as effects on lint yield and grade. (Greenberg)

Feeding and reproductive potential of boll weevils. We evaluated the feeding and reproductive potential of boll weevils as effected by the availability of cotton squares, by the different phenostages of the cotton fruits, and by insect female weight. We evaluated the numbers of egg and feeding punctures produced per boll weevil female per day, the damage inflicted by the female and the male weevil, boll weevil survival and female progeny. The results show that weevils moderate their oviposition activity based on the number of squares available for oviposition. Lifespan was not affected, therefore lifetime fecundity was negatively influenced when a weevil was provided only 1 or 5 squares per day for oviposition. Lifetime fecundity peaked at 10 and 15 squares per day, but unexpectedly decreased again when provided 20 squares daily. There was a significant positive relationship between female pupal weight and fecundity. Although small weevils produced fewer viable eggs, even the smallest females (3.2 mg) oviposited multiple viable eggs throughout their lifetime, and therefore cannot be ignored when evaluating boll weevil population dynamics. (Greenberg)

Survival and reproductive potential of overwintered boll weevils. Overwintered weevils captured in pheromone traps were characterized by very high mortality and low levels of body fat (mostly lean and extra lean). About 90% of captured females did not produce eggs. Some weevils developed oocytes with yolk but not chorionated eggs. Eggs produced per female per day, survival, and production of female progeny by overwintered weevils were significantly less than those of 1st or 2nd generations of weevils which developed in cotton fields. Our data suggest that overwintered weevils captured by pheromone traps are near death and have little remaining reproductive capacity. It is not known if this condition is typical of all overwintered weevils, or only those that respond to pheromone traps. In 2002, we will continue to evaluate survival, reproductive, and physiological potentials of overwintering boll weevils. (Greenberg)

Boll weevil population dynamics in conservation vs. conventional tillage. We compared the effects of conservation and conventional tillage systems in dry land cotton (2nd year study) and in irrigated cotton (1st year study) on population dynamics of the boll weevil. Soil temperatures, soil moisture content, plant phenology, density of boll weevils, mortality of weevils in cohorts from systematically-placed infested squares and from squares collected on the edge and in the middle of the fields (under plants and in the middle of the row between plants) were measured weekly throughout the growing season. Soil moisture in the no-tillage field was greater early in the growing season than in conventional tillage (2000), because crop residue on the soil surface in the no-tillage field shaded the soil and reduced evaporation. Unstressed no-tillage cotton quickly fruited while conventional tillage cotton grew more slowly at first, then put most of its resources into vegetative growth of stalks and leaves after a precipitation event. Plant height and leaf number increased significantly in the conventional tillage, thus providing more light interception and shading of the soil surface (about 70% area between rows) while that in no-tillage system was only 40%. The open crop canopy in the no-till field raised soil temperatures between the rows. The differences in the temperatures in open in the shade areas were about 35-40ºF between 12:00 and 4:00 PM. This resulted in higher mortality of boll weevils in fallen infested squares in the conservation tillage field, because about 60% of infested squares settled in the middle of the row. Boll weevil populations on plants were from 2.4 to 5 times greater in the conventional tillage field than in the no-tillage field. In 2001 we observed the same trends, but the data were not as pronounced as in 2000 because there was adequate soil moisture in early 2001 for the young cotton in both tillage and no-tillage fields. Irrigated no-tillage cotton was less infested with boll weevils than dry land no-tillage cotton. The reasons for this are not yet clear. In 2002 we will continue studies on the effects of conservation tillage in dry land and in irrigated cotton. (Greenberg)

Use of airborne digital imagery to survey boll weevil damage, and to assess defoliant efficacy. We monitored the growth of cotton plants with different levels of artificial square damage, and the quality of defoliation of cotton plants in preparation for harvest using remote sensing equipment. A cotton plant with heavily damaged fruit puts most of its resources into vegetative growth, thus changing the spectral response of the plants. Airborne digital imagery detected the differences in spectral response among various levels of square damage (2000). We did not observe differences in spectral response among cotton plants with different levels of artificial square damage in 2001, because a high level of natural infestation at the time of measurement, may have masked any differences between treatments. The airborne images were able to visually differentiate among several defoliation treatments as early as 3 days after the spray, though the images collected 6-7 d after the spray were most revealing of significant differences among the treatments. For quantitative analysis, the green, red, and near-infrared (NIR) bands of the airborne color-infrared (CIR) images and the normalized difference vegetation index (NDVI) derived from the NIR and red bands were used as spectral variables to compare differences among the treatments. Multiple comparisons showed that spectral variables differed significantly among some of the defoliation treatments. In 2002 we intend to explore the use of remote sensing equipment for developing models of dependence between cotton yield, cotton damage by boll weevil, and insect density. (Greenberg)

Beet armyworm oviposition preferences and development on different hosts. We determined beet armyworm consumption rates on five common host plants, effects of consumption rate on pupal weight and the pupal weight on fecundity, effects of host plant on beet armyworm life table parameters, and also beet armyworm oviposition preferences in no-choice situations and when in the presence of multiple potential hosts. Three key statistics were used to assess performance of beet armyworm on the different host plants: feeding index (pupal weight divided by total weight of leaf tissue consumed), intrinsic rate of natural increase (mean constant exponential rate of individuals per day), and growth index (percentage immature survival divided by immature development time). Using these measures, beet armyworm performance was best on pigweed, worst on cabbage, and intermediate on cotton, pepper, and sunflower. The oviposition preference of females mirrored their differential developmental performance on the five host plants. Beet armyworm females showed a significant non-preference for laying eggs on cabbage and sunflower, while pigweed and cotton elicited a positive oviposition preference. Pepper tended to be neutral or slightly unattractive. (Greenberg)

Boll Weevil Transport to Cotton Gins on Cotton Modules. There is a growing concern that cotton gins located in active eradication zones which receive modules from adjacent infested areas may be releasing weevils that disperse en route or in the gin yard. I and cooperators from Weslaco, Lubbock, and Dallas (ARS, Tx. A&M Exp. Stn, and Extn. Serv.) conducted a series of experiments in three regions of Texas designed to determine the potential for boll weevil transport on or in cotton modules to the gin yard. Surveys indicated that there were surprising numbers of adult weevils present in defoliated cotton just prior to harvest, especially if green bolls were still present on the plants. Live weevils were recovered in samples of harvested cotton taken from module builders, and the number of weevils that could disperse from the module during or after transport were calculated. Mark-release experiments indicated that most weevils rapidly disperse from the module surface if temperatures are warm enough; weevils under a tarp suffer high mortality on sunny warm days. Overall, our results indicate that one can expect at least a small number of weevils to make it to the gin alive inside a module depending on the starting population of weevils in the defoliated cotton. It is unlikely that live weevils will be transported on the surface of the module unless temperatures are too cool for flight. In 2002, these experiments will be repeated to collect data from as wide range of environmental conditions as possible. In addition, mortality of weevils under and not under a module tarp will be assessed repeatedly over much of the year and correlated with module surface temperature, air temperature, and humidity. (Sappington)

Boll Weevil Survival in Cotton Gins. Given that boll weevils are likely to arrive at the gin inside cotton modules, it is imperative to know whether they can survive the ginning process. With cooperators in Lubbock (ARS, Tx. A&M Exp. Stn), we conducted a number of experiments and groups of experiments to determine mortality rates of weevils as they pass through various subprocesses in the gin. Per cent survival of adult boll weevils was determined as a function of seed cotton cleaning level. Ten lots of 1000 weevils each were marked with fluorescent powder and 5 lots each fed into normal or enhanced seed cotton cleaning systems. No live weevils were detected in any of the 10 test lots of cleaned seed cotton. However, six live weevils, out of 9,950 fed into the gin, were found in the rock trap waste. These results suggest that modern seed cotton cleaning and extracting systems employed at U.S. cotton gins are quite effective in eliminating live adult boll weevils from seed cotton prior to the gin stand. Although a substantial number of the weevils were killed by the cleaning machinery, some survived and remained alive in the extracted trash. The next series of experiments were designed to determine minimum fan speeds necessary to ensure complete mortality of free adult boll weevils and of weevils in infested bolls that pass through trash fans. In preliminary trials, no free adults survived passage through a variable speed fan at any speed tested, but more replications are necessary. However, some larvae and teneral adults in green bolls survived even the highest safe fan speed. Other results indicated that locks of bolls occasionally passed through the fan intact, and could thus protect any weevils inside. The ability of weevils to survive in a Universal Density (UD) bale press was determined. All weevils were killed at tie-out densities of 32.5 lb/cu. ft. and higher. For typical UD press box dimensions and a platen separation of 19 inches, a 390-lb bale would be sufficient to produce this critical tie-out density. For lighter-weight bales, a smaller platen separation would have to be used to reach critical density. In 2002, we will examine survival of free adults and pupae in artificial pupal cells after passing through a field cleaner, dryers, the gin stand, and the lint cleaner. We will determine if weevils in bolls can be killed by passage through two fans in tandem or if a mechanical boll crusher placed before a fan can increase mortality of weevils in green bolls that are removed in the gin trash. Weevil survival in artificial pupal cells passing through the seed conveyance system and in a mote press will be determined. (Sappington)

Effects of microclimate and pheromone trap position on boll weevil captures. Improved understanding of interactions between wind speed, wind direction, and pheromone trap position within trap lines will lead to increased effectiveness, economy, and quality of information from trapping programs. A three-year study (completed in 2001) was conducted to determine if five traps placed in a line at two commonly used spacings (15 m and 20 m) interfere with one another. There was no evidence for interference on days when winds struck the trap line at a nearly perpendicular angle. However, for both spacings, there were significant and substantial effects of relative trap placement within a line on days when winds struck it at an angle away from the perpendicular. The largest and most consistent effect was that the trap furthest upwind in the line captured the most weevils. The upwind trap captured 1.5-2.0 times as many weevils as the next trap in the line, which usually had the lowest percentage capture of any of the traps. Placement of the trap line on the leeward or windward side of a brush line did not affect this pattern. These results have implications for trap-design (or lure) comparison studies, and for studies where trap captures are used to infer fine-scale spatial distribution of weevils. In 2002, studies will be conducted using instrumented traps developed by K. Beerwinkle (retired, APMRU) to more precisely define periods of weevil flight activity and microclimatic factors that interfere with trap efficiency. (Sappington)

Develop biochemical markers to distinguish diapausing vs. reproductive boll weevils. With cooperators in College Station (ARS, Tx. A&M) we have conducted research to characterize a storage protein (SP) discovered by our team which is present in high amounts in diapause boll weevils and is present only at background levels in reproductive weevils. The time course of SP expression was determined in response to a diapause-inducing feeding regime. Presence of the diagnostic SP was correlated with the presence of diagnostic fat body characters. It was detected as early as 6 days post eclosion from the pupa, but was commonly found at 9 days. Initial studies with methoprene, a Juvenile Hormone analog that triggers egg development and shuts down diapause in many other insects, surprisingly failed to demonstrate a stimulatory action on yolk protein (vitellogenin) synthesis in female boll weevils. A follow-up study was performed during this fiscal year using female weevils held under diapause conditions for 1 month to ensure a high percentage of diapause induction, which were treated three times with methoprene. Again, methoprene failed to stimulate yolk protein synthesis, and levels of the storage protein remained high. A genomic library was screened and the sequence of the SP cDNA determined. Multiple alignments and phylogenetic analyses revealed its evolutionary relationship to other insect storage proteins. Immunochemical experiments revealed that polyclonal antibodies recognized the N-terminus of the protein. Based on this information, a peptide antigen was designed and synthesized for the production of highly specific monoclonal antibodies, currently being tested. In 2002, the monoclonal antibodies will be characterized and used to design a "squash" kit for determining the diapause/reproductive status of individual weevils. (Sappington)

DNA fingerprinting of boll weevil populations from infested areas of the Cotton Belt. Coordinated collection of boll weevils from active eradication zones in 8 states. Weevils were deep frozen until genomic DNA can be extracted, an ongoing process in my laboratory. Conducted experiments demonstrating that DNA can be extracted intact from weevils that are left dead in traps in the sun for 1 week (a common condition in Eradication program traps). Also conducted experiments demonstrating that DNA can be extracted intact from weevils that have been immersed in hexane for 1 min to extract cuticular hydrocarbons for estimating weevil age. I have recruited a Post-doctoral Associate from South Korea (who is still awaiting [since July] the granting of a Visa), who is an expert in DNA fingerprinting and molecular ecology of animals to perform AFLP, RAPD, and microsatellite analyses on the DNA we have collected. (Sappington)

Effects of mixing reduced-rate insecticides with cotton defoliants on boll weevil mortality and behavior. Conducted mark-recapture studies in two fields to monitor interplot movement of boll weevils as well as dispersal from the field. Movement between the 6-row plots was considerable before application of insecticides, defoliants, and their combinations. However, interplot movement after treatment was not detectable, and we concluded that such movement was not an important factor impinging on the chemical efficacy results. The efficacy experiments revealed that a tank mix of half-rate Guthion with defoliants is as effective against boll weevils as full-rate Guthion alone. Dispersal out of the field was high, both before and after chemical application. A considerable portion of those weevils dispersing were recovered in flanking trap rows of late-planted okra-leaf cotton. However, only an extremely small proportion of dispersing weevils were captured in surrounding pheromone traps. (Sappington)

New Studies for 2002

Effects of square size on boll weevil oviposition preference, interval until abscission and

adult emergence, survivorship, and size of emerging adult. (Showler)

Effects of different planting dates on boll weevil infestations and yields. (Showler)

Extracts from the neem tree, a plant native to the Old World, will be assessed for

deterrence to boll weevils. (Showler with Greenberg).

Dispersal study with neutron activation analysis. (Showler with Sappington).

Boll weevil colonization patterns in cotton fields. (Showler with Greenberg).

Effects of various abiotic and possibly biotic stresses on cotton plants will be examined

for changes in foliar free amino acid accumulations and associations with cotton aphid

biology and populations. (Showler)

Effects of neem on the beet armyworm. (Showler with Greenberg)

Evaluate the effects of different temperatures on boll weevil development and survival. (Greenberg)

Suppression of boll weevil overwintering populations by late-season trap cropping. (Sappington)

Determining boll weevil age with cuticular hydrocarbons, and determining sources of age-independent variation. (Sappington)

Examining the usefulness of rare earth elements for marking field populations of boll weevils with detection via neutron activation analysis. (Sappington with Showler)

2. Areawide Pest Management Research Unit, College Station, TX

Field studies were initiated in 2000 and continued through 2001 to characterize the season-dependent morphological/physiological status of trap-captured boll weevils in comparison to that of weevils infesting the standing cotton crop. Dissections of weevils revealed distinct seasonal physiological differences between the two sources of weevils, suggesting that weevils captured in traps did not necessarily originate from adjacent cotton fields. Presence of oocyte and egg remnants in overwintered weevils captured in traps prior to planting of cotton suggested that some weevils had overwintered with eggs. Dissections also suggested that weevils were capable of producing mature eggs on pre-fruiting cotton. Both of these observations are contrary to previous reports. Studies also revealed that weevils were capable of resorbing oocytes and eggs, a phenomenon previously undocumented in the boll weevil literature. Seasonal trends in sex ratios and reproductive/diapause status of trap- and field-collected weevils were observed and are being analyzed. (Suh)

A series of laboratory studies examined the effects of diet switching on termination of reproduction (switching from squares to bolls) and subsequent host-free longevity, and the termination of dormancy (switching from bolls to squares). Switching females from squares to bolls resulted in a reduced egg complement (oocytes and mature eggs), increased the incidence of oosorption, and increased the proportion of weevils with hypertrophied fat bodies compared with females maintained on squares. Thus, switching from squares to bolls increased the incidence of morphological characters normally associated with diapause. Host-free survival of these weevils is currently being monitored. Switching females to squares after feeding on bolls for 14 d decreased the proportion of dormant females, but diet switching did not terminate the dormancy of males. When access to squares was delayed for 1 to 5 wk after the boll feeding period, the dormancy termination response of males increased with increasing age while the termination response by females was similar at all weevil ages. However, when weevils were allowed to fly on tethers after the boll feeding period and were switched to squares, a significant termination response was exhibited by both sexes. (Spurgeon)

Laboratory studies examining relationships between dormancy characters, temperature, and host-free longevity of boll weevils were completed. Longevity increased with an increase in the proportion of dormant weevils primarily because of higher early mortality in groups with low proportions of dormancy. This effect was more pronounced for females than for males. Longevity also increased as temperature was decreased from 85° to 65°F, then decreased as temperature was reduced to 55°F. Longevity at 55°F was similar to that at 75°F, and probably indicates that some chronic low-temperature injury occurs to overwintering weevils at temperatures <65°F. (Spurgeon)

A field study was conducted to determine the effects of meteorological factors on the pattern of boll weevil emergence from winter habitat (leaf litter), and to compare the physiological condition of boll weevils that emerged from leaf litter and those captured in traps. Temperature, relative humidity, solar radiation, and precipitation were significantly greater, and barometric pressure was significantly less, on emergence dates than on dates with no emergence. Trapped boll weevils had significantly greater reproductive development than emerged boll weevils. This information on the patterns and mechanisms of emergence from overwintering will help to improve predictive models, risk assessments, and pest management strategies for boll weevils. (Westbrook)

Sampling efficiency of the Keep-It-Simple Sampler was evaluated in field studies using mark-release-recovery techniques. Efficiencies were examined in cotton at pre-fruiting, pinhead/matchhead square, and third-grown square stages. About 21% of released weevils were recovered during the pinhead/matchhead square stage. Recovery from pre-fruiting and third-grown square stage plants was about 19% and 12%, respectively. (Esquivel)

A study was conducted to estimate the extent and time-course of both mortality and escape by trap-captured weevils in traps containing "kill strips" from one of two sources (Plato Industries and Hercon Environmental). Both types of "kill-strip" provided similar levels of mortality at all durations of exposure (1 to 46 hours). By 46 hours, mortality levels in traps with "kill-strips" were > 90%, whereas traps without "kill-strips" had < 5% weevil mortality. Neither type of "kill-strip" significantly reduced the incidence of weevil escape. The mean percentage of weevils escaped from traps with or without "kill-strips" ranged from 5 to 8%. (Suh)

Field evaluations were conducted during early-season in 2001 between suitable overwintering habitat and a pre-squaring cotton field to determine if relatively low concentrations of spinosad mixed with a feeding stimulant could be used to kill adult boll weevils. Yaupon shrubs in 15-gallon containers were placed in a line adjacent to the overwintering habitat in an equally spaced alternating pattern with Boll Weevil Eradication Foundation traps. Each shrub and trap was re-baited every two weeks with a single 10-mg laminated plastic Grandlure dispenser. Shrubs were sprayed with a mixture of sucrose and spinosad at a concentration of 300 ppm (weight active ingredient per volume). The results indicated that it was possible to kill adult weevils which responded to the Grandlure on the shrubs in numbers similar to those captured in the traps. These results suggest that it may be possible to kill adult boll weevils during early- and late-season when boll weevils are highly responsive to Grandlure by applying a mixture of a feeding stimulant and an insecticide in strips on vegetation in combination with Grandlure in dispensers or in a sprayable slow-release formulation. (Lopez)

Previous observations indicated that boll weevil oviposition is not always associated with sealed punctures, so a laboratory study was conducted to characterize types of punctures and evaluate their association with oviposition. Punctures were characterized as unsealed, wax sealed, frass sealed, or frass/wax sealed. About 2% of unsealed punctures contained eggs. The percentages of wax sealed, frass sealed, and frass/wax sealed punctures associated with eggs were 66, 59, and 70%, respectively. Also, we observed that the waxy nipple usually associated with an oviposition puncture did not appear until several hours after oviposition, and is likely a plant response. (Esquivel)

A laboratory study was conducted to examine egg production by overwintered weevils fed vegetative stage cotton. Compared with baseline data, feeding on cotyledon and four-leaf stage cotton significantly increased the total egg complement (oocytes and mature eggs) and the proportion of females containing oocytes with yolk; however, there was no significant increase in numbers of mature eggs. Differences among the treatments in numbers of mature eggs may have been obscured by oviposition before dissection. (Suh).

Such oviposition was documented in a companion study examining longevity of overwintered weevils on pre-fruiting cotton. In this study, weevils were held under controlled conditions and supplied either water alone, cotyledon stage, or four-leaf stage cotton seedlings. Weevils survived an average of 6.7 days on water alone, 81.1 days on cotyledons, and 61.9 days on four-leaf stage plants. Longevities observed on pre-fruiting plants exceeded those previously reported. (Esquivel)

Recent efforts to determine the influences of food types and sizes on the boll weevil dormancy response have concentrated on square versus boll diets, and on diets of squares of different sizes. We examined the influence of boll size on the dormancy response using procedures previously developed at this laboratory. The highest levels of dormancy were induced by bolls of 20-25 mm diameter, followed by bolls of 15-20 mm diameter. Differences among boll size classes in the proportions of weevils that became dormant were slightly greater for females than for males, but few weevils of either sex became dormant when fed the smallest boll size (10-15 mm diameter). (Spurgeon)

Field studies were conducted to investigate the effectiveness of electrostatic aerial application of bifenthrin in controlling thrips. Electrostatic application increased material deposits by 23.8-206.1% over conventional application of bifenthrin. Although the electrostatic application significantly increased deposition, there was no significant increase in control of thrips on seedling cotton in the three studies conducted. The studies showed that thrips could be significantly controlled with bifenthrin. (Hoffmann)

Studies were conducted to investigate the influence of crop canopies, such as corn, cotton, and soybeans, on spray deposition and movement from an aerial application. Using a fluorescent dye as a tracer, spray deposits were measured at the top of the canopy, at the ground within the crop canopy, and in a grazed pasture. Significantly higher deposits were measured in the top of the canopy in corn, cotton, and soybeans than in the ground or pasture samples. There were no differences in ground and pasture samples beyond 25 m (82 ft) from the aircraft flight line. Higher deposits were measured at the top of the crop canopy than in the pasture samples out to 120 m (394 ft). Leaf area index (a measure of canopy density) and wind speed were not found to consistently influence spray deposition and movement. (Hoffmann)

An aerial spray deposition study with ULV malathion was conducted to determine if spray swath widths specified in boll weevil eradication program contracts are appropriate for achieving uniform spray deposits across treated fields. The results of the study show that swath widths are too wide for uniform spray deposits using the two aircraft included in the study. Reduction of swath widths would improve uniformity of spray deposition, but this study was not designed to determine whether uniform spray deposits would increase boll weevil mortality in fields sprayed under boll weevil eradication program specifications. (Kirk)

El-Lissy commented on eradication in TX. Stalk destruction helps after harvest - program spent ½ M. After stalks destroyed need application of 2-4-D.

For Boll Weevil Eradication Across Country: Need to develop a system to protect investment of Boll Weevil Eradication; Originally targeting Eradication in US by 2005-2007.

TX: Boll Weevil Action Committee try to put together a plan for Post Erad Protection Program; Trapping at different levels depending upon stage in program (trap per 5, 10, 40, 180 acres); Each organization makes their own decision on when to move to the different levels of trapping with the exception of cotton growing areas close to Mexico.

El-Lissy reported on eradication statistics including start dates, eradication dates, acres involved in the program, etc. (see enclosed handouts). Eradicated areas included FL 1993, AL and TN Valley 2000, GA 1992, SC 1990, NC 1987, Parts of TX 2000, AZ 1991, Mexico 1993, and Southern CA 1990 (totaling 5,192,000, 32% of cotton acres. About 62% (10,000,000) acres of cotton are in active eradication programs. The following list shows the year in which the eradication efforts were initiated in each state and the approximate number of acres involved: MS (1997-1,600,000 acres), western TN (1998-615,000 acres), MO (2001-405,000 acres), AR (1997-750,000 acres), LA (1997-882,000 acres), KS (2001-53,000 acres; No weevils found), OK (1998-250,000 acres), TX (1994-5,000,000 acres).

Not currently in eradication are the Upper Coastal Bend (370,000acres, 2%) and Northern Blacklands (120,000 acres) of TX; both are proposed to expand in 2002 or 2003. All regions in TX except St. Lawrence (100,000 acres) and the Lower Rio Grande Valley (200,000 acres) have approved or are in eradication. NE Delta of AR (350,000acres), including Mississippi Co., just voted down another eradication program. The status of eradication in these areas has yet to be determined.

Southwest Zone Diapause Program

1998-3.96 weevils/trap

2001-0.065 weevils/trap (changed protocol)

Southeast Zone

2000-5.54 weevils/trap, 4.5 applications during diapause

2001-0.320 weevils/trap

No till cotton – regrowth problem, spray 2-4 D when shredding stalks

Central Zone - must be aggressive

2000-15.66 weevils/trap

2001-0.399 weevils/trap

Ridge Zone

2001-5.42 weevils/trap

NE Delta - 350,000 acres; 2001-11.56 weevils/trap

Trap line data were shown.

Damage survey - 10 fields/county; 1^st September some fields had economic damage

Boll Weevil Damage Survey—reduction in damage

Had good winter

Max. Acres 5,821,462

Southern Rolling Plains—2001— 0 w/trap

Central Rolling Plains—2001—0.0005 w/trap

South Texas/Winter Garden—2001—0.156 w/trap

El Paso/Trans Pecos—2001—0.0003 w/trap

Northern Rolling Plains—2001—0.056 w/trap

Northwest Plains—2001—0.015 w/trap

Western High Plains—2001—0.021 w/trap

Permian Basin—2001—0.01 w/trap

Southern Blacklands—2001—13.686 w/trap

So. High Plains/Caprock—2001—1.159 w/trap

Northern High Plains—2001—0.889 w/trap

Upper Coastal Bend, Northern Blacklands, Lower Rio Grande Valley and St. Lawrence - No eradication program

See attached chart and map.

Picked up 22 weevils late in season—southeast corner of OK. Late weevils caused increase in cost.

August started program, until 9/11 Low cost $10.00 / ac— this year $12.00/ac

Boll Weevil trapping program, 1 trap/4 ac, weevils down 95%

Big-time beekeeper complained of lost hives due to spray

Don’t stop spraying before 15^th October

Red River Area---N of Shreveport—NW Baton Rouge

6^th year of program voted on maintenance this year

Northeast Zone—4^th year is 2002

0.7 weevils/ac/wk

applied 3 applications

trapping starts March 25

expect cotton acres down 20-50%

Tennessee had approximately 589,500 acres in "active" eradication within 3 regions in the western part of the state and 26,000 acres "post eradication" in 6 counties in "middle" Tennessee. Region I encompass 6 counties along the Mississippi and Arkansas borders with portions of two additional counties to the north. This region started a diapause program in August of 1998 and currently has 193,000 acres. All applications have consisted of 10 ounces of ULV (97%) malathion. The average number of applications used per acre for region one from 1998-2001 was 10.5, 9.1, 11.4 and 2.3 respectively. The average number of boll weevils per trap has been reduced by 94%, from 1.38 in 1999 to 0.09 in 2001.

Organized Regional Research Efforts & Regional Publications on Cotton Insects

Luttrell - Interest in cooperative research, more applied research is needed. There is a need for national leadership and a national voice to help get funding.

Luttrell suggested group may consider using this meeting as platform for organizing Multi-State Regional Projects. Luttrell et al. had submitted a multi-state competitive grant monies in applied area’s of cotton IPM. There were good reviews but not funded.

Southern Directors stand point (Harper)—They would be receptive to new approaches (but funding issues need addressed). Directors are willing to consider approaches that group felt would improve value of this meeting.

Aubrey Harris questioned whether this would be a formal or informal project, and how you set up regional projects? A general discussion followed. It was suggested that this meeting could be extended to 2 days, including information exchange and information on funding and publications

The group concluded that four insect groups are of primary importance (stink bugs, lygus, heliothines, aphids). Any regional efforts should include ARS, and state extension and research scientists.

The meeting was adjourned for the day with the comment (by Stewart) that we will re-visit this topic the following day.

Gus Lorenz (seconded by Stewart) nominated Michael Boyd as secretary of the 2003 meeting. After a small amount of discussion, Boyd was approved by unanimous vote, and it was decided that Memphis would be a good meeting site. Boyd will be in charge of local arrangements in 2003 (and chair the following year). Next year’s chair (Stewart) will organize the program. Feb. 18-20 (or the first week of March) was suggested as the likely meeting dates for next year.

A discussion about the future role of the SERA-IEG "Boll Weevil" meeting was begun (led by Lorenz and Stewart). Current meeting format is becoming obsolete for many states because of boll weevil eradication. Is there a need to re-organize meeting structure and function? Stewart commented he felt this was true, and that this related to previous day’s discussion (led by Luttrell) concerning organizing cooperative research efforts and a "national voice" for key cotton pests/IPM projects.

Harper said we could consider ‘re-writing’ charter to broaden the meeting’s perspective and de-emphasize the weevil (it is possible to organize a formal project). There was some discussion whether a "formal" project was needed, or whether current meeting could be used as informal format for organizing research/extension projects on key pests. Hardee mentioned ARS annual plant bug meeting, and that this could be combined with this meeting. The group collectively decided that lengthening the meeting by at least ½ day (half day [information exchange] + full day [potential multi-state research projects]) would be appropriate. A program committee was tentatively organized for next year to address the value of using meeting as platform for organizing a regional, multi-state projects (do we want a regional project?). Likely members would be Luttrell, Hardee, Stewart, Leser, Ruberson, and possibly R. Leonard and J.R. Bradley (who were not in attendance). Luttrell agreed to chair this committee; Stewart will chair overall program.

R. Parker started with a review of new heliothine insecticides. Noted that pyrethroids do not work (including Leverage) unless dealing with bollworms only. Ranked Tracer, Denim, and Steward (in that order, on budworm). He also showed data indicating good activity of Denim on spider mites. Others remarked on the same observation.

A discussion, including data presentations about Centric and Assail (=Intruder) on cotton aphids ensued. Both appear better than Provado on aphids, but R. Parker was "reserving judgement". Cruiser, Gaucho, and Temik appear to have similar efficacy on thrips, but Temik is superior when nematodes are present. J. Leser commented that Gaucho does not perform well on western flower thrips. R. Parker said Gaucho appears to be improved, however.

Numerous results of efficacy trials were shown for multiple pests by R. Parker, Stewart, Reed, Lorenz, Hopkins, and others. Comments were made concerning the relative efficacy of compounds for control of plant bugs, heliothines, etc. A comment about Novaluron, a growth regulator being tested for plant bugs, was made. A test of J. Reed’s was very encouraging (these data were shown).

Stewart started session by indicating that plant bugs will be a focus insect in post-eradication, Bt cotton era. Stewart reiterated that next year’s program committee will include plant bugs as a topic of a possible regional research project. Layton indicated that he felt greatest research needs were in areas of sampling and thresholds.

Transgenics in Cotton Insect Control (John Adamczyk, Moderator) - Refugia, Resistance Monitoring, Bollgard II, New B.t.’s

Adjourn – The meeting was adjourned by Gus Lorenz at 12 noon after thanking everyone for their attendance.