Boll Weevil Eradication Program Research Articles

Applying machine learning classifiers to Sentinel-2 imagery for early identification of cotton fields to advance boll weevil eradication

Early identification of cotton fields is critical for boll weevil eradication programs to establish field traps for monitoring weevil populations. However, most studies on crop type mapping have focused on late- or post-season crop classification. This study proposed and evaluated a field-level classification method that integrated field boundary data and early-season Sentinel-2 imagery to identify cotton fields 20–60 days after planting. Three cloud-free images were selected from May and June 2020, covering a 110-square-km study area in Texas. To achieve field-level classification, the boundaries of all 320 fields in the study area were used, and 62 of them were selected as training fields. Three machine learning classifiers - random forest (RF), support vector machine (SVM), and k-nearest neighbor (KNN) - were applied to the four 10-m bands for pixel-based classification and to segmented images by mean shift segmentation for object-based classification to determine the optimal classifier. To assess the impact of additional bands and vegetation indices (VIs) on classification accuracy, the six 20-m bands were combined with the 10-m bands to create 10-band images with 10-m resolution, and six vegetation indices (VIs) were derived and combined with the images. Recursive feature selection was used to identify optimal band combinations and principal component (PC) analysis was applied to reduce the dimensionality of the images. Based on accuracy measures derived from 2160 error matrices for all classification maps, RF provided the highest accuracy with faster processing times for the two May dates, while SVM and KNN exhibited slightly higher accuracy for June 10. The integration of field boundary data significantly improved classification accuracy for all classification maps. The overall accuracy (OA) of the optimal RF classification maps for the 4-band images increased from 71.4 %, 76.3 %, and 82.6 % to 85.8 %, 90.2 %, and 92.6 % (a net increase of 14.4 %, 13.9 %, and 10.0 %) for May 1, May 6, and June 10, respectively. Moreover, by including the six 20-m bands, the OA further increased by 4.8 %, 2.9 %, and 3.0 % for the respective dates. Similarly, the F-score for cotton increased from 0.801, 0.845, and 0.882 to 0.936, 0.947, and 0.976 for the three respective dates. In contrast, the inclusion of VIs had minimal effect on classification accuracy. The optimal bands and the PCs provided better classification results and were used for image classification to reduce and optimize input feature to the classifiers. These results demonstrate that combining RF with 10-band Sentinel-2 imagery and field boundary data is an effective method for early identification of cotton fields. This study provides practical techniques for boll weevil eradication program managers to identify cotton fields over large geographic areas during early growth stages.

Assessing the performance of YOLOv5 algorithm for detecting volunteer cotton plants in corn fields at three different growth stages

The feral or volunteer cotton (VC) plants when reach the pinhead squaring phase (5–6 leaf stage) can act as hosts for the boll weevil (Anthonomus grandis L.) pests. The Texas Boll Weevil Eradication Program (TBWEP) employs people to locate and eliminate VC plants growing by the side of roads or fields with rotation crops but the ones growing in the middle of fields remain undetected. In this paper, we demonstrate the application of computer vision (CV) algorithm based on You Only Look Once version 5 (YOLOv5) for detecting VC plants growing in the middle of corn fields at three different growth stages (V3, V6 and VT) using unmanned aircraft systems (UAS) remote sensing imagery. All the four variants of YOLOv5 (s, m, l, and x) were used and their performances were compared based on classification accuracy, mean average precision (mAP) and F1-score. It was found that YOLOv5s could detect VC plants with maximum classification accuracy of 98% and mAP of 96.3% at V6 stage of corn while YOLOv5s and YOLOv5m resulted in the lowest classification accuracy of 85% and YOLOv5m and YOLOv5l had the least mAP of 86.5% at VT stage on images of size 416 × 416 pixels. The developed CV algorithm has the potential to effectively detect and locate VC plants growing in the middle of corn fields as well as expedite the management aspects of TBWEP.

Boll Weevil Eradication: A Success Story of Science in the Service of Policy and Industry

Abstract The boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), is an infamous pest of commercially cultivated cotton, Gossypium hirsutum L. (Malvales: Malvaceae). Once the most important agricultural pest in the United States, the boll weevil spurred an unprecedented mobilization of federal support and cooperation among stakeholders, culminating in the eventual eradication of the species from 98% of its invasive range in the United States. The US Boll Weevil Eradication Program, a joint effort of local, state, and federal governments and agencies, university and agency researchers, and the cotton producers themselves, is a prime example of a successful implementation of a community-wide integrated pest management (IPM). The program also dramatically reduced the use of insecticides in cotton production which led to further positive economic outcomes for producers and reduced the non-target impacts from those chemicals. Though the boll weevil has been mostly eradicated in the United States, the insect remains one of the most important and impactful cotton pests in Central and South America. In this review, we will revisit the agro-economic history of the boll weevil and examine the success of the US Boll Weevil Eradication Program. In doing so, we will learn how we can apply those lessons to boll weevil management abroad and community-wide management of other agricultural or invasive pests. Finally, we will conclude with a brief summary of the ongoing science that continues in service of eradication today.

Cotton Fleahopper1 Biology and Ecology Relevant to Development of Insect Resistance Management Strategies

Since the success of the U.S. Boll Weevil Eradication Program and widespread adoption of genetically modified crops, the cotton fleahopper, Pseudatomoscelis seriatus (Reuter), has reemerged as a significant cotton pest. Current management strategies for the pest are based primarily on foliar applications of insecticides. A line of cotton that produces modified Bt Cry51Aa2 protein was developed for Lygus spp., but the protein has also shown activity against the cotton fleahopper. Consequently, before this new Bt line can be released commercially, refuge requirements and other Insect Resistance Management (IRM) strategies mandated by the Environmental Protection Agency need to be established to prevent or delay development of resistance by cotton fleahopper to the new toxin. In response, we provide and discuss relevant information on the biology and ecology of the cotton fleahopper, including life history, host preference, dispersal, and population genetic structure, that may be useful for developing IRM strategies for the pest.

Assessing the Economic Impacts of Pesticide Regulations

Economic impacts of pesticide regulations are assessed using five alternative methodologies. The regulations include crop supply-enhancing eradication programs and crop supply-decreasing pesticide bans. Alternative assessment methodologies differ regarding assumptions about market price and crop acreage adjustments. Results show that market and producer adjustments substantially impact conclusions about winners and losers from regulations, and estimated welfare effects can differ widely between the different methodologies. For small technological changes such as the hypothetical pendimethalin regulation, farm budgeting and sector modeling yield similar estimates. For more severe technological changes—like the boll weevil eradication program—simple budgeting approaches lead to a substantial bias.

Early identification of cotton fields using mosaicked aerial multispectral imagery

U.S. Department of Agriculture-Agricultural Research Service, Insect Control and CottonDisease Research Unit, 2771 F&B Road, College Station, Texas 77845, United StatesAbstract. Early identification of cotton fields is important for advancing boll weevil eradicationprogress and reducing the risk of reinfestation. Remote sensing has long been used for cropidentification, but limited work has been reported on early identification of cotton fields.Theobjectiveofthisstudyistoevaluateaerialimageryforidentifyingcottonfieldsbeforecottonplants start to bloom. A two-camera imaging system was used to acquire red-green-blue andnear-infrared images with 1-m pixel resolution along two flight lines over an 8km×12 kmcropping area. The images were mosaicked using two approaches: manual georeferencing fol-lowed by position-based mosaicking in Erdas Imagine and content-based automatic mosaickinginPix4DMapper.Themosaickedimageswerethenclassifiedintodifferentcropsandcovertypesusing supervised classification techniques. Results showed that both types of mosaics wereeffective for cotton identification and that maximum likelihood classification produced thebest overall accuracy of 90% for the position-based approach and 91% for the content-basedapproach. The methodologies presented in this study will be useful for boll weevil eradicationprogram managers to quickly and efficiently identify cotton fields at relatively early growthstages using mosaicked aerial imagery.

Airborne multispectral identification of individual cotton plants using consumer-grade cameras

Although multispectral remote sensing using consumer-grade cameras has successfully identified fields of small cotton plants, improved detection sensitivity is needed to identify individual or small clusters of cotton plants that also can provide habitat for boll weevils. The imaging sensor of consumer-grade cameras is based on a Bayer pattern, which alternates red, green, and blue filters over individual sensor pixels. However, each pixel of the imaging sensor of consumer-grade cameras represents direct measurement of only one of the three spectral bands (red, green, and blue) and interpolation of the remaining two spectral bands. We present an analytical technique in which endmember sets were derived from bimodal histograms of each spectral band for cotton, other vegetation types and soil, and linear spectral unmixing was used to identify individual cotton plants. We achieved significant misclassification rates as low as 0.125 and 0.146 in frequently tilled plots for validation tests of remote sensing identification of volunteer okraleaf cotton plants and volunteer conventional cotton plants, respectively. Results of this study indicate that consumer-grade cameras can acquire multispectral images of sufficient quality to detect individual cotton plants at an early growth stage, which will aid boll weevil eradication programs in identifying and locating volunteer plants.

Airborne multispectral detection of regrowth cotton fields

Effective methods are needed for timely areawide detection of regrowth cotton plants because boll weevils (a quarantine pest) can feed and reproduce on these plants beyond the cotton production season. Airborne multispectral images of regrowth cotton plots were acquired on several dates after three shredding (i.e., stalk destruction) dates. Linear spectral unmixing (LSU) classification was applied to high-resolution airborne multispectral images of regrowth cotton plots to estimate the minimum detectable size and subsequent growth of plants. We found that regrowth cotton fields can be identified when the mean plant width is ∼0.2 m for an image resolution of 0.1 m. LSU estimates of canopy cover of regrowth cotton plots correlated well (r2=0.81) with the ratio of mean plant width to row spacing, a surrogate measure of plant canopy cover. The height and width of regrowth plants were both well correlated (r2=0.94) with accumulated degree-days after shredding. The results will help boll weevil eradication program managers use airborne multispectral images to detect and monitor the regrowth of cotton plants after stalk destruction, and identify fields that may require further inspection and mitigation of boll weevil infestations.

Using an Electronic Nose to Rapidly Assess Grandlure Content in Boll Weevil Pheromone Lures

Samples of pheromone lures used in boll weevil, Anthonomus grandis (Boheman), eradication programs are routinely analyzed by Gas Chromatography (GC) to ensure lures are adequately dosed with grandlure, the synthetic aggregation pheromone produced by male weevils. However, preparation of GC samples is tedious, time consuming, and requires a moderate level of experience. We examined the use of a commercially-available electronic nose (e-nose) for rapidly assessing the grandlure contents of lures. The e-nose was trained to recognize headspace collections of grandlure emitted from new lures and after lures were aged under field conditions for 4 d, 7 d, 10 d, and 14 d. Based on cross-validation of the training set, the e-nose was 82% accurate in discriminating among the different age classes of lures. Upon sampling headspace collections of pheromone from a different set of field-aged lures, the e-nose was <50% accurate in discriminating 4 d, 7 d, and 10 d aged lures from the other age classes of lures. However, the e-nose identified new and 14 d aged lure samples with 100% accuracy. In light of these findings, e-nose technology shows considerable promise as an alternative approach for rapidly assessing the initial grandlure contents of lures used in boll weevil eradication programs.

A model for long-distance dispersal of boll weevils (Coleoptera: Curculionidae)

The boll weevil, Anthonomus grandis (Boheman), has been a major insect pest of cotton production in the US, accounting for yield losses and control costs on the order of several billion US dollars since the introduction of the pest in 1892. Boll weevil eradication programs have eliminated reproducing populations in nearly 94%, and progressed toward eradication within the remaining 6%, of cotton production areas. However, the ability of weevils to disperse and reinfest eradicated zones threatens to undermine the previous investment toward eradication of this pest. In this study, the HYSPLIT atmospheric dispersion model was used to simulate daily wind-aided dispersal of weevils from the Lower Rio Grande Valley (LRGV) of southern Texas and northeastern Mexico. Simulated weevil dispersal was compared with weekly capture of weevils in pheromone traps along highway trap lines between the LRGV and the South Texas/Winter Garden zone of the Texas Boll Weevil Eradication Program. A logistic regression model was fit to the probability of capturing at least one weevil in individual pheromone traps relative to specific values of simulated weevil dispersal, which resulted in 60.4% concordance, 21.3% discordance, and 18.3% ties in estimating captures and non-captures. During the first full year of active eradication with widespread insecticide applications in 2006, the dispersal model accurately estimated 71.8%, erroneously estimated 12.5%, and tied 15.7% of capture and non-capture events. Model simulations provide a temporal risk assessment over large areas of weevil reinfestation resulting from dispersal by prevailing winds. Eradication program managers can use the model risk assessment information to effectively schedule and target enhanced trapping, crop scouting, and insecticide applications.

Oviposition and Development of the Tarnished Plant Bug (Heteroptera: Miridae) on Field Maize

Reduced insecticide use in cotton, Gossypium hirsutum L., as a consequence of the Boll Weevil Eradication Program and the broad adoption of Bt cotton, have helped make the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), a consistent pest of cotton each year in the mid-south. Maize, Zea mays L., has been implicated as having a role in the season-long dynamics of tarnished plant bug infestations in cotton. To date, no published information exists describing the quality of maize as a host for tarnished plant bug. No-choice field studies indicated that adult tarnished plant bug females oviposited into maize leaves, tassels, and ears. Laboratory studies showed that first-instar tarnished plant bugs could successfully develop to the adult stage when fed maize silks at the R1 growth stage, tassels before (VT) and during (R1) pollen shed, and milk stage (R3) kernels from the tip and base of the ear. The proportion of nymphs surviving to the adult stage on these tissues was often similar to that of broccoli, Brassica oleracea L. Nymphs did not develop to adults when fed V5 or R1 maize leaves. However, survival of first instars to the adult stage was improved when nymphs fed on tassels with pollen for 6 d and then moved to silks or leaves. Another field study showed that tarnished plant bugs reproduced in maize mainly during the tassel (VE and VT) and the R1-R3 ear growth stages, and a single new generation was produced in maize during these stages. The highest population recorded during the study (24 June 2005) consisted mostly of nymphs and was estimated to be 29,600/ha (12,000/acre). These studies showed that maize is a suitable host for tarnished plant bug reproduction and development, and its production plays a significant role in the population dynamics of the tarnished plant bug in the mid-south.

Evaluation of Extended-Life Pheromone Formulations Used With and Without Dichlorvos for Boll Weevil (Coleoptera: Curculionidae) Trapping

Boll weevil traps baited with a ComboLure (25 of mg grandlure + 30 mg of eugenol + 90 of mg dichlorvos [DDVP]), an extended-release lure (25 mg of grandlure + 30 mg of eugenol + 60 of mg DDVP kill-strip), and extended-release lure with no DDVP were evaluated for boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), captures in South Texas cotton, Gossypium hirsutum L., fields during February-March 2005 and March-April 2006. The traps were serviced once a week for five consecutive weeks by using the same methodology as active boll weevil eradication programs. Mean captured boll weevils from extended-release lures with no DDVP were significantly higher in five of 10 trapping weeks compared with captures of the ComboLure and extended lure. Weekly mortality of boll weevils captured was similar for the ComboLure (72.6 +/- 4.7%) and extended lure + DDVP (73.5 +/- 4.0%), and both were significantly higher than the extended lure (32.8 +/- 5.0%) with no DDVP. The presence or absence of DDVP did not significantly affect the sex ratio of field-captured boll weevils. We found no functional reasoning for using DDVP in large scale trapping of boll weevils regardless of the formulation or presentation in the trap. We conducted two additional trapping evaluations after the 2005 and 2006 studies, but the numbers of boll weevils captured were too low for statistical comparisons, indicating that boll weevil eradication is reducing populations in the Rio Grande Valley of Texas.

Evaluation of Extended-Life Pheromone Formulations Used With and Without Dichlorvos for Boll Weevil (Coleoptera: Curculionidae) Trapping

Boll weevil traps baited with a ComboLure (25 of mg grandlure + 30 mg of eugenol + 90 of mg dichlorvos [DDVP]), an extended-release lure (25 mg of grandlure + 30 mg of eugenol + 60 of mg DDVP kill-strip), and extended-release lure with no DDVP were evaluated for boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), captures in South Texas cotton, Gossypium hirsutum L., fields during February–March 2005 and March–April 2006. The traps were serviced once a week for five consecutive weeks by using the same methodology as active boll weevil eradication programs. Mean captured boll weevils from extended-release lures with no DDVP were significantly higher in five of 10 trapping weeks compared with captures of the ComboLure and extended lure. Weekly mortality of boll weevils captured was similar for the ComboLure (72.6 ± 4.7%) and extended lure + DDVP (73.5 ± 4.0%), and both were significantly higher than the extended lure (32.8 ± 5.0%) with no DDVP. The presence or absence of DDVP did not significantly affect the sex ratio of field-captured boll weevils. We found no functional reasoning for using DDVP in large scale trapping of boll weevils regardless of the formulation or presentation in the trap. We conducted two additional trapping evaluations after the 2005 and 2006 studies, but the numbers of boll weevils captured were too low for statistical comparisons, indicating that boll weevil eradication is reducing populations in the Rio Grande Valley of Texas.

Survival of boll weevil (Coleoptera: Curculionidae) adults after feeding on pollens from various sources

AbstractThe survival of overwintering boll weevil, Anthonomus grandis grandis (Boheman), adults on non‐cotton hosts in the Lower Rio Grande Valley (LRGV) of Texas was examined from 2001 to 2006. The success of the Boll Weevil Eradication Program, which was re‐introduced into the LRGV in 2005, depends on controlling overwintering boll weevil populations. Laboratory studies were conducted using boll weevil adults that were captured in pheromone traps from September through March. The number of adults captured per trap declined significantly in the field from fall to the beginning of spring (3.5‐7.0‐fold). The proportion of trapped males and females did not differ significantly. The mean weight of boll weevil adults captured in September was 13.3 mg, while those of captured adults from November to February were significantly lower and ranged from 6.7 to 7.8 mg. Our results show that boll weevil adults can feed on different plant pollens. The highest longevity occurred when adults were fed almond pollen or mixed pollens (72.6 days and 69.2 days, respectively) and the lowest when they fed on citrus pollen or a non‐food source (9.7 days or 7.4 days, respectively). The highest adult survival occurred on almond and mixed pollens [88.0%‐97. 6% after 1st feeding period (10 days), 78.0%‐90.8% after 3rd feeding period (10 days), 55. 0%‐83.6% after 5th feeding period (10 days), and 15.2%‐32.4% after 10th feeding period (10 days)]. The lowest adult survival occurred on citrus pollen [52.0%‐56.0% after 1st feeding period (10 days), 13.3% after 3rd and 5th feeding periods (10 days), and 0 after 6th feeding period (10 days)]. Pollen feeding is not a behavior restricted to adult boll weevils of a specific sex or physiological state. Understanding how boll weevil adults survive in the absence of cotton is important to ensure ultimate success of eradicating this pest in the subtropics.

Chemical cotton stalk destruction for maintenance of host‐free periods for the control of overwintering boll weevil in tropical and subtropical climates

In the Lower Rio Grande Valley (LRGV) of Texas, cotton regrows and produces fruit from undestroyed stalks throughout the winter, and in spring weevils from such locations become a serious threat. The success of the boll weevil eradication program, which was reintroduced in the LRGV in 2005, will be dependent on thorough stalk destruction following harvest. However, adverse weather conditions and conservation tillage often impede immediate and complete stalk destruction using typical tool implements, and alternative stalk control methods are needed. This study provides an examination of the efficacy for cotton stalk destruction of different herbicides (thifensulfuron-methyl + tribenuron-methyl, dicamba-diolamine, 2,4-D-dimethylammonium, flumioxazin, 2,4-DB-dimethylammonium and carfentrazone-ethyl) and their rates, spray volumes and application timings on shredded or standing cotton stalks after stripper or picker harvest. None of the tested herbicides, except 2,4-D-dimethylammonium, stopped post-harvest cotton regrowth and fruiting. 2,4-D-dimethylammonium sprayed once (0 or 7 days) after cotton was harvested at 1 lb AE acre(-1) (1.12 kg ha(-1)), in a spray volume of 10 gal water acre(-1) (93.5 L ha(-1)) with 5 mL L(-1) surfactant, was highly effective in stalk destruction (72-90%). The best results were achieved when the herbicide was applied immediately after the cotton was shredded, followed by standing stripper-harvested and standing picker-harvested cotton. 2,4-D-dimethylammonium applied twice, 0 and 14 (or 21) days after cotton harvest, was 100% effective in killing stalks, regardless of whether they were shredded or standing, or whether harvest was by stripper or picker. These findings showed that 2,4-D-dimethylammonium cotton stalk destruction eliminated food and reproductive opportunities for managing overwintering boll weevils [Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae)].

Using Genetic Markers and Population Assignment Techniques to Infer Origin of Boll Weevils (Coleoptera: Curculionidae) Unexpectedly Captured Near an Eradication Zone in Mexico

Several boll weevils, Anthonomus grandis Boheman, were captured in pheromone traps in 2004 near Tlahualilo, Durango, Mexico, an area where none had been reported for &ap;10 yr. It is possible that they were from an endemic population normally too low in numbers to be detected but that increased in response to more favorable rainfall conditions in 2004. Alternatively, they may represent an influx of migrants or the immediate descendents of migrants. To identify the most likely origin of the boll weevils captured in this area, we characterized microsatellite variation of the Tlahualilo weevils and compared it with the variation from three other populations in northern Mexico and from one in southern Texas. Measures of gene flow and individual assignment tests suggest that the boll weevils captured near Tlahualilo were primarily from an endemic low-level population, but that this area also is receiving immigrants from a cotton growing region &ap;200 km to the north, near Rosales, Chihuahua, which is currently under a boll weevil eradication program. Similarly, Rosales is receiving immigrants from Tlahualilo. This study shows that microsatellite markers and population assignment techniques will be practical tools for determining the most likely origins of boll weevils reintroduced to eradication zones in the United States and Mexico. Population assignment strategies based on genetic markers hold promise for replacing conventional, but spatially constrained, mark-recapture studies of insect dispersal. This relatively new and powerful analytical approach is widely used in conservation genetics and fisheries studies, but has been underused by entomologists. RESUMEN Varios picudos, Anthonomus grandis Boheman, fueron capturados en trampas con feromona en el 2004, cerca de Tlahualilo, Durango, México, área donde el picudo no había sido capturado en alrededor de 10 años. Es posible que los picudos procedían de una población endémica normalmente demasiado baja en número para ser detectada, pero que se incrementó en respuesta a condiciones de lluvia más favorables en el 2004. Alternativamente, estos picudos pueden representar un influjo de inmigrantes o sus inmediatos descendientes. Para identificar el más posible origen de los ejemplares de picudo capturados en esta área, nosotros caracterizamos la variación de microsatélites en picudos muestreados en otras tres poblaciones del norte de México y una de la parte sur de Texas. Se emplearon medidas indirectas de flujo genético y pruebas de asignación individual (individual assignment tests) para evaluar el movimiento interpoblacional. Los análisis sugieren que los picudos capturados cerca de Tlahualilo fueron primariamente de una población endémica de baja densidad, pero que esta área también esta recibiendo inmigrantes de una región algodonera &ap;200 Km al norte, en el área de Rosales, Chihuahua, la cual se encuentra bajo un programa de erradicación del picudo. Igualmente, Rosales esta recibiendo inmigrantes de Tlahualilo. Este estudio demuestra que el uso de microsatélites y las técnicas de asignación poblacional serían una herramienta practica para determinar el origen más probable de picudos reintroducidos a zonas libres de picudo en E. U. y México. Las estrategias de asignación poblacional, basadas en marcadores genéticos resultan prometedoras para reemplazar a los estudios convencionales de marcado-recaptura en la dispersión de insectos, los cuales son espacialmente restringidos. Este relativamente nuevo y poderoso medio es ampliamente usado en los estudios de conservación de germoplasma y piscicultura, pero ha sido subutilizado por entomólogos.

Comparisons of Standard and Extended-Life Boll Weevil (Coleoptera: Curculionidae) Pheromone Lures

The Southeastern Boll Weevil Eradication Program has proposed reducing maintenance program costs in eradicated zones by using an extended-life "superlure" in traps to detect populations of the boll weevil, Anthonomus grandis grandis Boheman. However, superlure effectiveness has not been extensively evaluated. We compared the superlure (30 mg of eugenol plus 25 mg of grandlure) to a standard lure (10 mg of grandlure) based on captures of weevils and changes in lure pheromone content. Lure treatments (standard and superlure, replaced biweekly or not replaced) were compared in 4-mo-long trapping periods. Captures of weevils did not generally reflect differences among lure treatments indicated by assays of lure contents. During the first 2 wk of exposure, amounts of pheromone released by the superlure were generally comparable with those of the standard lure, but pheromone composition was more stable. During the second 2 wk of exposure, the superlure usually released more pheromone than similarly aged standard lures, but less than half as much as the standard lure replaced biweekly. Based on numbers of captured weevils during the last 2 wk of an extended trapping period, the superlure performed similarly to the standard lure replaced biweekly. However, corresponding pheromone releases by the superlure were less than those by the standard lure replaced biweekly. This inconsistency suggests that numbers of captured weevils alone may be inadequate for evaluation of pheromone formulations. Our results suggest that better understanding of the consequences of reduced pheromone release during an extended trapping period is needed before adoption of the superlure can be recommended.

Plant-Parasitic Nematodes Attacking Cotton in the United States: Old and Emerging Production Challenges.

Cotton is the most important fiber crop in the world, and current U.S. lint production accounts for nearly one quarter of the world supply. The unique role of cotton in world and American history is profound. Primitive cottons have been used in Africa, Asia, and the Americas for millennia. Domestic and international demand for cotton fiber contributed greatly to the westward expansion of the United States, the American Civil War, and the industrial revolution (81). The land area devoted to cotton production in the United States peaked in 1926 with approximately 18 million hectares (Fig. 1). The advent of mechanized farming equipment and the availability of effective, relatively low-cost fertilizers, pesticides, and improved cotton cultivars after World War II allowed the production of significantly greater yields per unit of land area, and hectarage declined. U.S. production of cotton lint in the past 5 years has varied from 3.0 × 10 to 4.4 × 10 kg produced on about 5 million hectares (147). Additionally, cotton seed is a valuable source of vegetable oil and protein used in animal feed, with production of 4.9 × 10 to 5.9 × 10 kg of cotton seed annually. Since World War II, cotton cultivation was increasingly dependent on inputs of chemical pesticides for weed and insect control. Historically, the cotton boll weevil, Anthonomus grandis Boheman, was the most costly pest of cotton in the United States. The combination of crop loss due to this insect directly and the expense for insecticides that was incurred by cotton growers attempting to control it amounted to several billion dollars annually until recently (130). The successful establishment of the Boll Weevil Eradication Program coordinated by the U.S. Department of Agriculture in many states in the eastern half of the country has resulted in a reduction in insecticide usage, improved profitability for growers, and has led to a resurgence of cotton production in the Southeast (37). In addition, the current widespread use of transgenic cotton cultivars with resistance to herbicides and/or insects also has greatly reduced the need for inputs of pesticides. Currently, 71% of cotton grown in the United States is herbicide resistant, resistant to lepidopteran insects, or has resistance to both (3). Reductions in pest pressure from weeds and insects as a result of the deployment of transgenic resistance and the boll weevil eradication program have

Boll Weevil Eradication: A Model for Sea Lamprey Control?

Invasions of boll weevil ( Anthonomus grandis) into the United States and sea lamprey ( Petromyzon marinus) into the Great Lakes were similar in many ways. Important species (American cotton, Gossypium hirsutum, and lake trout, Salvelinus namaycush) and the industries they supported were negatively affected. Initial control efforts were unsuccessful until pesticides and application technologies were developed. For boll weevils, controls relying on pesticides evolved into an integrated program that included recommended farming practices and poisoned baits. However, the discovery of a boll weevil sex pheromone in 1964 allowed adoption of an ongoing program of eradication. Despite opposition over concept and cost, insecticides, pheromone traps, poisoned baits, and approved farming practices were used to eradicate boll weevils from Virginia, North Carolina, South Carolina, Georgia, Florida, and Alabama by 1999. Using the working back approach along the path of the original invasion, eradication was nearly completed by 2002 in Mississippi and eradication programs were underway in Arkansas, Tennessee, Oklahoma, Louisiana, and parts of Texas. Insecticide use for cotton production decreased 50 to 90%, and cotton yields and farm income increased an average of 78 kg/ha and $190 U.S./ha in areas where boll weevils were eradicated. For sea lampreys, integrated management uses lampricides, barriers to migration, trapping, and release of sterilized males. Although sea lamprey eradication is not currently feasible, recent research on larval and sex pheromones might provide the tools to make it possible. A successful eradication program for sea lampreys starting in Lake Superior and expanding to the lower Great Lakes would ultimately provide huge ecological and economic benefits by eliminating lampricide applications, removing barriers that block teleost fishes, and facilitating the recovery of lake trout. Should the opportunity arise, the concept of sea lamprey eradication should not be rejected out of hand. The successful boll weevil eradication program shows that sea lamprey eradication might be achievable.

The Metempsychosis of King Cotton

The body of King Cotton lies amouldering in the grave, but his soul has been metempsychosized. Cotton dominated the agriculture of the South in 1929, the peak year, when 1,719,165 farmers grew 42,579,522 acres of the crop. Few grew more than 15 acres, or produced more than one-third of a bale per acre. They grew it in small patches with backbreaking hand labor, especially for the tasks of chopping and picking. In 1997 only 24,860 farmers in the South grew cotton, but they grew 11,799,225 acres. They had consolidated the erstwhile patches into large open fields. They averaged 425 acres of cotton, and produced better than a bale per acre. Agrichemicals and machines had replaced hand labor, and one-fifth of the crop was irrigated. The boll weevil eradication program, which has spread outward from northeastern North Carolina, has decimated production costs, and the price had been favorable. Inadequate gin capacity has forced farmers to shift from field wagons to modules, and a new cotton landscape has been created in the South.