Bt Eggplant Project in Bangladesh: History, Present Status, and Future Direction.

The purpose of this article is to provide information on the history, accomplishments, and future direction of the Bt brinjal (eggplant) program in Bangladesh, formerly under the Agricultural Biotechnology Support Project II, now the South Asia Eggplant Improvement Partnership (SAEIP). The India-based Maharashtra Hybrid Seed Company (Mahyco) developed an eggplant expressing Cry1Ac (EE-1) for control of the eggplant fruit and shoot borer (EFSB). In a partnership among Mahyco, USAID, Sathguru Management Consultants and Cornell University EE-1 was provided to the Bangladesh Agricultural Research Institute (BARI) who bred it into local varieties. After regulatory approval, four varieties were distributed to 20 farmers who harvested Bt brinjal in 2014. Adoption in subsequent years has increased rapidly so that, in 2018, 27,012 farmers used this technology. This article provides background information on the process leading up to current adoption levels, the level of control of EFSB achieved and the economic benefits of Bt brinjal. Efforts on stewardship, farmer training and communication are discussed. In order to ensure the long-term future of the partnership, we discuss the need to enhance involvement of the private sector in the production and stewardship of Bt eggplant. Bt brinjal is the first genetically engineered crop to be commercially released in Bangladesh, and other GE crops are in the pipeline. Hence, success of the Bt brinjal partnership is likely to affect the future of other GE crops in Bangladesh, as well as other parts of the world where biotechnology is needed for food security and environmental safety.

Performance of arrhenotokous and thelytokous Thrips tabaci (Thysanoptera: Thripidae) on onion and cabbage and its implications on evolution and pest management.

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is an important pest on onion and cabbage. Two reproductive modes--arrhenotoky and thelytoky--are found in this species and co-occur in the field. We compared life table traits between arrhenotokous and thelytokous T. tabaci on cabbage and onion. Experiments were conducted in cages to determine which reproductive mode is more competitive. Additionally, host adaption of the arrhenotokous and thelytokous T. tabaci between onion and cabbage was investigated. On onion, arrhenotokous T. tabaci performed better than thelytokous T. tabaci, while on cabbage the opposite occurred. When comparing life table and demographic growth parameters (net reproductive rates R(o), mean generation time T, the intrinsic rate of natural increase r(m), finite rate of increase A, and population doubling time T(d)) on different host plants, we found that arrhenotokous T. tabaci performed better on onion than on cabbage, whereas thelytokous T. tabaci performed better on cabbage than on onion. Host-related performance differences in this species suggest that the divergence between two reproductive modes might be associated with host adaption. Pest management strategies for this global pest should recognize that the two reproductive modes can impact population dynamics on different crops.

Multi-state trials of Bt sweet corn varieties for control of the corn earworm (Lepidoptera: Noctuidae).

Field tests in 2010-2011 were performed in New York, Minnesota, Maryland, Ohio, and Georgia to compare Bt sweet corn lines expressing Cry1A.105 + Cry2Ab2 and Cry1Ab with their non-Bt isolines, with and without the use of foliar insecticides. The primary insect pest in all locations during the trial years was Heliocoverpa zea (Boddie), which is becoming the most serious insect pest of sweet corn in the United States. At harvest, the ears were measured for marketability according to fresh market and processing standards. For fresh market and processing, least squares regression showed significant effects of protein expression, state, and insecticide frequency. There was a significant effect of year for fresh market but not for processing. The model also showed significant effects of H. zea per ear by protein expression. Sweet corn containing two genes (Cry1A.105 + Cry2Ab2) and a single gene (Cry1Ab) provided high marketability, and both Bt varieties significantly outperformed the traditional non-Bt isolines in nearly all cases regardless of insecticide application frequency. For pest suppression of H. zea, plants expressing Bt proteins consistently performed better than non-Bt isoline plants, even those sprayed at conventional insecticide frequencies. Where comparisons in the same state were made between Cry1A.105 + Cry2Ab2 and Cry1Ab plants for fresh market, the product expressing Cry1A.105 + Cry2Ab2 provided better protection and resulted in less variability in control. Overall, these results indicate Cry1A.105 + Cry2Ab2 and Cry1Ab plants are suitable for fresh market and processing corn production across a diversity of growing regions and years. Our results demonstrate that Bt sweet corn has the potential to significantly reduce the use of conventional insecticides against lepidopteran pests and, in turn, reduce occupational and environmental risks that arise from intensive insecticide use.

Assessing the susceptibility of cruciferous Lepidoptera to Cry1Ba2 and Cry1Ca4 for future transgenic cruciferous vegetables.

Advances in transgenic plants expressing Bacillus thuringiensis (Bt) insecticidal gene(s) offer a promising alternative to traditional insecticides for control of lepidopteran pests on important cruciferous vegetable crops such as cabbage and cauliflower. A public-private partnership, the Collaboration on Insect Management for Brassicas in Asia and Africa (CIMBAA), was formed in 2005 with the goal of developing dual-gene Bt cauliflower and cabbage, initially for India, to replace the use of broad spectrum, traditional insecticides. As a first step in this effort, the major lepidopteran pests of cruciferous vegetable crops [Plutella xylostella (L.), Pieris rapae (L.), Pieris brassicae (L.), Crocidolomia binotalis (L.), Hellula undalis (F.), Diacrisia obliqua Walker, Spodoptera litura F., and Helicoverpa armigera (Hübner)] were collected over a large geographic area (India, Indonesia, Taiwan, China, Australia, and the United States) and tested against purified Cry1Ba2 and Cry1Ca4 toxins, the toxins proposed to be expressed in the CIMBAA plants. Our results demonstrate that Cry1Ba2 and Cry1Ca4 were effective against the primary target of the CIMBAA plants, P. xylostella, regardless of geographic location, and had LC50 values <1.3 ppm. Furthermore, one or both toxins were effective against the other major pest Lepidoptera, except for S. litura or H. armigera which were less susceptible. No cross-resistance has been found between Cry1Ba2 and Cry1Ca4, suggesting cry1Ba2+cry1Ca4 cauliflower and cabbage could be an effective and sustainable tool to control, P. xylostella, the key lepidopteran pest on cruciferous vegetable crops, as well as most other Lepidoptera. As the CIMBAA plants are being developed, further tests are needed to determine whether they will express these proteins at sufficient levels to control all the Lepidoptera. Sustainable use of the dual-gene plants also is discussed.

Impact of straw mulch on populations of onion thrips (Thysanoptera: Thripidae) in onion.

Development of insecticide resistance in onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), populations in onion (Allium spp.) fields and the incidence of the T. tabaci transmitted Iris yellow spot virus have stimulated interest in evaluating alternative management tactics. Effects of straw mulch applied in commercial onion fields in muck areas of western New York were assessed in 2006 and 2007 as a possible onion thrips management strategy. In trials in which no insecticides were applied for thrips control, straw mulch-treated plots supported significantly lower T. tabaci populations compared with control plots. In both years, the action thresholds of one or three larvae per leaf were reached in straw mulch treatments between 7 and 14 d later than in the control. Ground predatory fauna, as evaluated by pitfall trapping, was not increased by straw mulch in 2006; however, populations of the common predatory thrips Aeolothrips fasciatus (L.) (Thysanoptera: Aeolothripidae) were significantly lower in straw mulch plots in both years. Interference of straw mulch in the pupation and emergence of T. tabaci was investigated in the lab and their emergence was reduced by 54% compared with bare soil. In the field the overall yield of onions was not affected by the straw mulch treatment; however, the presence of jumbo grade onions (>77 mm) was increased in 2006, but not in 2007. These results indicate that populations of T. tabaci adults and larvae can be significantly reduced by the use of straw mulch without compromising overall onion yield. The use of this cultural practice in an onion integrated pest management program seems promising.

Advances in control of onion thrips (Thysanoptera: Thripidae) in cabbage.

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), feeding injury results in discoloration and a rough texture on cabbage, Brassica oleracea capitata (L.), leaves, and damage may occur deep inside the head. It has become a key pest of cabbage in the United States and many other countries. Previous studies have indicated poor control using insecticides. The present study identified imidacloprid drenches and sprays of acetamiprid, dimethoate, spinosad, and imidacloprid as insecticides that performed better than the industry standard, lambda-cyhalothrin. However, additional tests with foliar sprays of dimethoate and acetamiprid indicated there was not an ideal crop stage (precupping, cupping, or postcupping) at which either insecticide could be applied for reliable control of T. tabaci, possibly because of multiple flights of thrips into the crop or the asynchrony of flights and susceptible crop stages. In tests in a commercial field, a soil drench of imidacloprid 4 wk after transplanting reduced the number of damaged leaves in the head by 32%, whereas five sprays of acetamiprid reduced damage by 51%. Combining both insecticide regimes reduced damage by 85%, but resulted in a very costly management program. Cabbage varieties varied considerably in susceptibility with some having negligible thrips injury, regardless of being treated with an insecticide. Planting date affected susceptibility of cabbage to some degree, but not as much as other tactics. Overall, these studies indicate that increased emphasis should be placed on breeding cabbages to be resistant to T. tabaci as the foundation for its management.

Overwintering locations and hosts for onion thrips (Thysanoptera: Thripidae) in the onion cropping ecosystem in New York.

Identifying locations where onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), overwinter and subsequently disperse is important for designing control strategies. In upstate New York from 2003 through 2006, potential overwintering sites in the commercial onion, Allium cepa L., cropping system were investigated early in the spring before onion seedling emergence and again late in the season after onions were harvested. Onion thrips adults were sampled directly from the soil and indirectly from the soil by using emergence cages. Sampling locations included onion field interiors and edges and areas outside of these fields, including woods. Host material sampled included onion culls; volunteer onions, which sprout from cull onions left behind after harvest; and weeds. Onion thrips adults were found in all sections of onion fields and in locations outside of onion fields, with the fewest emerging from woods. Emergence began in early May and extended into June. Peak emergence occurred during the last half of May, at which time 50-75% of the population had emerged. Adults colonized volunteer onions as early as late March and as late as mid-November. No adults were found overwintering in onion cull piles. Adults also colonized several weed species, especially pigweed, Amaranthus hybridis L., and lambsquarters, Chenopodium album L., late in the fall. Our results indicate that onion thrips adults overwinter in the soil within and near onion fields and that they probably colonize volunteer onion plants before subsequent generations infest the onion crop in the spring. Volunteer onions and weeds also provide onion thrips with a host after onions are harvested. Consequently, onion thrips management strategies should include tactics that reduce volunteer onion and weed abundance.

Patterns of insecticide resistance in onion thrips (Thysanoptera: Thripidae) in onion fields in New York.

To develop an insecticide resistance management program for onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), on onions (Allium spp.), we surveyed populations in commercial onion fields in New York and evaluated their susceptibility to the two most widely used classes of insecticides plus two new insecticides during 2003-2005. All insecticide evaluations were conducted using the Thrips Insecticide Bioassay System (TIBS). As in our surveys conducted during 2002-2003, there were large temporal and spatial variations in susceptibility to the pyrethroid lambda-cyhalothrin (Warrior) across onion-growing regions in 2003. New data indicate that the field rate of methomyl (Lannate LV) still provides control but that the genes for resistance to methomyl are present in some populations. Tests with the two new insecticides, acetamiprid (Assail 70 WP) and spinosad (SpinTor 2CS), indicated they provided > 85% mortality at the field rate. To determine the spatial variation in insecticide susceptibility within a region, a series of systematic assays were conducted with lambda-cyhalothrin and methomyl. In 2004 and 2005, our data indicated that the within-region spatial variation in susceptibility to lambda-cyhalothrin was not large at the field rate or for the 100 ppm rate of methomyl. In 2005, a year in which T. tabaci densities in most fields were much higher than in 2004, growers were unable to control T. tabaci in particular fields and attributed this lack of control to resistance. Yet, we found similar levels of high susceptibility in all fields when using TIBS. This finding suggests that resistance had not developed and that variation in control may have been due to other factors, such as localized higher populations, poor spray coverage, too much time between spray applications, or different onion varieties.

Monitoring of diamondback moth (Lepidoptera: Plutellidae) resistance to spinosad, indoxacarb, and emamectin benzoate.

Six to nine populations of the diamondback moth, Plutella xylostella (L.), were collected annually from fields of crucifer vegetables in the United States and Mexico from 2001 to 2004 for baseline susceptibility tests and resistance monitoring to spinosad, indoxacarb, and emamectin benzoate. A discriminating concentration for resistance monitoring to indoxacarb and emamectin benzoate was determined based on baseline data in 2001 and was used in the diagnostic assay for each population in 2002-2004 together with a discriminating concentration for spinosad determined previously. Most populations were susceptible to all three insecticides, but a population from Hawaii in 2003 showed high levels of resistance to indoxacarb. Instances of resistance to spinosad occurred in Hawaii (2000), Georgia (2001), and California (2002) as a consequence of a few years of extensive applications in each region. The collaborative monitoring program between university and industry scientists we discuss in this article has provided useful information to both parties as well as growers who use the products. These studies provide a baseline for developing a more effective resistance management program for diamondback moth.

Concepts and applications of trap cropping in pest management.

Interest in trap cropping, a traditional tool of pest management, has increased considerably in recent years. In this review we propose a broader definition of trap cropping that encompasses the inherent characteristics of the trap crop plants themselves as well as the strategies associated with their deployment. Inherent characteristics of a trap crop may include not only natural differential attractiveness for oviposition and feeding, but also other attributes that enable the trap crop plants to serve as a sink for insects or the pathogens they vector. Successful deployment of trap crops within a landscape depends on the inherent characteristics of the trap crop and the higher value crop, the spatial and temporal characteristics of each, the behavior and movement patterns of insect pests, and the agronomic and economic requirements of the production system. Thus, trap cropping is more knowledge-intensive than many other forms of pest management. We review recent references on trap cropping, classify them according to their modalities and level of implementation, and provide a synthesis of the factors that influence the success of trap cropping. Last, we provide a list of recommendations and guidelines that should prove helpful in moving trap cropping forward to its full potential.

Novel genetic basis of field-evolved resistance to Bt toxins in Plutella xylostella.

Insecticidal toxins from Bacillus thuringiensis (Bt) are widely used to control pest insects, but evolution of resistance threatens their continued efficacy. The most common type of Bt resistance ('Mode 1') is characterized by recessive inheritance, > 500-fold resistance to at least one Cry1A toxin, negligible cross-resistance to Cry1C, and reduced binding of Bt toxins to midgut membrane target sites. Mutations affecting a Cry1A-binding midgut cadherin protein are linked to laboratory-selected Mode 1 resistance in Heliothis virescens and Pectinophora gossypiella. Here we show that field-evolved Mode 1 resistance in the diamondback moth, Plutella xylostella, has a different genetic basis, indicating that screening for resistance in the field should not be restricted to a previously proposed DNA-based search for cadherin mutations.

Laboratory evaluations of a wild crucifer Barbarea vulgaris as a management tool for the diamondback moth Plutella xylostella (Lepidoptera: Plutellidae).

The term 'dead-end trap cropping' has recently been proposed to identify a plant that is highly attractive for oviposition by an insect pest, but on which offspring of the pest cannot survive. The potential of the wild crucifer Barbarea vulgaris R. Br. to allure and serve as a dead-end trap crop for the diamondback moth Plutella xylostella (L.), an important pest of cruciferous crops worldwide, was examined in laboratory experiments. When P. xylostella adults were provided with a dual-choice of plants of B. vulgaris, and Chinese cabbage Brassica campestris (L.), in one arena, adult moths laid 2.5-6.8 times more eggs on the former than on the latter. When P. xylostella adults were provided with a dual-choice of plants of B. vulgaris and common cabbage Brassica oleracea L., adult moths laid virtually all their eggs on the former and ignored the latter. Nearly all P. xylostella eggs laid on the three species of plants hatched successfully, but nearly all individuals on plants of B. vulgaris died as neonates or early instar larvae, while 87-100% of the larvae on Chinese cabbage and common cabbage survived to pupation. Dual choice tests with a Y-tube olfactometer showed that volatiles from B. vulgaris were much more attractive to P. xylostella adults than those from common cabbage. The results demonstrate that B. vulgaris has a great potential as a dead-end trap crop for improving management of P. xylostella. Factors that may influence the feasibility of using B. vulgaris as a trap crop in the field are discussed, and ways to utilize this plant are proposed.

Regional and temporal variation in susceptibility to lambda-cyhalothrin in onion thrips, Thrips tabaci (Thysanoptera: Thripidae), in onion fields in New York.

Populations of onion thrips, Thrips tabaci Lindeman, from commercial onion fields in New York were evaluated for their susceptibility to the commonly used pyrethroid, lambda-cyhalothrin (Warrior T), using a novel system called the Thrips Insecticide Bioassay System (TIBS). To use TIBS, thrips are collected directly from the plant into an insecticide-treated 0.5-ml microcentrifuge tube that has a flexible plastic cap with a small well into which 0.08 ml of a 10% sugar-water solution with food colorant is deposited. The solution is sealed into the well with a small piece of stretched parafilm through which the thrips can feed on the solution. Thrips mortality is assessed after 24 h with the help of a dissecting stereoscope. In 2001, onion thrips populations were collected from 16 different sites and resistance ratios were >1,000 in five populations. Percent mortality at 100 ppm, a recommended field rate, varied from 9 to 100%, indicating high levels of variation in susceptibility. Particular instances of resistance appeared to be the result of practices within an individual field rather than a regional phenomenon. In 2002, we also observed large differences in onion thrips susceptibility, not only between individual fields but also between thrips collected in a single field at mid season and late season, again suggesting that insecticide-use practices within an individual field caused differences in susceptibility. Additional tests indicated no differences in susceptibility between adult and larval onion thrips populations and only relatively minor differences between populations collected from different parts of the same field. Using TIBS, several populations of onion thrips with different susceptibilities to lambda-cyhalothrin were identified and then subjected to lambda-cyhalothrin-treated onion plants. There was a highly significant positive relationship between percent mortality of thrips from TIBS and percent mortality from the treated onion plants, indicating that results from TIBS could be used to predict spray performance. These data suggest that use of TIBS for evaluating susceptibility to particular insecticides could be instrumental for developing a resistance management strategy for onion thrips.

Economic, ecological, food safety, and social consequences of the deployment of bt transgenic plants.

Transgenic plants expressing insecticidal proteins from the bacterium, Bacillus thuringiensis (Bt), are revolutionizing agriculture. Bt, which had limited use as a foliar insecticide, has become a major insecticide because genes that produce Bt toxins have been engineered into major crops grown on 11.4 million ha worldwide in 2000. Based on the data collected to date, generally these crops have shown positive economic benefits to growers and reduced the use of other insecticides. The potential ecological and human health consequences of Bt plants, including effects on nontarget organisms, food safety, and the development of resistant insect populations, are being compared for Bt plants and alternative insect management strategies. Scientists do not have full knowledge of the risks and benefits of any insect management strategies. Bt plants were deployed with the expectation that the risks would be lower than current or alternative technologies and that the benefits would be greater. Based on the data to date, these expectations seem valid.

The monarch butterfly controversy: scientific interpretations of a phenomenon.

The future development and use of agricultural biotechnology has been challenged by two preliminary studies indicating potential risk to monarch butterfly populations by pollen from corn engineered to express proteins from Bacillus thuringiensis. Likewise, these studies have also challenged the way in which science should be performed, published in scientific journals and communicated to the public at large. Herein, we provide a history of the monarch controversy to date. We believe a retrospective view may be useful for providing insights into the proper roles and responsibilities of scientists, the media and public agencies and the consequences when they go awry.

Identifying sources and mechanisms of resistance in crucifers for control of cabbage maggot (Diptera: Anthomyiidae).

The cabbage maggot, Delia radicum (L.) is an important insect pest of eruciferous crops in upstate New York. This species causes considerable damage to seedlings and young plants by feeding on roots and stems, resulting in plant stand loss and yield loss. Five crucifer accessions (Brassica oleracea variety italica L.,'Green Comet'; B. oleracea L.,'Rapid Cycling' [Crucifer Genetics Cooperative 3-1 ]; B. oleracea variety botrytis L., a standard cauliflower cultivar'Amazing'; B. carinata L.; and Sinapis alba L., 'Cornell Alt 543') were evaluated to identify sources and mechanisms of resistance for D. radicum. Of the accessions tested, S. alba Cornell Alt 543 demonstrated reduced oviposition by D. radicum, reduced weights and survivorship of larvae, pupae or adults, and reduced damage to plants. Thus, S. alba Cornell Alt 543 could be a potential source for resistance to be bred into cruciferous crops for control of D. radicum.

Variation in susceptibility of Diadegma insulare (Hymenoptera: Ichneumonidae) to permethrin.

Six field populations of the parasitoid Diadegma insulare (Cresson) were collected from Mexico and the United States and tested for their susceptibility to permethrin by using a glass-vial residue bioassay. Significant differences existed in susceptibility, with one population significantly more susceptible than the other five. Susceptibility of D. insulare increased when they were reared for several generations in the greenhouse in the absence of selection. D. insulare was less suceptible to permethrin than the adult stage of its host, Plutella xylostella (L.), from a laboratory colony, but more susceptible than those hosts collected from a commercial field. Our data suggest that a field population of D. insulare appeared to increase its tolerance to permethrin much more slowly than P. xylostella.

Comparison of Diadegma insulare (Hymenoptera: Ichneumonidae) and Microplitis plutellae (Hymenoptera: Braconidae) as biological control agents of Plutella xylostella (Lepidoptera: Plutellidae): field parasitism, insecticide susceptibility, and host-searching.

Parasitism of Plutella xylostella (L.) third and fourth instars was evaluated in a cabbage field in Geneva, NY, in 1999. Over the entire season, average parasitism was 33.6% for third instars and 53.6% for fourth instars, and the main parasitoids were Diadegma insulare (Cresson) and Microplitis plutellae Muesbeck. In the early season, total parasitism was low, and mainly caused by D. insulare. However, later in the season, parasitism reached >80% for the fouth instars and 50% for the third instars. Our survey indicated that M. plutellae heavily parasitized P. xylostella, and provided higher parasitism rates than D. insulare in the late season. Comparison of these two species in laboratory bioassays indicated there were no significant differences in susceptibility to four insecticides commonly used in crucifer fields. For both parasitoids, an experience with P. xylostella on a damaged leaf increased their host-searching efficacy. Compared with M. plutellae, D. insulare was a better host-searcher both for the naive and the experienced adults. Although both parasitoids can cause high mortality rates of P. xylostella, D. insulare may be more suitable to be released in fields to enhance natural control against P. xylostella.

Greenhouse tests on resistance management of Bt transgenic plants using refuge strategies.

Experimental evaluation of the effectiveness of resistance management tactics is vital to help provide guidelines for the deployment of transgenic insecticidal crops. Transgenic broccoli expressing a Cry1Ac gene of Bacillus thuringiensis (Bt) and the diamondback moth, Plutella xylostella (L.), were used in greenhouse tests to evaluate the influence of size and placement of nontransgenic refuge plants on changes in resistance allele frequency and pest population growth. In the first test with an initial Cry1Ac-resistance (R) allele frequency of 0.007, P. xylostella were introduced into cages with the following treatments: 0, 3.3, 10, 20, and 100% refuge plants. Results after four generations showed that resistance could be delayed by increasing the proportion of refuge plants in the cage. Population growth was also influenced by refuge size with the highest populations occurring in treatments that had either no refuge plants or all refuge plants. In the second test, we evaluated the effect of refuge placement by comparing 20% separate and 20% mixed refuges. P. xylostella with an initial frequency of resistant alleles at 0.0125 were introduced into cages and allowed to cycle; later generations were evaluated for resistance and population growth. Separating the refuge had a pronounced effect on delaying resistance and slowing establishment of resistant larvae on Bt plants. Combining information from both trials, we found a strong negative correlation between the number of larvae on Bt plants and the mortality of the population in leaf dip bioassays. Results from larval movement studies showed that separate refuges delayed resistance better than mixed refuges because they conserved relatively more susceptible alleles than R alleles and did not increase the effective dominance of resistance.

Nonwoven fiber barriers for control of cabbage maggot and onion maggot (Diptera: Anthomyiidae).

We investigated the use of nonwoven fiber barriers for control of cabbage maggot, Delia radicum (L.), and onion maggot, D. antiqua (Meigen). The barriers consist of arrangements of minute fibers loosely intertwined in "web" form. Results from a greenhouse experiment showed that manually applied graphite fibers placed at the base of broccoli plants reduced the number of D. radicum eggs by 64-98%, and that efficacy increased with greater fiber density. Using a melt extrusion process, we devised a method for on-site creation of nonwoven fibers of ethylene vinyl acetate (EVA). In field trials with broccoli and onion plants, EVA fibers significantly reduced the number of cabbage and onion maggots infesting plants. Fiber barriers provided comparable control to standard insecticide applications. The addition of blue, yellow, red, or black pigments, as well as optical brighteners that absorb UV light did not enhance fiber efficacy. Incorporation of capsaicin olfactory repellent to EVA also did not enhance fiber efficacy. Nonwoven fiber barriers may offer an alternative to insecticides for control of cabbage maggot and onion maggot and possibly other insect pests. Additional research is needed to improve the application process and to identify economically feasible and biodegradable compounds for fibers.