Key Lepidopteran Pests Research Articles

Efficacy of Soybean's Event DAS-81419-2 Expressing Cry1F and Cry1Ac to Manage Key Tropical Lepidopteran Pests Under Field Conditions in Brazil.

Bacillus thuringiensis (Bt) event DAS-81419-2 (Conkesta technology) in soybean, Glycine max (L.) Merrill, expresses Cry1F and Cry1Ac proteins to provide protection from feeding by several lepidopteran pests. A total of 27 field experiments across nine locations were conducted from 2011 to 2015 in southern and central Brazil to characterize the efficacy of DAS-81419-2 soybean infested with Anticarsia gemmatalis Hübner (Lepidoptera: Erebidae), Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae), Heliothis virescens (F.) (Lepidoptera: Noctuidae), and Spodoptera cosmioides (Walker) (Lepidoptera: Noctuidae) during vegetative (V4) and reproductive (R2 and R4) crop developmental stages. The efficacy of DAS-81419-2 was compared to that of a non-Bt isogenic variety managed with or without applications of commercial foliar insecticides for lepidopteran control. DAS-81419-2 soybean consistently experienced defoliation levels of 0.5% or less (compared with 20.05–56.74% in the non-Bt, nonsprayed treatment) and larval survival of < 0.1% in all four species across the vegetative and reproductive plant stages evaluated. The efficacy of DAS-81419-2 was significantly higher than commercial foliar insecticides applied to the non-Bt variety. DAS-81419-2 soybeans containing two highly effective Bt proteins are expected to be a more robust IRM tool compared to single-trait Bt technologies. The consistent efficacy of DAS-81419-2 soybeans across years, locations, and crop stages suggests that it will be a valuable product for management of hard-to-control key lepidopteran pests in South American soybean production.

Enhancing Integrated Pest Management in GM Cotton Systems Using Host Plant Resistance.

Cotton has lost many ancestral defensive traits against key invertebrate pests. This is suggested by the levels of resistance to some pests found in wild cotton genotypes as well as in cultivated landraces and is a result of domestication and a long history of targeted breeding for yield and fiber quality, along with the capacity to control pests with pesticides. Genetic modification (GM) allowed integration of toxins from a bacteria into cotton to control key Lepidopteran pests. Since the mid-1990s, use of GM cotton cultivars has greatly reduced the amount of pesticides used in many cotton systems. However, pests not controlled by the GM traits have usually emerged as problems, especially the sucking bug complex. Control of this complex with pesticides often causes a reduction in beneficial invertebrate populations, allowing other secondary pests to increase rapidly and require control. Control of both sucking bug complex and secondary pests is problematic due to the cost of pesticides and/or high risk of selecting for pesticide resistance. Deployment of host plant resistance (HPR) provides an opportunity to manage these issues in GM cotton systems. Cotton cultivars resistant to the sucking bug complex and/or secondary pests would require fewer pesticide applications, reducing costs and risks to beneficial invertebrate populations and pesticide resistance. Incorporation of HPR traits into elite cotton cultivars with high yield and fiber quality offers the potential to further reduce pesticide use and increase the durability of pest management in GM cotton systems. We review the challenges that the identification and use of HPR against invertebrate pests brings to cotton breeding. We explore sources of resistance to the sucking bug complex and secondary pests, the mechanisms that control them and the approaches to incorporate these defense traits to commercial cultivars.

Eco-friendly nets to improve vegetable production and quality in sub-Saharan Africa

Continuous coverage of vegetables with nets under different climate conditions in Benin and Kenya proved effective in prot ecting vegetable nurseries and main fields against key lepidopteran and dipteran pests. However, netting did not effectively protect the vegetables against small insects such as aphids and whiteflies, although a visual barrier could delay outbreaks. Hence, opening the nets during the day could be an alternative option to conserve the natu ral enemies for small insects. Moreover, the efficacy of the visual barrier may be complemented by a repellent compound impregnated in the net. The small-holder growers adopting the nets in Benin and Kenya have reduced the number of pesticid e applications required by 70-100%. They have also increased the yield in quality and quantity of production due to microclimate modification. Cost-benefit anal yses of the technology showed that with insect proof nets profitability rates of up to three times could be achieved when compared to the farmers' practices observed in the real environment. Hence, this technology could be a promising way to develop an agro-ecological approach for sustainable management of key horticultural crop pests. (Resume d'auteur)

Identification, inheritance, and fitness costs of Cry2Ab2 resistance in a field-derived population of sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae)

The sugarcane borer, Diatraea saccharalis (F.), is one of the major target pests of transgenic maize, Zea mays, expressing Bacillus thuringiensis (Bt) proteins in South America and mid-southern region of the U.S. The MON89034 maize expresses Cry2Ab2 and Cry1A.105 Bt proteins and it was developed to provide better control of key lepidopteran pests of maize including D. saccharalis. The objectives of this study were to select and characterize the resistance of D. saccharalis to Cry2Ab2 using a non-commercial Cry2Ab2 single gene Bt maize line. A Cry2Ab2-resistant strain (Cry2Ab2-RR) of D. saccharalis was established from 28 two-parent families collected from fields in northeast Louisiana, U.S. The Cry2Ab2-RR showed a high level of resistance to Cry2Ab2 in both diet-incorporated and whole maize plant bioassays. The Cry2Ab2 resistance in D. saccharalis was likely inherited as a single or a few tightly linked autosomal genes. The resistance was non-recessive and not associated with fitness costs. The results should provide valuable information in resistance monitoring, assessing resistance risk, and developing effective management strategies for the sustainable use of Bt maize technology for managing maize stalk borers.

Cadherin is involved in the action of Bacillus thuringiensis toxins Cry1Ac and Cry2Aa in the beet armyworm, Spodoptera exigua

Bacillus thuringiensis (Bt) insecticidal crystal (Cry) proteins are effective against some insect pests in sprays and transgenic crops, although the evolution of resistance could threaten the long-term efficacy of such Bt use. One strategy to delay resistance to Bt crops is to “pyramid” two or more Bt proteins that bind to distinct receptor proteins within the insect midgut. The most common Bt pyramid in cotton (Gossypium hirsutum L.) employs Cry1Ac with Cry2Ab to target several key lepidopteran pests, including the beet armyworm, Spodoptera exigua (Hübner), which is a serious migratory pest of many vegetable crops and is increasingly important in cotton in China. While cadherin and aminopeptidase-N are key receptors of Cry1 toxins in many lepidopterans including S. exigua, the receptor for Cry2A toxins remains poorly characterized. Here, we show that a heterologous expressed peptide corresponding to cadherin repeat 7 to the membrane proximal extracellular domain (CR7-MPED) in the S. exigua cadherin 1b (SeCad1b) binds Cry1Ac and Cry2Aa. Moreover, SeCad1b transcription was suppressed in S. exigua larvae by oral RNA interference and susceptibility to Cry1Ac and Cry2Aa was significantly reduced. These results indicate that SeCad1b plays important functional roles of both Cry1Ac and Cry2Aa, having major implications for resistance management for S. exigua in Bt crops.

Aphid honeydew quality as a food source for parasitoids is maintained in Bt cotton.

Bt-transgenic cotton has proven to be highly efficient in controlling key lepidopteran pests. One concern with the deployment of Bt cotton varieties is the potential proliferation of non-target pests. We previously showed that Bt cotton contained lower concentrations of insecticidal terpenoids as a result of reduced caterpillar damage, which benefited the aphid Aphis gossypii. It is thus important that non-target herbivores are under biological control in Bt cotton fields. The induction or lack of induction of terpenoids could also influence the quality of aphid honeydew, an important food source for beneficial insects. We therefore screened A. gossypii honeydew for cotton terpenoids, that are induced by caterpillars but not the aphids. We then tested the influence of induced insect-resistance of cotton on honeydew nutritional quality for the aphid parasitoid Lysiphlebus testaceipes and the whitefly parasitoid Eretmocerus eremicus. We detected the cotton terpenoids gossypol and hemigossypolone in A. gossypii honeydew. Although a feeding assay demonstrated that gossypol reduced the longevity of both parasitoid species in a non-linear, dose-dependent manner, the honeydew was capable of sustaining parasitoid longevity and reproduction. The level of caterpillar damage to Bt and non-Bt cotton had no impact on the quality of honeydew for the parasitoids.These results indicate that the nutritional quality of honeydew is maintained in Bt cotton and is not influenced by induced insect resistance.

Efficacy of SmartStax® insect-protected corn hybrids against corn rootworm: The value of pyramiding the Cry3Bb1 and Cry34/35Ab1 proteins

Monsanto Company and Dow AgroSciences have used conventional breeding techniques to develop the combined-trait corn (Zea mays L.) product MON 89034 × TC1507 × MON 88017 × DAS-59122-7 (“SmartStax® corn”) that confers insect resistance against key lepidopteran pests and the corn rootworm complex (Diabrotica spp.), as well as herbicide tolerance. This product contains the Cry3Bb1, Cry34Ab1, and Cry35Ab1 proteins for corn rootworm (CRW) control. Replicated field trials were conducted in 2006 and 2007 to test the efficacy of Cry3Bb1, Cry34Ab1/Cry35Ab1, and SmartStax under both natural and controlled infestations. In both years, root damage and adult beetle emergence were significantly less for Bt-containing hybrids than for non-Bt controls. In trials with heavy insect pressure, adult beetle emergence (a measure of larval control) was significantly reduced for SmartStax hybrids compared with hybrids with the individual traits and with non-Bt controls. Similarly, strip-plot testing in 2012 in grower fields with high levels of root injury to non-Bt hybrids showed significantly lower feeding on SmartStax than on the non-Bt control or on either single-trait product. In grower fields where single-trait Cry3Bb1 products incurred heavy CRW damage in 2011, SmartStax provided consistent protection against CRW in 2012. The combination of these insecticidal proteins in a single plant provides better rootworm control than current single-trait Bt corn products and represents an effective approach for corn rootworm resistance management.

Comparison of laboratory and field bioassays of laboratory‐reared Cydia pomonella (Lepidoptera: Tortricidae) quality and field performance

AbstractMaximum production and fitness of insect species that are mass‐reared for biological control programmes such as the sterile insect technique (SIT) have benefitted from the employment of quality control and quality management. With a growing interest in the use of SIT as a tactic for the suppression/eradication of key lepidopteran pests, such as the codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), there is a parallel interest in inexpensive bioassays that can accurately detect differences in insect quality and monitor insect field performance. In this study, we examined laboratory (mating and flight ability) bioassays and field (field cage and open field release) bioassays simultaneously to discern the ability of the different bioassays to predict quality and field performance of codling moths produced in a commercial mass‐rearing facility. Moth quality was degraded by different levels of radiation during the sterilization procedure. Both the laboratory flight bioassay and the field cage bioassay successfully detected quality and performance differences that were relevant to moth performance in the field. However, the study data suggest that the field cage bioassay was a better predictor of the daily performance of males that had been released in the orchard than the laboratory flight bioassay. Conversely, data suggest that the controlled climatic conditions of the laboratory allowed the flight cylinder bioassay to be more sensitive in detecting daily fluctuations in the quality of moths caused by factors within the mass‐rearing facility. Therefore, both laboratory and field bioassays may be required to provide feedback on quality and performance of mass‐reared moths in a SIT programme.

Selectivity of neem to Trichogramma pretiosum Riley and Trichogrammatoidea annulata De Santis (Hymenoptera: Trichogrammatidae)

Trichogramma pretiosum Riley and Trichogrammatoidea annulata De Santis are commonly found in avocado and persimmon orchards in northern Parana state. However, their abundance depends on whether insecticides are used or not to control the key lepidopteran pests Stenoma catenifer (Wals.) (Lepidoptera: Elachistidae) and Hypocala andremona (Stoll) (Lepidoptera: Noctuidae), respectively. The aim of this work was to evaluate the effects of an aqueous neem seed extract (ANSE) at 15, 3 and 1.5%, and of an emulsifiable concentrate neem oil (ECNO) at 2.5, 0.5 and 0.25% on lifetime parameters of these trichogrammatids as a way of testing the feasibility of integrating the biological and chemical control methods. Chemicals were applied on Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs before or after parasitization (one, three or five days). ANSE was more deleterious to both parasitoid species than ECNO, regardless of the concentration and the time of application. The chemicals acted on a concentration and time dependent manner. Treating the host with neem before parasitism was less deleterious to wasp emergence, especially for T. annulata. Pre-treatments (24h) of the host eggs with ECNO at concentrations varying from 0.5% to 0.25% did not affect T. pretiosum longevity, but 2.5% reduced T. annulata survival. Feeding wasps with honey mixed with 0.25% ECNO negatively affected T. annulata survival.

Impacts of Bt Transgenic Cotton on Integrated Pest Management

Transgenic cotton that produced one or more insecticidal proteins of Bacillus thuringiensis (Bt) was planted on over 15 million hectares in 11 countries in 2009 and has contributed to a reduction of over 140 million kilograms of insecticide active ingredient between 1996 and 2008. As a highly selective form of host plant resistance, Bt cotton effectively controls a number of key lepidopteran pests and has become a cornerstone in overall integrated pest management (IPM). Bt cotton has led to large reductions in the abundance of targeted pests and benefited non-Bt cotton adopters and even producers of other crops affected by polyphagous target pests. Reductions in insecticide use have enhanced biological control, which has contributed to significant suppression of other key and sporadic pests in cotton. Although reductions in insecticide use in some regions have elevated the importance of several pest groups, most of these emerging problems can be effectively solved through an IPM approach.

Diverse cadherin mutations conferring resistance to Bacillus thuringiensis toxin Cry1Ac in Helicoverpa armigera

Transgenic cotton expressing Bacillus thuringiensis (Bt) toxins has been widely adopted to control some key lepidopteran pests including the bollworm Helicoverpa armigera. Evolution of resistance to Bt cotton by target pests is a major threat to the continued success of Bt cotton. Previous results revealed 3 null alleles ( r1– r3) of a cadherin gene ( Ha_BtR) conferring Cry1Ac resistance in H. armigera. An F 1 screen of 123 single-pair families was conducted between a Cry1Ac-resistant strain (the SCD-r1 strain, homozygous for the r1 allele of Ha_BtR) and field-derived insects from Jiangpu population (Jiangsu province, China) in 2008. Five new null alleles of Ha_BtR ( r4– r8) were identified in six candidate single-pair families. These null alleles were created through either an insertion or a point mutation. Interestingly, intact alleles of Ha_BtR were found in two field-derived insects from another two candidate single-pair families. It suggests that these two field-derived insects may carry novel resistance alleles of Ha_BtR, with missense mutations resulting in a non-functional cadherin protein, or a major dominant mutation at a locus other than cadherin. The resistance allele frequency of Ha_BtR was detected at an appreciable level (0.024) in the Jiangpu population of H. armigera in 2008. Together with previous findings, a total of eight different resistance alleles of Ha_BtR were identified from three Chinese strains of H. armigera. Mutational diversity of Ha_BtR could impair DNA screening for Bt resistance allele frequency in the field, and an F 1 screen should be used routinely for monitoring cadherin-based resistance allele frequencies in H. armigera.

Tree fruit IPM programs in the western United States: the challenge of enhancing biological control through intensive management

The seminal work of Stern and his coauthors on integrated control has had a profound and long-lasting effect on the development of IPM programs in western orchard systems. Management systems based solely on pesticides have proven to be unstable, and the success of IPM systems in western orchards has been driven by conservation of natural enemies to control secondary pests, combined with pesticides and mating disruption to suppress the key lepidopteran pests. However, the legislatively mandated changes in pesticide use patterns prompted by the Food Quality Protection Act of 1996 have resulted in an increased instability of pest populations in orchards because of natural enemy destruction. The management system changes have made it necessary to focus efforts on enhancing biological control not only of secondary pests but also of primary lepidopteran pests to help augment new pesticides and mating disruption tactics. The new management programs envisioned will be information extensive as well as time sensitive and will require redesign of educational and outreach programs to be successful. The developing programs will continue to use the core principles of Stern and his co-authors, but go beyond them to incorporate changes in society, technology and information transfer, as needed.

Novel pink bollworm resistance to the Bt toxin Cry 1Ac: effects on mating, oviposition, larval development and survival.

Bt cotton plants are genetically engineered to produce insecticidal toxins from the Bacillus thuringiensis (Bt) Berliner (Bacillales: Bacillaceae) bacterium and target key lepidopteran pests. In all previous strains of pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) selected in the laboratory for resistance to insecticidal Cry1Ac toxin using an artificial diet containing the toxin, resistance to Cry1Ac and to Bt cotton is linked to three cadherin alleles (r1, r2, and r3). In contrast, the BG(4) pink bollworm strain was selected for resistance to Bt cotton by feeding larvae for four days in each of 42 generations on bolls of ‘NuCOTN33B®’ that expressed Cry1Ac toxin. After additional selection for eleven generations on Cry1Ac-incorporated diet, the susceptibility to Cry1Ac, fecundity, egg viability, and mating of this strain (Bt4R) was compared with the unselected Cry1Ac-susceptible parent strain. Some larvae of the Bt4R strain survived on diet containing ≥ 10 µg Cry1Ac per milliliter artificial diet, but none survived on transgenic cotton bolls. In contrast to strains selected exclusively on Cry1Ac diet, some survival of progeny of reciprocal moth crosses of Bt4R resistant and Bt-susceptible strains occurred on Cry1Ac-treated diet, suggesting differences in levels of dominance. The Bt4R resistant strain does not have the r1, r2, or r3 mutant cadherin genes as do all previous strains of pink bollworm selected on Cry1Ac-treated artificial diet. The combined results suggest a mechanism of resistance to Cry1Ac that is different from previously described cadherin mutations.

Reduced-Risk Pest Management Programs for Eastern U.S. Apple and Peach Orchards: A 4-Year Regional Project

Studies were conducted from 2002 to 2005 to determine the effectiveness of reduced-risk (RR) tactics for managing key pests in 50 commercial apple orchards (114 ha) in Michigan, North Carolina, New York, Pennsylvania, Virginia, and West Virginia; and 20 peach orchards (190 ha) in Michigan, New Jersey, Pennsylvania, and West Virginia. At each apple site, a block of up to 5 ha received a seasonal program of selective RR and organophosphate-replacement insecticides, with or without pheromones for mating disruption of key lepidopteran pests of apple (codling moth, oriental fruit moth, and obliquebanded leafroller) and peach (oriental fruit moth, lesser peachtree borer, and peachtree borer). A comparison block at each site with the same varieties and tree training was managed using each grower's standard program of conventional insecticides (STD). Pheromone traps for lepidopteran species were hung in all plots and monitored weekly. Foliar samples were taken during the season to estimate phytophagous and predator mite densities. Red sphere traps baited with fruit volatiles were used to monitor apple maggot adults in apple orchards. Fruits were inspected for insect damage at harvest, and graded according to USDA standards. Partial budget analysis was used to assess the net profitability of RR programs to produce apples and peaches for their intended market in each state. Fruit damage at harvest caused by direct fruit pests was generally low across all blocks and treatments. There were no statistically significant differences in fruit damage or mite populations between the RR blocks, with or without pheromones, and the growers' standards. Insecticide use patterns in the RR plots represented up to 88 and 78% reduction in the amount of active ingredient applied per hectare, and an 85 and 77% decrease in their Environmental Impact Quotient for apples and peaches, respectively. However, RR programs were more expensive and generally less profitable compared with growers' standard programs. Regression analysis estimated that RR apple programs with and without mating disruption were on average &dollar;465 and &dollar;144/ha more expensive, and &dollar;544 and &dollar;159/ha less profitable, respectively, compared with standard programs. RR+MD programs for peaches cost an average &dollar;314/ha more and returned about &dollar;284/ha less than STD peach programs.

TOXICITY OF RH-2485 (METHOXY FENOCIDE20F) AGAINST HELICOVERPA ARMIGERA (HUB.)

ABSTRACT RH-2485 is a molt accelerating compound and provides effective control of a wide range of key lepidopteran pests. It acts as an ecdysone agonist. The chemical upon absorption into the haemolymph of the insect, binds to the ecdysone receptor which initiates the moulting process. As the normal process disrupted the insects are prevented from shedding its old cuticle. The larvae die of dehydration and starvation within 2-5 days. Hence the toxicity tests were conducted for Helicoverpa armigera (Hub.) to fix the LD50.The LD50 of molt accelerating hormone RH-2485 was estimated by Bouquet method. It was found that the LD50 was 7.68, 15.95, 92.93 and 142.16 ppm for I, II, III and IV instar larvae of H. armigera respectively. It was concluded that the earlier instar was found to be more susceptible with lesser LD50 values and as the instars advances the values of LD50 was found to be increasing. Hence this formulation was found to be more toxic for the different instars of H. armigera and can be included in the Integrated Pest Management systems.

Impacts of transgenic cry1Ab rice on non-target planthoppers and their main predator Cyrtorhinus lividipennis (Hemiptera: Miridae)—A case study of the compatibility of Bt rice with biological control

Abstract Transgenic rice containing insecticidal protein(s) from Bt (Bacillus thuringiensis) effectively control lepidopteran pests under laboratory and field conditions. However, Bt rice has not been widely commercialized. A major concern regarding the deployment of Bt rice is its potential impact on non-target arthropods, including herbivorous insect pests and biological control agents (predators and parasitoids) in the rice ecosystem. A 2-year field study was conducted at 3 sites in Zhejiang Province, China to assess the impacts of a homozygous transgenic japonica rice line KMD1 (Bt rice) containing a synthetic cry1Ab gene from Bacillus thuringiensis Berliner. The impacts on three planthoppers (Homoptera: Delphacidae), Sogatella furcifera (Horvath), Nilaparvata lugens (Stal) and Laodelphax striatellus (Fallen), and the natural enemy, Cyrtorhinus lividipennis (Reuter) (Hemiptera: Miridae), were evaluated using two sampling methods: vacuum-suction and Malaise trap. Population densities of planthoppers and C. lividipennis were not significantly affected by rice type (Bt/non-Bt) over the season at any of the 3 sites in each year, regardless of sampling methods. Both in Bt rice and non-Bt rice plots, S. furcifera was the predominant species of planthoppers as determined by either of the two sampling methods, and comprised >50% of the planthoppers at each site. No consistent effects of Bt rice and Bt rice × sampling date interaction on population dynamics of the predominant planthopper species, S. furcifera, and the predator, C. lividipennis, were observed throughout the sampling period. Overall, this 2-year field study indicates that, in comparison with non-Bt rice, Bt rice did not lead to higher planthopper populations and did not negatively affect the predator C. lividipennis. These results suggest that use of Bt rice may provide control of the key lepidopteran pests while promoting the key biological control agent of planthopppers, C. lividipennis.

Binding of Bacillus thuringiensis toxin Cry1Ac to multiple sites of cadherin in pink bollworm

Toxins from Bacillus thuringiensis (Bt) are widely used for pest control. In particular, Bt toxin Cry1Ac produced by transgenic cotton kills some key lepidopteran pests. We found that Cry1Ac binds to recombinant peptides corresponding to extracellular regions of a cadherin protein (BtR) in a major cotton pest, pink bollworm ( Pectinophora gossypiella) (PBW). In conjunction with previous results showing that PBW resistance to Cry1Ac is linked with mutations in the BtR gene, the results reported here support the hypothesis that BtR is a receptor for Cry1Ac in PBW. Similar to other lepidopteran cadherins that bind Bt toxins, BtR has at least two Cry1Ac-binding domains in cadherin-repeat regions 10 and 11, which are immediately adjacent to the membrane proximal region. However, unlike cadherins from Manduca sexta and Bombyx mori, toxin binding was not seen in regions more distal from the membrane proximal region. We also found that both the protoxin and activated toxin forms of Cry1Ac bound to recombinant BtR fragments, suggesting that Cry1Ac activation may occur either before or after receptor binding.

Suppression of &lt;I&gt;Plutella xylostella&lt;/I&gt; and &lt;I&gt;Trichoplusia ni&lt;/I&gt; in Cole Crops with Attracticide Formulations

The three key lepidopteran pests of cole, Brassica oleracea L., crops in North America are diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae); cabbage looper; Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae); and imported cabbageworm, Pieris rapae (L.) (Lepidoptera: Pieridae). Two species-specific pheromone-based experimental attracticide formulations were evaluated against these pests: LastCall DBM for P. xylostella and LastCall CL for T. ni. No LastCall formulation was available against P. rapae. Laboratory toxicity experiments confirmed the effectiveness of each LastCall formulations in killing conspecific males that made contact. In replicated small plots of cabbage and collards in central Alabama, over four growing seasons (fall 2003, spring 2004, fall 2004, and spring 2005), an attracticide treatment receiving the two LastCall formulations, each applied multiple times at the rate of 1,600 droplets per acre, was compared against Bacillus thuringiensis. subspecies kursatki (Bt) spray at action threshold and a negative untreated control. Efficacy was measured by comparing among the three treatments male capture in pheromone-baited traps, larval counts in plots, and crop damage rating at harvest. LastCall provided significant reductions in crop damage comparable to Bt in three of the four seasons. Efficacy of LastCall was dependent upon lepidopteran population densities, which fluctuated from season to season. In general, reduction in crop damage was achieved with LastCall at low-to-moderate population densities of the three species, such as typically occurs in the fall in central Alabama, but not in the spring when high P. rapae population pressure typically occurs in central Alabama. Significant reductions in pheromone trap captures did not occur in LastCall plots, suggesting that elimination of males by the toxicant (permethrin), rather than interruption of sexual communication, was the main mechanism of effect.

Pheromone mating disruption offers selective management options for key pests

The direct management of insect pests using pheromones for mating disruption, or “attract and kill” approaches, can provide excellent suppression of key lepidopteran pests in agriculture. Important successes to date include codling moth in pome fruit, oriental fruit moth in peaches and nectarines, tomato pinworm in vegetables, pink bollworm in cotton and omnivorous leafroller in vineyards. Large-scale implementation projects have yielded significant reductions in pesticide use while maintaining acceptably low crop-damage levels. Because of some difficulties with high populations of pests, these programs should not be viewed as stand-alone strategies but rather as one tactic within a suite of integrated pest management options.