Modeling the Resistance Evolution to Insecticides Driven by Lepidopteran Species Competition in Cotton, Soybean, and Corn Crops.

Intra- and interspecific competition is considered a fundamental phenomenon in ecology. It acts as one of the most powerful selective forces that drives ecological diversity, the spatiotemporal distribution of organisms, fitness, and evolutionary aspects. Spodoptera frugiperda and Helicoverpa armigera are devastating pests and can co-occur in systems consisting of multiple agricultural crops and compete for food resources. Insecticide resistance in populations of these species has been a major threat to the sustainability of agroecosystems. No study to date has shown the effect of intra- and interspecific competition as a selective pressure agent on the evolution of insecticide resistance in lepidopteran pests in an experimental and theoretical way. Our study developed a parameterized computational model with experimental results for S. frugiperda and H. armigera competition. We simulated the behavior of heterozygous individuals with a competition capacity 100% equal to homozygous individuals resistant (100 RR) or susceptible to insecticides (00 RR), and intermediate between them (50 RR). Competition involving strains of these insect species can accelerate the evolution of their resistance to insecticides in agricultural crops. We found that competitive processes can result in a high probability of competitive exclusion for individuals with the susceptibility allele of these lepidopteran species. The results of this study are of paramount importance for understanding the impact of ecological factor competition on the evolution of insecticide resistance in lepidopteran pests, which until now has been neglected in these types of evolutionary dynamics studies.

Occurrence of fruit flies (Diptera: Tephritidae) in the municipality of Alvorada do Gurguéia in South Central Piauí, Brazil

The state of Piauí is in a Cerrado/Caatinga transition area, which is known the richness of its fauna and flora. Therefore, this work aims to know the diversity of fruit fly species in cashew orchards and native forest fragments in the south-central region of Piauí. Fruit flies were collected in McPhail traps and by sampling fruits. The material collected from the traps and the fruits in the two areas were taken to the Laboratory of Phytotechnics from Campus Prof. Cinobelina Elvas at the Universidade Federal do Piauí (UFPI/CPCE), municipality of Bom Jesus, Piauí, Brazil. In McPhail traps, six species of the genus Anastrepha: A. alveata, A. dissimilis, A. fraterculus, A. manihoti, A. obliqua, and A. zenildae were captured, of which A. fraterculus, A. obliqua, and A. zenildae were present in both areas. Anastrepha alveata, A. dissimilis and A. manihoti occurred only in the cashew orchard. In fruit sampling, A. fraterculus, A. obliqua, and A. zenildae infested wild-guava fruits, Myrcia tomentosa (Myrtaceae), in native forest. Anastrepha fraterculus, A. obliqua and A. zenildae were obtained directly from M. tomentosa fruits and from traps. The availability of host fruits is the factor that most influences the population fluctuation of fruit flies, mainly in the native forest area. Anastrepha manihoti is reported for the first time in the state of Piauí. This is the first record of A. fraterculus, A. obliqua and A. zenildae, infesting wildguava fruits, M. tomentosa.

Tritrophic relations and spatial distribution of fruit flies (Diptera: Tephritidae) in the Cerrado and Caatinga regions in Piauí, Brazil

ABSTRACT Knowledge about the spatial distribution of fruit flies (Diptera: Tephritidae) and tritrophic interactions (fruit-fruit fly parasitoid) contributes to the monitoring and maintenance of the numerical density at a level lower than economic damage. The purpose of this study was to identify the spatial distribution and associations of fruit flies with their parasitoids and host plants in the municipality of Bom Jesus-PI. The flies were obtained from fruit collection from July 2018 to May 2019. A total of 1,711 individuals were obtained, represented by six species: Anastrepha obliqua (Macquart, 1835), An. fraterculus (Wiedemann, 1830), An. alveata Stone, 1942, An. sororcula Zucchi, 1979, An. zenildae Zucchi, 1979 and Ceratitis capitata (Wiedemann, 1824). Anastrepha obliqua was the species with the widest distribution throughout the ecotone area. Ceratitis capitata is distributed only in the urban perimeter. A tritrophic relationship occurred between four species of parasitoids, Asobara anastrephae (Muesebeck, 1958) or Opius sp. associated with An. obliqua in Spondias mombin or S. tuberosa fruits. Opius sp. has also been associated with An. alveata in Ximenia americana. Pachycrepoideus vindemiae was obtained from C. capitata in Malpighia emarginata, in addition to An. obliqua in Averrhoa carambola. Therefore, fruit flies are associated with native fruit trees (S. tuberosa, S. mombin, S. purpurea, P. acutangulum, Inga laurina, X. americana) and exotic fruits (M. emarginata, A. carambola, P. guajava). Ceratitis capitata was recorded for the first time in the state of Piauí infesting I. laurina (Sw.) Willd. This is the first record of the parasitoid genus Spalangia. in An. obliqua in Piauí and in the semiarid region of Brazil.

Development of Tenebrio molitor (Coleoptera: Tenebrionidae) on Poultry Litter-Based Diets: Effect on Chemical Composition of Larvae.

In order to investigate a low-cost and sustainable food source, the present study evaluated the use of poultry litter for rearing Tenebrio molitor Linnaeus, 1758 (Coleoptera: Tenebrionidae). The experiment was performed with five diets containing increasing levels of poultry litter (0, 25, 50, 75, and 100%) replacing the control diet and five replicates with 50 larvae per sample unit. Larval growth and development were evaluated and the chemical compositions of diet and T. molitor larvae were determined. Larval development and reproduction efficiency of T. molitor were similar in all treatments. The sole use of poultry litter to feed T. molitor reduced the crude protein of flour by only 8%. Including 50% or more poultry litter in the standard diet is the best-suited formulation for larvae production and incorporation of minerals in the larvae. Mealworm can be grown successfully on diets composed by poultry litter, the diet did not affect survival, growth, and development; however, studies spanning several insect generations should be performed to determine the effects of diet composition on adult fecundity. The knowledge acquired using poultry litter to feed T. molitor will be useful to carry out new research, in addition to evidencing the possibility of low-cost mass rearing of these larvae.

Esterase activity in homogenates of Helicoverpa armigera (Hubner) (Lepidoptera: noctuidae) exposed to different insecticides and the behavioral effect / Atividade esterase em homogenatos de helicoverpa armigera (hubner) (lepidoptera: noctuidae) expostos a diferentes inseticidas e o efeito comportamental

The toxicity of some insecticides to Helicoverpa armigera was studied through sublethal effects, evaluating the enzymatic activity of esterase and the behavioral response. The commercial formulation of insecticides selected were chlorpyrifos, spinosad, indoxacarb, chlorantraniliprole, lambda-cyhalothrinand Bacillus thuringiensis, corresponding the most used by farmers to control of H. armigera. To determine the esterase activity, the larvae were fed with soybean leaf discs dipped in insecticide solution using the lethal concentration (LC50). For the behavioral response, filter paper were immersed in three concentrations of insecticides (LC50, LC95 and recommend dose.), then the behavior of the larvae observed in Videomex-One. The results for the enzymatic activity showed an increase in the activity of the esterase, with variation along the treatments and the time of exposure of the insects to the insecticides. With exception of spinosad, other insecticides showed an increase in EST-α activity, 6 and 24 hours after contact of caterpillars with insecticide.Different behavioral patterns of walking (walking distance, walking speed and resting time) were observed for H. armigera exposed to different insecticides. H. armigera exposed to chlorpyrifos, lambda-cyhalothrin and B. thuringiensis insecticides show greater esterase activity. Regarding walking behavior, the results confirms enzymatic activity, where H. armigera have behavioral alteration after exposure to insecticide.

A toxicidade de alguns inseticidas a Helicoverpa armigera foi estudada através de efeitos subletais, avaliando a atividade enzimática da esterase e a resposta comportamental. A formulação comercial dos inseticidas selecionados foram clorpirifos, espinosad, indoxacarb, clorantraniliprole, lambda-cialotrina eBacillus thuringiensis utilizados pelos agricultores para controle de H. armigera. Para determinar a atividade da esterase, as larvas foram alimentadas com discos de folha de soja mergulhados em solução de inseticida usando a concentração letal (CL50). Para os testes de características comportamentais, papel filtro foi imerso em três concentrações de inseticidas (CL50, CL95 e dose recomendada), posteriormente o comportamento das larvas foi observado em Videomex-One. Os resultados para a atividade enzimática mostraram aumento da atividade daesterase, com variação ao longo dos tratamentos e do tempo de exposição dos insetos aos inseticidas. Com exceção do spinosad, outros inseticidas mostraram um aumento na atividade EST-α, 6 e 24 horas após o contato das lagartas com inseticida. Diferentes padrões comportamentais de caminhada (distância percorrida, velocidade de caminhada e tempo de repouso) para H. armigera exposto a diferentes classes de inseticidas. H. armigera exposta aos inseticidas clorpirifos, lambda-cialotrina e B. thuringiensis mostraram maior atividade da esterase. Em relação ao comportamento ambulante, os resultados confirmam a atividade enzimática, onde H. armigera teve alteração comportamental após exposição ao inseticida.

Lepidopteran pests associated with the soybean cultivars phenology / Lepidopteros-praga associados com estágios fenológicos de cultivares de soja

Lepidopteran pests are one of the major constraints to the soybean production potential, whose defoliating caterpillars can occur throughout the crop cycle causing serious damage. Therefore, the objective was to study the population fluctuation of lepidopteran pests and the association of species with the growth stages of soybean cultivars in the Cerrado of Piaui State, Brazil, in order to obtain data to support integrated pest management in the crop. The experiments had as a source of variation thirteen cultivars with fourteen evaluations. The design used was completely randomized in split plots being the cultivars plots and subplots the cultivars phenological stages. The monitoring was conducted by shake-cloth method at random points. Weekly samplings were performed. Generally, species of lepidopteran pests occurred in all soybean phenological stages, especially Chrysodeixis includens and Anticarsia gemmatalis that were present from the beginning to the end of the crop.

Lepidópteros-praga estão entre os principais entraves ao potencial de produção de soja, cujas lagartas desfolhadoras podem ocorrer ao longo do ciclo da cultura, causando sérios danos. Portanto, o objetivo foi estudar a flutuação populacional de lepidópteros-praga e a associação dessas espécies com os estádios de crescimento de cultivares de soja no Cerrado do Estado de Piauí, a fim de obter dados para apoiar o manejo integrado de pragas na cultura. Os experimentos tiveram como fonte de variação treze cultivares com catorze avaliações. O delineamento utilizado foi inteiramente casualizado em parcelas subdivididas, sendo os cultivares as parcelas e as subparcelas os estádios fenológicos dos cultivares. O monitoramento foi realizado por meio do método de pano-de-batida em pontos aleatórios. Foram realizadas amostragens semanais. Em geral, espécies de lepidópteros-praga ocorreram em todos os estádios fenológicos da cultura da soja, especialmente Chrysodeixis includens e Anticarsia gemmatalis que estavam presentes desde o início até o final da cultura.

Record of Neosilba zadolicha Mcalpine & Steyskal (Diptera: Lonchaeidae) in Mandacaru fruits / Registro de Neosilba zadolicha Mcalpine & Steyskal (Diptera: Lonchaeidae) em frutos de Mandacaru

For the first time, the presence of Neosilba zadolicha McAlpine & Steyskal is being recorded in mandacaru fruits [Cereus jamacaru DC.], in the municipality of Alvorada do Gurgueia, in the south-central region of the State of Piauí, Brazil (8º22'35.63" S, 43º51'25,96" W). Eleven specimens were obtained from mandacaru fruits in an area of native forest between February and May of 2016. This is the first record of N. zadolicha in a Cactaceae species.(AU)

Registra-se a ocorrência de Neosilba zadolicha McAlpine & Steyskal pela primeira vez em frutos de mandacaru (Cereus jamacaru DC.), no município de Alvorada do Gurgueia, centro-sul do estado do Piauí (8º22'35.63" S, 43º51'25,96" W). Foram obtidos 11 exemplares de frutos de mandacaru, em área de mata nativa, de fevereiro de 2016 a maio de 2016. Este é o primeiro registro de N. zadolicha em uma espécie de Cactaceae.(AU)

Biological parameters of three Trichogramma pretiosum strains (Riley, 1879) (Hymenoptera: Trichogrammatidae) on eggs Helicoverpa armigera (Hübner, 1805) (Lepidoptera: Noctuidae) / Parâmetros biológicos de três linhagens de Trichogramma pretiosum (Riley, 1879) (Hymenoptera: Trichogrammatidae) sobre ovos de Helicoverpa armigera (Hübner, 1805) (Lepidoptera: Noctuidae)

This project has an objective to study the biological parameters of Trichogramma pretiosum on eggs of H. armigera. The three strains of T. pretiosum were evaluated: TM, TMC and TLEM, from different places. The experimental establishing was completely randomizing with twenty repeats per treatment, being used by a female parasitoid by repetition and later on they were offered 20 H. armigera eggs. The experiment was kept on BOD cameras to 25 ± 2° C, UR 60 ± 10% and photo phase of 14 hours. Evaluating the following biological parameters: parasitism percentage, emergency percentage, number of adults emerged per egg, sex ratio, viability, and longevity and cycle duration. The parasitism percentage, viability and number of individuals per egg were higher for TM and TMC. The TMC strain presented a larger sex ratio proportion, not being different statistically from the TM stream. The longevity of the strain TM was different regarding the others. There was no variation regarding the cycle duration. Therefore, according with the evaluated biologic parameters, it is concluded that Trichogramma pretiosum strain TM obtained a better egg development of H. armigera on laboratory conditions.

Este trabalho teve como objetivo estudar os parâmetros biológicos de Trichogramma pretiosum em ovos de H. armigera. As três linhagens de T. pretiosum avaliadas foram: TM, TMC e TLEM, oriundas de diferentes localidades. O delineamento experimental foi inteiramente casualizado com vinte repetições por tratamento, sendo utilizada uma fêmea do parasitoide por repetição e posteriormente foram oferecidos 20 ovos de H. armigera. O experimento foi mantido em câmaras BOD a 25 ± 2° C, UR 60 ± 10% e fotofase de 14 horas. Avaliou-se os seguintes parâmetros biológicos: porcentagem de parasitismo, porcentagem de emergência, número de adultos emergidos por ovo, razão sexual, viabilidade, longevidade e duração do ciclo. A porcentagem de parasitismo e viabilidade e número de indivíduos por ovo foram superiores para as linhagens TM e TMC. A linhagem TMC apresentou a maior proporção para razão sexual, não diferindo estatisticamente da linhagem TM. A longevidade da linhagem TM se destacou em relação às demais. Não houve variação com relação a duração do ciclo. Assim de acordo com os parâmetros biológicos avaliados, conclui-se que Trichogramma pretiosum linhagem TM obteve o melhor desenvolvimento nos ovos de H. armigera em condições de laboratório.

The damage caused by Callosobruchus maculatus on cowpea grains is dependent on the plant genotype.

BACKGROUND: Beans from cowpea cultivars fertilized with mineral N or inoculated with various rhizobium strains may contain different nitrogen concentrations and nitrogen metabolite composition, which affects the beans' defense mechanisms against pests. In this study, the population growth of Callosobruchus maculatus reared on beans from four cowpea cultivars fertilized with different nitrogen sources was evaluated. The factors tested were beans from four cowpea cultivars and seven different nitrogen sources: mineral N fertilization, inoculation with five strains of symbiotic diazotrophic bacteria, and soil nitrogen (absolute control). RESULTS: BRS Tapaihum and BRS Acauã cultivars had lower cumulative emergence and instantaneous rate of population growth of the insects compared with other cultivars, indicating antixenosis resistance against C. maculatus. Inoculation of BRS Acauã cultivar with the diazotrophic bacteria strain BR 3299 resulted in higher mortality of C. maculatus. For BRS Tapaihum cultivar, inoculation with diazotrophic bacteria strains BR3267, BR 3262 and BR 3299, and nitrogen fertilization resulted in higher mortality among C. maculatus. CONCLUSION: BRS Tapaihum and BRS Acauã cultivars showed the lowest cumulative insect emergence and instantaneous rates of population growth, and the highest insect mortality, mainly when the grains were obtained from plants inoculated with rhizobial strains. © 2016 Society of Chemical Industry.

Effects of croton urucurana extracts and crude resin on Anagasta kuehniella (Lepidoptera: Pyralidae)

Hundreds of plant species have been studied in order to find out the active ingredient responsible for their insecticidal activity against the pests of economic importance. To verify the insecticidal activity in the husk of stem of Croton urucurana Baillon 1864 (Euphorbiaceae) against Anagasta kuehniella Zeller 1879 (Lepidoptera: Pyralidae), the methanolic (EMeOH) extract, dichloromethane fraction (FDM), ethyl acetate fraction (FAE) and crude resin, incorporated into an artificial diet were evaluated. EMeOH (0.5, 1.0 and 2.0 percent) and crude resin (2.0 percent) interfered with neither the weight nor the survival of fourth instar larvae and other analyzed parameters. FDM (2.0 percent) fraction caused mortality of 65 percent, and the artificial diet containing 2.0, 1.0 and 0.5 percent FAE caused 100, 55 and 68 percent mortality respectively when compared with the control, confirming the least efficiency rates of food conversion for FDM(2.0 percent) and FAE(1.0 percent). The tryptic analysis performed with the midgut fluid of fourth-instar larvae demonstrated that tryptic and chymiotryptic activities for the larvae fed artificial diet containing EMeOH and crude resin were not different.

Atualmente centenas de plantas são investigadas para se conhecer os princípios ativos responsáveis pela atividade inseticida contra as diversas pragas de importância econômica. Com o objetivo de verificar a atividade inseticida das cascas do caule de Croton urucurana Baillon 1864 (Euphorbiaceae) em relação a Anagasta kuehniella Zeller 1879 (Lepidoptera: Pyralidae), avaliou-se o extrato metanólico (EMeOH), fração diclorometano (FDM), a fração acetato de etila (FAE) e a resina in natura, os quais foram adicionados à dieta artificial. O EMeOH (0,5, 1,0 e 20, por cento) e a resina in natura (2,0 por cento), não interferiram no peso, sobrevivência das larvas de 4ª ínstar, bem como nos demais parâmetros analisados. A fração FDM (2,0 por cento) causou mortalidade de 65 por cento, e a dieta artificial contendo 2,0, 1,0, e 0,5 por cento de FAE causou 100, 55 e 68 por cento de mortalidade respectivamente quando comparado com o controle, constatando-se as menores eficiências de conversão do alimento para a FDM (2,0 por cento) e FAE (1,0 por cento). Através do ensaio tríptico realizado com o fluido do intestino médio das larvas, foi possível verificar que a atividade tríptica e quimiotríptica para as larvas alimentadas com dieta artificial contendo o EMeOH e a resina in natura não apresentaram diferenças significativas.