ECOLOGY AND INTEGRATED PEST MANAGEMENT OF WESTERN BEAN CUTWORM \u3ci\u3eStriacosta albicosta\u3c/i\u3e (SMITH) (LEPIDOPTERA: NOCTUIDAE) IN FIELD CORN

Western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is a native pest of dry beans (Phaseolus vulgaris L.) and corn (Zea mays L.), and historically distributed in the western United States. The insect’s recent expansion eastward is documented since 1999. The species is univoltine, the adults typically emerge in the middle of July, lay eggs on corn leaves, and the larvae feed on different corn tissues. In the fourth instar, larvae start colonization of the ear where they feed on kernels. There is a narrow window for management and early detection of the pest in the field is essential. Larval feeding and dispersal of early larval instar studies of western bean cutworm are necessary to improve the understanding about how feeding requirements affect larval survival and establishment on the corn plant. A refinement of economic injury levels (EIL) and economic thresholds (ET) are also required for management decision-making. Studies during 2008 - 2011, across three ecoregions of Nebraska, had the following objectives: (1) developing a binomial sequential sampling plans for egg masses, (2) determine the feeding behavior and dispersal of the early instars on corn, and (3) development of EILs and the ETs that incorporate the dynamics of corn price, management cost, and pest survival. The results from the present study demonstrated that the binomial sequential sampling plans developed significantly reduce the effort required for effective management of this pest, reducing sampling effort from 100 plants sampled to an average of 38 to 41 plants sampled per field. The results indicate low larval survival of this species and that the early instars of western bean cutworm are the critical stage for establishment in corn. A behavior of initial larval movement toward the tassel was observed. The overall mean yield loss one western bean cutworm larva per plant was 945.52 kg/ha (15.08 bu/acre), based on 74,100 plants/ha. The ETs are expressed in percentage of plants with at least one egg mass, incorporate larval survival that was observed across three locations in Nebraska

DANOS CAUSADOS POR PERCEVEJO-DE-RENDA NA PRODUÇÃO DE PARTE AÉREA E RAÍZES DE MANDIOCA

This research evaluated the economic damage of lacebug Vatiga illudens (Drake, 1922) (Hemiptera: Tingidae) upon cassava root and foliage yield. The experiments were carried out from 1994 to 1997 at the experimental area of Embrapa Cerrados, at the municipality of Planaltina - DF. The experimental design used was completely randomized blocks with four replications, in a scheme of subdivided plots. The plots consisted of varieties and in the subplots, randomized within each block, treatments with or without chemical control of lacebug were applied, mediated by sprays every two weeks with insecticides based on monocrotophos, dimetoate and vamidotion. The results obtained revealed that 1) high levels of lacebug nymph and adult infestation reduced cassava foliage and root yield and that 2) the sprays with insecticides resulted in increases of cassava foliage and root yield.Esta pesquisa avaliou o dano provocado pelo percevejo-de-renda Vatiga illudens (Drake, 1922) (Hemiptera: Tingidae) na produtividade de raízes e da parte aérea em mandioca. Os experimentos foram conduzidos entre 1994 e 1997 na área experimental da Embrapa Cerrados, no município de Planaltina - DF. Utilizou-se o delineamento experimental de blocos ao acaso, com quatro repetições, em esquema de parcelas subdivididas. As parcelas foram constituídas pelas variedades e nas subparcelas, casualizadas dentro de cada bloco, foram testados os tratamentos sem controle e com controle químico do percevejo-de-renda, através de pulverizações quinzenais com inseticidas à base de monocrotofós, dimetoato e vamidotion. Os resultados revelaram que 1) elevados níveis de infestação de ninfas e de adultos do percevejo-de-renda reduziram a produtividade da parte aérea e das raízes em mandioca e 2) pulverizações com inseticidas resultaram em acréscimos de produção de raízes e parte aérea em mandioca

Morphological and molecular identification of Helicoverpa armigera (Lepidoptera: Noctuidae) and expansion of its occurrence record in Brazil

O objetivo deste trabalho foi descrever métodos para a caracterização morfológica e molecular de Helicoverpa armigera e ampliar o registro de ocorrência da praga no Brasil. As mariposas foram obtidas de lagartas coletadas nas culturas de algodão, milho e soja, com uso de armadilhas luminosas. As coletas foram realizadas na Bahia, no Distrito Federal, no Mato Grosso e no Paraná. A identificação foi baseada na genitália masculina e nas análises das sequências dos genes mitocondriais do citocromo B e da região cox1‑tRNALeu‑cox2. A genitália masculina foi comparada com as descrições morfológicas na literatura, e as sequências de genes, com as depositadas no GenBank. Ambas as análises confirmaram a presença de H. armigera nos locais de coleta. Ampliou-se o registro de ocorrência da praga para a região Sul do país.The objective of this work was to describe methods for molecular and morphological characterization of Helicoverpa armigera and to extend the pest occurrence record in Brazil. Moths were obtained from larvae collected in cotton, corn, and soybean crops, using light traps. Collections were done in the states of Bahia, Distrito Federal, Mato Grosso, and Paraná, Brazil. Identification was based on male genitalia and on the analyses of mitochondrial gene sequences of cytochrome B and of the cox1‑tRNALeu‑cox2 region. The male genitalia were compared with the morphological descriptions in the literature, and the gene sequences with the ones deposited at GenBank. Both analyses confirmed the presence of H. armigera in the collecting locations. The pest geographic range was expanded to the South region of the country

Biotic potential and reproductive parameters of Spodoptera dolichos (Lepidoptera: Noctuidae) in the laboratory

The biotic potential and reproductive parameters of Spodoptera dolichos (Fabricius, 1794) were evaluated under controlled conditions (25 ± 1°C, 70 ± 10% RH and 14 hour photophase). The longevity, pre-, post- and oviposition periods, fecundity, and fertility of 25 couples were evaluated. The longevity of females (12.9 days) was not significantly different than that of males (12.4 days). The mean durations of the pre-, post- and oviposition periods were 3.0, 0.4 and 10.4 days, respectively. The mean fecundity was 4,086.0 eggs per female and mean fertility was 3,557.8 larvae per female. On average, a female copulated 1.4 times. The biotic potential of S. dolichos was estimated at 7.138 x 1018 individuals/female/year. The net reproductive rate (Ro) was 1,711.98 times per generation and the mean generation time (T) was 56.19 days. The intrinsic rate of increase (rm) was 0.133, with a finite rate of increase (l) of 1.142 per day. These results are compared with other species from Spodoptera and their relevance for management strategies of S. dolichos

Noctuóides (Lepidoptera: Noctuoidea) associados a soja Bt e não-Bt no Cerrado brasileiro

O uso de OGM que expressam toxina Bt na produção de soja tem aumentado significativamente nos últimos anos no Brasil e são utilizados para conter os danos causados ​​pelos lepidópteros pragas. Neste estudo comparamos a riqueza e a abundância de Noctuoides (Noctuoidea) associados à soja Bt e não-Bt. Determinamos as variações temporais em função da fenologia e correlacionamos às variações populacionais das espécies mais comuns com variáveis ​​meteorológicas. A pesquisa foi conduzida na área experimental da Embrapa Cerrados. O método de coleta utilizado foi diferenciado sendo supressivo e absoluto. Um total de 13 espécies foram coletadas, das quais oito ocorreram em soja Bt. Os taxa mais representativos foram Chrysodeixis includens, Anticarsia gemmatalis e Spodoptera spp. O número de larvas pertencentes às espécies alvo da tecnologia Bt foram 10 vezes menores na soja Bt do que em soja não-Bt . Utetheisa ornatrix e Elaphria deltoides foram registradas na soja pela primeira vez, observando-se larvas de ambas espécies na soja não-Bt e as de U. ornatrix também na soja Bt. Somente as larvas de A. gemmatalis se correlacionaram (p <0,05) negativamente com a precipitação. Este estudo forneceu informações em campo sobre a abundância e riqueza de espécies na soja não- Bt, associada aos efeitos da soja Bt. A importância do monitoramento das lagartas é substancial, a fim de tomar a melhor decisão de controle, considerando-se os diferentes níveis de infestação entre cultivares como critério.The use of GMO expressing Bt toxin in soybean production has increased significantly in the last years in Brazil in order to manage the damage caused by lepidopteran pests. In this study, we compared the richness and abundance of owlet moths (Noctuoidea) associated with Bt and non-Bt soybean. We determined the temporal variations as a function of phenology, and correlated the population variations of the most common species with meteorological variables. The research was conducted at the experimental area of Embrapa Cerrados. The collection method used was differentiated being suppressive and absolute. A total of 13 species were collected, of which eight occurred on Bt soybeans. The most representative taxa were Chrysodeixis includens (72.87%), Anticarsia gemmatalis (18.17%) and Spodoptera spp (5.22%). The number of larvae belonging to species targeted by the Bt technology was 10 times lower on Bt than on non-Bt soybeans. Utetheisa ornatrix and Elaphria deltoides were recorded on soybean for the first time, observing larvae of both species in non-Bt soybean and those of U. ornatrix also in Bt soybean. Only A. gemmatalis larvae correlated (p <0.05) negatively with precipitation. This study provided field information on the abundance and species richness of owlet moths on non-Bt soybeans, associated with the effects of Bt soybean. When considering the different levels of infestation between cultivars as a criterion, larvae monitoring is of substantial importance in order to develop the lost control program

Comparação de duas dietas artificiais para criação de Elaphria agrotina

Com a crescente importância de Elaphria agrotina (Guenée) (Lepidoptera: Noctuidae) em cultivos de milho, especialmente no Bioma Cerrado, o presente trabalho objetivou comparar o seu desenvolvimento e sobrevivência em dieta artificial de Greene e Poitout & Bues (25±1ºC, 70±10% umidade relativa [UR] e fotofase de 12h). A dieta de Poitout & Bues foi mais adequada que a dieta de Grenne, proporcionando maior sobrevivência (77.51% e 5.57%), menor tempo de desenvolvimento (49.81 dias e 55.24 dias) e maior fecundidade (167.65 ovos e 84.9 ovos), respectivamente. Todas as lagartas alimentadas com dieta de Poitout & Bues passaram por seis instares, enquanto que praticamente metade das provenientes da dieta de Greene passou por um instar a menos. Lagartas alimentadas com dieta de Greene, apresentaram maior valor do tempo médio de cada geração (T) e menores valores das taxas líquida de reprodução (Ro), intrínseca de aumento (rm) e razão finita diária de aumento (λ). Os resultados deste estudo indicam a recomendação da dieta de Poitout & Bues para manutenção de colônias e criação massal de E. agrotina quando comparada com a dieta de Greene.Given the increasing importance of Elaphria agrotina (Guenée) (Lepidoptera: Noctuidae) in corn crops, especially in the Brazilian Savannah biome, the present research aimed to study its development and survival on Greene’s and Poitout & Bues’s artificial diets (25±1°C, 70±10% relative humidity [RH] and 12h photophase). Poitout & Bues’s diet was more suitable than Greene’s diet, providing higher survival percent (77.51% vs. 5.57%), lower development time (49.81 days vs. 55.24 days) and higher fecundity (167.65 vs. 84.9 eggs), respectively. All the caterpillars reared on Poitout & Bues’s diet passed through six instars, while almost half of the larvae reared on Greene’s diet went through one less instar stage. Regarding the main reproductive parameters, higher average time of generation (T) and lower values of net rates of reproduction (Ro), and increased (rm) intrinsic and finite reason of increase (λ), were observed for larvae reared on Greene’s diet. Results presented in this study indicated that Poitout & Bues’s diet is more suitable for maintenance of colonies of E. agrotina as compared to Greene’s diet

Potencial reprodutivo de Spodoptera eridania (Stoll) (Lepidoptera: Noctuidae) em laboratório : efeito de múltiplos casais e do tamanho

Este estudo objetivou avaliar o efeito de confinar três casais em cada gaiola e o tamanho de adultos emergidos de pupas pequenas, medias e grandes (278,67 mg, 333,20 mg e 381,58 mg, respectivamente), sobre o potencial reprodutivo de S. eridania (Stoll, 1782), em condições controladas (25 ± 1 °C, 70% UR e 14 horas de fotofase). Avaliou-se a sobrevivência, o número de cópulas, fecundidade e fertilidade dos adultos. A sobrevivência não diferiu significativamente entre fêmeas provenientes de pupas de diferentes tamanhos, mas os machos oriundos de pupas grandes tiveram sobrevivência significativamente menor que os demais tamanhos. A fecundidade diferiu significativamente e correlacionou-se positivamente com o tamanho. O número de cópulas (espematóforos) e a fertilidade não variaram em função do peso pupal. Os resultados enfatizam a importância de indicar o número de cópulas e o tamanho dos insetos estudados para que comparações entre os parâmetros reprodutivos possam ser efetuadas.This study aimed to evaluate the effect of keeping three couples in the same cage, and the size of adults emerged from small, medium-sized and large pupae (278.67 mg; 333.20 mg and 381.58 mg, respectively), on the reproductive potential of S. eridania (Stoll, 1782) adults, under controlled conditions (25 ± 1 °C, 70% RH and 14 hour photophase). We evaluated the survival, number of copulations, fecundity and fertility of the adult females. The survival of females from these different pupal sizes did not differ statistically, but the survival of males from large pupae was statistically shorter than from small pupae. Fecundity differed significantly and correlated positively with size. The number of effective copulations (espematophores) and fertility did not vary significantly with pupal size. Our results emphasize the importance of indicating the number of copulations and the size of the insects when reproductive parameters are compared

Divergência genética entre acessos açucarados e não açucarados de mandioca

The objective of this work was to estimate the genetic divergence among sugary and nonsugary cassava accessions, through molecular markers, and quantitative and qualitative characters, as well as to determine the correlation among these estimates. Four sugary cassava accessions and four nonsugary ones were used, including two landraces and two nonsugary improved varieties. The accessions were evaluated in field conditions and in laboratories, with RAPD markers, in 12 quantitative and 33 qualitative characters. Matrixes of genetic dissimilarity/distance among accessions were estimated, based on qualitative and quantitative characters, molecular markers, and on the correlation significance among matrixes. High genetic divergence among the evaluated accessions was observed, the sugary accessions were differentiated from the landraces and improved nonsugary varieties. The distances estimated through molecular markers and qualitative characters showed the high association among each other and moderate association with the distance estimated through quantitative characters.O objetivo deste trabalho foi estimar a divergência genética entre acessos de mandioca açucarados e não açucarados, por meio de marcadores moleculares, caracteres quantitativos e qualitativos, bem como determinar a correlação entre essas estimativas. Foram utilizados quatro acessos de mandioca açucarados e quatro não açucarados, com duas variedades locais e duas comerciais. Os acessos foram avaliados em campo, em laboratório, com marcadores RAPD, quanto a 12 caracteres quantitativos e 33 morfológicos. Foram estimadas as matrizes de dissimilaridade/distância genética entre os acessos, por meio dos caracteres qualitativos e quantitativos e da significância da correlação entre as matrizes. A divergência genética entre os acessos foi elevada e os acessos açucarados foram diferenciados das variedades não açucaradas locais e comerciais. As distâncias estimadas, por meio de marcadores moleculares e caracteres qualitativos, evidenciaram elevada associação entre si e associação moderada com a estimada por meio de caracteres quantitativos