ABSTRACT
ABSTRACT Cotton is an alternative host for Edessa meditabunda (Hemiptera: Pentatomidae), especially after the soybean harvest in surrounding areas, when large numbers of insects invade cotton fields and damage reproductive structures such as flowers and developing bolls. However, no studies on its occurrence and spatial distribution have been conducted in cotton. Therefore, this study was aimed to assess the temporal variation and spatial distribution of E. meditabunda in the alternative host plant, Gossypium hirsutum. The study was carried out in an area of 1.1 ha planted with cotton that was divided in 64 plots of 169 m2 each, where entire cotton plants were examined weekly and E. meditabunda nymphs and adults were counted. Dispersion rates and theoretical frequency distributions were calculated and analyzed with significance level at 5%. Assessments were carried out from seedling emergence until the appearance of bolls, but E. meditabunda was present only during the reproductive stage of cotton plants. This study detected the dispersal of this stink bug from late-cycle soybean fields to cotton, indicating cotton's potential as an alternative host plant, providing shelter and food. Based on aggregation indices, the spatial distribution of nymphs and adults in cotton was aggregated at the beginning of the infestation, but tended toward randomness as bolls reached maturity. The occurrence of E. meditabunda in cotton was best described by the Poisson distribution with significance level at 5%.
ABSTRACT
O percevejo-asa-preta-da-soja Edessa meditabunda (Fabricius) (Hemiptera: Pentatomidae) dispersa para o algodoeiro e utiliza essa planta como hospedeiro alternativo, após colonizar e multiplicar-se nas áreas de soja circunvizinhas. Visando conhecer o potencial desta espécie como praga em algodoais e auxiliar na tomada decisão quanto ao manejo deste inseto, hipotetizou-se nesse trabalho que o algodoeiro é nutricionalmente adequado para a reprodução e desenvolvimento de E. meditabunda. Os tratamentos testados foram: 1) folhas e maçã de algodoeiro e 2) dieta padrão, recomendada para criação de pentatomídeos fitófagos em laboratório, utilizada como testemunha. As características biológicas avaliadas foram: período de desenvolvimento ninfal, duração de cada ínstar, porcentagem de sobrevivência, peso dos adultos na emergência, longevidade de machos e de fêmeas, período de pré-oviposição e de oviposição, número total de ovos por fêmea e fecundidade das fêmeas. Observou-se que, apesar do prolongamento do período de desenvolvimento ninfal, as ninfas alimentadas com algodoeiro sobreviveram, atingiram a fase adulta e os adultos se reproduziram, o que nos permite sugerir que o algodoeiro seja uma planta nutricionalmente adequada para o desenvolvimento e reprodução de E. meditabunda, permitindo a manutenção do inseto em campo após as colheitas da soja.
At the end of soybean crop cycle, the Brown-winged stink bug Edessa meditabunda (Fabricius) (Hemiptera: Pentatomidae) scatter to cotton fields using this plant as an alternative host. In order to know if this specie has potential as a cotton pest and to help its management it was hypothesized that cotton is nutritionally adequate for reproduction and development of E. meditabunda. The tested food sources were: 1) cotton bolls and leaves, and 2) standard diet recommended for laboratory rearing of phytophagous pentatomids, used as control treatment. The following biological parameters were evaluated: nymph developmental time, instar duration, survivorship percentage, adult weight at emergence, male and female longevity, duration of pre-oviposition and oviposition periods, total amount of eggs laid by each female, and female fecundity and fertility. Even with an extended nymphal development time, we observed that nymphs fed on cotton structures survived and reached adulthood and the adults reproduced. The results allow us to suggest that cotton is a plant nutritionally suitable for development and reproduction of E. meditabunda, and it allows the insect maintenance in the field after soybean harvests.
El chinche Edessa meditabunda (Fabricius) (Hemiptera: Pentatomidae) al final del ciclo de la soja emigra al cultivo de algodón y utiliza esta planta como un huésped alternativo. Con el objetivo de conocer el potencial de esta especie como una plaga en los algodonales y ayudar en la toma de decisiones con respecto al manejo de este insecto, se planteó la hipótesis en este estudio que el algodón es nutricionalmente adecuado para la reproducción y el desarrollo de E. meditabunda. Los tratamientos fueron:1) las hojas y el fruto del algodón 2) dieta estándar recomendada para la cría de pentatómidos fitófagos en el laboratorio, utilizada como testigo. Los parámetros biológicos fueron: tiempo de duración de ninfa, duración de cada instar, porcentaje de sobrevivencia, peso de los adultos en la emergencia, longevidad de machos y hembras, periodo de pre-oviposición y oviposición, número total de huevos por hembra y fecundidad de las hembras. Se observó que a pesar que el período de desarrollo de ninfa es prolongado, las ninfas que se alimentaban de plantas de algodón sobrevivieron, alcanzando la fase adulta y reproducción de adultos, lo que nos permite sugerir que la planta de algodón es nutricionalmente adecuada para el desarrollo y la reproducción de E. meditabunda, lo que permite la presencia del insecto en el campo después de la cosechas de la soja.