Biologia comparada de Euschistus heros (Fabr.) E Nezara viridula (L.) (Hemiptera: pentatomidae) em soja Glycine max (L.) e algodoeiro Gossypium hirsutum (L.)

Abstract

Soybean (Glycine max L.) and cotton (Gossypium hirsutum L.) cultures are considered of great socio-economic importance in the Brazilian Cerrado. These crops are susceptible to attack by insect pests, among which stand out, the complex of phytophagous stink bug family Pentatomidae. In the culture of cotton these Pentatomidae had casual occurrence of secondary importance, and exercised, however, in recent harvests increased in frequency and intensity of these insects in cotton fields. The overall objective of this research was to determine the influence of reproductive structures of cotton on the biological aspects of stink Euschistus heros (Fabr.) and Nezara viridula (L.) (Hemiptera: Pentatomidae). The experiments were conducted in a room [25 ± 1 ° C (RH) of 60 ± 10% and photophase of 14 hours], the Laboratory of Applied Entomology, at Universidade Federal da Grande Dourados, in Dourados, Mato Grosso do Sul, Brazil. Nymphs and adults of E. heros and N. viridula were raised on six different foods composed of the reproductive structures of cotton and soybean: a standard diet (kidney bean pods, Phaseolus vulgaris L.+ raw peanuts, Arachis hypogaea L. + privet fruits, Ligustrum lucidam T.); soybean seeds; soybean pods; cotton seeds; cotton bolls; and the floral buds of cotton. The biological aspects of these insects were evaluated, including: nymphal development; the duration of each instar; percentage survival; adult weight at emergence; male and female longevity; the lengths of the periods of preovipositioning and ovipositioning; total number of eggs per female; and female fertility. The development and survival of nymphs as well as the weights and reproduction of adult individuals of E. heros fed with cotton bolls and seeds were inferior to those fed with soybeans. The cotton floral buds did not allow the development of nymphs nor the reproduction of the adults of E. heros, and cotton plant structures caused high nymph mortality and low adult fertility. Nymphs of N. viridula fed on reproductive structures of cotton plants died in the second or third instar. The development of nymphs N. viridula was better in soybean than in cotton. Adults of this insect fed on flower buds and seed cotton did not reproduce. Adults of N. viridula reproduce when fed apple cotton, however, no development of this food nymphs. Cotton was therefore observed to be an inadequate host for the development and reproduction of E. heros, and this study suggests that it may only occasionally disperse to this plant in search of shelter. Generally, this information is important to increase the likelihood of success in the management of populations of E. heros and N. viridula soybean and in particularon cotton, since there is a possibility that over time an adjustment occurs suchPentatomidae this new host.