Direct and Indirect Effect of Bt Cotton and No Bt Cotton on the Development and Reproduction of the Predator <i>Podisus nigrispinus</i>(Dallas, 1851) (Hemiptera: Pentatomidae)

This paper aimed to evaluate the direct and indirect effects of Bt cotton and no Bt cotton on the development and reproduction of the predator Podisus nigrispinus (Dallas). The experiments related to the direct and indirect effects on immature and adult stages of the predator were conducted, respectively, in greenhouse and laboratory of the Embrapa Agropecuária Oeste in Dourados, Mato Grosso do Sul State, Brazil. To evaluate the indirect effects of Bt cotton and non-Bt, larvae of Spodoptera frugiperda (Smith) were fed with these plants and later offered to the predator. To evaluate the direct effect of the Bt cotton and non-Bt, the predator P. nigrispinus was kept in contact with these plants and fed with pupae of Tenebrio molitor (L.). The direct and indirect effects were evaluated by the biological parameters as follows: period of nymphal development, nymphal survival, and duration of pre-oviposition and oviposition periods and longevity of adults (females and males) of P. nigrispinus. It was observed higher period of second instar of P. nigrispinus in Bt cotton, when compared to the development in its isoline non-Bt. All other biological parameters evaluated, have no influence of the Bt cotton plants considering the direct and indirect effects.

Population Fluctuation and Vertical Distribution of the Soybean Looper (<i>Chrysodeixis includes</i>) in Soybean Culture

The objective of this work was to study the population fluctuation and the vertical distribution of the Chrysodeixis includes (Walker) (Lepidoptera: Noctuidae) in the leaf canopy of soybeans. The experiments were conducted under field conditions in the experimental area of the Embrapa Agropecuária Oeste during the 2014/2015 harvest. Adult monitoring was performed using Delta-type traps, baited with the pest sexual pheromone. The eggs were collected in the soybean plants and the caterpillars monitored through the beat cloth. The population peaks of C. includes occurred in the reproductive period of the soybean plants, although the adults were also found in the season soybean. Although there was no significant relationship between the trapped adults and the immature forms of C. includes sampled with the beat cloth, a significant linear and positive relationship was found between the egg and caterpillar densities of the pest in the culture. Adults preferentially oviposited on the lower part of the soybean plants, while the caterpillars preferred to position themselves predominantly in the lower and mid region of the plants. However, at warmer temperatures during the day, the caterpillars migrate to the upper areas of the soybean plants.