Dinâmica populacional diurna e seletividade de inseticidas para Geocoris spp. (Hemiptera: Geocoridae), Zelus spp. (Hemiptera: Reduviidae) e Solenopsis spp. (Hymenoptera: Formicidae) na cultura da soja

Abstract

Predatism is a determining factor for the control of pest populations. Therefore, understanding the behavior of predators in the field is fundamental within a conservation strategy of Biological Control. Insecticides are phytosanitary pesticides that play an important role in protecting plants from attack by pests. On the other hand, problems may arise from the use of non-selective insecticides to natural enemies, such as the resurgence of primary pests, an increase in secondary pests and a contribution to the problem of pest resistance. However, even if the innocuousness of a product can be defined in the laboratory, it is under field conditions that toxicity can be confirmed, where species of natural enemies find natural conditions for shelter, protection, escape alternatives, food and survival. In the first chapter, the experiment aimed to analyze the behavior of three soybean pest predators (Geocoris sp., Zelus sp. And Solenopsis sp.) Regarding abundance, relative dominance and diurnal temporal distribution. In the second chapter, the two experiments aimed to apply and validate the experimental methodology of selectivity tests proposed by the Brazilian Soy Research Commission and to evaluate and classify the most widely used insecticides regionally in terms of selectivity to predatory arthropods in soybean culture. The experiments in the two chapters were conducted at the Experimental Farm of Agricultural Sciences (FAECA / UFGD). The experimental design of the study of temporal population dynamics of the three species mentioned above was that of randomized blocks with 5 treatments and 4 blocks (4 repetitions over time). In the two experiments of selectivity of insecticides, the design was that of randomized blocks with 5 treatments and 5 repetitions. In the study of temporal population dynamics (ch. 1) the most abundant species were: Zelus sp. (37%); Geocoris sp. (27%) and Solenopsis sp. (27%). The most dominant predators, according to the Simpson Index, were: Geocoris sp., Followed by Zelus sp. and Solenopsis sp. No significant differences were found regarding the diurnal temporal distribution for the foraging of Zelus sp. Geocoris sp. has preference for foraging after 3pm. The foraging rate of Solenopsis sp. increases from 17h. In the insecticide selectivity experiments (chap. 2), the most abundant arthropod-predator taxa in the first experiment were: Solenopsis sp. (47%), Geocoris sp. (16%) and Zelus sp. (9%). In the second experiment, the most abundant arthropod predators were: Zelus sp. (79%), Geocoris sp. (6%) and Solenopsis sp. (4%). Proclaim® 50 WG and Premio® 200 SC were the most selective insecticides to the predator complex. It is concluded that the methodology is valid to discriminate the impact of insecticides to natural enemies occurring in the field, in the short term, which contributes to the implementation in Integrated Pest Management.