População de insetos associados ao feijão-caupi na presença de vegetação espontânea

Abstract

Due to the high demand for food production, agricultural systems require sustainable strategies aimed at maintaining ecosystem balance. One alternative for pest control is environmental management using spontaneous plants capable of providing resources essential for the conservation of natural enemies. Thus, this study aimed to evaluate the composition of spontaneous plants and their effect on insects associated with cowpea crops. The study was conducted at the Teaching Farm and the Entomology Laboratory of the Department of Crop Science and Plant Protection at the State University of Maranhão (UEMA) in São Luís, Maranhão. Cowpeas of the 'Manteiguinha' variety — characterized by an indeterminate growth habit — were planted in an experimental area measuring 29.0 m by 29.0 m, which was divided into plots. A randomized complete block design (RCBD) was used, comprising six treatments and five replications. The treatments consisted of different weeding intervals: no weeding, and single weeding events at 7, 14, 21, 28, and 35 days after cowpea emergence. Sampling of the insect fauna was carried out on both the cowpea plants and the spontaneous vegetation; the floristic composition of the spontaneous plants was also assessed, and Shannon diversity (H’) and species richness (S) indices were calculated. The presence of spontaneous plants, by diversifying the environment, contributed to the presence of natural enemy families that may exhibit varying feeding preferences and habits unrelated to their primary prey or hosts; this suggests an increase in the functional diversity of the agricultural landscape and an enhancement of biological pest control services. Given the conditions observed in this study, the data suggest that the spontaneously growing plants Mentrasto and Apaga-fogo can be managed within agroecosystems to preserve and increase beneficial insect populations; they provide the resources necessary for these organisms' survival and reproduction — such as pollen, nectar, and alternative prey — while also serving as sites for shelter, mating, and egg-laying.