Effect of cowpea (Vigna unguiculata L. Walp.) sowing season on population dynamics of pest insects

Abstract

Several factors limit cowpea quality and yield, such as the choice of a cultivar better adapted to the region, the ideal sowing season, as well as diseases and pests. Aimed to evaluate the effect of different sowing seasons on the population dynamics of pest insects of cowpea crops. The study was carried out during the dry season, the rainy season, and the season recommended for sowing by the Experimental Farm of the Federal University of Amazonas (FAEXP-UFAM), Brazil. A total of 33 weekly collections were carried out during the three sowing seasons, distributed in two ways according to the phenological stage of the crop: manual collection per linear meter of plantation and entomological scanning net. The faunistic analysis detected the pest insects Acromyrmex laticeps nigrosetosus, Cerotoma arcuata, Crinocerus sanctus, Euschistus heros, Horciasinus signoreti, Liriomyza sativae, and Nezara viridula. Of these species, H. signoreti stands out for being recorded for the first time as predominant in cowpea crops in the Brazilian state of Amazonas. Infections by hemipterans such as C. sanctus, E. heros, H. signoreti, and N. viridula were detected throughout the study, regardless of the sowing season, except for H. signoreti, which was dominant in all three seasons. The highest infestation of C. arcuata occurred during the recommended sowing season for cowpeas (June to August). According to the Jaccard index, plantation I e II share 86% of the species. This study provides important information to programs in insect control and management and to the agronomic decision-making process.