Integração de bioinseticidas com inseticidas químicos no controle de mosca-branca (Bemisia tabaci) na cultura da soja

Abstract

One of the significant challenges in soybean production is pest control, with the whitefly (Bemisia tabaci) being particularly noteworthy. Categorized as a pest with high phytosanitary risk, the whitefly is considered one of the primary threats to soybeans. Managing the whitefly poses a considerable challenge, primarily due to its relatively short life cycle, high reproductive rate, and its nature as a polyphagous pest. These characteristics make it willing to evolve resistance to chemical insecticides commonly used for its control. In this context, biological control has emerged as a crucial agent for innovation and sustainability on whithefly management. Thus, our goal was to assess the effects of bio insecticides (entomopathogenic fungi and plant extracts) applied alone and in combination with chemical insecticides to manage whitefly on soybean. Two experiments were conducted, with 14 treatments tested under field and laboratory conditions. In the field, treatments involved two sprays, with a 10-day interval. Treatments effectiveness was evaluated on nine dates through evaluating the adults and nymphs of whitefly. In the lab, treatments were tested by immersing leaves in the insecticide solution, and effectiveness was assessed on seven dates. Randomized block and completely randomized designs were employed for field and lab experiments, respectively. Both followed a two-factor model, and the interaction between the analyzed factors (insecticide treatments x evaluation times) was significant for both experiments. In the field trials, all treatments exhibited positive effect in the control of whiteflies, with particular emphasis on the mixed group (bioinsecticide + chemical insecticide), showing significant mortality on both stages of B. tabaci on all evaluation dates. Notably, the strain ESALQ 1296 of Isaria fumosorosea, combined with the dinotefuran + piriproxyfen, achieved an average efficiency of 91.9% in the adults control of B. tabaci. However, on B. tabaci nymphs control, the strain ESALQ PL63 of Beauveria bassiana mixed with dinotefuran + Pyriproxyfen reached the highest control efficiency (78.1%). Among entomopathogenic fungi, the strain PL 63 of Beauveria bassiana exhibited the highest average efficiency (83.6%) in the adult control, while the strain ESALQ 1296 of Isaria fumosorosea showed the highest control on nymphs (67.6%) of B. tabaci. Between the plant extracts, the extract from the fruit of Trichilia claussenii showed the highest control averages (88.6% and 69.2% for adults and nymphs of B. tabaci, respectively), statistically standing out positively and distinguishing itself from the others. In lab trials, all treatments achieved 100% control of B. tabaci after 7 days. The observed high efficiencies demonstrate biological insecticides are crucial positive allies in the whitefly control in soybeans, reducing costs, mitigating insect resistance selection, and minimizing environmental impacts.