Atividade de diferentes moléculas inseticidas sobre Leucoptera coffeella (Lepidoptera: Lyonetiidae) e seletividade sobre Chrysoperla externa (Neuroptera: Chrysopidae) em cafeeiro

Abstract

The leaf miner Leucoptera coffeella (Guérin-Mèneville, 1842) (Lepidoptera: Lyonetiidae) is among the main pests of the coffee tree (Coffea arabica L.). The larvae attack the leaves of the coffee tree, causing losses of up to 80% in productivity when in high infestations. For its control, integrated management presupposes the association of several management tactics, however, chemical control is the most used. It is based on the use of systemic insecticides, applied by soil, preventively and spraying on the aerial parts of the plants, preferably with selective insecticides for the population of natural enemies, as advocated by the philosophy of the MIP. The objective of this work was to evaluate the efficiency of associations and doses of different insecticide molecules, for the preventive and curative control of the leafminer bug, as well as the effects on the Chrysoperla externa (Neuroptera: Chrysopidae) population, under field conditions. The experimental design was a randomized block with nine treatments and four replications, with each plot consisting of a 10 m long crop row. The treatments were: control; chlorfenapyr + chlorantraniliprole at doses of 114 g + 20 g a.i., 180 g + 25 g a.i. ha-1 and 216 g + 30 g a.i. ha-1; cyantraliprol + acetamiprid at doses of 100 g + 80 g a.i. ha-1; novaluron + chlorantraniliprole at doses of 52.4 g + 60 g a.i. ha-1; bifenthrin + sulfoxaflor at doses of 150 g + 125 g a.i. ha-1; spinetoram methoxyfenozide at doses of 15 g +75 g a.i. ha-1; and indoxacarb + novaluron at doses of 120 g + 40 g a.i. ha-1. The experiment was installed in June 2021. The application was performed with a motorized knapsack sprayer (YAMAHO LS - 937), equipped with an empty cone tip (TXVK6) and a syrup volume of 400 L.ha-1. Evaluations were performed at 15 and 30 days after application. To evaluate the preventive effect of insecticides, five branches on each side of the plot were marked with colored tape with no symptoms of leaf minerworm attack. To evaluate the curative effect, 50 leaves were collected randomly from each side of the plot and taken to the laboratory, where the number of active mines and the number of live mineworm larvae were counted. The evaluation of the impact of treatments on the Chrysoperla externa population was done by counting the insects in flight after turning over each plant in the plots, after which the percentage of mortality was calculated and the insecticides were classified into toxicity classes, according to the recommendations suggested by the IOBC (International Organization for Biological and Integrated Control of Noxious Animals and Plants). High efficiencies were presented by the association of spinetoram 15 g i.a. ha-1 + methoxyfenozide 75 g i.a. ha-1 (250 mL p.c. ha-1). The association of chlorfenapyr 180 g i.a. ha-1 + chlorantraniliprole 25 g i.a. ha-1 at a dose of 1000 mL p.c. ha-1, showed better results for preventive and curative control of L. coffeella. The tested treatments showed little effect on the population of C. externa.