Thermal requirements and estimation of the number of generations of Leucoptera coffeella (Guérin-Méneville, 1842) (Lepidoptera: Lyonetiidae) in Minas Gerais state, Brazil

Abstract

Unfavorable climate conditions with asynchronous rainy periods and relatively high temperatures during 2019 led to increasing outbreaks of Leucoptera coffeella in some coffee-producing regions of Minas Gerais. L. coffeella is one of the most significant insect pests of coffee crops worldwide. The present study used the thermal requirements of L. coffeella to determine the climatic zones that favor its development in Minas Gerais. Biological experiments on L. coffeella were conducted in the laboratory and in the field. In the laboratory, L. coffeella was studied in incubators at 18, 22, 25, 28, 30, 32 and 35 ± 1 °C, 65 ± 10% RH, a photoperiod of 14:10 h [L:D] and with leaves from C. arabica, var. Obata. In the field, 125 eggs were collected from 18 of the 24 total leaves on each branch, for a total of 500 eggs. The results indicated a temperature threshold (Ttemp) of 13.6 °C and a thermal constant (K) of 228.5°-days. This laboratory estimate of thermal requirements and the Geographic Information System (GIS) were combined to generate insect life-span distribution maps for Minas Gerais. In this state, the coffee leaf miner can produce approximately 8–16 generations annually, and thermal conditions are suitable year-round for L. coffeella attack; however, population dynamics are modulated by rainfall. The biological data for L. coffeella obtained in the laboratory were similar to those found in the field. This information could be used in integrated pest-management programs to forecast L. coffeella outbreaks and population growth based on favorable thermal conditions and monthly rainfall distribution, which in turn could be used to define zones for this pest under different climatic conditions.