Conservation biological control of coffee leaf miner: role of green lacewings and parasitoids
Authors:   , Martins Elem Fialho 
Published: March 2024

Coffee leaf miner, Leucoptera coffeella, is a key coffee pest in the Neotropics. The larvae feed on the parenchyma between surfaces of coffee leaves causing decrease of the photosynthesis rate leading to significant losses in yield and in the longevity of coffee plant. Several natural enemies are involved in coffee leaf mine biological control, such as wasps, ants, parasitoids and green lacewings. However, normally their populations are not enough to decrease or to maintain the coffee leaf mine populations below threshold levels in coffee monocultures, due to their dependence on resources, such as pollen and nectar, which are scarce in conventional systems. The association of plant species to coffee crops might represent an effective strategy through the provision of alternative food and refuge for natural enemies. I investigate here whether the diversification of Coffea arabica crops with Inga edulis “erva-baleeira”, Varronia curassavica “inga”, Senna macranthera “fedegoso” and non-crop plants favors the biological control of coffee leaf miner by its predators and parasitoids. These plants can provide resources such as nectar and pollen constantly, shelter and oviposition and mating sites for natural enemies with either extrafloral nectaries (I. edulis and S. macranthera) and/or inflorescences (V. curassavica). Firstly, we performed laboratory experiments to evaluate whether the immature stages of the green lacewing Ceraeochrysa cubana are able to prey on the immature stages of coffee leaf miner (Chapter I). Larvae of C. cubana successfully prey on eggs and pupae of coffee leaf miner, being the first report about green lacewing predation on the pest eggs. We also investigate whether V. curassavica provides selective resources to C. cubana without benefiting coffee leaf miner adults (Chapter II). Larvae of C. cubana survived longer in the presence of V. curassavica inflorescences, and decrease the population growth rate of the pest. In the field, we evaluated the visitors of the inserted plants and whether the strategic diversification with I. edulis, S. macranthera and V. curassavica added to non-crop areas under management of no pesticide use influence the abundance and richness of predatory green lacewings and wasps, increase the parasitism and control coffee leaf miner compared to conventional coffee systems (Chapter III). I found that ants are the most abundant visiting insects of I. edulis, S. macranthera and V. curassavica. In addition, I found that although there was no significant difference in the abundance of green lacewings and wasps between systems, parasitism rate was higher in the diversified. Despite that, there was no difference in the pest infestation comparing to conventional coffee systems in 2019 and 2021, but in 2020 it was higher in the diversified. However, CLM populations did not reach threshold in any system. Our study demonstrates through laboratory and field experiments that it is possible to improve the biological control of coffee leaf miner with safe strategies to environment and humans, in addition to maintaining biodiversity in coffee agroecosystems. Keywords: Leucoptera cofeella. Conservation biological control. Ceraeochrysa cubana, Varronia curassavica