Host marking pheromone and GF120TM applied in a push–pull scheme reduce grapefruit infestation by Anastrepha ludens in field-cage studies

Abstract

Conventional fruit fly control via insecticides or the combination of a bait and an insecticide rarely achieves optimal results and faces mounting pressure due to its negative environmental impact. Host marking pheromones (HMPs) represent a biorational alternative that can be used as a repellent (‘push’) either alone or in combination with a lethal bait spray such as GF120TM (‘pull’) to enhance fruit fly control efficacy. Here, we tested the synthetic HMP (Anastrephamide) of Anastrepha ludens in combination with a laced protein bait, to reduce grapefruit infestation in field-cage studies and evaluate the effectiveness of a ‘push–pull’ system. GF120TM and four Anastrephamide concentrations were used: 2.5, 5, 10, and 20 g active ingredient (AI) per 100 L of water. Our control was spraying only water. ‘Push,’ ‘pull,’ and ‘push–pull’ approaches were tested by treating only one-half of the canopy with Anastrephamide (‘push’) or only with GF120TM (‘pull’), or one-half with Anastrephamide and the other with GF120™ (‘push–pull’ system). The ‘push–pull’ system worked well, as A. ludens ovipositions were mostly recorded in the GF120TM-treated half. Regardless of the deployment strategy, the highest reduction in A. ludens infestation was obtained with 5 g AI/hl Anastrephamide, reaching efficacies (Abbott index) of 63/65% (reduction in infested fruit) and 64/61% (reduction in mean larvae and pupae/fruit) in the ‘push’ and ‘push–pull’ approaches, respectively. Several hurdles still need to be overcome, as fly behavior is more complex than originally envisioned, and a more efficient attractant is needed to increase the power of the ‘pull’ part of the system.