The relationships between the development of Hylesinus taranio (Dantoine) (Coleoptera, Curculionidae, Scolytinae) and the olive grove phenology predict the emergence of the bark beetle adults

Abstract

Considering the cryptic life cycle of Hylesinus taranio (Dantoine), the prediction of adult emergence is the first step to establish the optimum timing for its management. The fieldwork was carried out over four years (2016 - 2019) in Lécera (Zaragoza, Spain). H. taranio was monitored from early April in larval phase until adult emergence in June when all pupal chambers were empty. The H. taranio development and the olive grove phenology were the variables considered to test whether there is a relationship between them. The strength of this relationship and the uncertainty coefficient were assessed. The most significant relationships (p < 0.001) were examined, being the association pupae/corolla coloration change and pupal chamber empty/freshly formed fruits those which show the highest contribution percentage to the relationship. The results substantiate that the olive grove phenology predicts the H. taranio development, becoming an easy strategy for the farmer to predict the adults on release, which could to decide the optimum timing of H. taranio management by only watching for olive grove phenophases. Accordingly, some management measures are suggested for reducing the density of H. taranio in the olive groves.