Evaluating the effect of alternative hosts in Drosophila suzukii infestation in cherry orchards

Drosophila suzukii (Matsumura) is known to be an emerging and invasive pest presenting a wide distribution abroad. It arrives in Southern Chile in 2017, and two years later was detected in the Central Valley. The understanding of insect species' behavior, according to local weather conditions and landscape composition, is fundamental for the proper design of long-term pest control strategies. In Chile, there are 29 confirmed host plants, and of them, 16 belong to non-crop species. Thus, the occurrence of alternative host plants located close to the crops can increase the risk of infestation because they provide a suitable microclimate, food, and shelter. In this study, we addressed the effect of alternative hosts in the landscapes surrounding cherry production fields, on the presence of D. suzukii infestation, from six localities in the O´Higgins region in the Central Valley of Chile. We characterized four host plant species, from the genus Rubus, Vaccinium, Hedera, and Crataegus, by phenological monitoring, trapping, and fruit sampling. Preliminarily, we found that cherry orchards with alternative host plants showed a significantly higher number of flies in the trap captures but differs among non-crop host plants. We propose a risk assessment of D. suzukii infestation for the “occurrence of alternative host” factor. The proper characterization of the landscape, and particularly, the occurrence and phenology of host plants can estimate the risk of infestation, helping in improving pest control decisions and finally, reducing the impact of this pest.