Integrated Management of Chrysodeixis chalcites Esper (Lepidoptera: Noctuidae) Based on Trichogramma achaeae Releases in Commercial Banana Crops in the Canary Islands

Abstract

Chrysodeixis chalcites is one of the major pests on banana in the Canary Islands (Spain), where it is widely distributed and causes significant economic losses when larvae feed on developing leaves and fruits. Control of this pest is based on a limited number of pesticides, as growers lack other effective solutions, including biological control. Nevertheless, previous studies have shown some potential against C. chalcites of the egg parasitoid Trichogramma achaeae. We conducted two field trials over two consecutive years in commercial banana crops, comparing the results against C. chalcites of augmentative T. achaeae releases (IPM) and conventional chemical control. In total, 215 and 366 wasps/m2 were released in 2016 and 2017, respectively. Naturally occurring Trichogramma species contributed to C. chalcites control in both treatments, but the maximum number of parasitized eggs in IPM plots nearly tripled and doubled those recorded in chemical control plots in 2016 and 2017. Thus, T. achaeae releases significantly increased the parasitism by more than 10% compared to that observed in chemical control plots, amounting to 65.6 ± 7.7% and 56.7 ± 5.8% in 2016 and 2017, respectively. This was enough to keep the pest at tolerable levels in IPM plots, avoiding the need for pesticide applications, whereas in chemical control plots, repeated applications were needed during the experiment for that. Moreover, there were not significant differences in the abundance of larvae and severity of plant damage (<6% in 2016 and <12% in 2017), even when pest pressure in 2016 was two-fold greater in IPM plots. Fruit damage was also similar between treatments in 2016 (<2%) but was significantly reduced from 5.1 ± 1.5% in chemical control to 4.2 ± 1.4% in IPM in 2017. Overall, this study provides guidelines for the biological control of C. chalcites in banana, based on augmentative releases of T. achaeae, and demonstrates that this method can be effective, constituting an environmentally and sustainable alternative to conventional chemical control for banana growers.