Mite damage provides refuges and affects preference and performance of a subsequent herbivorous moth

Damage by herbivores often modifies plant structure and physiology, which may change the behaviour and performance of future herbivores. Here, we studied such interactions among the major coconut pest, the mite Aceria guerreronis (Acari: Eriophyidae), and two minor pests, the mite Steneotarsonemus concavuscutum (Acari: Tarsonemidae) and the moth Atheloca bondari (Lepidoptera: Pyralidae). All these species develop in the meristematic zone of coconuts, which is difficult to access because of the small opening between the epicarp and perianth. Both mites cause necrosis on the epicarp of the nuts, which may facilitate access to the meristematic zone by caterpillars of the moth. However, the caterpillars co-occur predominantly with A. guerreronis and not with S. concavuscutum. We show that caterpillars did not colonize nuts without mites and colonized nuts with A. guerreronis most frequently, in agreement with the openings caused by this mite and caterpillar size. When the opening between epicarp and perianth was artificially increased, caterpillars also colonized nuts without mites and nuts with S. concavuscutum. When offered a choice, caterpillars preferred nuts with easy access to the meristematic region, regardless of the presence of mites. Caterpillars performed better on the A. guerreronis-infested nuts than on other nuts, but moth females did not preferentially oviposit in coconut bunches infested with mites. Hence, caterpillars, not adults, select suitable feeding sites within a bunch of coconuts, and A. guerreronis facilitates the infestation of coconuts by A. bondari. We discuss how damage by mites affects the relevance of A. bondari as a coconut pest.