New perspective on the role of Doru luteipes as a predator of the fall armyworm: Non-consumptive effects, predatory preference and functional response

Abstract

In Brazil, the common earwig Doru luteipes (Scudder) (Dermaptera: Forficulidae) is considered an important biocontrol agent for the maize crop, consuming the fall armyworm Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) eggs and caterpillars from 1st to the 3rd instar. Despite this, several aspects of the interaction between these species have not yet been studied. We aim to evaluate the non-consumptive effects of earwigs on the oviposition of moths, the earwig's predatory preference between eggs and neonates and its functional response to S. frugiperda eggs. In no-choice tests between plants with or without the presence of the predator, S. frugiperda moths deposited a smaller number of eggs on plants with risk of predation. In choice-based tests, earwigs initially attacked newborn caterpillars, but preferred to feed on eggs. Males and females fed more on eggs with increasing supply density and consumption was adjusted to the type II functional response curve. D. luteipes males were more efficient predators than females when exposed to higher egg densities. These findings clarify aspects of the predatory role of D. luteipes on S. frugiperda that had not yet been addressed and suggest that the earwig has potential for impacting the colonization and population growth of S. frugiperda in maize crops, if conditions are favourable to its early arrival.