Multiple lines of anti-predator defence in the spotted lanternfly,Lycorma delicatula(Hemiptera: Fulgoridae)

Abstract

Many species have evolved a suite of anti-predator defences, rather than a single defence. These multiple defences may operate in synchrony or separately at different stages of predation sequence to protect the prey. However, empirical documentation on how multiple defences, as a whole, combine to protect prey, as well as quantitative evaluations of how and when they are deployed, are scarce. In the present study, we investigated the univoltine spotted lanternfly, Lycorma delicatula, which has cryptic forewings, defensive chemicals, and multiple behavioural defences, including rapid jumping away, sudden display of its conspicuous hindwings and abdomen (a startle/deimatic display), and death feigning. The aims of the present study were to: (1) characterize the modality of sensory stimuli that trigger the behavioural defences; (2) identify the stage(s) of the predation sequence in which L. delicatula employs each behavioural defence; and (3) investigate a range of intrinsic/extrinsic factors that might affect the execution of anti-predator responses. First, a preliminary test that simulated a range of sensory stimuli on L. delicatula suggested that they rarely responded to nontactile stimuli. This suggests that the species relies on crypsis as a primary defence unless it is physically contacted. Next, we simulated predatory attacks on the species at two different times of year (early and late season as adults). When physically contacted, the primary response of individuals was jumping away. However, when jumping was initially hindered (by grabbing), they then tended to employ deimatic display. Intriguingly, we found clear seasonal differences in these post-attack defences: after performing deimatic display, individuals were more likely to jump away in the early season, whereas death feigning was more frequent in the late season. We present adaptive explanations for this seasonal switch in anti-predator responses.