Functional response of the native natural enemy of Dryinus sinicus (Hymenoptera: Dryinidae) to different instars of spotted lanternfly (Lycorma delicatula, Hemiptera: Fulgoridae).

Abstract

Dryinus sinicus Olmi (Hymenoptera: Dryinidae) is a key natural enemy of the nymphs of spotted lanternfly, Lycorma delicatula White (Hemiptera: Fulgoridae), a significant pest in agricultural and forest ecosystems. This study investigates the functional response of female D. sinicus to the first-, second-, and third-instar nymphs of L. delicatula, as well as the intraspecific competition within D. sinicus populations. D. sinicus responded to the increasing prey density of L. delicatula nymphs of different instars by consuming more number of prey than prey consumed at lower prey densities and exhibited Holling's type II curvilinear responses. However, search efficiency decreases with increasing prey density. The predation effect of D. sinicus on the first-instar L. delicatula nymphs was the best, the attack rate per handling time (a'/Th) was 14.9712 and an individual female wasp's attack rate (a') was 1.0091, the handling time (Th) to 1 instar L. delicatula nymphs was 0.0674 and the maximum theoretical rate of prey consumed per 24 h (T/Th) was 14.8368. The intensity of the scrambling competition increasing with increases predator density, but the capita prey consumed level and per capital predation efficiency decreased significantly when the predator density ranged from 1 to 5. The results indicate that intraspecific interference occurs when multiple females of D. sinicus prey on L. delicatula in the same area. Overall, this study demonstrates that D. sinicus is an effective biological control agent for L. delicatula, with significant potential for further development in the management of this pest.