Oviposition preference and adult performance of the whitefly predator Serangium japonicum (Coleoptera: Coccinellidae): effect of leaf microstructure associated with ladybeetle attachment ability

Abstract

The leaf surface microstructure can greatly influence predator feeding behavior. However, its effects on predator oviposition preference, which is crucial for arthropod fitness at the population level, are largely unknown. This study aimed to test leaf discs and plants of five common host plant species of Bemisia tabaci, including Chinese kale, cotton, cucumber, eggplant, and sweetpotato, to determine the oviposition preference and offspring and adult performance of the whitefly predator Serangium japonicum. Cannibalism risk, attachment force, microstructure of the abaxial leaf surface (ALS), and ladybeetle tarsal morphology were examined. Ladybeetle's oviposition preference had no correlation with offspring performance but positively correlated with fecundity. Further, oviposition preference to leaf discs and fecundity positively correlated with attachment force. The cannibalism risk was not significantly different between plant species. The ALS of Chinese kale and eggplant supported the smallest and the largest attachment forces, respectively. The first one had epicuticular wax crystals, whereas the latter had stellate trichomes. The ALS of cotton and sweetpotato did not bear wax crystals or long trichomes. Cucumber leaves were covered with tapered trichomes. Tenant setae on the distal second tarsomere and a pair of curved, tapered claws on the distal fourth tarsomere were the attachment structures of S. japonicum, which interacted with the plant surface structures and generated the attachment force. Plant morphological traits, associated with ladybeetle attachment force and adult performance might be key factors in ladybeetle oviposition preference, and are expected to occur in other host plant herbivore-predator systems.