Host-produced wax affects the searching behavior and efficacy of parasitoids of the giant whitefly Aleurodicus dugesii (Hemiptera: Aleyrodidae)

Insects possess a variety of defenses against natural enemies including physical attack, chemical repellency, physiological suppression, and visual camouflage. The hypothesis that wax production by the whitefly Aleurodicus dugesii Cockerell (Hemiptera: Aleyrodidae) functions as a defense against natural enemies was tested using two parasitoid species, Encarsia noyesi Hayat (Hymenoptera: Aphelinidae) and Idioporous affinis LaSalle & Polaszek (Hymenoptera: Pteromalidae). Parasitoids were allowed to forage on A. dugesii nymphs that had their wax either left intact or removed. Percent parasitism and the proportion of time spent grooming and searching were recorded and compared between treatments. There was a significant interaction between wax presence and parasitoid species on observed parasitism. Wax presence appeared to negatively impact I. affinis more than E. noyesi. In the presence of wax, the percentage of A. dugesii nymphs parasitized by I. affinis was reduced 30-fold, whereas E. noyesi parasitism was reduced 2-fold. Although both species spent more time grooming in the presence of wax, only I. affinis spent more time searching. The greater proportion of time devoted to these behaviors by I. affinis appeared to be due to its inability to remove wax particles from its body. The results from this study highlight the importance of considering whitefly-produced wax in mediating parasitoid-prey interactions. The differential impact of host defenses must be taken into consideration when selecting candidate natural enemies for biological control programs.