Old Parasitoids for New Mealybugs: Host Location Behavior and Parasitization Efficacy of on .

The Comstock mealybug, (Hemiptera: Pseudococcidae) is a primary pest of orchards in the North and Northwest of China. This pest appeared recently in Europe, including Italy, where it is infesting mainly vineyards as well as apple and pear orchards. The present study investigated the efficacy of , a known biological control agent (BCA) of , on to evaluate a potential use for the management of this new pest. No-choice tests were conducted to quantify the parasitoid behavior against and . The parasitoid successfully parasitized both species (parasitization rate: 51% and 67% on and , respectively). The developmental time (19.67 ± 1.12 vs. 19.70 ± 1.07 days), sex ratio (1.16 ± 1.12 vs. 1.58 ± 1.07) and hind tibia length of the progeny showed no differences when . and . respectively, were exploited as hosts. Two-choice tests, conducted by providing the parasitoid with a mixed population of and , showed no host preference for either of the two mealybug species (23 vs. 27 first choices on . and . , respectively). The parasitization rate (61.5% and 64.5% in and , respectively) did not differ between the two hosts. Overall, our study adds basic knowledge on parasitoid behavior and host preferences and confirms the use of this economically important encyrtid species as an effective BCA against the invasive Comstock mealybug.