How Do Host-Parasitoid Interactions Shape the Effectiveness of Anagyrus aberiae as a Biological Control Agent?

The invasive mealybug Delottococcus aberiae (De Lotto) has become a major citrus pest in eastern Spain during the last decade. The parasitoid Anagyrus aberiae (Guerrieri) is currently used in a classical biological control program against this pest, although important aspects of the interaction between both species remain poorly understood. We evaluated host-stage suitability and the effects of parasitism on host reproduction, as well as demographic performance and parasitoid response to host density under laboratory conditions. The parasitoid successfully parasitized D. aberiae stages from second-instar nymphs to adults, but preferred adult females, which accounted for 86% of parasitism when different stages were offered simultaneously. Parasitism reduced reproductive output by more than 93% in pre-reproductive females and caused oviposition cease within two days in females that had already initiated egg laying. Anagyrus aberiae exhibited an intrinsic rate of increase (r_m) of 0.099, and a Type II functional response, reaching a maximum parasitism rate of 8.7 hosts per day. The strong suppression of host reproduction and favorable population growth parameters highlight the biological control potential of A. aberiae. These findings provide valuable information for optimizing mass-rearing protocols and release strategies, thereby improving the implementation of biological control programs against D. aberiae.