How a slow-ovipositing parasitoid can succeed as a biological control agent of the invasive mealybug Phenacoccus peruvianus: implications for future classical and conservation biological control programs

Phenacoccus peruvianus Granara de Willink (Hemiptera: Pseudococcidae) is an invasive mealybug that has become a pest of ornamental plants in Europe and has recently been detected in California, USA. In this work, we studied the tritrophic interaction among this mealybug, its main parasitoid Acerophagus n. sp. near coccois (Hymenoptera: Encyrtidae) and tending ants to disclose the success of this parasitoid controlling P. peruvianus. Acerophagus n. sp. near coccois accepted mealybugs for parasitism regardless of their size but did not host-feed. We recorded three active defenses of P. peruvianus. Host handling time was not influenced by these host defenses but was a time-consuming process that required more than 30 min. Tending ants, Lasius grandis (Hymenoptera: Encyrtidae), reduced the time spent by parasitoids in a patch and disrupted oviposition attempts. The low numbers of ants tending mealybug colonies in Spain and France could explain why this parasitoid, with a long handling time, is an efficient biological control agent for P. peruvianus