Defensive behaviors of the new mealybug citrus pest, Delottococcus aberiae (Hemiptera: Pseudococcidae), against three generalist parasitoids

Abstract

Delottococcus aberiae De Lotto (Hemiptera: Pseudococcidae) is an invasive mealybug that has become a citrus pest in Europe. This mealybug species causes serious damage because it deforms the fruits. Here, we studied the defensive behavior of D. aberiae when it was attacked by three parasitoid species: Acerophagus angustifrons (Gahan), Anagyrus sp. near pseudoccoci (Girault), and Leptomastix algirica Trjapitzin (Hymenoptera: Encyrtidae). Anagyrus sp. near pseudoccoci and L. algirica detected and accepted nymphs and adult females of D. aberiae, whereas A. angustifrons only accepted adults. We recorded four defensive responses of D. aberiae to parasitoid attacks: abdominal flipping, swiveling around the inserted stylet, withdrawing the stylet and walking away, and, occasionally, they secreted ostiolar fluids. Despite these defensive behaviors, the mealybug did not escape parasitism from any of the tested parasitoids, even though A. angustifrons needed more than 15 min to parasitize. We also analyzed the nutritional value of the honeydew excreted by D. aberiae for A. angustifrons and A. sp. near pseudococci. Females and males of these parasitoids lived more than 28 d when fed sucrose, but they lived fewer than 3 d when fed D. aberiae honeydew. Therefore, D. aberiae excretes honeydew of poor uality for parasitoids. The consequences of these biological traits of D. aberiae for its biological control are discussed.