Biological control of Heliococcus bohemicus Sulc. (Hemiptera: Pseudococcidae)with the natural enemy Ericydnus sipylus (Walker) (Hymenoptera: Encyrtidae)

Abstract: The control of mealybugs by growers currently relies on the use of neurotoxicinsecticides. The possible use of the predator Chrysoperla lucasina (Lacroix) is the uniquealternative method. We propose to evaluate the biological activity in situ of the bred Ericydnussipylus (Walker), major parasitoid of Heliococcus bohemicus Sulc. The releases of parasitoidswere carried out in 2007 and 2008.During the 2007 season, the first three releases of E. sipylus did not appear to have anyeffect on the population of mealybugs. However the fourth and fifth release made later in theseason did show significant differences between the experimental plots. The biological controlshowed positive results in 2008 and 2009, as the number of H. bohemicus in the “release” blockswas significantly lower than those of the “control” blocks. A reduction of 50 to 60% of thenumber of H. bohemicus was found for the 2007 winter generation and from 75 to 85% for the2008 summer generation. Despite of stopping the release of E. sipylus rates of 80% were found inthe 2008 winter generation, and 80% in early 2009 summer generation.If the difference of the population of Pseudococcidae between the experimental plots wasdue to the introduction of the parasitoid E. sipylus, the lower level of the population found insummer 2008 and 2009 in the “control” blocks was probably due to: a) the presence of otherparasitoids like Anagyrus szodensis or predators like Exochomus quadripustulatus (Linné),Hippodamia variegata Goeze, Harmonia axyridis (Pallas), Coccinella septempunctata Linné,Nephus quadrimaculatus (Herbst) and Chrysoperla carnea (Stephens) b) the dispersion andactivity of E. sipylus beyond the plots where it was introduced.