Assessing the Prey Specificity of Neoleucopis spp. against Marchalina hellenica

Abstract

Marchalina hellenica Gennadius (Hemiptera: Marchalinidae) is a scale insect native to Greece and Turkey and presently invasive in Australia, where it damages pine plantations. The silver fly, Neoleucopis kartliana Tanasijtshuk (Diptera: Chamaemyiidae), is the most abundant predator of M. hellenica in Greece and is presently being investigated as a potential biological control agent following the scale’s introduction in Australia. This study, conducted in Northern Greece, revealed the presence of a second lineage, closely related to N. kartliana, referred to as Neoleucopis n. sp. B. Field surveys and laboratory experiments were conducted on M. hellenica and a taxonomically related scale insect, Icerya purchasi Maskell (Hemiptera: Monophlebidae), to test the larval growth and survival of the flies on the two prey species and assess their specificity for M. hellenica. The results suggest that both Neoleucopis spp. exhibit a high preference for M. hellenica when compared to I. purchasi. Larval growth was higher on M. hellenica than on I. purchasi but the difference was significant for N. kartliana only. Survival was significantly higher for both predators when provided M. hellenica compared to I. purchasi. Field surveys showed that both predators are abundant on M. hellenica colonies, whereas none of the two Neoleucopis lineages was found to have preyed on I. purchasi.