Impact of the parasitic wasp Nasonia spp. (Walker, 1836) Hymenoptera: Pteromalidae) on populations of bird blowflies Protocalliphora spp. Hough, 1899 (Diptera: Calliphoridae)

Abstract

The immature stages of a large number of blowflies are parasitized by parasitic wasps with local or cosmopolitan distribution.2‒4 Several species parasitize pupae of bird blowflies by penetrating the host pupae. One such group of parasitic wasps, are solitary or gregarious ectophagous parasitoids from the Pteromalidae family. The most commonly world-wide distributed is Nasonia vitripennis. Its life cycle is well established because it has been widely used in genetic and field studies5,6 and pupal parasitoids have attracted a lot of attention because of their potential control of house and stable flies in farms.1 A female parasite with matured eggs drills through the host pupae with her ovipositor laying eggs externally on the pupa and injects a substance, to narcotize or kill the host. The female feeds on haemolymph from the host tissues. The parasite larvae feed throughout the three instars, and then pupate, and the adult’s enclose approximately 24 hours before biting one or more holes and emerging from the host pupa. The same emergence hole is used by successive emerges, and the males usually emerge before the females.6‒8 The females do not drill pupae which have an emergence hole of a fly or parasites, otherwise it drills without laying eggs if the host is not pupated or is dead or contains late instars parasite larvae or adults.7 Temperature and humidity are important factors in the survival of the wasp, and in unsuitable conditions for further development the third instar can be diapaused. Previously there has been little information about the parasitization of bird blowflies under natural conditions. Eshuis van der Voet9 recorded that 48.8 % of Protocalliphora spp. pupae were infested by this parasitic wasp in Parus major nests in Holland, while in the USA, 20.1 % of these species pupae found to be parasitized by the same wasp.2 The parasitization of N. vitripennis reported by Peters4 was 42.1% in Protocalliphora azurea (cele meno) pupae and 15.8% in Protocalliphora falcozi (cele meno) pupae.