Effect of Host–feeding on Reproduction in Ooencyrtus nezarae (Ishii) (Hymenoptera: Encyrtidae), an Egg Parasitoid of the Bean Bug Riptortus clavatus

Abstract

Adult of many parasitoid species, in particular females, feed on host and non–host foods (e.g., sugar sources) for reproduction and maintenance (Lewis et al., 1998; Jervis et al., 1993; Jervis and Kidd, 1996; Onagbola et al., 2007). Feeding on host material such as host haemolymph is referred as to host–feeding. Host feeding is very common among adult females of synovigenic parasitoids that produce yolk–rich eggs throughout their lifetime, and has been observed for over 140 species across 17 families of Hymenoptera (Jervis and Kidd, 1986) and for several species of parasitic Diptera (Nettles, 1987). Female parasitoids, through host feeding, can gain nutrients that are used to mature eggs (Jervis and Kidd, 1986; Heimpel and Collier, 1996). Although sugar feeding has been demonstrated to increase the longevity of adult parasitoids in the majority of parasitoid species examined (e.g., Jervis et al., 1993; Fadamiro and Chen, 2005; Fadamiro et al., 2005), some studies have suggested that host meal or haemolymph may be a good source of nutrients for parasitoid survival and fecundity than sugars (Jervis and Kidd, 1986; van Lenteren et al., 1987; Heimpel and Collier, 1996). Although feeding on hosts is essential to maximizing female’s fecundity, its contribution to reproduction varies from species to species (Sandlan, 1979; Collier, 1995a; Rivero and Casas, 1999; Ueno, 1999; Rivero et al., 2001; Ueno and Ueno, 2007). Jervis and Kidd (1986) divided host feeding in terms of its concurrency and destructiveness: concurrent or non–concurrent, and destructive or non–destructive. Concurrent feeding means that female parasitoids use the same host individual for both feeding and oviposition, while non–concurrent means that different hosts are used for the different purposes. Destructive host feeing means that hosts die or heavily damaged upon host feeding, while in the case of non–destructive host feeding, hosts survive or are not damaged. Most evidence implies that host feeding in egg parasitoids always occurs on hosts that are also used for oviposition (Jervis and Kidd, 1986; Takasu and Hirose, 1993). For egg parasitoids, hosts may be important for maximizing both egg production and longevity. Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) is an egg parasitoid wasp of several phytophagus Hemiptera including the bean bug, Riptortus clavatus Thunberg (Takasu and Hirose, 1985, 1986; Effect of Host–feeding on Reproduction in Ooencyrtus nezarae (Ishii) (Hymenoptera: Encyrtidae), an Egg Parasitoid of the Bean Bug Riptortus clavatus