Helicoverpa armigera as an alternative host of the larval parasitoid Microplitis croceipes (Hymenoptera: Braconidae)

Abstract

Microplitis croceipes is a solitary larval parasitoid of Helicoverpa/Heliothis species in North America. Laboratory experiments were conducted to determine suitability of the non-natural host, a Japanese strain of Helicoverpa armigera for parasitism by M. croceipes. Females oviposited in the third instar of H. armigera. When the parasitized hosts were reared with artificial diet at 15-30°C with 16L:8D, 67-92% of them produced parasitoid pupae. However, only 9% at 13°C and 53% at 33°C produced parasitoid pupae, and none of those parasitoid pupae developed to adults at these temperatures. Mean time taken from oviposition to adult emergence varied from 14.8 d at 30°C to 53.2 d at 15°C for males and from 15.5 d at 30°C to 60.7 d at 15°C for females. The proportions of females in the emerged adults were 0.45-0.56. Mean lengths of forewings varied from 4.4 mm at 30°C to 4.9 mm at 15°C for males and from 4.3 mm at 30°C to 4.7 mm at 15°C for females. H. armigera was as suitable for parasitism by M. croceipes as H. zea and H. virescens, natural hosts of this parasitoid. The optimal temperature range for development of M. croceipes was 20-28°C.

An acquired distaste: Sugar discrimination by the larval parasitoidMicroplitis croceipes(Hymenoptera: Braconidae) is affected by prior sugar exposure

“…The parasitoid stock culture originated from the USDA-ARS Crop Protection and Management Research Unit (CPMRU) in Tifton, GA, USA, and has been reared at Kyushu University since June 2001, with no infusion with feral wasps. The parasitoids were reared on Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) larvae with honey as food under a 16 h:8 h light:dark photoperiod at 25°C (Hoang and Takasu, 2005). For the experiment, newly emerged adults were kept in a plastic rearing cage (30×30×25 cm, length × width × height) and provided with distilled water only.…”

“…Microplitis croceipes (Cresson 1872) (Hymenoptera: Braconidae) is an endo-larval parasitoid of Helicoverpa and Heliothis species (Lewis and Burton, 1970;King and Coleman, 1989;Knipling and Stadelbacher, 1983;Hoang and Takasu, 2005). Microplitis croceipes was chosen for this study because it does not host feed (Takasu and Lewis, 1993) or feed on pollen (Jervis, 1998), and therefore it represents the large group of parasitoids whose diet is restricted to sugar sources, such as nectar and honeydew (Takasu and Lewis, 1993;Takasu and Lewis, 1996;Stapel et al, 1997;Röse et al, 2006;Wäckers et al, 2006;Zhou et al, 2012).…”