Host movement initiates oviposition behavior of Meteorus pulchricornis, a braconid parasitoid of free-living lepidopteran larvae

Abstract

Meteorus pulchricornis is a solitary endoparasitoid of various lepidopteran larvae that attacks free-living hosts exposed on plant foliage. We tested the necessity of host movement for oviposition behavior in M. pulchricornis using dummy hosts as well as natural host larvae (Spodoptera litura). We quantified the occurrence of three steps in oviposition behavior, i.e., host orientation, oviposition stance, and oviposition attack, to natural hosts under light and dark conditions. We also examined the incidence of these behaviors on natural hosts, moving dummy hosts, and motionless dummy hosts under light conditions. Few successful attacks occurred on natural hosts under dark conditions and no oviposition attempts were made against motionless dummy hosts. These results indicate that visual cues from moving host larvae are necessary for successful oviposition. Furthermore, host movement seems important for female wasps to orient the ovipositor toward the host body, since the location of the oviposition attack on natural hosts changed markedly with the mode of host movement.

Causes of polymorphic melanism and its thermoregulatory function in a parasitoid wasp Meteorus pulchricornis (Hymenoptera: Braconidae)

“…In this study, we investigated the variation in body colour and its thermoregulatory function in adults of the wasp Meteorus pulchricornis (Wesmael) (Hymenoptera: Braconidae), whose larval stage is a koinobiont endoparasitoid of Spodoptera and other free-living lepidopteran larvae (Huddleston, 1980;Maeto, 1989;Takashino et al, 1998;Berry & Walker, 2004;Liu & Li, 2006;Yamamoto et al, 2009). There are both biparental (arrhenotokous) and uniparental (thelytokous) strains of this wasp (Fuester et al, 1993) and the body colour of uniparental strains varies from almost totally brownish yellow to mostly black (as shown below).…”

Daily locomotor activity of the parasitoid wasp Meteorus pulchricornis (Hymenoptera: Braconidae) that attacks exposed lepidopteran larvae

“…The second hypothesis is more likely supported by the fact that larvae of Mythimna separate (Walker), a common host of M. pulchricornis, are nocturnal, and they conceal themselves in folding leaves in the daytime (Sato et al 1983). Adults of M. pulchricornis need visual cues from moving larvae for oviposition (Yamamoto et al 2009); thus, they could not attack the concealed larvae in the daytime. However, other common host species, Spodoptera exigua (Hübner) and S. litura, are nocturnal only in middle or late larval instars (Griswold and Trumble 1985;Parasuraman and Jayaraj 1983).…”

“…When nighttime lighting is used to control nocturnal moths, the leaves of crops are irradiated with a yellow or green light of 1-50 lux at night (Kosaka and Yase 2003;Yamada et al 2006); such lighting might to some extent affect the activity of M. pulchricornis, which was markedly reduced by exposure to constant nighttime light conditions in our experiments. Instead, nighttime lighting might be able to promote oviposition by this species, as the process uses visual cues (Yamamoto et al 2009), but further experiments under 1-50 lux light are necessary to confirm this. The effects of nighttime lighting on the foraging and oviposition behavior of nocturnal parasitoids should be elucidated in order to improve IPM systems to protect vegetable crops.…”

Will competition from Meteorus pulchricornis (Wesmael) (Hymenoptera: Braconidae) limit the success of the potential biocontrol agent Cotesia urabae Austin & Allen (Hymenoptera: Braconidae)?

“…Meteorus pulchricornis , by contrast, has slow, deliberate oviposition behaviour composed of three steps: orientation to host; oviposition stance with ovipositor held forward under the body; and attack by thrusting the ovipositor forward into the host larva (Fuester et al . 1993; Yamamoto et al . 2009).…”

“…2009). This species does not have a high rate of larval probing, with probes by M. pulchricornis on preferred host Spodoptera litura (F.) (Lepidoptera: Noctuidae) recorded at a mean of 1.7 ± 0.8 times per 20 min (Yamamoto et al . 2009).…”