The effect of host stage and temperature on selected developmental parameters of the solitary endoparasitoid Meteorus gyrator (Thun.) (Hym., Braconidae)

Abstract

The development of the solitary endoparasitoid Meteorus gyrator was compared in the six larval stages of its host, the tomato moth Lacanobia oleracea, and at five constant temperatures. The host instar at the time of parasitism had a marked effect on the larval developmental period of the parasitoid, such that larvae derived from eggs oviposited in first instar hosts took approximately 18 days to egress, whilst those derived from eggs oviposited in sixth instar hosts took <10 days. The weight of cocoons was greatest when oviposition was into final instar hosts, where female cocoons averaged 12.8 mg, and lowest in those derived from eggs oviposited into first instars (9.2 mg). The parasitoid's larval development rate in third instar hosts increased with temperature increments in a linear fashion up to 25°C, after which development times were only marginally increased. At 10°C, the mean larval development time was approximately 90 days and pupal development 35–40 days, whilst at 25°C development times were 10–11 days for larvae and 6–7 days for the pupae. In the majority of cases, overall development times were marginally longer (<1 day) in females than in males.

The effects of host age and superparasitism by the parasitoid, Microplitis rufiventris on the cellular and humoral immune response of Spodoptera littoralis larvae

“…The released hemolymph led to a vigorous cellular defense response by the host, so that some giant capsules were observed particularly in L 1 -L 3 hosts. These results are not consistent with findings on the braconid wasps, Macrocentrus cingulum (Lu et al, 2006) and Meteorus gyrator (Bell et al, 2003). The wasps choose early instars because their immune systems are less able to respond to the wasp's egg or lrava.…”

Interactions Between the ParasitoidMeteorus gyrator(Hymenoptera: Braconidae) and a Granulovirus inLacanobia oleracea(Lepidoptera: Noctuidae)

“…In our experiments, parasitoid cocoon weights also were mostly unaffected by treatment of the host with LoGV. However, both in control and in virus-treated hosts, parasitoid cocoon weights were signiÞcantly affected by the age of the host at the time of parasitism; larger hosts produced larger parasitoid cocoons, results consistent with those of Bell et al (2003). In this study, the weight of the adult parasitoids that subsequently emerged from the cocoons was not determined.…”

“…When hosts were treated with LoGV on day 0, and subsequently parasitized from 0 to 11 d later, most mortality in host larvae was due to the virus (parasitoids only developed successfully in those hosts that survived LoGV treatment). This result may well have been due to the differences in the time required for the two biocontrol agents to kill the host; LoGV takes Ϸ7 d to kill its host (Matthews et al 2002) whereas M. gyrator takes as long as 14 d (Bell et al 2003). Therefore, in the majority of cases, those host larvae that were treated with LoGV and then parasitized died of viral infection before the parasitoid had had time to develop inside the host.…”

The comparative biology of the solitary endoparasitoid Meteorus gyrator (Hymenoptera: Braconidae) on five noctuid pest species

“…Further studies into the ovipositional behaviour of M. gyrator are currently ongoing in order to clarify this aspect of the parasitoids behaviour. Bell et al (2003) reported that this parasitoid could parasitize and develop in all larval stages of L. oleracea that it was presented with. However, the potential for this parasitoid to parasitize a range of hosts had not been investigated.…”