Implications of host weevil circadian activity for parasitism by <i>Microctonus aethiopoides</i> (Hymenoptera: Braconidae)

Abstract

Previous studies have suggested that the braconid parasitoid Microctonus aethiopoides Loan oviposits in its target host Sitona discoideus (Kuschel) primarily during light periods, and therefore, diurnally active non-target weevils may be more susceptible to parasitism than nocturnally active weevils. A laboratory investigation was carried out to measure the circadian feeding and oviposition activity patterns of three known non-target hosts of M. aethiopoides. M. aethiopoides was also exposed to Listronotus bonariensis Gyllenhal, a crepuscularly active weevil, in light or dark periods or continuously over a 16 hour light: 8 hour dark photoperiod. Feeding by two native species increased during the light period, while that of the introduced Rhinocyllus conicus (Froelich) remained relatively constant throughout the light-dark cycle. Neither of the native species showed a consistent circadian oviposition pattern. R. conicus laid more eggs during light than dark periods. M. aethiopoides oviposited in L. bonariensis equally during light and dark periods.

Diurnal rhythms of emergence host feeding and oviposition of <i>Eretmocerus warrae</i> (Hymenoptera Aphelinidae)

“…The present results also show that E. warrae is active throughout a 24 hour period, suggesting that oviposition and host feeding by E. warrae is not controlled by endogenous oscillator or exogenous factor (i.e. the light), but rather the parasitoid may respond to cues from the host (Couch 1997). These properties may enable E. warrae to act successfully as an agent in the biological control of greenhouse whitefly.…”

Emergence sexual maturation and oviposition of <i>Aphidius ervi</i> (Hymenoptera Aphidiidae)

“…Insect emergence events are usually rhythmic (Saunders 1982). In the parasitic hymenopterans, such rhythmicity is often synchronised with mating (Gordh & DeBach 1976;Nadel & Luck 1985) and oviposition (Armstrong et al 1996;Couch et al 1997) activities for an optimal reproductive fitness.…”

“…Daily activity patterns have been studied in detail in some parasitic hymenopterans (Vogt & Nechols 1991;Armstrong et al 1996;Couch et al 1997). Quicke (1997) suggested that for many parasitoid species, most oviposition occurs in the morning, for example, the squash bug egg parasitoid, Gryon pennsylvanicum (Vogt & Nechols 1991).…”

“…However, in some other species, such as the Sitona weevil parasitoid, Microctonus aethiopoides Loan, oviposition may occur during light and dark with the circadian oviposition activity corresponding with its host activity (i.e. feeding and oviposition) (Armstrong et al 1996;Couch et al 1997). Knowledge of parasitoids' emergence, mating and oviposition patterns is vital to an understanding of the ecology and evolution of their reproductive strategies, which in turn contributes to the development and implementation of biological control programs.…”