Host choice and offspring sex allocation in a solitary parasitic wasp

Abstract

Females of the parasitic wasp Antrocephalus pandens can detect differences in the quality of their hosts (pupae of Corcyra cephalonica, a stored-product moth) and allocate offspring of either sex accordingly. Larger and younger hosts are accepted more often in both dead and live hosts; more female offspring emerge from the perceived better hosts, while more males emerge from the smaller, older ones. These patterns are consistent with a sex allocation strategy by the mother, since females from a given size host tend to be larger than males and larger females produce more eggs. However, when wasps lay their eggs in groups of hosts of different size and age rather than encountering them one at a time, no difference in number or sex ratio of offspring is detected between groups. This result and evidence from the change in offspring sex ratio with female age and with numbers of females foraging on a group of hosts are interpreted and discussed in the context of sex allocation (Charnov 1979) and local mate competition (LMC, Hamilton 1967) theories.

Adult size and reproduction in the ectoparasitoid Agrothereutes lanceolatus Walker (Hym., Ichneumonidae)

“…1a), a trend widely recognized in many parasitoids (e.g. Assem 1989 ; Heinz 1990 ; Brault 1991; Tillman 1993) . However, there was no correlation between size and longevity in male A. lanceolatus ( Fig.…”

Mixed sex allocation strategies in a parasitoid wasp

“…The sex ratio strategy of the female is influenced by both the probability of mating between siblings and by the fitness consequences of placing either sex in different-sized hosts. Such models have helped explain the reproductive strategies of a number of parasitoids of stored-product pests (Werren and Simbolotti 1989;Brault 1991;Ikawa et al 1993).…”

Bethylids attacking stored‐product pests: an overview

“…The sex‐allocation strategy can have a negative impact on a biological control program if the sex bias is towards males. Published data indicate that individual females can vary sex allocation under laboratory conditions, but unfortunately nothing is known about potential methods to manage the sex‐allocation strategies of bethylids during a pest control treatment (Charnov et al., ; Brault, ; Ode & Hardy, ). We have reviewed seven species of bethylid wasps as candidates for the biological control of stored‐product pests, but the family contains at least 2 200 species (Hawkins & Gordh, ), so the list will likely be expanded.…”

“…The ways in which female parasitoids adjust the sex ratio can significantly influence population dynamics and have also been used to understand the reproductive strategies of other parasitoids of stored‐product pests (Hardy & Mayhew, ; Hardy et al., ; Tang et al., ; Kapranas et al., ). Host size (female eggs are laid on larger hosts), resource availability, clutch size, risks of immature‐male mortality, probability of mating between siblings, environmental constraints, and level of competition can all influence sex allocation (Hamilton, ; van den Assem, ; Werren, , ; Charnov et al., ; Charnov, ; King, , ; Brault, ; Mayhew & Godfray, ; West et al., ; Lebreton et al., ).…”