Influence of host availability on rates of oviposition and host-feeding, and on longevity in Dicondylus indianus Olmi (Hym., Dryinidae), a parasitoid of the rice brown planthopper, Nilaparvata lugens Staal (Hem., Delphacidae)
1991
Sahragard, A.C. (University Coll. of Wales, Cardiff (United Kingdom). School of Pure and Applied Biology) | Jervis, M.A. | Kidd, N.A.
Female Dicondylus indianus were provided with host densities of 2, 4, 8, 10, 20, 40 or 60 for the duration of their lives. Rates of oviposition (and consequently of parasitism) and host-feeding varied both with host availability and parasitoid age. The period of intensive egg-laying shifted from a later to an earlier age as host availability increased. Whilst the wasps both oviposited and fed less at lower host densities, the ratio of feeding: oviposition attacks (F:O ratio), measured on both a lifetime total and age-specific basis, increased with decreasing host availability, in accordance with the predictions of the behavioural models of Jervis and Kidd (1986). There is a strong positive relationship between a wasp's lifetime fecundity and the number of hosts fed upon over its lifetime. In wasps supplied with hosts, longevity was shortest at the lowest host densities, but it exceeded the longevity of wasps deprived of hosts. The total number of eggs laid by a female over her lifetime was a strongly positive function of lifespan
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