Effects of parental age at mating on the fecundity and progeny sex ratio of <Emphasis Type="Italic">Campoletis chlorideae</Emphasis>, an endolarval parasitoid of the pod borer, <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> |
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Authors: | Amarendra K Pandey Sonal Tripathi C P M Tripathi |
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Institution: | (1) Department of Zoology, Entomological Research Laboratory, DDU, Gorakhpur University, Gorakhpur, UP, 273009, India |
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Abstract: | Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), commonly called gram pod borer, is a serious pest of pulse crops in India and damages
chickpea (Cicer arietinum L). On average a 30% crop loss is reported. One of the potential natural enemies reported for its biological control is Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae), an idiobiont parasitic wasp that attacks second instar larvae of the pod borer. Male-biased
sex ratios hinder efforts to mass release parasitic Hymenoptera for biological control by making the production of females
costly. Parental age at time of mating is known to affect the progeny sex ratio in some Braconidae. In this view, we examined
the reproduction and survival of the parasitoid C. chlorideae in the laboratory 22 ± 4°C, 70 ± 10% R.H. and 10:14 h light:dark photoperiod]. All the nine (i.e. 3 × 3) combinations of
possible mating were made for males and females, being each of different age groups (0–12, 48–60 and 96–108 h old). Second
instar larvae of the pod borer were reared on chickpea and exposed to mated females of different mating age group combinations.
Results revealed that (a) newly emerged females (0–12 h old) mated to aged males yielded more progeny contrasted to the older
females inseminated by newly emerged males (0–12 h old). This implies that increased maternal age at mating caused greater
reduction in the progeny yield than that of paternal age; (b) the progeny sex ratio was lowest (0.344 ± 0.057) (mean ± SD)
when parents mated just after emergence (0–12 h old). It became more and more male biased as parents were deprived of mate
and was highest (0.666 ± 0.701) for 96–108 h old parents. The analysis of variance of the data shows that mate deprived males
caused greater contribution in the production of sons, resulting a male-biased progeny sex ratio. Our conclusion indicate
that newly emerged parasitoids (0–12 h old) are most fecund and should be used in rearing practices in order to enhance the
progeny yield, particularly with respect to daughters.
Handling Editor: Torsten Meiners |
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Keywords: | Male and female ageing Progeny sex ratio Premating latency Biological control |
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