Population Dynamics of the Grasshopper Species Aiolopus thalassinus under Controlled Laboratory Conditions Showing the Influence of Intrinsic Reproductive Factors (Orthopteroidea: Caelifera: Acrididae)

Abstract

A laboratory culture of Aiolopus thalassinus (Fabricius 1781), initiated with insects collected in Karachi/Pakistan, was maintained under controlled laboratory conditions for 24 consecutive generations. The study aimed at understanding the importance of the intrinsic factors for the population dynamics of this species. Several reproductive parameters, such as egg production, number of eggs per pod, the hatching rate of nymphs, the duration of the nymphal period, and the rate of adult eclosion were studied. Taking all generations in account, the sex ratio was F:M = 1:1. Peak oviposition occurred between weeks-3 and -5 after adult eclosion, and normally stopped after 15 weeks. A weak correlation was found with the number of eggs/pod and the number of egg pods / F. No correlation was found between the number of egg pods and the length of the oviposition period. Egg pods were produced throughout the year with a photoperiod of 12/12 L/D, and up to 5 generations per year were produced. The hatching rate of the nymphs varied between 8-94%, and no relationship was observed between this parameter and either the mean number of eggs/pod or the rate of adult eclosion. Fertility and fecundity were not correlated, and, in general, the hatching rate was highest under summer and lowest under winter conditions. In the sequence of generations studied, each reproductive parameter varied independently from all others.