Life Table for the Tef Grasshopper, Aiolopus longicornis, under Laboratory Conditions and Demographic Effects of the Pathogen Nosema locustae

The tef grasshopper Aiolopus longicornis is a pest of cereals in central Ethiopia. We studied the effects of a biocontrol microorganism, Nosema locustae, on the grasshopper in the laboratory. The demography of a cohort inoculated with N. locustae in the third instar was compared with a noninoculated control cohort. Whereas 55% of the noninoculated grasshoppers reached adulthood, only 19% of the inoculated hoppers survived to adulthood. Per capita reproduction also was lower for the inoculated grasshoppers. Overall, treatment with N. locustae reduced the intrinsic rate of population growth (rm) and net reproductive rate (Ro) from 0.255 per week and 38.6 per generation to 0.038 per week and 1.7 per generation. Sensitivity analysis of the growth rate (λ) of the control cohort indicated that the largest effect on the population growth rate would be obtained by affecting survival and developmental rate during the last larval instars. We conclude that N. locustae is a potential control agent worth testing in the field.