Seasonal Abundance and Breeding Habits of Aiolopus longicornis sjostedt(Orthoptera : acrididae) in Cereal Crops in Central Ethiopia

Abstract

Seasonal patterns in the abundance and breeding activity of A. longicornis in cereals in central Ethiopia, about 50 km south east of Addis Ababa, were studied from August 1986 to September 1988. Adult grasshoppers were sampled fortnightly by sweepnetting
for 30 minutes and by making visual counts in strip-transects. In addition, adult females of A. longicornis were collected from tef (Eragrostis tef) fields during the same period and dissected. In all three years, peaks in the abundance and breeding activity of adult
A. longicornis largely coincided with periods of short and long rains. The insect often started laying eggs very soon after the onset of rains, while spending the dry seasons as reproductively inactive adults. Peaks in abundance and breeding activity closely coincided with periods of active growth and development of tef and wheat crops, and it appears that up to four generations per year can occur. Differences in population levels between localities were apparently due to differences in the availability of surface water. The results are discussed in relation to the land use system and compared with the situation in a related species, A. thalassinus, in other parts of Africa.