The Biology and Ecology of Busseola fusea and Sesamia Species in South-Western Nigeria. I. Distribution and Population Studies

The distribution of maize stem borers, Busseola fusca Fuller, Sesamia calamistis Hampson, and S. penniseti Bowden, throughout south-western Nigeria was studied between November and December 1964. The maize-sample survey revealed that B. fusca was more abundant than S. calamistis . While B. fusca was prevalent in the southerly, more humid lowland rainforest zones, S. calamistis was generally distributed and was more prevalent in the dry savanna zones of the region. S. penniseti was not abundant and was very sparsely distributed. There was a marked difference in the position of egg masses on the maize plants. All egg masses of B. fusca were laid within 30 inches of the maize whorl, while S. calamistis egg masses were spread over greater distances from the whorl. This distribution appears to be associated with the larval habits of both B. fusea and S. calamistis . Larval populations studies revealed that in lbadan (and probably south-western Nigeria) there are 4 generations of B. fusca in maize per annum. There are 2 generations between April and July, 1 in September-October, and another in November. It is the larvae of the November generation which go into the dry-season diapause and which later give rise to the 1st-generation adults the following year. S. calamistis ,, although not so numerous as B. fusca , was observed to breed throughout the year.