The gelechid bud borer Anarsia achrasella (Latreille) has become an increasingly serious pest of sapodilla Manilkara zapota Van Royen in India. The objective of the present study was to estimate the pest damage potential and determine the influence of abiotic factors and plant phenology on the pest incidence. The results indicate that each larva of A. achrasella could damage up to 36.9–46.6 buds before reaching pupation. Correlation analysis indicates that the pest incidence is not influenced by plant phenology and that the effect of abiotic factors is minimal. Of all weather parameters studied, only minimum temperature and wind speed correlated significantly with bud borer infestation. The linear and non-linear analyses showed that, in the case of minimum temperature, polynomial model order (2) Y=0.4108x2−11.95x+92.329 was found to explain 46% of the variability in bud borer incidence. However, in the case of wind speed, none of the tried models could explain variability in A. achrasella incidence beyond 53%. The implications of these results are discussed.

This paper reports the results of extensive pest surveys conducted on farmers' fields and pest population studies at two national research stations between 1979 and 1981 in Burkina Faso. Major findings indicate that, under normal planting conditions, infestation of the sorghum shootfly, Atherigona seccata is very low in farmers' fields. This pest appears to be restricted to research stations. Stem borer infestation is caused by a complex of species, and species predominance varies with rainfall. South of latitude 12°N, Busseola fusca is the predominant species but further north it is replaced by Acigona ignefusalis, which is a primary pest of pearl millet. Panicle damage caused by the sorghum midge, Contarinia sorghicola, varies with season; is usually very low in the dry northern Sahelian zone but severe south of latitude 13°N. Maximum midge populations occurred between mid-September and early October.

The plant factors that contribute to the abundance of beetles in coffee fields were studied and analysed relative to shoot and canopy features of the host plant. During infestation Dirphya nigricornis Olivier constructed niches within specific heights (145.0–210.0 cm) of the canopies such that there was a highly significant (r = 0.99, P = 0.001) availability of adequate habitat for larval development. The adaptation of the pest to the host plant was good, irrespective of varieties and culture systems of the coffee plant. It was concluded that the alignment of eggs to tip internodes synchronised the newly hatched larvae with the coffee tissues, usually between 0.5 to 30 cm off the shoots, of extremely low dry matter, and high moisture content, such factors favouring early larval development.