Abstract:

A study conducted in Uganda on Callosobruchus chinensis showed that adults emerging from dry
seed-infested and immature pod-infested pigeonpea di?ered in a number of morphological and
biological characteristics in one or both sexes. Adults emerging from dry seed-infested pigeonpea were
more or less uniform in a number of these characteristics; in contrast, adults emerging from green podinfested pigeonpea di?ered depending upon when they emerged: the di?erences were greatest between
those emerging during the 2nd to the 6th days from ®rst emergence, and those emerging from the 8th to
the last days of emergence. In one or both sexes, these di?erences were expressed in terms of elytral hue
and size, body length, distance between the compound eyes, length of pygidium, body water content,
pre-maturation periods, fecundity and adult longevity. We suggest that these di?erences are due to
polymorphism, and speci®cally the predominance of ¯ight forms among late emergers from pod-infested
pigeonpea. The di?erences observed in the two morphs of C. chinensis and ascribed to the ¯ight and
¯ightless forms, are thought to be adaptations for survival and propagation under ®eld and storage
conditions, respectively. The predominance of emerged adults of the ¯ightless forms from dry seed and
the ¯ight forms from green pods were associated with low moisture content in dry seed and high
moisture content in green pods, respectively. These observations show that bruchid control measures are
needed in the ®eld as well as in storage