Effect of field infestations of immature pigeonpea (Cajanus cajan (L.) Millsp.) pods on production of active (flight) and sedentary (flightless) morphs of Callosobruchus chinensis (L.)

M.Silim Nahdy, S.N Silim, R.H Ellis, 'Effect of field infestations of immature pigeonpea (Cajanus cajan (L.) Millsp.) pods on production of active (flight) and sedentary (flightless) morphs of Callosobruchus chinensis (L.)', Journal of Stored Products Research, vol. 35(4), pp.339-354, Elsevier BV, 2011

A study conducted in Uganda on Callosobruchus chinensis showed that adults emerging from dry seed-infested and immature pod-infested pigeonpea differed 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 pod-infested pigeonpea differed depending upon when they emerged: the differences were greatest between those emerging during the 2nd to the 6th days from first emergence, and those emerging from the 8th to the last days of emergence. In one or both sexes, these differences 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 differences are due to polymorphism, and specifically the predominance of flight forms among late emergers from pod-infested pigeonpea. The differences observed in the two morphs of C. chinensis and ascribed to the flight and flightless forms, are thought to be adaptations for survival and propagation under field and storage conditions, respectively. The predominance of emerged adults of the flightless forms from dry seed and the flight 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 field as well as in storage