Studies on the seasonal changes in the population of Acanthomyia tornentosicollis Stat (Hemiptera: Coreidae) on Cajanus cajan (Linnaeus) Druce (pigeon pea) in Ibadan, Nigeria

EGWUATU. R.I. and TAYLOR, A.T.

ABSTRACT: Wide seasonal fluctuations were observed in the field populations of Acanthomia tomentosicollis Stal on Cajanus cajan (Linnaeus) Druce. The insect was observed all the year round and did not diapause. About 9 generations a year were estimated on C. cajan and a sex ratio of 1.23: 1.00 in favour of males was
recorded for the species. The main population peaks were clearly associated with the flowering and podding cycles of the host plant with the cessation of fresh pod production and high levels of field parasitisation being responsible for the usually marked population decline in or about March.

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