Seasonality of the cocoa-pod -husk miner(Marmara sp., Lepidoptera, Gracillariidae)
1973
Majer, J.D., Inperial College Field Station, SIilwood Park, Ascot, Berkshire, England(previosly of the Department of Zoology University of Ghana Legon, Ghana)
The seasonality and influence of spraying and its cessation on the cocoa-pod-husk miner (Marmara sp.) were studied between December 1970 and January 1972 at the University of Ghana Agricultural Research Station, Kade. Pods were scored monthly for presence or absence of Marmara damage in a DDT sprayed plot and one in which spraying had recently ended. In the unsprayed plot, percentage of pods damaged was high in December, dropped towards May for unknown reasons and reached 19% in July when new pods grew faster than the miner could attack them. Damage increased rapidly after a delay of 1 month and reached 95% in December. Build up was slower in the sprayed plot but became 99_5 % in December. Percentage damage on 25 individual trees in both plots showed no significant difference at this time, indicating that there had been no recovery from attack in the unsprayed plot in the 14 months since spraying ended. Comparison of these results and the low damage at Aburi and Amanokrom, which have little history of cocoa spraying, suggests that regular spraying results in a long-term upset of the natural controls of Marmara.
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