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Insect phenology in a forest cocoa-farm locality in West Africa

by Gibbs, D.G; Leston, D.
Publisher: 1970Subject(s): THEOBROMA CACAO | INSECTOS DAÑINOS | FENOLOGIA | CLIMA | FACTORES AMBIENTALES | MUESTREO | METODOS | HABITOS ALIMENTARIOS | HABITAT | DINAMICA DE POBLACIONES | INSECTOS DEPREDADORES DE LAS HOJAS | INSECTOS DEPREDADORES DE LOS FRUTOS | INSECTOS DAÑINOS DEL TALLO | DEPREDADORES | CICLO VITAL | CUBIERTA DE COPAS | BIODIVERSIDAD | TIEMPO METEOROLOGICO | GHANA | THEOBROMA CACAO | PEST INSECTS | PHENOLOGY | CLIMATE | ENVIRONMENTAL FACTORS | SAMPLING | METHODS | FEEDING HABITS | HABITATS | POPULATION DYNAMICS | FLOWER DAMAGING INSECTSLEAF EATING INSECTS | FRUIT DAMAGING INSECTS | STEM EATING INSECTS | PREDATORS | LIFE CYCLE | CANOPY | BIODIVERSITY | WEATHER | GHANA | THEOBROMA CACAO | INSECTE NUISIBLE | PHENOLOGIE | CLIMAT | FACTEUR DU MILIEU | ECHANTILLONNAGE | METHODE | COMPORTEMENT ALIMENTAIRE | HABITAT | DYNAMIQUE DES POPULATIONS | INSECTE DEPREDATEUR DES FLEURSINSECTE PHYLLOPHAGE | INSECTE DEPREDATEUR DES FRUITS | INSECTE DEPREDATEUR DES TIGES | PREDATEUR | CYCLE DE DEVELOPPEMENT | COUVERT | BIODIVERSITE | TEMPS METEOROLOGIQUE | GHANA | INSECT FAUNA;AGROFOREST;INSECT POPULATION;CLIMATIC CONDITIONSOnline Resources: En In: Journal of Applied Ecology (RU) v. 7(3) p. 519-548Summary: Sampling by light trap, insecticide knockdown and other methods has given data on seasonal population changes in many insects and a few spiders in an area of semideciduous high forest largely devoted to cocoa growing at Tafo, Ghana. Populations of most species showed seasonal change and in every month some species were in a period of major increase. There are several characteristic seasonal population curves which, when associated with botanic and climatic events, lead to the conclusion that six seasons should be recognized. These can be defined by a combination of mean rainfall (more or less than 4 in./month) and mean monthly sunshine (more or less than 5.5 h/day). The seasons, listed together with some of the events we have discussed, are: (1) Dry sunny. Maximum fruit production, abundance of fruit-feeding and seed-feeding insects, continuing into the following season. Species thought to be favoured by effects of drought and related stress factors on host-plant nutrition also increase. (2) First wet sunny. Maximum leaf productionSummary: abundance of leaf-feeding insects and their predators. Maximum breakdown of leaf litterSummary: abundance of litter-feeding and fungus-feeding insects. (3) First wet dull. Decline in leaf feeders and their predators. Abundance of timber-borers. (4) Dry dull. Biologically similar to wet dull seasonsSummary: forms with numbers closely correlated with rainfall, for example timber-borers, may decline. (5) Second wet dull. (6) Second wet sunny. Shorter than the first wet sunny season, but period of submaximum leaf productionSummary: abundance of leaf feeders and their predators. Species that depend for food on primary production of plant tissues in the form of leaves or fruits have maximum numbers in the three sunny seasons. Their populations appear to respond directly to seasonal changes in the amount of food
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Ilus. 50 ref. Sum. (En)

Sampling by light trap, insecticide knockdown and other methods has given data on seasonal population changes in many insects and a few spiders in an area of semideciduous high forest largely devoted to cocoa growing at Tafo, Ghana. Populations of most species showed seasonal change and in every month some species were in a period of major increase. There are several characteristic seasonal population curves which, when associated with botanic and climatic events, lead to the conclusion that six seasons should be recognized. These can be defined by a combination of mean rainfall (more or less than 4 in./month) and mean monthly sunshine (more or less than 5.5 h/day). The seasons, listed together with some of the events we have discussed, are: (1) Dry sunny. Maximum fruit production, abundance of fruit-feeding and seed-feeding insects, continuing into the following season. Species thought to be favoured by effects of drought and related stress factors on host-plant nutrition also increase. (2) First wet sunny. Maximum leaf production

abundance of leaf-feeding insects and their predators. Maximum breakdown of leaf litter

abundance of litter-feeding and fungus-feeding insects. (3) First wet dull. Decline in leaf feeders and their predators. Abundance of timber-borers. (4) Dry dull. Biologically similar to wet dull seasons

forms with numbers closely correlated with rainfall, for example timber-borers, may decline. (5) Second wet dull. (6) Second wet sunny. Shorter than the first wet sunny season, but period of submaximum leaf production

abundance of leaf feeders and their predators. Species that depend for food on primary production of plant tissues in the form of leaves or fruits have maximum numbers in the three sunny seasons. Their populations appear to respond directly to seasonal changes in the amount of food

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