Sensibilité du clone UF 667 aux degats d'une noctuelle du cacaoyer: Earias biplaga (WLK)
In growing cacao on a large scale, the choice of planting material for common use must meet two requirements: high yield and resistance to disease. For several reasons, chemical control of pests is not always satisfactory. It adds considerably to cost and may upset the ecological equilibrium. In the light of this, I.F.C.C., Cote d'Ivoire, has devoted considerable time in recent years to a study of the susceptibility of the Trinitarios to the attacks of a moth: Earias biplaga (WLK). The caterpillars of this moth, together with Mirids are the most serious enemies of young hybrids. In this study, the behaviour of 2860 young cacao trees, comprising 12 Upper Amazon hybrids and 4 clones has been followed for 4 years. The observations are continuing. In the first phase, more than 12.000 caterpillars have been collected, 10.000 eggs listed, 4.000 to 5.000 hyperparasites mostly identified. Statistical examination of these results has shown that the seedlings and cuttings do not react to the moths in the same way. In the field, the vertical stems of young seedlings are more attractive than the fan branches. The exception is the cuttings of clone UF 667, which in certain trials are more attacked than the seedlings. At the same time, it is remarkable that hybrids with UF 667 as one parent are significantly more susceptible than those of other clones. The particular susceptibility of UF 667 seems to lie in the marked hairiness of its leaves. In a previous laboratory study, it has been shown that a rough surface stimulates the laying of eggs by the Earias female. (J. Nguyen-Ban "Café-Cacao-Thé Volume XII - No.2:135-142). Moreover, other results show that UF 667 is also attractive to Mirids. In conclusion, the study of the susceptibility of young cacao plants to attacks by parasites has shown that UF 667 has an attractive character. There are strong reasons to believe that, apart from the hairs on the leaves, other hidden factors contribute to the attraction of insects to UF 667. In short, this study of the relation of cultivated plants to their surroundings is of economic value. We are convinced that, in this field, research is far from complete
| Main Authors: | , , , , , , , , |
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| Format: | biblioteca |
| Published: |
St. Augustine (Trinidad y Tobago)
1972
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| Subjects: | THEOBROMA CACAO, CLONES, EARIAS BIPLAGA, LEPIDOPTERA, INSECTOS DEPREDADORES DE LAS HOJAS, RESISTENCIA A LAS PLAGAS, CLONES UF, |
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| Summary: | In growing cacao on a large scale, the choice of planting material for common use must meet two requirements: high yield and resistance to disease. For several reasons, chemical control of pests is not always satisfactory. It adds considerably to cost and may upset the ecological equilibrium. In the light of this, I.F.C.C., Cote d'Ivoire, has devoted considerable time in recent years to a study of the susceptibility of the Trinitarios to the attacks of a moth: Earias biplaga (WLK). The caterpillars of this moth, together with Mirids are the most serious enemies of young hybrids. In this study, the behaviour of 2860 young cacao trees, comprising 12 Upper Amazon hybrids and 4 clones has been followed for 4 years. The observations are continuing. In the first phase, more than 12.000 caterpillars have been collected, 10.000 eggs listed, 4.000 to 5.000 hyperparasites mostly identified. Statistical examination of these results has shown that the seedlings and cuttings do not react to the moths in the same way. In the field, the vertical stems of young seedlings are more attractive than the fan branches. The exception is the cuttings of clone UF 667, which in certain trials are more attacked than the seedlings. At the same time, it is remarkable that hybrids with UF 667 as one parent are significantly more susceptible than those of other clones. The particular susceptibility of UF 667 seems to lie in the marked hairiness of its leaves. In a previous laboratory study, it has been shown that a rough surface stimulates the laying of eggs by the Earias female. (J. Nguyen-Ban "Café-Cacao-Thé Volume XII - No.2:135-142). Moreover, other results show that UF 667 is also attractive to Mirids. In conclusion, the study of the susceptibility of young cacao plants to attacks by parasites has shown that UF 667 has an attractive character. There are strong reasons to believe that, apart from the hairs on the leaves, other hidden factors contribute to the attraction of insects to UF 667. In short, this study of the relation of cultivated plants to their surroundings is of economic value. We are convinced that, in this field, research is far from complete |
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