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Accueil du site → Master → Afrique du Sud → 2008 → Small holder farmers’ perceptions, host plant suitability and natural enemies of the groundnut leafminer, Aproaerema modicella (Lepidoptera : Gelechiidae) in South Africa

North-West University (2008)

Small holder farmers’ perceptions, host plant suitability and natural enemies of the groundnut leafminer, Aproaerema modicella (Lepidoptera : Gelechiidae) in South Africa

Van der Walt, Anchen

Titre : Small holder farmers’ perceptions, host plant suitability and natural enemies of the groundnut leafminer, Aproaerema modicella (Lepidoptera : Gelechiidae) in South Africa

Auteur : Van der Walt, Anchen

Université de soutenance : North-West University, Potchefstroom Campus

Grade : Thesis (M. Environmental Science) 2008

Résumé partiel
The groundnut leafminer (GLM), Aproaerema modicella (Lepidoptera : Gelechiidae), is a well known pest of groundnut and soybean in Asia. It has been reported in Southern Africa on groundnut since 2000. The groundnut leafminer causes a reduction in crop yield by tunneling in the leaves and thereby reducing the leaf area for photosynthesis. Larvae tunnel into the leaves where they feed between the upper and lower epidermis causing defoliation of groundnut crops. Last-instar larvae web two leaves together and pupate in between these leaves. Since GLM is a new pest in South Africa, no integrated management program for control of this insect exists. A survey was conducted among the small holder farmers at the Tshiombo irrigation scheme where GLM is an important pest in groundnut fields. Results showed that the majority of residents involved in farming activities were females aged between 41 and 60 years. It was also observed that groundnut is important as part of the daily diet and a cash crop in the surrounding villages and Thohoyandou, the nearest town. Farmers were familiar with the damage symptoms caused by GLM larvae, but they did not know the agent causing the damage to their groundnut fields. They regarded chemical control as the only pest control strategy capable of reducing crop losses caused by GLM. Since chemical control of GLM is not a sustainable strategy there is a need to carry out investigations likely to generate reliable GLM management strategies and this requires using live insects of known age and sex. One of the constraints encountered when conducting experimental studies on GLM moths was the fact that these moths are small, very agile and the sex of live moths cannot be easily identified. Male and female moths lack easily identifiable distinguishing characteristics. Another area of investigation was directed towards identifying cultivated and wild host plants that serve as either off-season or alternative hosts of GLM. When such plants are identified they can serve as trap crops in strategies designed to manipulate the groundnut crop environment in order to reduce crop damage due to GLM. With this objective in mind behavioral bioassays designed to compare the preferences of GLM for groundnut, soybean, lucern and cowpea were carried out. A Y-tube olfactometer bioassay was used to examine moth orientation to test plant odors.

Mots Clés : Aproaerema modicella ; GLM ; Small holder farmers ; Host plants ; IPM ; Natural enemies ; GBM

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Page publiée le 1er avril 2020