Browsing by Subject "Parasitoids"

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    Effect of mulch application in combination with NPK fertilizer in cowpea (Vigna unguiculata (L.) Walp.; Leg.) on two key pests, M. vitrata F. (Lepidoptera: Pyralidae) and M. sjostedti Trybom (Thysanoptera: Thripidae), and their respective parasitoids
    (1999) Zenz, Nikolaus; Zebitz, Claus P. W.
    African farmers use mulch to preserve soils from physical and nutritional degradation. No clear evidence exists whether mulch may also be used successfully to control pests. This study aimed to assess the effect of mulch in combination with NPK fertilizer on two key pests of cowpea (Vigna unguiculata (L.) Walp.; Leguminosae), the legume pod borer Maruca vitrata F. (Lepidoptera: Pyralidae) and the flower thrips Megalurothrips sjostedti Trybom (Thysanoptera: Thripidae), inclusive of their parasitoids. Trials were carried out in three regions of Benin, West Africa, from 1995 to 1997. This study focused on plant physiology, soil properties, climate as well as habitat structure, all of which were assumed to have a strong influence on pest abundance. Data on plant development represented by number of nodes, flowers, and pods were collected periodically. Flowers were sampled in parallel to monitor the abundance of both pests. Eggs and living larvae of M. vitrata and larvae of M. sjostedti were collected periodically and reared for studies on parasitism. Mortalities due to three braconid parasitoids were assessed belonging to the order of hymenoptera, Dolichogenidea sp., Phanerotoma leucobasis Kriechbaumer, and Braunsia kriegeri Enderlein, which represented the dominant species on larvae of M. vitrata. Ceranisus menes Walker (Hymenoptera: Eulophidae) was the only parasitoid found on M. sjostedti. Pods were harvested and assessed for damage of M. vitrata. Pod number, weight per pod, relative pod and grain damage were investigated and estimates were made of the yield losses. Yield of cowpea was measured and related to preceding pest abundance. Pods were counted, weighed, and husked, and grains were weighed. Flowers were collected from potential wild host species of both pests in the vicinity of cowpea fields. Insect counts from flowers in the adjacent cowpea fields served as comparison.