Population of bruchid (Callosobruchus maculatus Fabricious) in three thickness of pod wall of cowpea under different storage periods

• Published in: Thai Agricultural Research Journal (Thailand)
• Main Authors: Payoaw Phompanjai(Department of Agriculture, Bangkok (Thailand). Field Crops Research Institute. Ubonratchathani Field Crop Research Centre), Somjai Kowsurat(Department of Agriculture, Bangkok (Thailand). Field Crops Research Institute. Ubonratchathani Field Crop Research Centre), Pornparn Sudidhyam(Department of Agriculture, Bangkok (Thailand). Field Crops Research Institute. Ubonratchathani Field Crop Research Centre), Vichon Nawnoi(Department of Agriculture, Bangkok (Thailand). Field Crops Research Institute. Ubonratchathani Field Crop Research Centre)
• Format: Journal Article
• Language: Thai
• Published: 01.05.2003
• Subjects: Callosobruchus maculatus; Cowpeas; Fruit; Pest insects; Population density; Storage; Thickness
• ISSN: 0125-8389

Cowpea weevil (Callosobruchus maculates Fabricious) is a serious storage pest in cowpea. It reduces seed germination and causes a foul smell. Female weevil lays eggs on mature green pods. The chance of bruchid larva gets through a pod wall to the seed of cowpea is high as 41 percent. Thickness of cowpea pod wall can lower that chance of bruchid down to as low as only 1 percent. The experiment was conducted to screen cowpea lines with pod wall which are not suitable to growth of cowpea bruchid. There were three groups of cowpea lines according to thickness of their pod walls viewed by the stereo microscope. Those are thin wall group e.g. IT 85F-2687 and KKU 305, medium thin wall, IT 83S-742-13, TVx 1839-09D and thick wall, IT 82E-16 and TVx 4661-07D. Experimental design was RCB with 6 treatments (cowpea lines) and 4 replications. The cowpea was inspected for bruchid eggs in the field at 55 and 60 DAE but were not found due to a heavy rainfall. Some of harvested pods were shelled to measure their thickness by a micro stage. Then 200 g of dry pods analysed for nitrogen, tannin, protein, lipid and crude fiber. It was found that the number of bruchid larva in the cowpea seed was not significantly. However, cowpea line IT 82E-16 with its thickest pod wall (0.8 mm) was least damaged by the bruchid larva. This line also has low nitrogen and protein but high tannin and crud fiber.