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1Department of Biochemistry, Kenyatta University, Kenya
2Microbiology and Biotechnology, Kenyatta University, Kenya
The cowpea (pigeon pea) weevil, Callosobruchus maculatus, is a significant pest of stored pulses, particularly affecting crops like cowpea and pigeon pea in tropical and subtropical regions. This review examines the biology, life cycle, and the damaging effects of C. maculatus on stored pigeon pea grains. The insect undergoes a holometabolous life cycle, with rapid development influenced by temperature and humidity, which allows for multiple generations during a single storage season. The damage caused by C. maculatus includes direct feeding on seeds, resulting in weight loss, reduced seed viability, and compromised nutritional quality, along with contamination from insect frass and remains, further degrading the grains' marketability and safety. The economic impact is substantial, particularly in regions where pigeon peas are a staple crop, affecting food security and farmers' livelihoods. Control measures for C. maculatus include a combination of cultural, physical, chemical, and biological strategies. These include proper storage practices, the use of inert materials like diatomaceous earth, irradiation, low temperature treatments, and chemical controls, each with their advantages and limitations. Integrated pest management, utilizing multiple strategies, is essential for effective control and minimizing losses.
The cowpea (pigeon pea) weevil, Callosobruchus maculatus (Fabricius) is a major pest of stored pulses, more specifically the cowpea and pigeon pea. This insect is of the order Coleoptera, Chrysomelidae family, and Bruchinae subfamily. Also referred to as the cowpea weevil or cowpea seed beetle, it is a global bug that results in considerable crop losses of stored legumes in the tropical and subtropical climates as noted by Akbar et al. (2022). Adult C. maculatus beetles are small in size and are usually between 2.5 to 3.5 millimetres in length (Magaji et al., 2020). They have a very unique brown fur with black and grey markings. Elytra (wing covers) are especially distinctive; they are coloured black with large spots also helping to identify the species. The insects are sexually dimorphic, where the females are slightly larger than the males. The antennae are grooved and are segmented into 11 different sections which is a distinct feature of the species (Salunkhe & Gaikwad, 2023).
Figure 1: Mature Male and Female Pigeon Pea Bruchid (Callosobruchus maculatus). Adapted from Ethan Estabrook, BCE-Research Associate at Insects Limited
2.0 Life Cycle of Callosobruchus maculatus
C. maculatus undergoes holometabolous development, characterized by complete metamorphosis through four distinct stages: These stages are the egg stage, larvae stage, pupal stage, and the adult stage (Salunkhe & Gaikwad, 2023). The overall development time depends on the environmental conditions in terms of temperature and humidity.
Athanas Alexander Katoo*, Mathew Ngugi, Stephen Gitahi, Callosobruchus Maculatus: A Biotic Enemy to Pigeon Pea Productivity, Int. J. Sci. R. Tech., 2025, 2 (3), 483-487. https://doi.org/10.5281/zenodo.15085157
10.5281/zenodo.15085157