Heteronychus arator Population Dynamics and its Influencing Climatic Factors in the Humid Rainforest Maize Field in Cameroon

Nelson Suh, Christopher Ngosong, Nambangia Okolle and Nelson Ntonifor

Background and Objective: Maize (Zea mays L.) is an important versatile food and industrial crop in Cameroon but its production is constraint by many pests including the black maize beetle, Heteronychus arator currently an emerged, serious subterranean perennial pest of the crop. This study aimed to monitor the population dynamics of the pest in maize fields together with influential climatic factors. Materials and Methods: Monthly samples of H. arator adults were collected in 2020 and 2021 in fields planted at a rate of three per hole at 75×50 cm inter and intra-row spacing at 5 cm depth, respectively. Adult beetles were trapped via pitfall and litter traps once every week and data was combined monthly from January to December. Results: In 2020, 9637 adults were caught in both traps and 8980 in 2021 giving a total of 18617. During the peak rainy season, higher numbers were caught in litter traps than the pitfall while during the dry season, the pitfall traps caught higher numbers. Temperature was positively correlated with the number of beetles caught with r = 0.713 in 2020 and r = 0.700 in 2021. In contrast, rainfall and soil moisture were negatively correlated with r = -0.695 and -0.435 in 2020 and r = -0.761 and -0.657, respectively for rainfall and soil moisture in 2021. Conclusion: Baited pitfall and litter traps can be used to monitor and/or sample for H. arator adults in maize fields while the environmental factors can be used to predict the periods of high and low populations of the pest.

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