Relative Abundance and Diversity of Insect Species on Nine Genotypes of Pepper (Capsicum spp.) Grown under Field Conditions in Ghana

Abstract

Aim: To identify the different types and relative abundance of insect species on the nine genotypes of pepper, as a guide to instituting control measures against unacceptable crop damage. Study Design: The experimental treatments were deployed in a Randomized Complete Block Design (RCBD), replicated three times. Place and Duration of Study: Nuclear Agriculture Research Center (NARC) farms and the laboratories of Radiation Entomology and Pest Management Center (REPMC) of Biotechnology and Nuclear Agriculture Research Institute (BNARI). The study was conducted during June-October, 2011. Methodology: Seeds of the nine pepper genotypes (Anloga, Antillas, Archard, Big Sun, Bombardier, Forever F1, Legon 18, Poivron California Wonder (PCW) and Sunny F1) were sown in a nursery and transplanted 35 days after germination to an experimental plot measuring 40 m x 11.4 m in the centre of one acre area such that the experimental plot was surrounded by a homogeneously managed terrain. The experimental treatments were deployed in a Randomized Complete Block Design (RCBD), replicated three times. Each replicate was allotted a plot size of 12 m x 11.4 m. Each replicate was subdivided into nine sub-plots, with each sub-plot planted to one genotype consisting of 30 plants at a spacing of 0.8 m x 0.6m. Plots were separated by a distance of 2 m. Random sampling technique was used on weekly basis to study the relative abundance, diversity and behaviour of the insect species on the genotypes. Results: Thirteen different insect species were identified from the vegetative through to the maturity stage with relative abundance ranging from 0.04– 54.29%. The highest number of insects were found on the genotypes Forever F1 (26.2%) and Anloga (25.9%). Legon 18 and Sunny F1 registered the highest diversity of insect species, while PCW, Big Sun and Forever F1 recorded the least diversity. Aphis craccivora (Koch) (Hemiptera, Aphididae) was the most dominant pests sampled on four genotypes (Anloga, Antillas, Forever F1 and Legon 18) of the nine pepper genotypes. Similarly, Camponotus sp. was the most dominant predator on the pepper genotype Archard. For the rest of the genotypes, there were no significant difference (P=.05) in mean number of insects sampled per genotype. Three mutualistic insects namely Camponotus sp., Cheilomenes lunata (Fabricius) (Coleoptera, Coccinellidae) and A. craccivora were sampled on the pepper genotypes. The degree of association between any of these is displayed in Table 4. Mean number of C. lunata was highly significantly correlated (P=.01) with that of A. craccivora. Conclusion: The high abundance of insect pests in the study area coupled with the pest status of the majority (53.28%) necessitates control measures to prevent economic loss during commercial cultivation in the area. Further work needs to be done on designing a friendly IPM strategy for the major insects encountered in the study so that crop loss due to insect pest infestation can be minimized.