Prevailing insects in Roselle plants, Hibiscus sabdariffa L., and their efficiency on pollination

Abstract

Field surveys of Roselle plant fields were conducted during two successive seasons of 2006 and 2007. The total counted insects on Roselle, Hibiscus sabdariffa attained 16 species belong to seven insect Orders [(Hemiptera (3 species), Homoptera (1 species), Lepidoptera (3 species), Neuroptera (1 species), Coleoptera (3 species), Diptera (1 species), Hymenoptera (4 species)]. Variable numbers of insects were counted on different Roselle varieties and in the two seasons. The most prevailing insect species were the piercing sucking pests [Empoasca spp.; Spilostethus longulus Dallas; Nezara viridula L. and Oxycarenus hyalinipennis (Costa)] and the predators [Polistes sp., Coccinella undecimpunctata and Scymnus syriacus]. Honeybee (Apis mellifera L.) proved to be the most abundant pollinator, averaging 13, 17, 18 individuals/25double strikes in cultivations of Sudani, Masri and White varieties of Roselle plants during flowering of the first season respectively. Similar results were also obtained in the second season. The highest number of honeybees was recorded around 10 am to midday during the flowering stage for the two seasons. It was obvious that the effects of the two hydrothermal, factors temperature and relative humidity, had slight or negligible effects on the occurrence of insect pollination throughout the two seasons of the study, while statistical analysis of the obtained results showed that the productivity of Roselle plant (mean number of seeds and mean weights of seeds) were significantly affected by pollinators.