Notes on the biology of Nysius natalensis Evans (Hemiptera: Orsillidae)

Abstract

Four of the more than 100Nysius species known worldwide, occur in South Africa, viz. Nysius natalensis Evans, Nysius binotatus (Germar), Nysius pallidus Evans and Nysius stali Evans. Although, N. natalensis is a sporadic pest of sunflower in South Africa, no description of the different life stages has been published. Such information would facilitate monitoring of the pest and contribute to the improvement of management practices. This study showed that N. natalensis oviposits mainly in flowers and attach eggs to the ovaries in the flowers or to the pappus in the case of the Asteracea. Eggs were also laid next to fruits of host plants. The majority of these plant species are weeds occurring in natural vegetation, with eggs most frequently observed in the seed heads of the Asteraceae. Differences in head width and pronotum width of N. natalensis can be used to distinguish between the five nymphal instars and adult females, which were significantly larger than adult males and can easily be distinguished by the ovipositor cleft visible on the underside of the abdomen.