The attraction of Zonocerus variegatus (L.) (Orthoptera: Pyrgomorphidae) to the weed Chromolaena odorata and associated feeding behaviour

Abstract

In studies in Nigeria, all instars of Zonocerus variegatus (L.) were found to be strongly attracted to flowers of the common exotic composite weed Chromolaena odorata. Experiments in the field and with caged nymphs suggested that the attraction is due to a volatile compound(s) concentrated in the conspicuous stigmas and released when the buds open. Although very palatable, the flowers seemed inadequate as food, and most of the nymphs roosting on C. odorata even during the flowering season had fed on leaves of C. odorata or other plants. Feeding diminished the attraction to the inflorescences in experimental cages, and of the field nymphs attracted between 11.00 and 15.00 h, a significantly higher proportion than on other plants had relatively empty foreguts. The numbers of field nymphs attracted were maximal at 08.00–10.00h and minimal at 11.00–12.00 h. Both in the cages and in the field, interest in the inflorescences diminished after about 17.00 h, when the highest points within reach are being looked for as roosting sites. Reduction of C. odorata around plantations is unlikely to lessen crop damage by Z. variegatus, but insecticides for Z. variegatus control could be applied conveniently to the tops of C. odorata at roosting time during the flowering season.