Efficacy of entomopathogenic nematodes against western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae), under laboratory conditions

Western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is an important field and greenhouse pest of many crops worldwide. To control F. occidentalis is extremely challenging, because of its cryptic behaviour, short life cycle, and resistance to many insecticides. The life history and success rate of WFT on chrysanthemum (Dendranthema grandiflora) leaflets and green bean pods (Phaseolus vulgaris) showed that more first instar larvae hatched, and developed faster, with a higher survival rate, on the former than on the latter, making chrysanthemum a more attractive and suitable host than were the green beans. A total of 11 local South African entomopathogenic nematode species and the exotic Steinernema feltiae, were tested, under laboratory conditions, for pathogenicity against WFT. Generally, Heterorhabditis spp. were more virulent than were the Steinernema spp. The study showed that locally isolated Sleinernema yirgalemense (66 %), Heterorhabditis baujardi (67 %), and Heterorhabditis bacteriophora (60 %) had potential for the control of F occidentalis, in terms of targeting its soil-dwelling stages. Results from the temporal development study showed that both S. yirgalemense and H. baujardi were able to complete their life cycles in the host, and to produce a new cohort of infective juveniles.