Assessment of Augmentative Releases of Parasitic NematodeThripinema nicklewoodifor Control ofFrankliniella occidentalisin Impatiens Bedding Plants

Abstract

The efficacy of Thripinema nicklewoodi Siddiqi as a biological control agent of Frankliniella occidentalis (Pergande) was tested on caged impatiens bedding plants in a greenhouse. Inoculative releases of parasitized female thrips were made seven times into the caged impatiens preinfested with adult thrips. Two rates were used, one or two parasitized thrips per release date, and impacts on thrips population and flower production were compared with spinosad insecticide treatment and untreated control. Sampling began 9 January 2003 and repeated every 100 degree-days until 4 March 2003. The best thrips control was achieved in the spinosad treatment. None of the four thrips life stages was found at levels higher than 0.09 thrips per flower. Nematode release treatments also reduced thrips population up to 56% for second instars, 72% for adult females, and 62% for adult males, compared with thrips numbers in untreated control cages. However, no difference in reduction of thrips populations was found between the two nematode treatments with different release rates. Both spinosad and nematode treatment cages produced up to 3 and 1.4 times as many flowers compared with the control, respectively. A simpler rearing method for production of T. nicklewoodi also was presented. Using a “thrips-egg-embedded” rolled bean leaf as the transmission arena, 2.7 F1 parasitized female F. occidentalis were produced for each P1 parasitized thrips used for inoculum.