Susceptibility of the taro beetle,Papuana uninodis,to entomopathogenic nematodes

Six strains of entomopathogenic nematodes, Steinernema glaseri (Steiner) (Biosys #326, nc 34, gb), S. feltiae = bibionis (Filipjev) (Biosys #349), S. carpocapsae Weiser (Biosys #25) and Heterorhabditis zealandica Poinar, were evaluated in laboratory tests against taro beetles, Papuana uninodis Prell. Larvae of this species and adult Papuana Arrow spp. were found to be susceptible to entomopathogenic nematodes. The best results were obtained with S. glaseri #326 in larval and adult P. uninodis . The dose causing 50% mortality (LD ) for third instar P. uninodis larvae in Petri dish assays ranged from almost 7000 nematodes/larva for 1 days exposure to less than 250 nematodes/larva for 6 days; in pot assays the concentration causing 50% mortality (LC ) in 2 weeks was 1.4 106 nematodes/m2. For 50 adults in Petri dishes with soil, the LD was ca 20 000 nematodes/ 50 adult for 1 weeks exposure and ca 6000 nematodes/adult for 3 weeks. In pot assays the LC was 2.5 106 nematodes/m2 in 3 weeks. 50 Preliminary tests showed that P. huebneri (Fairmaire) and P. woodlarkiana laevipennis Arrow adults were also most susceptible to S. glaseri #326. A field test on adults Papuana uninodis did not result in damage reduction but served to illustrate the practical difficulties of applying nematodes in remote areas. 50