The reproduction potentials of four entomopathogenic nematode strains related to cost-effective production for biological control

Abstract

• The biocontrol potentials of four entomopathogenic nematode strains were evaluated. • The high virulence of four nematode strains to insect hosts was revealed. • The reproduction capacity was different between nematode strains and insect hosts. • The mealworm is the best choice for mass production of H-KT3987 strain with lowest cost. • The in vivo production cost was little cheaper than in vitro production cost. Bioassays to evaluate the mortality, virulence and reproduction potentials of four indigenous EPN strains, S-PQ16, S-BM12, H-KT3987 and H-CB3452 on insect larvae of mealworm ( Tenebrio molitor ) and greater wax moth ( Galleria mellonella ) revealed the highest mortality rates of two insect larvae at the highest inoculation dose of 100 IJs to range from 89 to 100 percent and 94.3–100 percent at 48 h after inoculation, respectively. Virulence was high for all nematode strains, with LC 50 values between 29.6 and 47.3 IJs/insect host. The highest IJ yields were different between nematode strains and insect host, from 66.8 × 10 3 IJs (S-PQ16) to 118.6 × 10 3 IJs (H-KT3987) on T. molitor , and from 54.2 × 10 3 IJs (S-BM12) to 163.3 × 10 3 IJs (H-KT3987) on G. mellonella . The culturing cost in terms of food expenditure for rearing insect larvae varied between insect larvae and nematode strains, from 6.76 to 26.63 USD per billion IJs for nematode strains cultured on T. molitor larvae and from 3.54 to 7.81 USD per billion IJs for nematode strains cultured on G. mellonella larvae. The full cost for a nematode product of 2.5 × 10 9 IJs per hectare, produced through in vivo mass culturing , of the most efficient nematode strain, H-KT3987, was 191.3 USD, slightly cheaper than 199.4 USD for the same nematode product produced through in vitro mass culturing.