Diet composition and lipids of in vitro-produced Heterorhabditis bacteriophora

Several entomopathogenic nematode species are currently under evaluation fo r mass production and field efficacy for biological control of insect pests . However, quality and quantity of in vitro-produced entomopathogenic nemat odes vary considerably, depending on media, temperature, and production met hod, In addition, nematode production should be cost effective. We investig ated nematode yield, production time, total lipid content, and fatty acid c omposition of Heterorhabditis bacteriophora produced in artificial media su pplemented with different lipid sources. Lipid source significantly affecte d lipid quantity and quality in H. bacteriophora. Media supplemented with e xtractable insect lipids produced yields 1.9 times higher than did beef fat - or lard-supplemented media. Moreover, the developmental rate in media sup plemented with host lipids was 1.7 times faster than that in media suppleme nted with beef fat or lard. Nematodes grown in media supplemented with inse ct lipids accumulated significantly higher lipid proportion per dry biomass than those grown in media supplemented with other lipid sources. H. bacter iophora produced in media supplemented with insect lipids, olive oil, or ca nola oil had similar fatty acid patterns, with oleic (18:1) acid as the maj or lipid fatty acid. Media supplemented with other lipid sources produced n ematodes with fatty acid patterns different from those of media supplemente d with insect lipids. We recommend addition of fatty acid mixtures that res emble natural host lipids for mass-producing entomopathogenic nematodes. Th is could provide nematode quality similar to in vivo-produced nematodes and could improve yield. (C) 2000 Academic Press.