Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and fungus gnats Bradysia spp. (Diptera: Sciaridae) are major insect pests of greenhouse production systems (Cloyd, 2008, 2009; Hamlen and Mead, 1979; Lewis, 1997), with life stages that reside in the soil or plant-growing medium. Western flower thrips pupal life stages (prepupae and pupae) are located in the soil or plant-growing medium (Helyer et al., 1995; Holmes et al., 2012), and the larvae of fungus gnats reside in the soil or plant-growing medium (Cloyd, 2000; Dennis, 1978; Kennedy, 1974).
The bacterium Bacillus pumilus is not considered an insect pathogen like B. thuringiensis or B. sphaericus (Molina et al., 2010). However, there are unsubstantiated allegations made by a manufacturer that certain plant-growing media containing B. pumilus and an arbuscular mycorrhizal fungus, Glomus intraradices, negatively affect the survival of western flower thrips pupae and fungus gnat larvae (Bloodnick and Naasz, 2019). Consequently, we conducted a series of replicated experiments to determine whether plant-growing media containing B. pumilus and/or G. intraradices have a negative effect on western flower thrips pupal and fungus gnat larval survival under laboratory conditions.
Cloyd, R.A. 2000 Fungus gnat and shorefly management strategies: Panel discussion, p. 57–59. In: A.I. King and I.D. Greene (eds.). Proceedings of the 16th Conference of Insect and Disease Management. Ornamental Society of American Florists, Alexandria, VA
Cloyd, R.A. 2009 Western flower thrips (Frankliniella occidentalis) management on ornamental crops grown in greenhouses: Have we reached an impasse? Pers. Technol. 3 1 9
Helyer, N.L., Brobyn, P.J., Richardson, P.N. & Edmondson, R.N. 1995 Control of western flower thrips (Frankliniella occidentalis) pupae in compost Ann. Appl. Biol. 127 405 412
Holmes, N.D., Bennison, J.A., Maulden, K.A. & Kirk, W.D.J. 2012 The pupation behaviour of the western flower thrips, Frankliniella occidentalis (Pergande) Acta Phytopathol. Hun. 47 87 96
Kennedy, M.K. 1974 Survival and development of Bradysia impatiens (Diptera: Sciaridae) on fungal and non-fungal food sources Ann. Entomol. Soc. Am. 67 745 749
Lewis, T. 1997 Pest thrips in perspective, p. 1–14. In: T. Lewis (ed.). Thrips as crop pests. CAB International, Wallingford, UK
Molina, C.A., Caña-Roca, J.F., Osuna, A. & Vilchez, S. 2010 Selection of a Bacillus pumilus strain highly active against Ceratitis capitata (Wiedenmann) larvae Appl. Environ. Microbiol. 76 1320 1327
SAS Institute 2012 SAS/STAT user’s guide, version 9.4. SAS Institute, Cary, NC