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Raymond A. Cloyd, Amy Dickinson, Richard A. Larson, and Karen A. Marley

have been used to collect fungus gnat species in the family Mycetophilidae ( Mikolajczyk, 2001 ). Fungus gnats, Bradysia spp. (Diptera: Sciaridae), are major pests in greenhouses ( Dennis, 1978 ; Hamlen and Mead, 1979 ). Although fungus gnat adults

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Raymond A. Cloyd and Amy Dickinson

Fungus gnats (Bradysia spp.) are major insect pests in greenhouses. The adult stage is primarily a nuisance whereas the larval stage is directly responsible for plant injury by feeding on plant roots or tunneling into stems. Insecticides are used to deal with fungus gnat larvae in growing medium, although sometimes with limited success. This study evaluated the potential of using a soil amendment—diatomaceous earth (DE) incorporated into growing media—for controlling the fungus gnat Bradysia sp. nr. coprophila. Two experiments were conducted by testing a series of growing media containing various concentrations of diatomaceous earth, and several without diatomaceous earth. The effects of the growing media containing diatomaceous earth on both the 2nd and 3rd instars of fungus gnat larvae were determined by recording the number of adults captured on yellow sticky cards (2.5 × 2.5 cm). Based on the results obtained from both experiments, the addition of DE to growing medium, at the concentrations tested, did not negatively affect or increase efficacy against both the 2nd and 3rd instars. This suggests that incorporating DE into commercially available growing medium may not be beneficial to greenhouse producers. However, further research is needed to assess whether differential larval susceptibility and moisture content influence the ability of DE to control soil-dwelling arthropods.

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Raymond A. Cloyd, Karen A. Marley, Richard A. Larson, and Bari Arieli

Fungus gnats ( Bradysia spp.) are common insect pests of greenhouse-grown crops ( Dennis, 1978 ; Hamlen and Mead, 1979 ). The adult flies are considered a nuisance causing minimal direct plant damage ( Cloyd, 2000 ); however, eggs laid by adult

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Raymond A. Cloyd and Amy Dickinson

The soft-bodied larvae of fungus gnats ( Bradysia spp.) reside in growing medium and require constant moisture for survival ( Ellisor, 1934 ). Moisture content is an essential factor responsible for the development and survival of insect stages

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Nathan J. Herrick and Raymond A. Cloyd

Fungus gnat, Bradysia sp. nr. coprophila (Lintner) (Diptera: Sciaridae), larvae can damage plants grown in greenhouse production systems, especially during propagation ( Cloyd, 2000 ). Fungus gnat larvae feed on plant roots, which inhibits the

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Raymond A. Cloyd, Karen A. Marley, Richard A. Larson, and Bari Arieli

Fungus gnats ( Bradysia spp.) are common insect pests of greenhouse-grown crops ( Dennis, 1978 ; Hamlen and Mead, 1979 ). The adults are primarily considered a nuisance causing minimal actual plant damage ( Cloyd, 2000 ), although the eggs laid

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Amy L. Raudenbush, Raymond A. Cloyd, and Erik R. Echegaray

Fungus gnats are a commonly encountered insect pest of greenhouses ( Dennis, 1978 ; Hamlen and Mead, 1979 ) and are typically a problem in moist environments such as those that occur in propagation or plug production ( Cloyd, 2000 ). Adults cause

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Nathan J. Herrick and Raymond A. Cloyd

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

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Nathan J. Herrick and Raymond A. Cloyd

The fungus gnat, Bradysia sp. nr. coprophila (Lintner) (Diptera: Sciaridae), is a major insect pest of greenhouse-grown horticultural crops, especially during propagation ( Cloyd, 2000 ). The larvae damage plants directly by feeding on plant

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Michael R. Evans, James N. Smith, and Raymond A. Cloyd

Coir and peat-based substrates were tested for their effectiveness in inhibiting the development of fungus gnat populations. The first experiment was conducted in July under relatively high temperatures (20 to 35 °C) and a second experiment was conducted in April under relatively low temperatures (20 °C). Euphorbia pulcherrima Willd. ex Klotzch `Freedom' plants were planted into 18-cm-diameter containers filled with substrates containing 80% sphagnum peat or coir, with the remainder being perlite. Half of the containers of each substrate were inoculated with fungus gnat larvae and sealed with either cheesecloth or thrips screen for Expts. 1 and 2, respectively. After 6 and 8 weeks for Expts. 1 and 2, respectively, fungus gnat adult and larval populations were sampled. Adults and larvae were recovered from coir and peat-based substrates in both experiments. In Expt. 1, significantly more adults and larvae were recovered from coir-based than peat-based substrates. In Expt. 2, significantly more adults and larvae were recovered from the peat-based than coir-based substrates. In a third experiment, the peat- and coir-based substrates used in Expts. 1 and 2 were used as well as the Iowa State greenhouse substrate, which contained 40% Sphagnum peat, 40% perlite, and 20% loam (v/v). Helianthus annuus L. `Pacino' seeds were sown into 18-cm-diameter containers filled with the test substrates. Natural infestation was allowed to occur for 6 weeks, after which time potato disks were used to sample the fungus gnat larvae population. Larvae were recovered from all substrates, and there was no significant difference in the number of larvae collected from the three substrates. Based on the results of these experiments, we concluded that coir does not inhibit the development of fungus gnat larvae populations and, when presented with options, fungus gnats will infest coir-based substrates as readily as peat-based substrates.