Two different biological control agents for boosting thrip mortality

Two different biological control agents together can boost thrip mortality

Western flower thrips (Frankliniella occidentalis) are tiny insect pests that cause a serious damage to many plant species by directly feeding on their leaves and flowers and by transmitting disease causing viruses such as impatiens necrotic spot virus and tomato spotted wilt virus.

Western flower thrips damage many plant species including african violet, apples, celery, chrysanthemum, cucumber, dahlia, fuchsia, gerbera, geranium, gladiolus, gloxinia, impatiens, ivy, lettuce, onions, orchids, peanuts, peas, peppers, petunia, primula, roses, sweet pepper, tomatoes etc.

Western flower thrips develop through four different life stages including eggs, larvae, pupae and adults.  Generally, eggs, larval, prepupal and adult stages found on the leaves and flowers whereas pupal stages found in the soil.

Management of thrips with biological control agents including beneficial entomopathogenic nematodes and predatory mites is a good strategy because they are not harmful to people, animals and environment.

Beneficial entomopathogenic nematodes, Heterorhabditis bacteriophora and Heterorhanbditis indica

Two beneficial entomopathogenic nematodes including Heterorhabditis bacteriophora and Heterorhanbditis indica have showed a very high efficacy against soil dwelling larval and pupal stages of the western flower thrips (Frankliniella occidentalis).  Since these beneficial nematodes are not harmful to people, pet animals and even beneficial insects like honey bees, they are safe to apply in the greenhouses, nurseries and fields against thrips using traditional sprayers and even water cans.  The beneficial entomopathogenic nematodes are commercially available and generally applied in the soil to target second stage thrip larvae that move into the soil for pupation.  These nematodes can also infect and kill pupal stages of thrips in the soil which in turn will reduce the emergence of adult thrips.

Beneficial predatory mite, Neoseiulus =Amblyseius cucumeris

A Beneficial predatory mite scientifically known as Neoseiulus =Amblyseius cucumeris are applied on plant foliage to target larval, prepupal and adult stages of thrips.  These beneficial predatory mites feed indiscriminately on especially immature stages of different species thrips including the western flower thrips (Frankliniella occidentalis), the flower thrips or eastern flower thrips (Frankliniella tritici), the onion thrips (Thrips tabaci), the greenhouse thrips (Heliothrips haemorrhoidalis) and the melon thrips (Thrips palmi).  Amblyseius cucumeris are commercially available and easy to apply as biological control agents for the management of thrip populations in the greenhouses.

Combined effects of beneficial entomopathogenic nematodes and predatory mites on the western flower thrips

An interesting research published by scientist from Germany and Kenya (Ebssa et al., 2006) showed that the simultaneous applications of both the predatory mites (Amblyseius cucumeris) and beneficial entomopathogenic nematodes (Heterorhabditis bacteriophora and Heterorhanbditis indica)as biological control agents have potential to enhance the mortality of thrips in the greenhouses.  These researchers observed that the predatory mites when applied on the plants infested with thrips, second larval stages of thrips tend to fall off the plants either to escape attack by mites or for pupation in the soil but these fallen thrip larvae became easy target for beneficial entomopathogenic nematodes that were already present in the soil (Ebssa et al., 2006). This means predatory mites can feed as many as immature stages of thrips that are present on the foliage and flowers and entomopathogenic nematodes will kill larval and pupal stages that are present in the soil.  So these findings suggest that the efficacy of both the biological control agents against the western flower thrips can be enhanced if the predatory mites and beneficial entomopathogenic nematodes are applied simultaneously on the foliage and in the soil, respectively.

Literature:  Please read following literature for more information on the interaction between beneficial entomopathogenic nematodes or predatory mites and thrips.

  1. Arthurs, S. and Heinz, K.M.  2006. Evaluation of the nematodes Steinernema feltiae and Thripinema nicklewoodi as biological control agents of western flower thrips Frankliniella occidentalis infesting chrysanthemum. Biocontrol Science and Technology 16: 141-155.
  2. Ebssa, L., Borgemeister, C. and Poehling, H.M. 2004. Effects of post-application irrigation and substrate moisture on the efficacy of entomopathogenic nematodes against western flower thrips, Frankliniella occidentalis. Entomologia Experimentalis Et Applicata 112: 65-72.
  3. Ebssa, L., Borgemeister, C. and Poehling, H.M. 2006. Simultaneous application of entomopatho genic nematodes and predatory mites to control western flower thrips Frankliniella occidentalis. Biological Control 39: 66-74.
  4. Ebssa, L., Borgemeister, C., Berndt, O. and Poehling, H.M.  2001. Efficacy of entomopathogenic nematodes against soil-dwelling life stages of western flower thrips, Frankliniella occidentalis(Thysanoptera: Thripidae). Journal of Invertebrate Pathology 78: 119-127.
  5. Navarro-Campos, C., Pekas, A., Moraza, M.L., Aguilar, A. and Garcia-Mari, F. 2012. Soil-dwelling predatory mites in citrus: Their potential as natural enemies of thrips with special reference to Pezothrips kellyanus (Thysanoptera: Thripidae). Biological Control 63: 201-209.
  6. North, J.P., Cuthbertson, A.G.S. and Walters, K.F.A. 2006. The efficacy of two entomopathogenic biocontrol agents against adult Thrips palmi(Thysanoptera: Thripidae).  Journal of Invertebrate Pathology 92: 89-92.
  7. Premachandra, D.W.T.S., Borgemeister, C., Berndt, O., Ehlers, R.U. and Poehling, H.M. 2003.  Laboratory bioassays of virulence of entomopathogenic nematodes against soil-inhabiting stages of Frankliniella occidentalis Pergande (Thysanoptera: Thripidae). Nematology 5: 539-547.
  8. Rahman, T., Spafford, H. and Broughton, S. 2012. Use of spinosad and predatory mites for the management of Frankliniella occidentalis in low tunnel-grown strawberry.  Entomologia Experimentalis Et Applicata 142: 258-270.
  9. Trdan, S., Znidarcic, D. and Vidrih, M. 2007.  Control of Frankliniella occidentalis on glasshouse-grown cucumbers: an efficacy comparison of foliar application of Steinernema feltiae and spraying with abamectin.  Russian Journal of Nematology 15: 25-34.

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