Thrips as pests in New Zealand

Of the 6150 described species of Thysanoptera, less than 100 have been recorded as pests around the world. Most of these pests are localized, but a few are widespread and cause serious crop loss. In New Zealand, Thrips tabaci, the polyphagous Onion Thrips, was the major thrips crop pest for many years. However, the Western Flower Thrips, Frankliniella occidentalis from western USA, was recorded in New Zealand for the first time in 1994 and has become widespread in greenhouses (Teulon & Nielsen 2005), along with the related European species Frankliniella intonsa. All three of these species can also cause damage to garden plants and open field crops. The Greenhouse Thrips, Heliothrips haemorrhoidalis, is a recurrent problem under glass, but is a particular problem on smooth skinned Kiwifruit varieties (McKenna et al. 2009). This thrips has also been associated with damage to Pinus radiata seedlings (Zondag 1977). There are many species of thrips that live on grasses, and Chirothrips manicatus was at one time considered a pest of Cocksfoot production in New Zealand (Doull 1956).

The most important economic problem associated with thrips is the ability of a few species to vector Tospoviruses (Rotenberg et al. 2015). The three known vector thrips found in New Zealand are associated with the following viruses (* indicates known from New Zealand): Frankliniella occidentalis: Chrysanthemum stem necrosis virus, Groundnut ringspot virus, Impatiens necrotic spot virus*, Tomato zonate spot virus, Alstroemeria necrotic streak virus, Tomato chlorotic spot virus, and Tomato spotted wilt virus*. Frankliniella intonsa: Chrysanthemum stem necrosis virus, Groundnut ringspot virus, Impatiens necrotic spot virus*, Tomato chlorotic spot virus, and Tomato spotted wilt virus*. Thrips tabaci: Iris yellow spot virus*, Tomato yellow fruit ring virus, and Tomato spotted wilt virus*.

Of the thrips species not currently present in New Zealand, but that are included in this system as ‘high risk invaders’, Frankliniella schultzei, Thrips palmi and Scirtothrips dorsalis are also vectors of several tospoviruses.