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February 2007. The Great Glasshouse at the National Botanic Garden of Wales, a huge dome devoted to the display and conservation of Mediterranean-climate plants, has outbreaks Heliothrips haemorrhoidalis. It has been kept under control by spraying intermittently with a mixture of Savona (fatty acids) and Spraying Oil (petroleum derived oil product), but other solutions are requested. Orius was found to be an ineffective predator. Information is required on lifecycle/reproduction rates/preferred plant species, etc.
Two predator species are available in other countries: in Italy and Israel, a predatory thrips (Franklinothrips vespiformis) and a parasitic wasp (Thripobius semiluteus) are used. Information was also requested on these, too.
Low concentrations (0.25% v/v) of mineral oils (good quality, meeting proper standards) dramatically reduces feeding and oviposition. They are safe to use and, when used according to recommendations, the risk of phytotoxicity is low.
Thripobius semiluteus is a very effective parasitoid. It is produced commercially in the USA, in California (it was introduced to California from Australia). It is very easy to rear. There was also a suggestion to try Amblyseius swirskii. It is said to be active against a wide range of thrips.
Information on the life cycle is in the CABI Crop Protection Compendium.
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