Thermal biology of Typhlodromips montdorensis: implications for its introduction as a glasshouse biological control agent in the UK

The recent unexpected local establishment of a non-native predatory mite, Neoseiulus californicus (McGregor) (Acari: Phytoseiidae), in the UK prompted us to undertake this study, which investigated the thermal biology of an alien species Typhlodromips montdorensis (Schicha) (Acari: Phytoseiidae). Laboratory and field experiments on its cold tolerance were used to assess its establishment potential outside of glasshouse environments in the UK. Currently, T. montdorensis is being tested as a glasshouse biological control agent against thrips and spider mites, but is not yet licensed for release in the UK. Typhlodromips montdorensis has a developmental threshold of between 10.3 and 10.7 degreesC, and a thermal budget of between 108.7 and 105.3 degree-days when estimated by weighted and simple linear regression, respectively. Under outdoor conditions, T. montdorensis could theoretically complete up to six generations a year. The supercooling points of female and larval T. montdorensis were -22 to -24 degreesC with 100% pre-freeze mortality apparent in both acute and chronic low temperature exposures. Typhlodromips montdorensis were unable to enter diapause under a selected laboratory regime. No reproduction occurred in the field from November to March, with 100% mortality within 7-14 days of release during this period. It is concluded that T. montdorensis would be a 'safe candidate' for introduction as a glasshouse biological control agent in the UK.