Arthropod Ecophysiology Group 

Climate change, arthropod overwintering and pest outbreaks

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Availability of wild prey as a factor affecting the

establishment of non-native biocontrol agents in the UK

Ian Hatherly

I did my undergraduate at the University of Birmingham in Environmental biology and my interest in insects led to my research project on the effects of competition on the fitness of the aphid Myzus persicae. I went on to do an MSc in Applied Entomology at Imperial College, Silwood Park. My MSc thesis work was done at the University of Queensland and Gatton research station (Australia) on intercropping to improve performance of parasitoids, such as Diadegma semiclausum of the Diamondback moth, Plutella xylostella. I then returned to Birmingham, to do my PhD funded by CSL on the cold tolerance and establishment potential of non-native biological agents in the UK. I am currently doing a post-doctoral project on effects of the availability of wild prey on the establishment of glasshouse biocontrol agents in the UK.

Current work: Availability of wild prey as a factor affecting the establishment of non-native biocontrol agents in the UK

In 1998 Defra commissioned a project led by the University of Birmingham in collaboration with Central Science Laboratory to design and test an experimental protocol to examine the cold tolerance and overwintering potential of four non-native biological control agents. The project aimed to (i) acquire data on the four species of relevance in its own right (four species had either been recently released into the UK or were under consideration for licenses), and (ii) analyse the combined data sets to determine whether laboratory assessed indices of cold tolerance could be used to predict the survival of non-native species in the field. The final project report was submitted to Defra in January 2001 and subsequently discussed at the 84^th meeting of ACRE in November 2001 (Assessment methodologies for establishment potential of non-native arthropods). The document contained detailed experimental protocols to obtain the data required to enable a prediction of establishment potential of non-native biological control agents outside the glasshouse. Further the work identified a laboratory index that appears to reliably predict survival under field conditions (LTime₅₀ at 5ºC).

The report also outlined the importance of availability and suitability of wild prey for establishment outside the glasshouse environment. It was noted that there was no recommended experimental protocol to obtain the relevant information. ACRE recognised the importance of establishing a second protocol to assess the ability of non-native glasshouse biological control agents to utilise wild prey and this has led to this current project.

The two main glasshouse pests in the UK are the glasshouse spider mite Tetranychus urticae (Koch) (Acari:  Tetranychidae) and glasshouse white fly Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae). Most non-native biological control agents are targeted against these two species, with other targets including thrips and aphids. It is evident that a pilot study on utilisation of wild prey by non-native biological control agents should focus on species used primarily for the control of T. urticae and T. vaporariorum. The predatory mite, Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) (against T. urticae) and the predatory mired bug Macrolophus caliginosus (Wagner) (Hemiptera: Miridae) (against T. vaporariorum) are considered ideal species for this study.