Thermal biology and establishment potential in temperate climates of the predatory mirid Nesidiocoris tenuis

Nesidiocoris tenuis Reuter (Hemiptera: Miridae) is a polyphagous mirid currently used for the control of leafminers, thrips, whitefly and spider mites in Mediterranean regions to which it is indigenous. This study investigates the establishment potential of N. tenuis in cool temperate climates typical of northern Europe through assessment of its thermal biology and low temperature tolerance in laboratory and field experiments. The developmental threshold of N. tenuis was estimated to be 12.9A degrees C with no indication of ability to diapause. Supercooling points of the acclimated and non-acclimated adults and nymphs of the mirid were between -17.6A degrees and -21.5A degrees C and the LTemp(50) was around -12A degrees C, indicating a high level of pre-freeze mortality. The LTime(50) at 5A degrees C was nine days and 100% mortality occurred after less than four weeks of winter field exposure. Collectively these data suggest that N. tenuis is unlikely to establish in northern Europe and would therefore have little or no non-target effects on native species in such regions.