Cold tolerance of biological control agents Amblydromalus limonicus and Amblyseius degenerans

Knowledge about cold tolerance of non-native biological control agents is
critical to avoid permanently establishing them in new temperate areas.
The cold tolerance of the predatory mites, A. limonicus and A. degenerans,
was investigated in the laboratory to assess their establishment potential
in northern Europe, particularly Sweden. The lethal time of A. degenerans
declined steeply from 5°C to 0°C and was almost zero at -5°C. The lethal
time of A. limonicus did not differ between 5°C and 0°C but was reduced at
-5°C. For both species, LTime50 was longer for fed than for unfed mites.
In the lethal temperature experiments, a temperature as low as -17.75°C
was required to achieve a 100% mortality rate for A. limonicus,
whereas most A. degenerans died at -8.5°C. LTemp50 was lower for A.
limonicus (-9.8°C) than for A. degenerans (-0.1°C). Collectively, these
findings suggest that A. degenerans is unlikely to be established in
Sweden but that A. limonicus is more cold-tolerant. This highlights the
risk associated with releasing A. limonicus in Sweden, due to
concerns about potential establishment.

明确外来生防天敌的耐寒性相关知识，对于防止其在新生温带区域永久定殖至关重要。本研究于室内测定了两种捕食螨——柠檬钝绥螨（A. limonicus）与德氏钝绥螨（A. degenerans）的耐寒性，以评估它们在北欧（尤其是瑞典）的定殖潜力。德氏钝绥螨的致死时长从5℃急剧下降至0℃区间，并在-5℃时几乎趋近于零；柠檬钝绥螨的致死时长在5℃与0℃间无显著差异，但在-5℃时有所缩短。就两种捕食螨而言，取食个体的半致死时长（LTime50）均长于未取食个体。在致死温度实验中，柠檬钝绥螨需达到-17.75℃的低温方可实现100%死亡率，而德氏钝绥螨多数个体在-8.5℃时即死亡。柠檬钝绥螨的半致死温度（LTemp50，-9.8℃）低于德氏钝绥螨（-0.1℃）。综合上述实验结果可知，德氏钝绥螨几乎无法在瑞典定殖，而柠檬钝绥螨的耐寒性更强。这表明在瑞典释放柠檬钝绥螨存在潜在的定殖风险。