The twospotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) is an important agricultural pest. Population dynamics and pest outbreaks highly depend on the overwintering success of the mite specimens; therefore, it is necessary to assess winter survival dynamics of this pest. Seasonal changes in supercooling point (SCP) and acute cold tolerance (2-h exposure at -5, 10, -15, -20, -23, or -25°C) were assessed in field-collected females during the winter in 2010–2011 in Iran. The SCP values varied from a minimum of -30.5°C (January 2011) to a maximum of -12.6°C (April 2011 ). Significant differences were recorded in the SCP distribution patterns between autumn-and winter-sampled females, depicting the acquisition of cold hardiness over the winter. The mean ambient air temperature was the lowest in January (4°C), when the females showed the highest supercooling ability. Correlated patterns between monthly temperatures and acute cold tolerance also were found. At -20°C, the survival of the mites was very low (10%) when they were sampled in October 2010; whereas it was high (97.5%) in January 2011, before decreasing to 5% in April 2011. The present data show that T. urticae females are chill tolerant and capable of adjusting their cold tolerance over the winter season. Acute cold tolerance ( -15 and -20°C) and SCP represent valuable metrics that can be used for predicting the seasonal changes of the cold hardiness of T. urticae females.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 42 • No. 6