Relationship between temperature and developmental rate of Schizotetranychus smirnovi (Acari: Tetranychidae) on almond

Temperature is an important climatic factor which influences development, reproduction and population dynamics of insects and mites and plays an essential role in pest management. In the present article, the development of Schizotetranychus smirnovi Wainstein (Acari, Tetranychidae) was studied on almond (variety Mamaei) at 11 constant temperatures ranging from 10 degrees C to 36 degrees C (including 10 degrees C, 13 degrees C, 15 degrees C, 17.5 degrees C, 20 degrees C, 22.5 degrees C, 25 degrees C, 27.5 degrees C, 30, 33 degrees C and 36 +/- 1 degrees C), all at 50 +/- 10% RH and 14:10 (L:D) h under laboratory conditions and modelled developmental rate of the mite as a function of temperature. Based on the results, no development was observed at 10 degrees C and no juvenile developed to adult at 36 degrees C. Moreover, egg-to-adult developmental rate decreased gradually from 13 degrees C to 30 degrees C and increased at higher temperatures. The longest (25.18 +/- 1.86 and 23.13 +/- 1.88days) and shortest (2.36 +/- 0.42 and 2.36 +/- 0.42days) female and male immature period was observed at 13 degrees C and 30 degrees C, respectively. The lower temperature threshold for S. smirnovi was obtained as 10.70 degrees C and the total degree-days required for female and male development were calculated as 136.67 and 125.31 DD, respectively. Growth data were fitted to various non-linear models and lower and upper temperature thresholds were estimated along with all model parameters. Most models were rejected for failure to satisfy criteria of goodness of fit and estimable temperature threshold parameters. The Lactin-2 model was selected for estimating the lower and upper temperature thresholds and optimal temperature. Results could be useful in developing S. smirnovi population models to predict the activity and seasonal population dynamics of the pest under the field conditions.