Effect of temperature on the biological and demographic parameters of two citrus pests: Eutetranychus orientalis (Klein) and Panonychus citri (McGregor) (Acarina: Tetranychidae)

The brown citrus mite, Eutetranychus orientalis (Klein), and the red citrus mite, Panonychus citri (McGregor), are important mites that may cause considerable damage to citrus fruit in Tunisia and other countries around the word. In the present study, we investigated some biological and demographic parameters of the already cited mites under controlled laboratory conditions. To do so, various temperature levels were tested on the fitness of E. orientalis (30-35 °C) and P. citri (25-30 °C) at fixed relative humidity (50%) and photoperiod (16L:8D). Concerning E. orientalis, our results indicated that its development time from egg to adult was longer for females (12.1 and 10.7 days at 30 and 35 °C respectively) compared to males (11.3 and 10.2 days at 30 and 35 °C respectively). The average longevity of females ranged from 5.9 (at 35 °C) to 9.7 days (at 30 °C). The total fecundity was 21 and 17.1 eggs per female at 30 and 35 °C respectively with a female offspring sex ratio of about 65%. The intrinsic growth rate (iGR) varied from 0.172 at 30 °C to 0.141 at 35 °C. Our study demonstrated also that P. citri females laid over their lifetime an average of 19.5 eggs and 13.6 eggs at 25 and 30 °C respectively with a sex ratio of about 69%. Longevity of fertilized females was shorter at 30 °C (6.2 days) compared to 25 °C (10.5 days). Development time was longer for female (15.4 days at 25 °C and 9.8 days at 30 °C) compared to male (14.5 days at 25 °C and 9.3 days at 30 °C). The intrinsic growth rate (rm) was 0.125 at 25 °C and 0.159 at 30 °C. These findings underscore the considerable adaptability of E. orientalis and P. citri to diverse temperature variations, emphasizing the importance of this study for integrated mite management in Tunisian citrus cultivation, therefore to understand their population dynamics, ecological interactions, and optimal intervention periods.