ارزیابی اثرات زیرکشندگی سم اسپیرومسیفن روی کارایی بیولوژیک کنه‌ی شکارگر Neoseiulus californicus (Acari: Phytoseiidae) در شرایط آزمایشگاهی

The predatory mite Neoseiulus californicus McGregor is one of the main natural enemies of the two-spotted spider mite in some countries. Two- spotted spider mite control, is often performed using chemical pesticides. One of the most important ways to reduce the use of acaricides and their biological risk is to combine the biological control agents with compatible acaricides. Spiromecifen is a contact insecticide-acaricide with a 3-day pre-harvest interval (PHI). By doing bioassay tests, sub-lethal values of (LC10, LC20 and LC30) Spiromecifen were estimated 92.344, 171.007 and 266.672 ppm, respectively. Then the sub-lethal effects of mentioned concentrations and control were studied on biological parameters of this predatory mite in laboratory conditions, at 25 ± 2 °C, and relative humidity of 65 ±.5 % and a photoperiod of 16: 8 (L: D) h. Thus 60 of the same-aged eggs were collected randomly from treated females with different concentrations and control, then individually placed into leaf discs without any pollution. After the appearance of adult insects, the number of results generated by each substance was counted and recorded every day until the death of the last one. Data analysis was performed using Age-stage two sex life table theory. According to the obtained results sub-lethal concentrations of Spiromesifen (except LC30) had no significant effect on oviposition period. The lowest total fecundity rate was recorded for the LC30 of Spiromesifen (35.76 eggs/female) that was significantly different from other treatments. The lowest values of the intrinsic rate of increase (r) 0.190 ± 0.006 (day-1), gross reproductive rate (GRR) 36.872 ± 1.77 (offspring), net reproductive rate (R0) 26.657 ± 2.300 (offspring) and finite rate of increase (λ) 1.211 ± 0.008 (day-1) were recorded at LC30 that there was a significance difference with other treatments. However, the results indicated that the mean generation time (T) was not affected by sub-lethal concentrations. Our findings revealed that by increasing concentrations of Spiromesifen, its negative effects on the life table parameters of N. californicus significantly increased. Therefore, for the efficiency of the integrated pest management programs, low quantity of this pesticide should be used in combination with this predatory mite or the predator should be released within appropriate intervals after chemical control.