Temperature-dependent life history of Eutetranychus africanus (Acari: Tetranychidae) on papaya

Abstract

This study was conducted to further understand the biology of Eutetranychus africanus Tucker, a newly invasive pest mite in Taiwan that can cause serious damage to papaya. We report the life history of E. africanus on papaya in laboratory conditions at 12, 17, 22, 27 and 32 ± 0.5 °C, with 70 ± 5 % relative humidity and a photoperiod of L12: D12. Eggs did not hatch at 12 °C. Both developmental duration and longevity were significantly shortened with the increase of temperature. The longest and shortest developmental durations of the immature stage were 37.28 days at 17 °C and 8.70 days at 32 °C, respectively. The longevity of both sexes varied similarly with the change in temperature, with shorter lifespan in males: Females survived for 3.64 days (shortest) at 32 °C to 17.50 days (longest) at 17 °C, whereas males survived for 11.00 days (longest) at 17 °C to 2.57 days (shortest) at 32 °C. The differences in fecundity were significant among all tested temperatures, with 17.61 eggs/female at 27 °C being the highest. The low developmental threshold and thermal summation of the full immature stage were 11.48 °C and 163.93 degree-days, respectively. In two-sex life table analysis, population parameters were significantly affected by temperature except the net reproduction rate. The highest intrinsic rate of increase was 0.1221 day−1 at 27 °C; the average generation time was the shortest (12.61 days) at 32 °C and the longest (48.70 days) at 17 °C. The highest net reproduction rate was 5.06 eggs/female at 27 °C. This report contributes background knowledge to the management of the damage caused by E. africanuson papaya.This study was conducted to further understand the biology of Eutetranychus africanus Tucker, a newly invasive pest mite in Taiwan that can cause serious damage to papaya. We report the life history of E. africanus on papaya in laboratory conditions at 12, 17, 22, 27 and 32 ± 0.5 °C, with 70 ± 5 % relative humidity and a photoperiod of L12: D12. Eggs did not hatch at 12 °C. Both developmental duration and longevity were significantly shortened with the increase of temperature. The longest and shortest developmental durations of the immature stage were 37.28 days at 17 °C and 8.70 days at 32 °C, respectively. The longevity of both sexes varied similarly with the change in temperature, with shorter lifespan in males: Females survived for 3.64 days (shortest) at 32 °C to 17.50 days (longest) at 17 °C, whereas males survived for 11.00 days (longest) at 17 °C to 2.57 days (shortest) at 32 °C. The differences in fecundity were significant among all tested temperatures, with 17.61 eggs/female at 27 °C being the highest. The low developmental threshold and thermal summation of the full immature stage were 11.48 °C and 163.93 degree-days, respectively. In two-sex life table analysis, population parameters were significantly affected by temperature except the net reproduction rate. The highest intrinsic rate of increase was 0.1221 day−1 at 27 °C; the average generation time was the shortest (12.61 days) at 32 °C and the longest (48.70 days) at 17 °C. The highest net reproduction rate was 5.06 eggs/female at 27 °C. This report contributes background knowledge to the management of the damage caused by E. africanus on papaya.