<p class="Body"><strong>Temperature-dependent life history of <em>Eutetranychus africanus</em> (Acari: Tetranychidae) on papaya</strong></p>

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.

Temperature-Dependent Biology and Population Performances of the Coffee Berry Borer Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae) on Artificial Diet

“…Many studies on insect species have used linear regression to analyze the relationship between temperature and the development rate. This approach has often been employed to estimate the lower developmental threshold and thermal summation [ 40 , 41 , 42 ]. With the use of coffee berries as the food source for rearing H. hampei , the lower developmental thresholds of the immature stage were 14.9, 13.03 and 13.9 °C, and the thermal summations were 262.47, 312.50 and 386 degree-days, respectively [ 15 , 31 , 33 ].…”

Field and Laboratory Observations on the Biology of Aceria angustifoliae with Emphasis on Emergence of Overwintering Mites

“…This is the case of many phenological models which use growing degree days (DD) for predicting the time for a higher probability that a specific instar/stage of the pest could be found or for how long generations last [10]. In acarology, apart from ticks and other non-plant feeding taxa, these models have been used for some spider mites [11][12][13][14] and eriophyoids [8,15,16] and a few others among the obligate phytophagous mites. They represent a valid and useful tool if well-developed and validated in the field.…”