We reported data on thermal preference, thermal tolerance and the thermal dependence of digestive performance for two Phrynocephalus lizards （P. frontalis and P. versicolor）, and compared data among lizards so far s...We reported data on thermal preference, thermal tolerance and the thermal dependence of digestive performance for two Phrynocephalus lizards （P. frontalis and P. versicolor）, and compared data among lizards so far studied worldwide. Mean values for selected body temperature （Tsel） and critical thermal maximum （CTMax） were greater in P versicolor, whereas mean values for critical thermal minimum （CTMin） did not differ between the two species. The two lizards differed in food intake, but not in food passage time, apparent digestive coefficient （ADC） and assimilation efficiency （AE）, across the experimental tem- peratures. Four general conclusions can be drawn from published data. Firstly, thermal preference and thermal tolerance differ among lizards differing in distribution, temporal activity pattern and habitat use. Lizards in thermally more variable regions are better able to tolerate low and high temperatures. Diurnal lizards generally select higher body temperatures than nocturnal lizards, and lizards using habitats with direct sun exposure generally selected higher body temperatures and are better able to tolerate high temperatures. Secondly, CTMax is positively correlated with Tsel. Lizards more likely exposed to extremely high temperatures while active select higher body temperatures than those using shaded habitats. Thirdly, the effects of body temperature on food intake, food passage time, ADC and AE differ among lizards, but it seems to be common among lizards that ADC and AE are less thermally sensitive than food intake and food passage time. Lastly, ADC is dependent on the type of food ingested, with insectivorous lizards digesting food more efficiently than herbivorous lizards展开更多
Under stressful thermal environments, insects adjust their behavior and physi- ology to maintain key life-history activities and improve survival. For interacting species, mutual or antagonistic, thermal stress may af...Under stressful thermal environments, insects adjust their behavior and physi- ology to maintain key life-history activities and improve survival. For interacting species, mutual or antagonistic, thermal stress may affect the participants in differing ways, which may then affect the outcome of the ecological relationship. In agroecosystems, this may be the fate of relationships between insect pests and their antagonistic parasitoids un- der acute and chronic thermal variability. Against this background, we investigated the thermal tolerance of different developmental stages of Chilo partellus Swinhoe （Lepi- doptera： Crambidae） and its larval parasitoid, Cotesia sesamiae Cameron （Hymenoptera： Braconidae） using both dynamic and static protocols. When exposed for 2 h to a static temperature, lower lethal temperatures ranged from -9 to 6 ℃, -14 to -2 ℃, and -1 to 4 ℃ while upper lethal temperatures ranged from 37 to 48 ℃, 41 to 49 ℃, and 36 to 39 ℃ for C partellus eggs, larvae, and C. sesamiae adults, respectively. Faster heating rates improved critical thermal maxima （CTmax） in C partellus larvae and adult C partel- lus and C sesamiae. Lower cooling rates improved critical thermal minima （CTmin） in C partellus and C. sesamiae adults while compromising CTmin in C. partellus larvae. The mean supercooling points （SCPs） for C. partellus larvae, pupae, and adults were -11.82 ± 1.78, -10.43 ±1.73 and -15.75 ±2.47, respectively. Heat knock-down time （HKDT） and chill-coma recovery time （CCRT） varied significantly between C partellus larvae and adults. Larvae had higher HKDT than adults, while the latter recovered significantly faster following chill-coma. Current results suggest developmental stage differences in C partellus thermal tolerance （with respect to lethal temperatures and critical thermal limits） and a compromised temperature tolerance of parasitoid C. sesamiae relative to its host, suggesting potential asynchrony between host-parasitoid population phenology and con- sequently biocontrol efficacy under global change. These results have broad implications to biological pest management insect-natural enemy interactions under rapidly changing thermal environments.展开更多
文摘We reported data on thermal preference, thermal tolerance and the thermal dependence of digestive performance for two Phrynocephalus lizards （P. frontalis and P. versicolor）, and compared data among lizards so far studied worldwide. Mean values for selected body temperature （Tsel） and critical thermal maximum （CTMax） were greater in P versicolor, whereas mean values for critical thermal minimum （CTMin） did not differ between the two species. The two lizards differed in food intake, but not in food passage time, apparent digestive coefficient （ADC） and assimilation efficiency （AE）, across the experimental tem- peratures. Four general conclusions can be drawn from published data. Firstly, thermal preference and thermal tolerance differ among lizards differing in distribution, temporal activity pattern and habitat use. Lizards in thermally more variable regions are better able to tolerate low and high temperatures. Diurnal lizards generally select higher body temperatures than nocturnal lizards, and lizards using habitats with direct sun exposure generally selected higher body temperatures and are better able to tolerate high temperatures. Secondly, CTMax is positively correlated with Tsel. Lizards more likely exposed to extremely high temperatures while active select higher body temperatures than those using shaded habitats. Thirdly, the effects of body temperature on food intake, food passage time, ADC and AE differ among lizards, but it seems to be common among lizards that ADC and AE are less thermally sensitive than food intake and food passage time. Lastly, ADC is dependent on the type of food ingested, with insectivorous lizards digesting food more efficiently than herbivorous lizards
文摘Under stressful thermal environments, insects adjust their behavior and physi- ology to maintain key life-history activities and improve survival. For interacting species, mutual or antagonistic, thermal stress may affect the participants in differing ways, which may then affect the outcome of the ecological relationship. In agroecosystems, this may be the fate of relationships between insect pests and their antagonistic parasitoids un- der acute and chronic thermal variability. Against this background, we investigated the thermal tolerance of different developmental stages of Chilo partellus Swinhoe （Lepi- doptera： Crambidae） and its larval parasitoid, Cotesia sesamiae Cameron （Hymenoptera： Braconidae） using both dynamic and static protocols. When exposed for 2 h to a static temperature, lower lethal temperatures ranged from -9 to 6 ℃, -14 to -2 ℃, and -1 to 4 ℃ while upper lethal temperatures ranged from 37 to 48 ℃, 41 to 49 ℃, and 36 to 39 ℃ for C partellus eggs, larvae, and C. sesamiae adults, respectively. Faster heating rates improved critical thermal maxima （CTmax） in C partellus larvae and adult C partel- lus and C sesamiae. Lower cooling rates improved critical thermal minima （CTmin） in C partellus and C. sesamiae adults while compromising CTmin in C. partellus larvae. The mean supercooling points （SCPs） for C. partellus larvae, pupae, and adults were -11.82 ± 1.78, -10.43 ±1.73 and -15.75 ±2.47, respectively. Heat knock-down time （HKDT） and chill-coma recovery time （CCRT） varied significantly between C partellus larvae and adults. Larvae had higher HKDT than adults, while the latter recovered significantly faster following chill-coma. Current results suggest developmental stage differences in C partellus thermal tolerance （with respect to lethal temperatures and critical thermal limits） and a compromised temperature tolerance of parasitoid C. sesamiae relative to its host, suggesting potential asynchrony between host-parasitoid population phenology and con- sequently biocontrol efficacy under global change. These results have broad implications to biological pest management insect-natural enemy interactions under rapidly changing thermal environments.
