In insects,larval and adult defenses against predators have been well studied.However,pupal(also known as resting stage)defenses have been overlooked and not examined thoroughly.Although some pupa possess antipredator...In insects,larval and adult defenses against predators have been well studied.However,pupal(also known as resting stage)defenses have been overlooked and not examined thoroughly.Although some pupa possess antipredator strategies such as hairs,spines,cryptic coloration,and exudation of chemicals,few studies have tested these responses and the factors affecting them.Here,we investigated the behavioral responses in tobacco hornworm Manduca sexta that pupates in soil by introducing an external stimulus using vibrations from an electric toothbrush to mimic predation.We observed that M.sexta made violent wriggling(twitching),followed by pulsating movements in response to the vibrational stimulus.Detailed examination showed that these twitches and pulsating events occurred more frequently and for longer periods of time in male pupa and were dependent on the magnitude of the stress(high and low frequency).However,when we estimated the angular force exerted by pupa using radian and angular momentum of twitches,it was found to be independent of pupal sex.A follow-up experiment on possible cascading effects of stress exposure on eclosion success revealed that low-and high-frequency stress exposure didn’t cause any of the common defects in eclosed adults.Our study clearly demonstrates that the so-called defenseless pupal stage uses a wide range of measurable defense behaviors that can actively defend against predators and should be examined further-linking observed behavior with underlying mechanisms.展开更多
When fed ad libitum （AL）, ectothermic animals usually grow faster and have higher metabolic rate at higher ambient temperature. However, if food supply is limited, there is an energy tradeoff between growth and meta...When fed ad libitum （AL）, ectothermic animals usually grow faster and have higher metabolic rate at higher ambient temperature. However, if food supply is limited, there is an energy tradeoff between growth and metabolism. Here we hypothesize that for ectothermic animals under food restriction （FR）, high temperature will lead to a high metabolic rate, but growth will slow down to compensate for the high metabolism. We measure the rates of growth and metabolism of 4 cohorts of5th instar hornworms （Manduca sexta larvae） reared at 2 levels of food supply （AL and FR） and 2 temperatures （20 and 30 ℃）. Our results show that, compared to the cohorts reared at 20 ℃, the ones reared at 30 ℃ have high metabolic rates under both AL and FR conditions, but a high growth rate under AL and a low growth rate under FR, supporting this hypothesis.展开更多
文摘In insects,larval and adult defenses against predators have been well studied.However,pupal(also known as resting stage)defenses have been overlooked and not examined thoroughly.Although some pupa possess antipredator strategies such as hairs,spines,cryptic coloration,and exudation of chemicals,few studies have tested these responses and the factors affecting them.Here,we investigated the behavioral responses in tobacco hornworm Manduca sexta that pupates in soil by introducing an external stimulus using vibrations from an electric toothbrush to mimic predation.We observed that M.sexta made violent wriggling(twitching),followed by pulsating movements in response to the vibrational stimulus.Detailed examination showed that these twitches and pulsating events occurred more frequently and for longer periods of time in male pupa and were dependent on the magnitude of the stress(high and low frequency).However,when we estimated the angular force exerted by pupa using radian and angular momentum of twitches,it was found to be independent of pupal sex.A follow-up experiment on possible cascading effects of stress exposure on eclosion success revealed that low-and high-frequency stress exposure didn’t cause any of the common defects in eclosed adults.Our study clearly demonstrates that the so-called defenseless pupal stage uses a wide range of measurable defense behaviors that can actively defend against predators and should be examined further-linking observed behavior with underlying mechanisms.
文摘When fed ad libitum （AL）, ectothermic animals usually grow faster and have higher metabolic rate at higher ambient temperature. However, if food supply is limited, there is an energy tradeoff between growth and metabolism. Here we hypothesize that for ectothermic animals under food restriction （FR）, high temperature will lead to a high metabolic rate, but growth will slow down to compensate for the high metabolism. We measure the rates of growth and metabolism of 4 cohorts of5th instar hornworms （Manduca sexta larvae） reared at 2 levels of food supply （AL and FR） and 2 temperatures （20 and 30 ℃）. Our results show that, compared to the cohorts reared at 20 ℃, the ones reared at 30 ℃ have high metabolic rates under both AL and FR conditions, but a high growth rate under AL and a low growth rate under FR, supporting this hypothesis.
