Critical Temperatures Affect Energy Cost And Injury In Capped Brood Honeybee Apis Mellifera Ligustica

The honeybee brood was stenothermic and suboptimum temperatures imposed detrimental effects on their development.To better understand the physiological mechanisms underlying the detrimental effects of temperatures on development,this research examined the energy cost,tissue damage and redox levels of capped brood,Apis mellifera ligustica,reared at critical constant temperatures(low temperatures 29? and 31?,high temperature 37? and 38 ?).More than 80%of Apis mellifera ligustica capped brood reared at 29? or 38? could not complete development or emerge(P<0.01).The development duration of capped brood decreased as the rearing temperature increased from 29 ? to 37 ?.The consumption rate of energy use in capped brood were reduced at 29 ?,31 ? and 38 ?,but the total amount of energy used to complete the capped stage development was increased at 29 ?,not at 31 ? or 3 8 ?.A 5 d,6 d and 10 d exposure at 38? caused 7%,32%and 100%MT cell death,respectively,which was significantly more than those in control group.A long term exposure of 20 d exposure to low temperature 29 ? caused a considerable amount of cell damage of 26%in MT cell death(P<0.05).A ten day of low temperature stress significantly increased capped brood protein carbonyl concentration and anti-oxidative capacity;However,a ten day of high temperature stress significantly increased brood protein carbonyl concentration but decreased their anti-oxidative capacity.The results showed that lower critical temperature depressed the energy consumption rate but increased total amount of energy use to complete its capped brood stage.Both lower and higher critical temperatures resulted in severely detrimental oxidative damage and tissue damage to honeybee brood leading to developmental damage or mortality in a long-term stress.Our data shed light on mechanisms underlying the thermal detrimental effects on honeybee brood,and help to develop management strategies in beekeeping activities under critical temperatures.