Fitness Consequences Of The Cooperation Between Females In Sclerodermus Guain(Hymenoptera:Bethylide)

Sclerodermus wasps are unique for their quasi-sociality in parasitoids.Therefore,they can be considered as an ideal model system for studying the evolution of insect sociality in Hymenoptera.Previous studies have shown that Sclerodermus parasitoids can cooperate in subduing hosts and tending their communal offspring.Yet,it remains to be explored about the adaptation of cooperation in Sclerodermus parasitoids.This thesis research aimed at addressing following questions using S.guani and the host flour beetle Tenebrio moliter.(1)What are breeding consequences of the cooperation varied in time and stage?(2)What is the fitness cost for altruism in cooperation to foundresses? This research indicates that foundresses restrain their oviposition in response to the length of cooperation,but not the stage when the cooperation takes place.In addition,foundresses pay survival costs for the cooperation.What follows is a summary of main results and conclusion from this research.1.Effects of cooperation duration on oviposition and offspring performancesTo explore if the length of cooperation is the cue foundresses garner to make the decision of adjusting their oviposition,three cooperating durations(0.5,1.5 and 2.5 d)by two and five foundresses were set up;the control was one foundress alone.After the cooperation,one foundress was chosen at random and allowed to continue oviposition and tend brood.The results showed that pre-oviposition time was shortened with an increase in cooperation duration,and reduced by 8.9 %,7.4 % and 2.9 % under the 2.5 d,compared to the control,the 0.5 d and 1.5 d,respectively.The number of eggs laid increased significantly with the extension of cooperation duration,lowest(37 on average)under the2.5 d as decreased by 11.9 %,5.1 % and 5.1 %,compared to the control,the 0.5 d and 1.5 d,respectively.Body weight of female offspring adults increased with the cooperation duration,increasing by 11.8 %,4.7 %,and 3.5 % under the 2.5 d,0.5 d,and 1.5 d compared to the control,respectively.The duration of cooperation had no significant effect on the number of emerged offspring adults,their sex ratio and egg duration.Our results suggest that cooperative foundresses may garner the information of cooperation duration to make the decision of constraining oviposition and the duration influences breeding outcomes.2.Effects of cooperation at a specific stage on oviposition and offspring performancesTo determine whether short-term cooperation at any particular parasitism stage affects the decision of oviposition by foundresses,three parasitism stages were allowed for the cooperation by 2 and 5 foundresses: subduing,cleaning-feeding,and ovipositing stages.After the cooperation,one foundress was taken at random and left on the host to oviposit and tend brood.What follows is the results.The stage treatment did not influence the number of eggs laid by the foundress,though average number of eggs for the feeding-cleaning stage was 12.8 % lower than that for the subduing stage and 8.1% than that for the ovipositing stage.Similarly,the stage treatment had no significant effect on developmental parameters of offspring,including the number of offspring adults(26),male proportion(4.9 %),female body weight(0.81 mg),and egg duration(4.35 d).The results suggest that the information about short-term cooperation at any parasitism stage may not be cued to make the decision of oviposition.3.Fitness costs to foundresses performing altruistic behavior in the cooperationTo measure the cost of altruistic behavior of foundresses,three levels of duration(0.5,1.5 and 2.5 d)and stage(subduing,cleaning-feeding,and ovipositing stages)of the cooperation were set up to obtain altruistic and beneficiary foundresses.The two types of foundresses were compared in oviposition and offspring performances.Under the treatment of the cooperation duration,mortality of altruistic foundress(26.5 %)was lower than that of beneficiary one(4.9 %).The same pattern was also shown under the cooperation stage treatment,with altruistic foundress of 20.9 % mortality as opposed to 6.6 % of beneficiary one.Altruistic and beneficiary foundresses did not differ in pre-oviposition time,oviposition,offspring sex ratio,female body weight,and egg duration.They differed in offspring larval duration.Altruistic and beneficiary foundresses under the cooperation stage treatment in egg duration but not in larval duration.These results suggest that altruistic behavior causes a survival cost to the foundress.