Survival of parent and brood adult bark beetles, Ips typographus, in relation to size, lipid content and re‐emergence or emergence day

. This study investigated a possible trade‐off between bark beetle reproductive effort and future survival. Parent adult Ips typographus (L.) (Coleoptera: Scolytidae) were collected when they re‐emerged from a laboratory culture after completing their first brood and held at constant temperatures of 4 or 25 o C. As a comparison, emerging brood adults were collected and held at 25 o C. The longevity of the beetles was related to when they re‐emerged or emerged (measured in days since parent introduction) and to their size (pronotal width), fresh weight and lipid content at collection, by multiple regression analysis. The expression (fresh weight x pronotal width ‐2.6 ), used as an estimate of lipid content of the living beetles, was significantly correlated (r=0.67, P<0.001) with the actual (extracted) lipid content. At 25 o C, fat content was the variable most strongly correlated with survival time in all beetle groups except parent females. In both parent and brood females, re‐emergence or emergence day, respectively, contributed significantly to the explanation of survival time, whereas pronotal width and fresh weight never contributed significantly to the regression equation. At 4 o C, fat content was not estimated but, re‐emergence day was negatively correlated with survival time. In conclusion, beetles with high fat content and re‐emerging or emerging early have longer expected survival than beetles leaving the log later or containing less fat. This means that females laying a large first brood might suffer a somewhat higher mortality than females laying a smaller brood.