Cerambyx cerdo (Cc) is a protected saproxylic beetle in Europe, although it is increasingly reported as an oak ‘pest’. Cc ecological features are relatively well known, but, its reproductive biology is still poorly understood. Hence, we investigated the reproductive traits of Cc under laboratory conditions. In females, body length was 44.1 ± 0.9 mm, 28–53 (mean ± SE, range); fecundity 143 ± 11 eggs, 33–347; fertility 78 ± 1%, 65–93; oviposition period 44 ± 3 days, 13–128 and longevity 59 ± 5 days, 16–157. Fecundity was positively correlated with female size, longevity and oviposition period. Daily fecundity was 3.5 ± 0.2 eggs/day, 0.9–6.5 showing a fluctuating synovigenic pattern with a slight decreasing trend over time. Egg length was 3.74 ± 0.01 mm, 2.3–6.0 and egg volume 5.45 ± 0.04 mm3, 2.4–9.6. Egg size was correlated with female size, but, the relative size of eggs was larger in smaller females. Incubation time was 13.5 ± 0.1 days, 7–28. Hatching was superior in larger eggs and neonate size was positively correlated to egg volume. Females were polyandrous (up to 19 matings), but, multiple mating did not enhance fecundity or fertility. In males, body length was 41.8 ± 0.8 mm, 29–53 and longevity 49 ± 3 days, 9–124. Male longevity was unrelated to body size. Males were polygynous (up to 16 matings) and mating number did not affect male longevity. Overall, females were larger and lived longer than males. Cc reproductive traits are compared with those other Cerambycidae, especially with the congeneric pest Cerambyx welensii. Our data may be valuable to improve the protection/management measures of Cc in dehesa woodlands and other oak forests.

The longhorn beetle Cerambyx welensii is an emerging pest involved in oak decline episodes, whose damage is increasingly reported in dehesa open woodlands. Knowledge of the reproductive biology of C. welensii is a crucial goal due to its new pest status. In this study, we assess the reproductive traits of both sexes in the laboratory (25°C and 60% relative humidity ). In females, body length was 44.9 ± 0.9 mm (mean ± SE), fecundity 132 ± 12 eggs, fertility 70 ± 1 %, longevity 70 ± 3 days, preoviposition period 2 ± 0.2 days, oviposition period 44 ± 3 days and postoviposition period 19 ± 3 days. Fecundity was positively correlated with female size, longevity and oviposition period. Daily fecundity was 3.0 ± 0.2 eggs/day and showed a fluctuating synovigenic pattern with a slight decreasing trend over time. Egg length was 4.24 ± 0.01 mm and egg volume 8.14 ± 0.04 mm3. Egg size was correlated with female size but the relative size of eggs was larger in smaller females. Incubation time was 13.9 ± 0.1 days and hatching did not depend on egg size. Neonate size was positively correlated with egg length. Females were polyandrous (more than 20 lifetime matings) but multiple mating did not increase fecundity, fertility or longevity. In males, body length was 43.7 ± 0.6 mm and longevity 52 ± 3 days. Unlike with females, longevity was positively correlated with male size. Males were polygynous (up to 30 lifetime matings) but mating history did not affect male longevity. Rather to the contrary, long-lived males mated more times because they had more mating chances. Lastly, C. welensii reproductive traits were compared with those other Cerambycidae species and discussed from an adaptive perspective. Our data will be useful to improve management of C. welensii in order to prevent or mitigate its impact in dehesa woodlands and other oak forests.