Analysis of the temperature dependent development of the spruce bark beetleIps typographus(L) (Col., Scolytidae)

Following individual development by means of the ‘sandwich method’ the duration of egg, larval, and pupal stages, as well as of adult maturation feeding of the spruce bark beetle (Ips typographus) was measured at constant temperatures in the range between 12° and 33° C. At 20° C complete development from egg to adult emerging from pupa averaged 29 days. The proportion of the duration of larval development relative to total preimaginal development increased with temperature. Developmental rates, i.e. the speed of development increased linearly with temperature in a range between 15° and 25°C. Based on linear regressions, lower developmental thresholds were calculated to be 10.6°C (eggs), 8.2°C (larvae), 9.9°C (pupae), and 8.3°C (preimaginal development egg to pupa), respectively. Differing heat sums reported in the literature matched ours when recalculated with our developmental thresholds. A nonlinear model (Logan/Lactin) was fitted to the data which allowed to describe development in the entire temperature range. It further permits to identify lower and upper (≅ 40°C) developmental thresholds as well as optimum temperatures (30–33°C) of the instars.