Epsilon Open Archive

Abstract

1 The spruce bark beetle Ips typographus is the major tree-killing bark beetle in Eurasia. To increase knowledge about its seasonal flight patterns and also about the thermal sums required for emergence a field study was conducted in southern Sweden from 2006-2010.
2 Flight began on average 27 April (after 47 degree-days (dd) > 5°C). More than 50% of flight activity occurred after mid-June, and continued to mid-August.
3 Re-emergence of parental beetles after they had produced the first brood started on average 24 May (after 122 dd). Continued flight and oviposition demonstrated that sister broods were frequent. A much higher proportion of parental beetles re-emerged from trees colonized in May (95%) than in July (20%). Beetles that colonized trees late had to accumulate a much higher thermal sum before re-emerging (400 dd).
4 Filial beetles began to emerge on average 29 June (after 437 dd), and started to fly in early July, giving rise to at least a partial second generation in each year. A much higher proportion of filial beetles had emerged from trees colonized in May (75%) than in July (15%).
5 Knowledge of these region-specific flight patterns and the associated thermal sums required for emergence will facilitate efficient pest management by enabling the timely removal of fallen and standing weakened host trees. The obtained data will also be useful for parameterization of models that predict the population dynamics in a warmer climate.