The number and sex of spruce bark beetles, Ips typographus (L.), caught in pheromone traps as related to flight season, trap type, and pheromone release
1988
Weslien, J. (Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Division of Forest Entomology) | Bylund, H.
The influence of season, and pheromone release rate on the number and sex of Ips typographus caught in flight-(barrier), landing- (sticky), and entering (pipe) traps were investigated in the field. During the first 6 days of flight in spring the proportion of males among beetles caught flying around, landing on, and entering pheromone-baited pipe traps was estimated to be 41 per cent, 29 per cent and 18 per cent respectively. During this period the proportion of males among beetles caught decreased with time by ca 20 per cent in all three trap types. The first flight period was probably the time during which most beetles left their hibernation sites. Thereafter the sex ratio was constant over time, corresponding to ca 30 per cent males among beetles caught on the landing traps. All three trap types caught more females at a high release rate of pheromone than at a low release rate. Although the catch of males was higher in the flight traps at the high release rate, there was no effect of release rate on male catch in landing traps and entering traps. The results are discussed in contexts of beetle behaviour, trap technology, and forest protection
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