Comparing the toxicity of two fumigants to insects from the field vs laboratory – does insect origin matter?
The golden-haired bark beetle, Hylurgus ligniperda, is one of the most common insects normally associated with New Zealand export logs. Here we tested the dose-mortality responses of H. ligniperda adults, from two different origins (field vs laboratory), to methyl bromide (MB) – the most widely used fumigant worldwide and ethanedinitrile (EDN), a new fumigant currently being considered as very promising for MB replacement. Naked insects were fumigated with either MB or EDN at 10°C for 4 and 3 hours, respectively. Adults from the laboratory had been reared on an arti cial diet and under controlled conditions for over 10 generations at the time of the experiments. Field adults, on the other hand, had been recently collected from Lindgren funnel traps with lures of alpha-pinene and ethanol. Our results showed that there is a significant difference in the tolerance to the two fumigants tested according to the origin of the insects, with field-collected adults being less tolerant to MB and EDN than laboratory-reared ones. The implications of our results for the development of disinfestation schedules for New Zealand export logs will be discussed.