Field assessment of predation by Lonchaea corticis (Diptera: Lonchaeidae) on Pissodes strobi (Coleoptera: Curculionidae) in Picea sitchensis
1990
Hulme, M.A.
Leaders of Picea sitchensis (Bong.) Carriere freshly attacked by Pissodes strobi (Peck) were covered with sleeve cages to exclude Lonchaea corticis Taylor. Unsuccessful empty pupal cells of P. strobi formed during the summer were associated with leaders without cages where L. corticis larvae were present. Unsuccessful empty pupal cells were generated during the winter in the presence of L. corticis. Examination of all leaders in a plantation attacked by P. strobi in each of 2 yr showed predation by L. corticis on P. strobi brood that had formed pupal cells but little if any predation of P. strobi eggs or mining larvae. When the mean percentage of successful P. strobi emergence from pupal cells was 7%, no P. strobi emerged from leaders with more than two L. corticis per pupal cell formed by P. strobi; the following year mean emergence was 25% and the threshold for no emergence was near four L. corticis per pupal cell. With mean L. corticis numbers near one per pupal cell formed by P. strobi, the success of mature P. strobi brood may have been largely regulated by weather and resultant L. corticis predation.
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