The biology and control of the pine sawfly, Nesodiprion biremis (Konow) (Hymenoptera, Diprionidae), in northern Thailand

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Abstract
Nesodiprion biremis (Konow) is a potential pest of pine nurseries and plantations in northern Thailand, attacking both native and exotic species. The eggs are laid in an aggregated pattern on fairly young or mature needles. There are normally six larval instars in both sexes. The larvae feed almost entirely on mature foliage unless food is short, and show little preference for particular species of pine. They are not markedly gregarious. Larval defence mechanisms are discussed. Cocoons are spun among the bases of living needles close to the stem. The life-cycle takes at least six weeks at 25–30°C, and there are probably 5–6 broadly overlapping generations each year. Egg mortality is normally low, but mortality of first-instar larvae due to inability to initiate a feeding site is high. Two parasites attack the larvae and at least four more species the cocoons. Shortage of food leads to the production of smaller adults with a reduced fecundity. Possible control strategies are discussed.