Sawfly, larch

Materials produced by crystalliferous bacilli which elicit a toxic response in susceptible insects may be separated into two types. The first type, the true toxins, include the crystalline protein inclusion body the parasporal body of Hannay (14)], a heat-stable, water-soluble exotoxin active against flies, a heat-stable, dialyzable water-soluble exotoxin, toxic to Lepidoptera on injection (23), and a heat-labile, water-soluble, filterable exotoxin, toxic toward larch sawfly larvae (Hymenoptera) which was reported by Smirnoff (31). 

Type 3. A heat-labile material, toxic on ingestion to several species of larch sawfly (31). 

The exotoxin reported by Smirnoff (31) is definitively different from other soluble toxins, as indicated by its reported heat lability. This soluble toxin was obtained from the supernatant of a sporulated B. thuringiensis culture. In testing, it was found to be very toxic by ingestion to 18 species of larch sawfly larvae. No further studies on this toxin have been reported at this time. 

Mortality in larch sawfly larvae May be partially responsible for gut cell destruction... 

A number of diterpenes are known to be active against herbivores ( ). The diterpenes abietic, dehydroabietic, 12-methoxy-abietic, sandaracopimaric, and isopimaric acid serve as feeding deterrents for the larch sawfly, Pristiphora erichsonii in single needles from new shoots of tamarack (Larix laricina) (133). The larvae of this insect do eat tufted needles on short shoots of the same trees. 

Histological studies of infected larch sawfly larvae suggest that the damage to midgut cells and other tissues in the body involves parts of the cells that are known to be partially made up of phos-pholipides. 

Mammals are often overlooked for their pest-control abilities. For example, in Canadian forests, shrews control larch sawflies and other pests. Lizards and toads are important natural enemies of pest insects, and snakes can help control problems with mice and voles. In many communities in Europe and North America, farmers encourage birds to control pests by placing nesting boxes around their fields. Even domesticated animals can assist in pest control. If you have a small orchard and keep chickens, let the chickens feed in the orchard. They will peck pests such as plum curculios out of dropped fruit and other ground litter. 

European (see Larix decidua) Japanese (see Larix kaempferi) Larch branch canker. 132 Larch casebearers, 132 Larch sawflies... 

Ohigashi, H., M. R. Wagner, F. Matsumura, and D. M. Benjamin, Chemical basis of differential feeding behavior of the larch sawfly, Pristiphora erichsonii (Hartig), J. Chem. Ecol., 7, 599-614 (1981). 

The most destructive insect pest of tamarack is the larch sawfly (Pristiphora erichsonii). Periodic epidemics of this defoliator occur across Canada and the northern United States. Another serious defoliator of tamarack is the larch casebearer Coleophora laricella). Severe outbreaks have caused extensive mortality of trees of all ages (Johnston, 1990). 

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