Specificity of cultured insect tissue cells for bioassay of entomocidal protein from Bacillus thuringiensis.

Cultured tissue cells from lepidopteran and dipteran sources displayed an order-specific response to entomocidal protein from crystals of Bacillus thuringiensis. Protein isolated from crystals of B. thuringiensis subsp. kurstaki was effective against cells of the spruce budworm (Choristoneura fumiferana) and the tobacco hornworm (Manduca sexta), but was inactive against both mosquito cell lines tested (Aedes aegypti and Anopheles gambiae). Conversely, protein from inclusion bodies of B. thuringiensis subsp. israelensis was fully active only against the mosquito cell lines but displayed reduced (four- to seven-fold) toxicity for the lepidopteran cell lines. One exception to this pattern of specificity was observed with a Plodia interpunctella cell line, which failed to respond to either crystal protein preparation. The moth toxin was stable at 4 degrees C for months, whereas the mosquito toxin was susceptible to proteolytic degradation and was unstable for periods longer than 2 wk.