Intestinal bacteria affect growth of Bacillus thuringiensis in larvae of the oriental tea tortrix, Homona magnanima Diakonoff (Lepidoptera : Tortricidae)
J. Takatsuka et Y. Kunimi, Intestinal bacteria affect growth of Bacillus thuringiensis in larvae of the oriental tea tortrix, Homona magnanima Diakonoff (Lepidoptera : Tortricidae), J INVER PAT, 76(3), 2000, pp. 222-226
Spores and parasporal crystals of a Bacillus thuringiensis serovar aizawai
were fed to fifth instar larvae of the oriental tea tortrix, Homona magnani
ma, that had been reared aseptically or that had been reared normally. Viab
le cell numbers of B. thuringiensis and other bacteria in H. magnanima larv
ae mere estimated by homogenization of samples and dilution plating on pept
one-polymyxin agar medium for B. thuringiensis cells and on nutrient agar m
edium for the other bacterial cells. B, thuringiensis did not grow in the l
arval cadavers of normally reared H. magnanima while bacteria other than B.
thuringiensis grew rapidly. In contrast, B. thuringiensis within the larva
l cadavers of aseptically reared H. magnanima. grew and increased 20 times.
The bacteria other than B. thuringiensis from the sample homogenates of no
rmally reared larvae that were fed on B. thuringiensis-treated diets had th
e same characteristics as the bacteria isolated from the guts of healthy H.
magnanima larvae, which were putatively identified as Streptococcus spp. a
nd Staphylococcus spp., typical intestinal bacteria of insects. The results
strongly suggest that intestinal bacteria influence the growth of B. thuri
ngiensis in the larvae. (C) 2000 Academic Press.