Enhancement of δ-Endotoxin Activity by Toxin-Free Spore of Bacillus thuringiensis against the Diamondback Moth, Plutella xylostella

Purification of Vip3Aa from Bacillus thuringiensis HD-1 and its contribution to toxicity of HD-1 to spruce budworm (Choristoneura fumiferana) and gypsy moth (Lymantria dispar) (Lepidoptera)

“…Because enhanced mortality likely results from toxin produced during vegetative growth in infected larvae, it stands to reason that Vip3Aa will play a role primarily in species that die from septicaemia following B. thuringiensis spore germination. Such is the case in many species (e.g., Donovan et al, 2001;van Frankenhuyzen, 1994;Miyasono et al, 1994;Burgess et al, 1976;Johnson and MacGaughey, 1996), but certainly not in all (Nishiitsutusji-Uwo and Endo, 1980;Schesser and Bulla, 1978;Suzuki et al, 2004). Reduced toxicity of the Vip3Aa-producing HD-1 strain to gypsy moth larvae suggests that the contribution of the toxin to pathogenicity could be even more complex in that species.…”

Characterization study of the sporulation kinetics ofBacillus thuringiensis

“…In other words, extremely high spore density will inhibit crystal protein formation and is not a guarantee of mortality. However, the fact that the presence of spores increased the toxin activity in some Lepi- dopterous larvae has been mentioned (Miyasono et al, 1994). This indirectly demonstrated that the existence of spores in the crystal protein mixture exhibits an enhancement of toxin activity effects.…”

CytA enables CryIV endotoxins of Bacillus thuringiensis to overcome high levels of CryIV resistance in the mosquito, Culex quinquefasciatus

“…Although no evidence exists that spores contribute to the toxicity of B. thuringiensis subsp. israelensis to mosquitoes, it is known that against some species, such as Spodoptera exigua (45) and P. xylostella (46), the spore can synergize Cry toxicity. Despite these obstacles to precise characterization of CytA͞ CryIV interaction, the data from the experiments where the CytA powder was combined with the powders of CryIVA and CryIVB, or CryIVA, CryIVB, and CryIVD, show clearly CytA was the critical component enabling these proteins to suppress or reduce substantially CryIV resistance (Fig.…”