Use of Bacillus thuringiensis Toxin as an Alternative Method of Control against Haemonchus contortus

Abstract

The biocide activity of Bacillus thuringiensis (B. thuringiensis) IB-16 strain was evaluated against the blood-feeding nematode Haemonchus contortus (H. contortus) in vitro and in vivo assays. Twenty experimental jirds (Meriones unguiculatus) and 32 sheep were infected with H. contortus by oral route. Fourteen days post infection 10 jirds were treated with 0.2 mg per mL of IB-16 soluble toxin by intraperitoneal (i.p.) route and 8 sheep were treated with 0.5 mg of toxin per kg of body weight by intramuscular route 35 days after H. contortus infection. Same number of treated jirds and sheep were used as control. Fecal and blood samples were analyzed from experimental sheep to estimate the number of parasitic eggs, percentage of eosinophils, packed cell volume (PCV), and IgG title. All experimental jirds and 16 sheep (8 treated and 8 controls) were sacrificed at days 5, 7, and 30 after B. thuringiensis treatment. The percentage of nematode reduction was estimated from L(4) and H. contortus adults. The percentage of protection was 80.0 to jirds and 73.8 and 53.3 to sheep, sacrificed at days 7 and 30, respectively. Moreover, nonsignificant difference (P > or = 0.05) was detected from parasitic eggs, eosinophils, and PCV parameters. Significance level of IgG was observed only before H. contortus treatment with B. thuringiensis soluble toxin (P < or = 0.05) but nonsignificant difference was observed after treatment. These results showed that B. thuringiensis activity was similar to those observed by anthelmintic treatment and it could be used as an alternative biological method.