International indoor and outdoor evaluation of Bacillus sphaericus products : complexity of standardizing outdoor protocols

1997

Article

Thiery I., Baldet Thierry, Barbazan Philippe, Becker N., Junginger B., Mas J.P., Moulinier C., Nepstad K., Orduz S., Sinègre G.

Journal of the American Mosquito Control Association, 1997, 13 (3), p. 218-226 ISSN 8756-971X

Only one Bacillus sphaericus strain, strain 2362, is currently used commercially to control Culex larval populations. A reliable methodology, easily used, was developed to identify new strains for field application. Larvicidal activities of 3 highly mosquitocidal strains, strains C3-41, Mal, and LB24, previously selected in the laboratory, were compared with that of strain 2362 in tropical and European countries. The following steps were performed : production and titration of acetonic powders from these 4 strains on local Culex species, survey of initial and residual activity under standardized indoor and outdoor conditions, and evaluation of the efficacity of liquid formulations of the 4 strains in natural breeding sites of Culex. In indoor conditions, strain C3-41 showed the highest activity on both Culex pipiens and Culex quinquefasciatus; strain Mal was the least active. The residual activity causing 80% mortality differed from 20 to 90 days according to the strains and the country. Outdoor experiments with powder (0,02-1,6 mg/liter) were performed and the initial toxicities were similar in all cases. Residual activities were different, from 6 to 95 days posttreatment. Liquid formulations were applied to larval habitats (from 0,1 to 10 g/m2). In tropical countries, larval recolonization in cesspits or ponds occured after 10-35 days. In Europe, higher doses were needed in polluted water than in clear water (from 3 to 10 liter/ha) for the same control, and the time before 80% residual activity was reached was less than 9-12 days. However, in cesspits, residual activity could be observed for 12 days to 5 mo. A strain 3-5 times more active than the others in bioassays is not significantly detectable from those strains in field trials. (Résumé d'auteur)

Méthodes de lutte, insecticides : lutte non chimique, pièges [052LUTIN01]

INSECTICIDE BIOLOGIQUE ; EFFICACITE ; SOUCHE ; ETUDE COMPARATIVE ; PROTOCOLE ; POPULATION LARVAIRE

Fonds IRD [F B010012152]

fdi:010012152