5 research outputs found
Insecticidal efficacy of diatomaceous earth against Sitophilus oryzae (L.) (Coleoptera : Curculionidae) and Tribolium confusum du Val (Coleoptera : Tenebrionidae) on stored wheat: influence of dose rate, temperature and exposure interval
Laboratory experiments were conducted in order to assess the
insecticidal effect of a diatomaceous earth formulation (Silicosec(R),
Biofa GmbH, Germany) against Sitophilus oryzae and Tribolium confusum on
stored wheat. Adults of the two species were exposed on wheat treated
with diatomaceous earth at four dose rates: 0.25, 0.5, 1 and 1.5 g/kg of
wheat, respectively. For each dose rate, the treated wheat was placed at
22degreesC, 25degreesC, 27degreesC, 30degreesC and 32degreesC. Dead
adults were counted after 24 and 48 h, 7 and 14 d of exposure. After the
14-d interval, the live adults were removed and placed for 7 d in
untreated wheat (in the case of S. oryzae) or untreated flour (in the
case of T confusum), and the production of F-1 was recorded. For both
species, dose rate, temperature and exposure interval significantly
affected mortality (P<0.001). Mortality was higher at longer exposure
intervals. The efficacy of SilicoSec against S. oryzae increased with
temperature, but for T confusum mortality was lower at 32degreesC,
compared to 30degreesC, for 24 and 48 h exposure intervals. Tribolium
confusum proved less susceptible to SilicoSec than S. oryzae. In
general, the rates of 1 and 1.5g/kg of wheat provided a satisfactory
level of protection against the two species examined. For S. oryzae, F-1
emerged only at 22degreesC, in wheat treated with 0.25 or 0.5 g/kg.
However, for T confusum, F-1 were recorded at 22degreesC for 0.5 g/kg
and at 22degreesC, 25degreesC, 27degreesC and 30degreesC for 0.25 g/kg.
(C) 2004 Elsevier Ltd. All rights reserved