Evaluation of pathogenic and Epidemiologic effects of Naturalis-L containing fungus Beauveria bassiana on the European honeybee Apis mellifera L. in Iran
2007
Tahmasebi, Gholam Hoseyn | Ariyana, Ardeshir | Ghaznavi, Mehran | Khalili Mahani, Marjan | Asgari, Hasan
This study was conducted to determine the safety of a new biopesticide, Naturalis-L, based on Beauveria bassiana strain ATCC 74040, for honeybee as a non-target organism, economic and useful insects. This microbial pest control agent has been newly suggested for Bemisia tabaci controlling in cotton farms in the north of Iran. For evaluating of its contact and oral effects, two series experiments were done, in a completed random design with four replications. Every replication was a wood-frame cage with approximately150 newly emerged honeybees, which were incubated at 28 2°C and 80% 5% relative humidity (RH). Treatments for contact method were 2.3 102 cfu/cm2, 11.5 102 cfu/cm2, 2.3 103 cfu/cm2 and 2.3 104 cfu/cm2 and sterile distilled water was used for control. Treatments were sprayed using a calibrated hand atomizer. For preparing treatments in oral method, compound was suspended in 50 %( wt/wt) sucrose syrup at four concentrations of 1.7 106 cfu/L (equivalent to Expected Environmental Concentration, EEC), 1.7 107cfu/L, 1.7 108 cfu/L, 1.7 109cfu/L, per 20 ml syrup. After consuming all of the treated syrup, bees were given untreated syrup up to the end of experiment. Dead bees were counted daily and removed from the cages then fungus isolation was accomplished. After data analyzing statistically, comparison among the means and grouping were done by Dunkan&rsquos test. Results (analysis of variance) revealed no significant effects of treatments in oral experiments (P 0.05), but concentration of 2.3 104 cfu/cm2 resulted in significantly higher mortality than the control (P 0.05) in the contact evaluation. In order to evaluation of epidemiological aspect of this product, three sets of 5, 10 and 20 numbers of marked one-day honeybees treated with 2.3 102 cfu/cm2 , have been added to cages containing 100-150 non-treated honeybees in four replications. Control was non-treated honeybees. Similar experiment was done for evaluation of feeding aspects with EEC concentration. Both feeding and contact phases of epidemiological study showed statistically no significant honeybee mortality due to suggested concentrations in laboratory conditions. It can be concluded that although suggested concentration of this bio-product apparently is risk free, because of its potential pathogenisity for insects it should be applied during hours in which the farm activity of honeybees is minimum.
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