Toxicity and field efficacy of cryolite against Colorado potato beetle (Coleoptera: Chrysomelidae) larvae
1995
Huang, H.W. | Smilowitz, Z. | Sauders, M.C.
The toxicity of cryolite (sodium aluminofluoride) against the Colorado potato beetle, Leptinotarsa decemlineata (Say), was determined by feeding larvae on cryolite-treated potato foliage. At 48 h, the LC50 was 15.3 and 18.5 microgram/cm2 for 1st and 3rd instars, respectively. Larvae consumed less foliage at higher concentrations, and the reduction of leaf consumption was correlated to the concentration of cryolite. A feeding choice test indicated that cryolite does not repel or inhibit larval feeding. Field tests showed that the effectiveness of cryolite was stable at 2 h and 1 d after application but variable after 2 d, and that cryolite toxicity was dependent on the application rate and rainfall. Significantly less mortality caused by cryolite was observed at the rate of 6.5 kg/ha than at 12.9 kg/ha. Larval mortality was also significantly lower when 0.64 cm of simulated rainfall was applied compared with the treatments without rain.
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