Effects of sublethal doses of selected botanical molluscicides on oxygen consumption of the brown garden snail, Eobania vermiculata

ABSTRACT

Laboratory bioassays were carried out for evaluating the efficacy of certain plant materials including Nicotine, Thymol, Menthol, Caffeine and Camphor as molluscicides against the brown garden snail, Eobania vermiculata using the topical application method. The obtained results proved that Nicotine and Thymol were the most promising from the molluscicidal point of view with LD [50]204.02 and 551.20 micro g/snail for the two materials, respectively. The effects of sublethal doses [LD[25] and LD[50]] of the most potent materials, Thymol and Nicotine, on the oxygen consumption of E. vermiculata snails after 1, 7 and 15 days post treatment were evaluated. Results indicated that only snails treated with LD [50] Thymol showed significant decrease in their oxygen uptake; while all the other treatments stimulated significant increase in the oxygen consumption along the three periods of estimation. This stimulation was most pronounced with the low sublethal doses of the both examined botanical molluscicides. The succession of time post exposure did not enable the treated snails to eliminate the adverse effects of the applied materials. Depending on the results of the current investigation, we can conclude that the both examined botanical materials, Thymol and Nicotine, are effective in killing the agricultural pest E. vermiculata but further studies are needed to evaluate the efficacy of these materials as safe and economic molluscicides in the field