V. Borek et al., TOXICITY OF ALIPHATIC AND AROMATIC ISOTHIOCYANATES TO EGGS OF THE BLACK VINE WEEVIL (COLEOPTERA, CURCULIONIDAE), Journal of economic entomology, 88(5), 1995, pp. 1192-1196
Plant-derived isothiocyanates are rode to a number of soil organisms;
however, the differential toxicity of various isothiocyanates to many
soil-borne plant pests has not been determined. We tested the contact
toxicity of methyl, propyl, allyl, phenyl, benzyl, and 2-phenylethyl i
sothiocyanates to eggs of the black vine weevil, Otiorhynchus sulcatus
(F.). Eggs were collected every 2 d from a colony of field-collected w
eevils and preconditioned over a 5-d period. To reduce the variability
of responses, only eggs with melanized chorions were used for all bio
assays. Eggs were clipped into acetone solutions of isothiocyanates fo
r 2 min. Controls were treated with acetone alone. Treated eggs were i
ncubated for 14 d at 24 +/- 2 degrees C and 100% RH. Mortality respons
e curves of black vine weevil eggs were analyzed using probit analysis
. AU isothiocyanates tested were toxic to weevil eggs; however, isothi
ocyanates containing an aromatic moiety (phenyl, benzyl, and e-phenyle
thyl) were considerably more toxic than aliphatic (methyl, propyl, and
allyl) isothiocyanates. Average mortality in acetone-treated controls
was <6%. These results suggest that soil amendments of Brassica aroma
tic isothiocyanates may have greater insecticidal potential than those
producing aliphatic isothiocyanates.