Glucosinolate breakdown products as insect fumigants and their effect on carbon dioxide emission of insects.
BACKGROUND
Glucosinolate breakdown products are volatile, therefore good candidates for insect fumigants. However, although they are insecticidal, the mode of action of such natural products is not clear. We studied the insecticidal effect of these compounds as fumigants, and monitored the production of carbon dioxide by the insects as a probe to the understanding of their mode of action.


RESULTS
The fumigation 24-h LC50 against the house fly (Musca domestica L.) of allyl thiocyanate, allyl isothiocyanate, allyl cyanide, and l-cyano-2-hydroxy-3-butene was 0.1, 0.13, 3.66, and 6.2 microg cm-3, respectively; they were 0.55, 1.57, 2.8, and > 19.60 microg cm-3, respectively, against the lesser grain borer (Rhyzopertha dominica Fabricius). The fumigation toxicity of some of the glucosinolate products was very close to or better than that of the commercial insect fumigants such as chloropicrin (LC50: 0.08 and 1.3 microg cm-3 against M. domestica and R. dominica, respectively) and dichlorovos (LC50: < 0.02 and 0.29 microg cm-3 against M. domestica and R. dominica, respectively) in our laboratory tests. Significantly increased CO2 expiration was found in insects exposed to the vapor of allyl isothiocyanate, allyl thiocyanate and allyl isocyanate. Allyl isothiocyanate was also found to increase the CO2 expiration of the American cockroach (Periplaneta americana L.).


CONCLUSIONS
Glucosinolate breakdown products have potential as biodegradable and safe insect fumigants. They may act on the insect respiratory system in their mode of action.
Tsao
Rong
R
Food Research Program, Agriculture & Agri-Food Canada, Ontario NIG 5C9 Canada. caor@em.agr.ca
Peterson
Chris J
CJ
Coats
Joel R
JR
D000498:Allyl Compounds / Q000494:pharmacology*; D000818:Animals; D001673:Biodegradation, Environmental; D002245:Carbon Dioxide / Q000378:metabolism*; D031218:Crambe Plant / Q000378:metabolism; D005651:Fumigation; D006793:Houseflies / Q000378:metabolism; D007313:Insecta / Q000378:metabolism*; D007306:Insecticides / Q000494:pharmacology*; D017953:Isocyanates / Q000494:pharmacology*; D017879:Isothiocyanates / Q000494:pharmacology*; D007928:Lethal Dose 50; D009348:Nematoda / Q000187:drug effects; D010572:Pest Control, Biological / Q000379:methods*; D013861:Thiocyanates / Q000494:pharmacology*
D000498:Allyl Compounds; D007306:Insecticides; D017953:Isocyanates; D017879:Isothiocyanates; D013861:Thiocyanates; C491149:allyl isocyanate; C491148:allyl thiocyanate; D002245:Carbon Dioxide; C004471:allyl isothiocyanate