Study On The Fumigation Activity Of Three Plant Essential Oils Of Artemisia And Ethyl Formate Against Two Stored Grain Insects

In this paper, the author chose Artemisia annua L.、Artemisia lavandulaefolia DC.、Artemisia scoparia Waldst.et Kitag and Sitophilus zeamais Motschulsky、Callosobruchuschinensis（L.） as experimental materials. The fumigant extracted from Artemisia annua L.、Artemisia lavandulaefolia DC.、Artemisia scoparia Waldst.et Kitag by steam distillation andethyl formate were tested on the adults of Sitophilus zeamais Motschulsky andCallosobruchus chinensis（L.）. Furthermore, the synergy of mixture of essential oils and ethylformate were studied. The main results are as follows:1. The fumigants from the three essential oils tested on Sitophilus zeamais Motschulskyadults showed that:When Sitophilus zeamais Motschulsky adults were fumigated for36h at25℃, the LC₅₀of the essential oils of Artemisia annua L.、Artemisia lavandulaefolia DC.、Artemisia scopariaWaldst.et Kitag were84.71μl/l、73.07μl/l and97.96μl/l respectively. This indicated thatessential oils of Artemisia annua L.and Artemisia lavandulaefolia DC. had a stronger effectthan Artemisia scoparia Waldst.et Kitag. However, when the temperature was increased to29℃for36h,the LC₅₀of the essential oils of Artemisia annua L.、Artemisia lavandulaefoliaDC.、Artemisia scoparia Waldst.et Kitag were91.88μl/l、66.73μl/l and92.04μl/l respectively.Thus at29℃the essential oil of Artemisia lavandulaefolia DC had the strongest activity.2. The fumigant activity of the three essential oils on Callosobruchus chinensis（L.） adultsindicated that:When Callosobruchus chinensis（L.） adults were treated for36h at25℃, the LC₅₀of theessential oils of Artemisia annua L.、Artemisia lavandulaefolia DC.、Artemisia scopariaWaldst.et Kitag were respectively3.23μl/l、4.29μl/l and4.72μl/l.This demonstrated that thefumigant activity of essential oil of Artemisia annua L. was far higher than that of Artemisialavandulaefolia DC.and Artemisia scoparia Waldst.et Kitag. Conversely, the LC₅₀of essentialoils of Artemisia annua L.、Artemisia lavandulaefolia DC.、Artemisia scoparia Waldst.etKitag were respectively3.80μl/l、1.75μl/l and1.99μl/l, when fumigated for36h at29℃.Thisresult showed that the fumigant function of the essential oil of Artemisia annua L. was farbelow that of Artemisia lavandulaefolia DC. and Artemisia scoparia Waldst.et Kitag.3. Comparing the fumigant activity of the three essential oils on Sitophilus zeamaisMotschulsky and Callosobruchus chinensis（L.） adults demonstrated that:The efficacy of the essential oils can last for-years, since they were no change in theadjusted mortality and median lethal concentration during the stipulated period of the trials.4. The fumigant activity of ethyl formate on Sitophilus zeamais Motschulsky andCallosobruchus chinensis（L.） adults demonstrated that: When the adults of Sitophilus zeamais Motschulsky were treated with ethyl formate for36h at25℃and29℃, the LC₅₀were respectively43.26μl/l and51.49μl/l. Meanwhile, theLC₅₀of ethyl formate on Callosobruchus chinensis（L.） adults were3.38μl/l and16.61μl/l,when fumigated for36h at25℃and29℃respectively. All in all, the fumigant activity ofethyl formate on Sitophilus zeamais Motschulsky and Callosobruchus chinensis（L.） adultswas high at low temperature. In addition, at the same temperature, the fumigant activity ofethyl formate on Sitophilus zeamais Motschulsky adults was more effective compared tothat on Callosobruchus chinensis（L.） adults.5. The fumigant activity from the mixture of ethyl formate and essential oils onSitophilus zeamais Motschulsky and Callosobruchus chinensis（L.） adults showed that:When the Sitophilus zeamais Motschulsky adults were fumigated for36h at25℃、29℃with the mixture of ethyl formate and Artemisia annua L.（1:18） showed synergy.Besides, there was an increase in synergy of the mixture on Callosobruchus chinensis（L.）adults treated for36h at29℃, when the ratio of ethyl formate and the essential oil ofArtemisia annua L. were1:18and1:8.The result show that: essential oils of Artemisia lavandulaefolia DC. had a stronger effectthan Artemisia scoparia Waldst.et Kitag.and Artemisia annua L.while Artemisia annua L.mixed with ethyl formate showed synergy.