Feeding preference of larvae of three species of armyworm on four host plants

ObjectiveIn order to provide scientific basis for prediction and control of armyworms,the present experi-ment was conducted to investigate feeding preference of Mythimna separata(Walker),Leucania loreyi(Duponchel)and Leucania roseilinea(Walker)larvae at each instar to four species host plants viz. maize,rice,sugarcane and barnyard grass.MethodIn this study,feeding preference of three species armyworm larvae to four species host plants was evalu-ated by leaf disc method. And the number of larvae selection for each plant was recorded at 6 and 24 h after insect inocula-tion respectively.ResultThe results showed that the feeding preference of larvae at each instar of the three species army-worm varied at 6 and 24 h after insect inoculation. All the instar larvae of M. separata preferred maize most at 24 h obser-vation time,of which the feeding preference rates of 1st instar and 2nd instar reached as high as 82% and 89%. And the feeding preference rates of 1th-6th instar larvae to maize were significantly higher than those to the other three species host plants(P<0.05,the same as below).Larvae of 1st-6th instar of L. loreyi preferred to feed on maize,the feeding preference rates of 1st instar ,2nd instar and 3rd instar larvae to maize exceeded 50%(78%,70%and 55%respectively)which were also significantly higher than those to the other three species host plants. L. roseilinea 1th-6th instar larvae showed feeding preference to rice. While the feeding preference rates of 2nd to 4th instar larvae to rice and maize had no significant differ-ences with each other(P>0.05).ConclusionThe results suggest that the larvae at each instar of three species armyworm show different feeding preference to different host plants. All the three species larvae prefer maize and rise most,while the selectivity of them to sugarcane and barnyard grass is weak. Young larvae of M. separata and L. loreyi prefer maize and young larvae of L. roseilinea prefer rice and maize. The feeding preference of older larvae to host plants is not as strong as that of young larvae.