Study On The Selectivity And Oviposition Preference Of Sesamia Inferens To Different Host Plants

The pink stem borer,Sesamia inferens(walker)(Lepidoptera:Noctuidae)is a polyphagous insect pest,which has a wide range of host plants.In recent years,the borer has caused more serious damage year by year with the change of cropping system and crop species and varieties,and become one of important pests of rice even in some areas.Host plant is one of the major environmental factors that affect the dynamics of phytophagous insect populations.To elucidate the relationship between phytophagous insects and host plants is helpful to understand their occurrence regularity and is of great significance to explore new ways for controlling pests.At present,it is not well known on the selectivity to host plants of S.inferens.The previous studies have reported some related reports with field investigation results.In this study,the selectivity and oviposition preference to rice,maize,vetiver grass,cattail,water-oat,sugarcane and wheat of the borer was investigated by Y-type olfactory test and laboratory cage and field plot experiments.The trend response to these seven plants of S.inferens was determined by the Y-type olfactory.In meantime,oviposition preference tests of S.inferens were carried out in the laboratory and the field.The results will provide a scientific basis for the integrated control,forecasting and resistance management of the borer.1.Selectivity of Sesamia inferens to different host plantsThe selectivity of the female adults of the pink stem borers to rice,wheat,maize,sugarcane,water-oat,vetiver grass and cattail were determined using the Y-type olfactometer,at the same time,it is studied whether the mechanical damage of the plant affected the selectivity of the borer.The results showed that the rice is the most attractive to the borer among the seven kinds of the plants compared to water with the selection rate 59.4%.The selectivity of S.inferens between the mechanical damage and the healthy plants of the same kind host had no significant difference.The results indicated that the female adults of S.inferens had significant selectivity to rice and the mechanical damage of the plants did not affect their selectivity significantly.2.Study on oviposition preference of Sesamia inferensThe oviposition preference to the above seven host plants of S.inferens was investigated by laboratory cage and field plot experiment.In laboratory cage experiments,the average number of egg masses laid by S.inferens on rice,maize,vetiver grass,cattail,wheat,sugarcane and water-oat was 4.7?1?1.3?1?2?1.7 and 1 respectively with the proportion of egg amounts 67%,5.7%,4.93%,4.82%,7.97%,6.12%and 3.46%respectively.The average number of eggs laid by per female on rice is significantly higher than that on other plants.Under field conditions,the results showed that the average number of egg masses laid by S.inferens on rice,maize,vetiver grass,cattail,sugarcane and water-oat was 9.3,0.3,1,0.7,0 and 0 respectively with the proportion of egg amounts 87%,2.4%,6.7%,3.9%,0%and 0%.It was clear that the oviposition rate of the borer on rice was the highest followed by vetiver grass,cattail and maize,and no eggs on sugar cane and water-oat.It demonstrated that the female of borers significantly preferred rice for oviposition and also may oviposit on the other six host plants with less eggs.Our results indicated that the pink stem borers had the highest selectivity and the oviposition preference to rice among the seven kinds of plants tested and had lower oviposition preference on the other plants,which may provide scientific basis for the forecasting of the population dynamics and control of the borer.