| Biological invasion not only brings great loss to the national economy,but also causes great harm to the local ecosystem.The fall armyworm(FAW),Spodoptera frugiperda,is an invasive species native to tropical and subtropical America.This insect species has invaded China in January 2019 and posed a huge threat to the corn production.However,there is no relevant report on the impact of the moth on the local Lepidoptera corn pests.In this study,two local lepidopteran corn pests,the Asian corn borer(ACB),Ostrinia furnacalis,and the Oriental armyworm(OAW),Mythimna separate,were selected,and the indoor and outdoor experiments were conducted to explore the inter-species competitive relations among the three species in the larval stage.The purpose of this study is to find out whether there are competition and substitution among them,and to provide some reference for the effective control of FAW in the future.The results are as follows:1.The niche breadth values of three pests in the maize plants at jointing stage were ACB(0.8474)> OAW(0.7738)> FAW(0.6568).The data showed that the competition within the ACB was less and the competition within FAW was more.From the interspecies point of view,the niche of FAW and ACB was very similar,the similarity was 0.8508,and they preferred to eat the stem part;and the competition coefficient between FAW and ACB is the largest,which reached 0.9749.2.When FAW coexists with other pests on the corn plants at jointing stage,the number of insect mouths and niche are not significantly different from FAW when they are connected alone.When the ACB coexisted with FAW,the number of insects was 0.33 per plant,which was significantly smaller than that of the control(1.75 per plant);and the niche of ACB also changed,which was on the stalk The proportion of insect population decreased from 71.46% of the control to 3.57%.When the armyworm coexisted with FAW,the number of insect mouths also decreased significantly,and the proportion of insect mouths on the stalks decreased from 23.10% of the control to 2.50%.3.The order of occupation of the seven resources has no significant effect on the population and niche of FAW.Under the order of different resource occupancy order,the number and niche of the ACB were greatly affected,and the highest value of the insect population was only 0.52 per plant.The populations of OAW differ greatly in the treatment order of different resource occupancy orders.Among them,the populations of OAW are the lowest,which is only 0.4350 per larvae under the treatment of “mythimna separata first,and then 6 hours later.Strain.4.Under the condition of sufficient corn leaves,FAW and other pests coexist indoors,the mortality rate is not significantly different from FAW when it is connected alone.With the increase of age,the mortality rate of ACB and FAW coexisted gradually,and the highest mortality rate reached 40.63%,which was significantly higher than that of the control.When OAW and FAW co-exist,the mortality rate gradually increases with the growth of age,the highest is 71.88%.In the absence of corn leaves,larvae of FAW larvae at the age of 3 and above will mutually prey when they coexist alone,and the mortality rate can reach a maximum of 21.88% at 24 hours;while indoors with other pests When coexisting,FAW has a low mortality rate and preys on two other pests.When coexisting with FAW alone,the mortality of OAW and corn borer reached 100% at 12h;when the three pests coexisted at the same time,the mortality of OAW and corn borer reached 100% at 24 h.5.With sufficient corn leaves,the weight gain of FAW gradually increased with the increase in the number of ACBs and OAW,and was significantly greater than the control.In the absence of corn leaves,the weight gain of FAW feeding on the other two pests gradually increased,while the weight gain of FAW in the control group was negative. |
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