Study On The Community Structure Of Grassland Locusts On Fengning Dam In Hebei Province And Its Green Prevention And Control Technology

In order to explore the green control technology of grassland locusts on Fengning Dam in Hebei Province,from June to September 2021,the composition of locust communities in this area was investigated;On the basis of the analysis of the feeding volume of local high-quality pastures by locusts of dominant grassland species in local grasslands,three kinds of high-quality pastures were screened out to replant local degraded grasslands,and the changes of locust communities after replanting were analyzed;At the same time,the control effects of different dosage forms of Metarhizium anisopliae on grassland locusts in the region were also compared.The results of the study are as follows:(1)A total of 12978 individual locusts were collected,and 39 species of locusts belonged to 7 families and 21 genera.Among them,there are 2 dominant species,namely 24.06% of Tetrix japonica,15.45% of Chorthippus fallax,10 common species,and 27 rare species.(2)Select the dominant species of Chorthippus fallax,and Myrmeleotettix palpalis in the replanting test area,and the common species of Oedaleus decorus asiaticus Dasyhippus barbipes to feed local high-quality pasture.The results showed that Chorthippus fallax,Oedaleus decorus asiaticus and Dasyhippus barbipes had the highest intake of Leymus chinensis,0.0271±0.0021g/day,0.0187±0.0034g/day and 0.0134±0.0002g/day,respectively,and Myrmeleotettix palpalis has the highest feeding(0.0234±0.0007g/day)for Cleistogenes squarrosa.High-quality forage grasses with less locust intake were selected for replanting at the test site.The number of locust populations was the lowest(12.67±2.65)in the mixed sowing area and the highest in the control area(112.33±26.69).The number of locust populations in the replanting area was significantly lower than that in the control area(P<0.05),and the number of locust mouths was significantly negatively correlated with plant height and coverage(P<0.01).The Shannon-Wiener diversity index of locust communities was significantly positively correlated with the plant community diversity index(P<0.05),and the locust community diversity index(1.84±0.17)in the three forage mixed-sown areas was significantly higher than that of the control(0.93±0.36).The Simpson dominance index of locust communities was highest in single-sown Medicago sativa(0.45±0.09),followed by control areas(0.41±0.08),and the locust community dominance index and plant community diversity index were significantly negatively correlated(P<0.05).The Pielou uniformity index of locust communities and plant communities did not differ significantly across sample areas.(3)Field control effect experiments were conducted on grassland locusts on Fengning Dam with different dosage forms of Metarhizium anisopliae,and the population decline rate and control effect of grassland locusts and dominant species of Altichorthippus fallax were counted after application.The results showed that three different dosage forms of Metarhizium anisopliae(Metarhizium anisopliae-Bait,Metarhizium anisopliae-Powder,and Metarhizium anisopliae-Wettable Powder)had similar effects on the entire locust colony and the number of Altichorthippus fallax.On the 19 th day of spraying,the control effect of the three dosage forms was greatly improved,and the control effect of the wettable powder was significantly higher than that of the other two dosage forms(P<0.05).Among them,the prevention effect of the Metarhizium anisopliae-wettable powder was the best on the 29 th day of spraying(the prevention effect of locust colonies reached 92.10±11.0%,and the control effect of Altichorthippus fallax reached 94.38±3.00%);The Metarhizium anisopliae bait was significantly better than that of the other two dosage forms in the early post-control period of control against locust communities and Altichorthippus fallax,and the effect was the best on the 24 th day of control(Chorthippus fallax control effect: 70.12±17.98%,locust community prevention effect: 66.80±4.34%);There was no significant difference between the control effect of the Metarhizium anisopliae-powder in the locust community and the Metarhizium anisopliae-wettable powder within 6-19 days after the control,and its prevention effect was optimal on the 29 th day of control(the prevention effect of the Altichorthippus fallax was 73.07±13.00%,and the control effect of the locust community was80.70±16.31%).