Isolation,identification And Pathogenicity Evaluation Of The Pathogenic Fungi Of Ostrinia Furnacalis In The Corn Producing Area Of Xinjiang

Ostrinia furnacalis is one of the important pests on corn in Xinjiang.Its existing comprehensive control technology mainly based on chemical control has many outstanding problems such as"3R".One of the important methods of prevention and control is more in line with the needs of the green and healthy development of Xinjiang’s corn industry.However,there are few reports on the pathogenic fungi of O.furnacalis in Xinjiang desert oasis irrigated maize production area.This study identified its species by isolating,purifying,splicing and identifying the pathogenic fungi of O.furnacalis in typical corn growing areas in Xinjiang.According to the diversity analysis,the dominant strains were screened out,and indoor biological characteristics and virulence studies were carried out on them.On this basis,Aspergillus nomius with fast growth rate,large spore yield and high insecticidal activity against O.furnacalis was screened out,and the optimization experiment of inoculum was carried out.Through indoor stress resistance experiments and bioassay experiments,screened out the best compatibility for Aspergillus erythraea agent,Aims to provide technical reserves for biological control of O.furnacalis in Xinjiang corn growing areas.The main findings are as follows:（1）The species,identification and diversity analysis of pathogenic fungi of O.furnacalis overwintering larvae in typical corn planting areas in Xinjiang showed that from 2019 to 2020,185 sample sites in 5prefectures/prefectures and 6 counties/cities in Xinjiang were collected from overwintering O.furnacalis larvae（534 in total）were isolated,and 136 fungi were obtained.The isolated strains were back-connected to the third instar larvae of the healthy O.furnacalis,and the pathogenicity was determined.The results showed that the cumulative mortality rate of the parasites in 7 days was 16.7%-94.44%.The pathogenic strains were isolated again,and the morphological characteristics and r DNA-ITS sequence analysis,identified as 7 orders,7 families,9 genera and 14 species.Among them,A.nomius（22.1%）,Beauveria bassiana（19.9%）,Fusarium sp.（13.2%）were the dominant species,Fusarium anthophilum（9.6%）,Penicillium polonicum（2.9%）,Penicillium raistrickii（1.5%）,Lecanicillium attenuatum（6.6%）,Fusarium equiseti（3.7%）,Fusarium proliferatum（2.2%）,Mortierella polycephala（5.9%）,Alternaria alternata（5.2%）,Acremonium strictum（2.9%）,C.perangustum（3.68%）are common species;Fusarium solani（0.7%）is a rare species.The results of diversity analysis showed that the relative abundance of entomopathogenic fungi in Xincheng District,Urumqi City was the highest（41.4%）,followed by Changji City,Changji Prefecture（21.4%）,and Shule County,Kashgar Prefecture（11.4%）was the lowest;Horguo,Ili Prefecture The abundance,diversity index and evenness of pathogenic fungi in Sicheng were high,and the two-year fungal lethality rate was the highest in the new urban area of Urumqi（28%and 14.6%）.（2）The results of the biology and virulence determination of the four main pathogenic fungi showed that the colony growth rate of A.nomius was fast（11.10 mm/d）,the spore germination rate was high in 48hours（96.83%）,and the spore production was large in 14 days.(1.84×10¹⁰spores/m L);leukocytosis attenuated second.The results of indoor virulence test showed that A.nomius had the strongest virulence to the third instar larvae of O.furnacalis,its LT₅₀and LC₅₀were 4.16d and 4.283×10²spores/m L,and the cumulative corrected mortality rate was as high as 93.94%in 7d;Secondly,the LT₅₀and LC₅₀were 5.03d and 1.724×10⁴spores/m L,respectively,and the cumulative mortality rate was 73.48%in 7d.There was no statistical difference in the virulence of 0.05),its LT₅₀,LC₅₀and 7d cumulative mortality were 5.04d,1.829×10⁴spores/m L,69.80%respectively;Penicillium reethus had poor virulence against O.furnacalis,LT₅₀,LC₅₀were 6.04d,4.062×10⁵Spores/m L,7d cumulative mortality was 53.03%.In conclusion,A.nomius has strong virulence and high lethality to 3-year-old O.furnacalis,and has the potential to be developed as an insecticidal microbial inoculant.（3）In the preparation of biocontrol bacteria A.nomius and its virulence to O.furnacalis,the results of short-time high temperature treatment showed that the treatment effect of the components containing almond oil was relatively good(the spore germination rate was 75.40%～84.92%,the average daily growth rate of the colony was 3.50mm/d-4.22mm/d,and the spore production on the 14th day was1.00×10¹⁰～1.87×10¹⁰spores/m L);the results of UV irradiation for 10min showed that the components containing almond oil The treatment effect was also relatively good(the germination rate of spores was22.22%～26.19%,the daily growth rate of colonies was 4.28mm/d～6.11mm/d,and the spore production on the 14th day was 1.05×10¹⁰～1.51×10¹⁰spores/m L);The results of the force assay showed that the overall insecticidal activity of almond oil（component A）was relatively the best(the cumulative mortality was77.78%,and the LT₅₀and LC₅₀were 4d and 3.43×10⁴spores/m L,respectively),which was significantly better than other compatibility（p<0.05）.In conclusion,the addition of almond oil to A.nomius spore suspension was the best component.