Temperature Stress Tolerance Of Sirex Noctilio And Its Symbiotic Fungi Amylostereum Areolatum

The European woodwasp Sirex noctilio is a forest-boring pest,native to Europe and North Africa.It has invaded in many countries,mainly harming Pinus,and is a major international quarantine pest.In China,it has been found that it invaded the northeastern region,which endangered Pinus sylvestris.It has a strict symbiotic relationship with its symbiotic fungi(Amylostereum areolatum),which is an essential nutrient source for the growth and development of its larvae.In this paper,the tolerance of European woodwasp to temperature stress and the tolerance of symbiotic fungi to temperature were studied.Combined with the microenvironment of the tunnel and the historical temperature data of the distribution,the suitable temperature range of European woodwasp was determined.According to the laboratory data,the model parameters of the European woodwasp climate suitable area were determined,and the global potential distribution area and domestic transmission risk were fitted and analyzed,in order to provide a theoretical basis for the prevention and control of European woodwasp.1.A.areolatum have a wide temperature range but are not resistant to high temperatures.The mycelium is moderate-temperature with a suitable temperature of 20-25?;the optimum temperature for sporulation and spore germination is 30?.There are differences in the suitable temperature range between the strains in different distribution areas,which are related to the ambient temperature and are easily domesticated.2.The cold-tolerant strategy of European woodwasp overwintering larvae is freezing-intolerance.It cannot survive for a long time at temperatures below the supercooling point(-20.77 ± 0.44 ?).The over-winter larval supercooling point(-24.27±0.62?)was the lowest in the whole wintering period,and the larvae at the same time(-18.72±0.94?)were lower than the adults(-11.78±0.67?).The cold tolerance of different geographical populations is related to the ambient temperature.European woodwasps are not resistant to high temperatures,and temperatures above a long time(>30?)and 43? can cause death during short periods(?4h).At the same time,the heat resistance of adults is stronger than that of larvae.Under high-temperature stress,the water content and fat percentage of adults will decrease,and the protein content will increase slightly within a certain temperature range.Therefore,it is speculated that high temperature is an important factor limiting the further spread of European woodwasps.3.The temperature of the European woodwasp tunnel has the characteristics of time lag and no extreme value.It has a protective and buffering effect on wintering larvae and adult feathers in summer,but the average temperature difference is not obvious(<1?).Based on the temperature characteristics of the domestic distribution area,the temperature in the tunnel and the ambient temperature were linearly fitted.By analyzing the European woodwasps,symbiotic fungi,tunnel influence and historical temperature data,the relevant parameters were fitted to 4.09?(lower growth temperature),22.3?(optimate low temperature limit),27.71?(optimate high temperature limit),30.60?(growth upper limit temperature),-32.5?(cold stress temperature)and 33.80?(heat stress temperature).4.The global potential climate suitability areas of the European woodwasp,compared with previous studies,the fitting degree of domestic distribution points is increasing,the domestic suitable range is larger,the proportion of highly suitable areas is higher,and the coastal areas near the known distribution areas are highly risky.The potential distribution areas in China are mainly limited by the distribution of host and the fragmentation of the regional environment.In a short period of time,it will only cause harm in the vicinity of the known distribution area in Northeast China,but it does not rule out the possibility of further spread.In a short period of time,it will only cause harm in the vicinity of the known distribution area in Northeast China,but it does not rule out the possibility of further spread.In summary,the study on the temperature tolerance of European woodwasp(and its symbiotic fungi)and its potential suitable areas,provides a theoretical basis for the effective monitoring and early warning of European woodwasp.