| Oedaleus decorus asiaticus belongs to order Orthoptera,family Oedipodidae,which is one of the dominant grasshopper in the northern grassland and adjacent farming-pastoral region in Northern China.In recent years,pathogenic microorganisms such as Metarhizium anisopliae have been used for biological control measures on locusts.In this paper,the oviposition behavior of O.d.asiaticus under natural environment and the factors affecting the egg hatching under indoor conditions were conducted in order to determine the suitable conditions for the oviposition and hatching of O.d.asiaticus.The body temperature changes of 3rd-instar of O.d.asiaticus after infection with M.anisopliae were determined so as to determine the body temperature response by infected with M.anisopliae,and provide theoretical basis for biological control of O.d.asiaticus.The main research results are as follows:1.Effects of vegetation,orientation and soil moisture content on ovipositionVegetation had a significant effect on the number of eggpods and eggs of O.d.asiaticus(P < 0.01).The average number of eggpods and eggs in Cleistogenes squarrosa were the highest,which were 0.76±0.06 and 15.47±1.34,respectively,and significantly higher than that of Stipa krylovii,Leymus chinensis and Artemisia frigida(P < 0.05).The average number of eggpods(0.42±0.06)and eggs(7.53±1.34)in Stipa krylovii took the second place,and significantly higher than that of Leymus chinensis and Artemisia frigida(P < 0.05).The lowest average number of eggpods(0.14±0.06)and eggs(2.67±1.34)in Artemisia frigida,there was no significant difference with the average number of eggpods(0.15±0.06)and eggs(2.75±1.34)in Leymus chinensis(P > 0.05).Orientation had a significant effect on the number of eggpods and eggs of O.d.asiaticus(P < 0.01),of which,the average number of eggpods(0.45±0.04)and the number of eggs(8.47±0.95)in the south were significantly higher than that(0.28 ± 0.04)and(5.75 ± 0.95)in the north.In addition,the interaction between orientation and soil moisture content had a significant effect on the number of eggpods and eggs of O.d.asiaticus(P < 0.01).Among the number of eggpods and eggs in the south,the average number of eggpods(0.64±0.12)and the number of eggs(12.20±2.46)under the condition of high soil moisture content were the highest,the second were the number of eggpods(0.44±0.08)and the number of eggs(7.64±1.42)under the condition of medium soil moisture content,and the min were the number of eggpods(0.28±0.09)and the number of eggs(5.56±2.00)under the condition of low soil moisture content,The differences among the three groups were significant(P < 0.05).2.Effects of soil type and soil moisture content on egg hatchingThe effect of soil type on the hatching duration of O.d.asiaticus was very significant(P < 0.01).The hatching duration in brown calcic soil(3.6±0.2)d was significantly shorter than that in black soil and sandy soil(P < 0.05).Soil type,soil moisture content and their interaction have a significant effect on the eggs hatching rate of O.d.asiaticus(P < 0.01).The hatching rate was the highest(42.5%~61.4%)in brown calcic soil,followed by black soil and sandy soil.In brown calcic soil,the hatching rate(60.3%~61.4%)under soil moisture content with 10%~20% was significantly higher than the rate(42.5%)under soil moisture content with 5%.In black soil,the hatching rate(49.8%~42.7%)under soil moisture content with 15%~20% was the highest,followed by the hatching rate with 28.4% and 13.5% under soil moisture content with 10% and 5% respectively.In sandy soil,the hatching rate(38.7%)under soil moisture content with 5% was the significantly higher than the hatching rate(12.9%~19.8%)under other soil moisture contents(42.5%~61.4%).The relative hatching rate accounted for 73.1%~98.0% at first three days regardless of the different soil types.It reached a peak at 1 d under sandy soil,but there was no significantly different found comparing to other two soil types.While the relative hatching rate reached a peak at 2 d in brown calcic soil and black soil,which were significantly higher than that of sandy soil.3.M.anisopliae occurrence rate in different parts of deaded O.d.asiaticusHumidity cultivating about deaded O.d.asiaticus,The M.anisopliae occurrence rate of O.d.asiaticus infestation reached 62.6%,the rate was the highest(26.53%±2.63%)of the hind foot,which was significantly higher than that of other body parts(P < 0.05),but no significant difference between frontfoot and midfoot(P > 0.05).The lowest M.anisopliae occurrence rate(6.14%±1.93%)of mouthparts,which was significantly lower than that of foot(P < 0.05),but was not significantly different from that of other body parts(P > 0.05).4.Body temperature response of O.d.asiaticus after M.anisopliae infectionThe body temperature of infected O.d.asiaticus was higher than that of uninfected ones for 5 days in the morning.On the 8th day,the difference between the average body temperature of infected O.d.asiaticus and that of uninfected ones was significantly higher than that of other days,reaching 1.56±0.40 ℃,which showed obvious phenomenon of behavioral fever.At noon,the average body temperature of infected O.d.asiaticus on 9 days was higher than that of uninfected O.d.asiaticus,showing the phenomenon of behavioral fever.On 6th day,the maximum difference between the average body temperature of infected O.d.asiaticus and that of uninfected O.d.asiaticus was 4.11±0.77 ℃.On 7th day,the difference between the average body temperature of infected O.d.asiaticus and that of uninfected O.d.asiaticus was 0.51 ± 0.70 ℃,but there was no significant difference(P > 0.05). |
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