Diapause Induction And Low Temperature Storage Of Exorista Civilis Rondani

Exorista civilis Rondani (Diptera: Tachinidae) is one of an parasitic natural enemy of themeadow moth (Loxostege sticticalis Linnaeus) and Mythimna separata (Walker) larva.It isone of an important control factor of the number of meadow moth and Mythimna separata(Walker) and play a key role of insect pest populations. In order to evaluate the controllingeffects of predators on their hosts, protective utilization of Exorista civilis Rond. and guidethe biological control of meadow moth and Mythimna separata (Walker),this papersystematically investigated the diapause induction,diapause after physiological andbiochemical characteristics, and cold storage of Exorista civilis Rond..The results were asfollows:1.The diapause induction of Exorista civilis Rond.Photoperiod and temperature were the main environmental factors of diapause induction.Chilling temperature and short-day photoperiod were the key factors of diapause induction inExorista civilis Rond..No diapause was inducted at25℃at any photoperiod,while the daylength less than12h was beneficial to diapause at17℃;With the increase of photoperiod,diapause rate gradually decreases at21℃.The larval phase was the most sensitive stage fordiapause induction,the egg stage and adult stage is not sensitive to short-day photoperiod.Thecritical day length of Exorista civilis Rond. was12.53h at16℃and12.12h at18℃.2.The main chemical change of Exorista civilis Rond.after diapauseComparing essential substanc change during diapause and non-diapause, glycogen contenthas been higher than that of trehalose, glycerol, protein content, the results showed that themain cold resistance material of Exorista civilis Rond. on diapause is glycogen. The changetrend of glycerol and protein are similar and smoothly, but the protein content is significantlyhigher than glycerol content.3.Cold storage of Exorista civilis Rond.Exorista civilis Rond. in eggs and larvae stage is sensitive to low temperature, lowtemperature storage is not well,but at the pupa stage is much better and at7士1℃is the best,temperature too high or too low,storage effect is bad, cold storage has little influence on sexratio. The cocoons are parasitized by Exorista civilis Rond. storage are most suitable for 90-110d at4℃. The supercooling point and freezing point of Exorista civilis Rond. in eachinsect stages are different, cold tolerance is also different. The freezing point of trend andsupercooling point are pretty much the same, But the value of freezing point is slightly higherthan the supercooling point.In the same developmental stages of Exorista civilis Rond., maleand female of supercooling point are not significant. Pupal stage of the supercooling point andfreezing point are the lowest,so the cold tolerance is also the strongest.10day age pupa ofsupercooling point and freezing point reach the minimum and with other development periodwas found significant difference.