Research On Diapause Characteristics Of Hyphantria Cunea(Drury)in Shandong Province

Adopting the method of biology and ecology to go further study on the biology characteristics and diapause inducing factors of Hyphantria cunea （Drury） in jinan and tai’an city of Shandong Province; Based on the physiological and biochemical methods, to study the physiological and biochemical indexes differences between different insect state which under diapause and non-diapause situation. The main research results are as follows:1. In the natural environment conditions, the diapause rate of first generation pupae is13.44%, the second is1.14%, the third generation all go into diapause and over-wintered as pupae in2010; Diapause rate of first generation pupae is10.65%, the second is1.69%, the third generation over-wintered as pupae in2011. This indicated that H. cunea has summer diapause phenomenon.2. Under the raised experiment,observering diapause rates of H. cunea at different temperature, photoperiod and food conditions.In the long daylight conditions （above15h）, there is no diapause phenomenon.In the short daylight conditions （less than14.5h）, induced the diapause, H.cunea is long photoperiod development-short photoperiod diapause type.At20℃, the critical light cycle （lead50%into the state of individual diapause） of H.cunea is13h45min,23-26℃is14h10min,29-32℃is14h15min.With the temperature increased, the critical light cycle extended, this means temperature and light cycle can work together and influence diapause of H.cunea,and temperature is the secondary induced diapause factor; Morus alba L., Platanus×acerifolia, Malus micromalus Makino, Prunus serrulata and Populus nigra leaves have no significant differences on the diapause of H.cunea.3. Based on the biochemical methods, a study was conducted on the changes of glycerol, fat content, proteins, amino acids and small molecular carbohydrates of larvae and pupae of H.cunea under diapause and non-diapause condition. The results show that:in the whole period of diapause,the levels of glycolysis （glycerol,glucose,alanine） and the Krebs cycle （glutamate,proline,aspartic acid） are significantly changed form decline-to rise-and then to the trend of decline.3.1. From4th-instar larvae to prepupae, the gycerol content of H. cunea under diapause and non-diapause condition increased gradually.Glycerol content of larvae under non-diapause condition increased from1.44mg/g to9.89mg/g,while larvae under diapause condition increased from1.59mg/g to10.11mg/g. Entering the pupal stage, glycerin content of non-diapause pupae decreased gradually from8.87mg/g to6.57mg/g,while diapause pupae decreased in early diapause,down to3.97mg/g, up to9.85mg/g in middle diapause,and fell to4.01mg/g before the termination of diapause.3.2. Throughout the larval and pupal stage, the free fat content of H.cunea under non-diapause condition is higher than that under diapause condition.From4^th-instar larvae to prepupae, showed a straight rise. Free fat content of H.cunea under non-diapause condition increased from27.58%to51.21%, and H.cunea under diapause condition increased from20.65%to45.26%.Entering the pupal stage, free fat content of non-diapause pupae decreased gradually throughout the pupal period, but the decline was small, only fell by3.75%to7^th-days age. In the early-and mid-diapause stage, free fat content is in a linear decline, and rose rapidly before diapause termination, basically in line with early-diapause.3.3. In the larval stage, the protein content of H.cunea which under diapause and non-diapause condition have the consistent change trend-with gradually rising trend. The protein content of4^th-instar H.cunea under non-diapause condition is19.65%, to late larvae is the highest-about25.31%. Protein content of6^th-instar H.cunea under diapause condition is the highest, up to21.81%, and reduced to18.36%at late larvae; Entering the pupal stage, differences of protein content between the diapause and non-diapause pupae are significant, the protein content of non-diapause pupae gradually declined-from23.97%to21.62%,while protein content of diapause pupae was2.5times higher than the non-diapause pupae, dramatically increased to52.31%in early diapause, down to47.58%in the middle diapause, rose to55.84%before the termination diapause.3.4. Homocysteine, methionine, isoleucine, glutamic acid, leucine and lysine are important cold material of diapause H.cunea. In the larval stage, total amino acid content gradually increase with mature-up to peak in6^th-instar larvae, under diapause condition is36.21mg/100mg, under non-diapause condition is36.95mg/100mg.Entering the pupal stage, total amino acids content of the diapause and non-diapause pupae began to decline, to the minimum in early diapause stage; Then the total amino acid content of non-diapause pupae rose gradually, continued to emergence. And rise sharply in the middle diapause-up to43.96mg/100mg, much higher than the highest level of larvae stage, before the diapause termination and start to drop to35.21mg/100mg, slightly lower than the highest level of larvae stage.Aspartic acid and glutamic acid are main amino acids of H.cunea.while homocysteine and methionine,with relative least content, not the main amino acids.3.5. Trehalose is one of the important indexes of diapause H.cunea. In the whole larval and pupal stage, trehalose, mannitol, sorbitol and glucose content of H.cunea under diapause and non-diapause condition is high, as the main small molecules carbohydrates, and fructose and lactose remain low, not the main small molecules carbohydrates. In the larval stage under non-diapause condition,along with the development of the insect,6kinds of small molecules carbohydrate rose gradually, trehalose, glucose, fructose and lactose content peaked in5^th-instar larvae stage were30.89mg/g,14.92mg/g,3.29mg/g,2.07mg/g, respectively, mannitol and sorbitol peaked in6^th-instar larva stage, were52.77mg/g and27.55mg/g, then began to decline.Entering the pupal stage, the6kinds of small molecular carbohydrate content continue to fall. In the larval stage of H.cunea under diapause condition, along with the its development,6kinds of small molecules carbohydrate content level rose gradually, trehalose, glucose, fructose and lactose peaked in5^th-instar larva stage,were64.28mg/g,13.88mg/g,3.87mg/g,2.38mg/g, mannitol and sorbitol peaked in6^th-instar larvae stage,were34.68mg/g and25.42mg/g, then began to decline.Into the early diapause period,6small molecular carbohydrate content continued to fall,5small molecules carbohydrate increased obviously in middle-diapause, and began to fall before the diapause termination.