Effects Of Temperature And Photoperiod On Inducing And Development Of Aphis Glycines Autumnal Morphs

Soybean aphid,Aphis glycines Matsumura,is an important pest in soybean fields.The A.glycines life cycle is characterized as heteroecious and holocyclic.There are parthenogenesis reproduction and sexual reproduction stage and nine species of A.glycines biotypes in their life cycle.Gynoparae and males of A.glycines were induced by low temperature with reduced photoperiod in the laboratory.Occurring dynamics of gynoparae and males at different temperatures and occurring period in the field were studied.Life tables of A.glycines experiment population were constructed,effects of temperature on development of gynoparae,males and oviparae were studied.Morphological characters of A.glycines gynoparae,males and oviparae were also studied.The conclusions were as follows:Gynoparae and males of A.glycines could be successfully induced at 17-26?,and they could not be induced at 29?.Gynoparae and males could be induced at 17? with photoperiods of 10L: 14 D,12L: 12 D,and 10L: 14 D.At 20 and 23? with photoperiod 10L: 14 D or 12L: 12 D,gynoparae could be induced.Gynoparae of A.glycines could not be induced,but males could be induced at 26?.It also showed that the optimal inducing conditions were 20? and 10L: 14 D.It showed that males of A.glycines occurred earlier than gynoparae in the laboratory and in soybeans.In the laboratory,males occurred at 26? and gynoparae occurred at 23?.At 23 and 20?,gynoparae occurred and disappeared together with males.At 17?,there were still larger number of males when gynoparae disappeared.In Harbin,Heilongjiang province,northeast China,males of A.glycines occured on 10 August and gynoparae occurred on 21 August in the field.Survival rates of A.glycines gynoparae,male,and oviparae were higher at 13 and 18?,survival rates of these autumnal morphs were lower at 33?.Nymph stages of these autumnal morphs decreased when temperatures increased gradually from 13 to 28?.At 28?,nymph stages of gynoparae,male,and oviparae were all shortest,which were 5.42±0.13,7.58±0.13,and 8.70±0.30 days.Gynoparae nymphs could develop into adults at 13 to 33?,nymphs of male and oviparae could develop into adults at 13 to 28?.Adult longevity of gynoparae,virgin males,and virgin oviparae decreased gradually when temperatures creased.Fecundity of gynoparae was largest at 23?,with 15.87±0.33 oviparae per adult.Intrinsic rate of increase and finite rate of increase both increased when temperature increased from 13 to 28?.At 28?,intrinsic rate of increase and finite rate of increase of gynoparae were 0.34±0.0135 and 1.40±0.0189.There were all significant differences in body length,body with,and body sizes of A.glycines gynoparae,male,and oviparae when they developed among different temperatures.Gynoparae,males,and virginoparae of A.glycines were identified morphologically.Wax-powdered areas were regularly distributed on the dorsum of male abdomens and there were a few white wax-powdered areas on gynoparae dorsal abdomens.Dorsal abdomens of winged virginoparae were smooth.There were visible external genitalia at the ends of male bodies,which resembled small hooks with eyes.Adult bodies of oviparae were grayish green and fusiform,and their abdomens were protuberant.The ends of their siphunculi were dark.Coloration of their hind leg tibiae were darker than those of their fore and middle legs.The ends of their siphunculi were dark.The heads and thoraxes of gynoparae adults were dark,and their abdomen were green to yellowish green.Siphunculi of gynoparae were black.Distal parts of hind leg femurs were grayish black,and were darker than those of winged virginoparae.