| Aphelinus mali(Haldeman)was first found in the east of the North America,an effective natural enemy used in China to control woolly apple aphid,Eriosma lanigerum(Hausmann).It's control ability is very strong.It was introduced to 51 countries to control woolly apple aphid.In China,the A.mali was introduced from Japan to Dalian,Liaoning province in 1942 and from the former Soviet Union to Qingdao,Shandong province in 1955,which has covered most apple-producing areas.Woolly apple aphid was a worldwide pest that it has distributed in more than 70 countries,it was first found in the east of the American,The woolly apple aphid invaded Shandong and Liaoning province in the initial period of 20th century and introduced to Yunnan province from American in 1930 and latter spread to many apple growing areas.Previous studies have found that the populations of A.mali in China fall into two distinct genetic clades.To clear whether differences exist between the two genetic clades in the biological characteristics of A.mali,in this study,with physiological and ecological characteristics of different genetic clades of A.mali in different regions as the key,studying the control ability,reproduction ability and adaptability to low temperature with ecology means,the main results were summarized as follows:First,with the woolly apple aphid in Shandong(Qingdao)as the host,the control ability of the Shandong clade of A.mali(a/Th = 2.447)was found to be stronger than that of the Liaoning clade(a/Th=1.278);the search parameter(Q)and the mutual interference parameter(m)of the Shandong clade(0.112,0.242)were both significant higher than that of the Liaoning clade(0.076,0.173).The egg production and life(64.4 ± 10.44 eggs and 16.26 ± 1.04(female),13.54±0.75(male)days,respectively)of the Shandong clade were both significantly higher than they were for the Liaoning clade(30.67 ± 4.02 eggs and 9.34 ±0.67(female),7.64 ± 0.48(male)days,respectively),and the Shandong clade had a longer oviposition period for one oviposition(Shandong 86.6 s,Liaoning 61.4 s).The developmental threshold temperature of the Shandong clade(9.82±1.44?)was lower than that of the Liaoning clade(10.72 ±0.24?),while the effective accumulated temperature of the Shandong clade needed for development from oviposition to adult eclosion(126.45 ± 16.81 degree-days)was significantly higher than that of the Liaoning clade(107.99 ±3.44 degree-days).Second,as the cold resistance ability of overwintering larvae of A.mali,The supercooling point and freezing point of the Liaoning clade(-27.66 ?,-27.17 ?)were significantly lower than those of the Shandong clade(-26.04 ?,-25.54 ?).The content of fat,trehalose and protein of overwintering larvae of the Liaoning clade(60.8%,7.57 ?g/one insect,10.11 ?g/one insect)were both significantly higher than that of the Shandong clade(45.5%,5.73 ?g/one insect,8.05 ?g/one insect).Third,with the woolly apple aphid in Hebei(Qinhuangdao)as the host,we found no significant differences in the developmental threshold temperature,effective accumulated temperature,fecundity and longevity of the two clades,but the duration of host searching of the Shandong clade was significantly longer than that of the Liaoning clade,and the duration of grooming and resting was significantly shorter for the Shandong clade than of the Liaoning clade.At densities of 3,4,and 5 pairs of mali per petri dish,the searching efficiency of the Shandong clade was significantly higher than that of the Liaoning clade.The instantaneous attack rate of the Shandong clade of A.mali on WAA was higher(0.0946)than that of the Liaoning clade(0.0713),and the control ability(a/Th,a is the attack rate and Th the handling time associated with each prey consumed)of the Shandong clade(0.543)was also higher than that of the Liaoning clade(0.382).The search parameter(Q)of the Shandong clade(0.073)was higher than that of the Liaoning clade(0.038),and therefore,with WAA from Hebei Province as the host,the host adaptability of the Shandong clade of Aphelinus mali was not worse than that of the Liaoning clade,while the pest control ability of the Shandong clade was still greater than that of the Liaoning clade.In conclusion,the ecological adaptability and control ability of A.mali of Shandong clade are better than that of Liaoning clade,we can domesticate the better clade of A.mali to control the woolly apple aphid in the biological control. |
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