用不同蚜虫作猎物对大灰食蚜蝇生长发育的影响

INFLUENCE OF DIFFERENT APHID PREY ON THE DEVELOPMENT OF METASYRPHUS COROLLAE [DIP.: SYRPHIDAE]

在20～25℃室温下用5种蚜虫分别饲养大灰食蚜蝇的结果表明,用麦长管蚜、禾谷缢管蚜、麦无网长管蚜、豌豆蚜作猎物,均能使食蚜蝇完成发育。幼虫期历期分别为11.0、10.2、10.1和10.6天,发育全期(幼虫+予蛹+蛹期)分别为29.0、30.6、27.4和26.1天,蛹重为33.9～40.7mg,差异不显著。但取食甘蓝蚜的食蚜蝇则不能完成个体发育。每天分别供应5、10、20、40和80头2～3龄麦无网长管蚜饲养食蚜蝇,在5头处理中,幼虫历期明显较长,予蛹及蛹期历期最短,其它4个处理间差异均不显著;幼虫成活率、蛹重和羽化率,则随取食蚜虫量的增加而明显增加。试验结果指出,人工饲养食蚜蝇必需选择适合的蚜种,虽然食蚜蝇幼虫取食86头2～3龄蚜虫即能完成发育,但提供更丰富的猎物还是必要的。

Rearing of Metasyrphus corollae, an important predator of aphids in wheat, rapeseed and broad bean fields in Guizhou Province, was carried out at room temperatures of 20°-25℃in Guiyang, using five different species of aphids as the prey. The predator completed its normal development on four aphid species, Macrosiphum avenae, Rhopalosiphum padi, Acyrthosiphon dirhodum and A.pisum. The duration of the larval development on the four species was 11.0, 10.2,10.1 and 10.6 days, respectively; And the total duration of development (larval+pre-pupal +fpupal) was 29.0,30.6, 27.4 and 26.1 days, respectively. The pupal weight was 33.9-40.7 g. No significant difference was shown among the four prey species. The predator did not, however, complete its development on Brevicoryne brossicae. In a laboratory experiment of supplying one syrphid larva with 5, 10, 20, 40 and 80 2nd-3rd instar nymphs of A. dirhodum daily, the larval developmental period of the predator was significantly longer when 5 aphids were supplied each day than that with other prey densities, which showed no significantly different influence on the predator's larval developmental period. The larval survival rate, weight of pupa and the adult emergence rate increased as the prey density increased. The results indicated that it is necessary to select suitable aphid species for the mass rearing of syrphid predators. An adequate prey supply is also necessary to obtain syrphid colonies with greater pupa! weight, larval survival rate and adult emergence rate, although 80 aphid nymphs were satisfactory for a M. corollae larva to complete its normal development.