大络新妇(蜘蛛目:园蛛科)的形态特征与生物学

大络新妇是广东电白县人工阔叶混交林中的优势种。8月间产卵,孵出的幼蛛留在卵袋中越冬。翌年3月幼蛛离散。7月成熟交配。捕食对象随季节而改变。网上常有锥腹蛛寄食。大络新妇国内罕见,文内作了形态描述。

ON MORPHOLOGICAL CHARACTERISTICS AND BIOLOGY OF THE SILK SPIDER NEPHILA IMPERIALIS (ARANEAE: ARANEIDAE)

The present paper deals with the morphology and biology of the silk spider Nephila imperialis Doleschall, 1857, which was found in an artificial deciduous forest in Dianbai County, Guangdong Province and played an important role in the biological control of insect pest there.The adult females measure from 35 to 40 mm. The carapace is silvery-grey in colour when alive and dark brown after being presersed in spirit. The ocular quadrangle is wider than long (1,35:1.11 mm) and slightly narrower in front (1.35:1.19 mm). The cephalic region is armed posteriorly with two tubercles. The sternum has a large conical tubercle behind labium and seven submarginal tubercles, among which the posteior three are larger than the others. The abdomen is long with nearly parallel sides, gras green or yellow green variously marked with yellow spots and stripes. The markings of the young differ somewhat from those of the adult. The adult males measure from 6 to 17 mm. The cephalic region and sternum lack any tubercles characterisitc of female.N. imperialis has only one generation a year. The adult appears in July and the female builds a large orb-web at the higher part of the forest. At that time 2 or 3 mature males are usually found near a female's web. After copulation, the female moves to the lower part of the forest where twigs and leaves are much denser and then deposits egg-sacs on leaves. Each female only lays one egg-sac and each sac contains about 1,000-2,000 eggs. The eggs hatct in about 19-21 days, but the spiderlings .still remain within the sac membrane for hibernation. Spiderlings disperse in mid-march and begin to migrate to other places. The diet of N. imperialis changes with the growing of the spider. It feeds mainly on insects of small size, such as winged termites in May, cicadas in Jufie, rhinoceros beetles and locusts in July. In June and July two other spiders Conopistha miniacea and C. bon-adea are found living on cob-web of N. imperialis as inquilines.