| As a new invasive pest in China, Obolodiplosis robiniae (Haldemann) is destructive for forestry. It mainly infests Robinia pseudoacacia L., Robinia hisqida L. and Robinia pseudoacacia Aurea and speads over Hebei, Shandong, Jilin and Liaoning at present. So it's necessary to carry out the research on biology of Obolodiplosis robiniae (Haldemann) and its parasitoids Platygaster robiniae.In this paper, the combination of indoor and outdoor observation was used as the method of studying the morphological characteristics of Obolodiplosis robiniae, the state of insect developmental period and the effective accumulative temperature. Meanwhile, the morphological characteristics and biological habit of O.robiniae's parasitic natural enemies Platygaster robiniae had been preliminary described.The main results are as follows:1. The morphological characteristics and biology of Obolodiplosis robiniae (Haldemann)(1) The adult body length is between 1.6 and 3.4 mm, the wingspan is 5.6 ~ 6.7 mm. Some features differ from females and males. For example, females are a little bit larger than the males. Length and thick of the egg are 0.27 ~ 0.29 mm, 0.07 ~ 0.09 mm, respectively. Its color changes with development: light orange in hatching, orange in the middle and dark red finally. There are 3 instars for the larvae .The mature one is 2.73 ~ 3.92 mm in length and has no feet, half of the head retracts into thorax like the maggot. The pupae length is 2.23~2.95 mm and its color changes in the stage: white in the early and reddish-brown before emergency .(2) It was observed that the development time for O.robiniae egg and pupae was about 3.49 days and 5.22 days.The threshold temperature of the egg and pupae is estimated to be 5.06℃and 4.75℃,and the effective accumulative temperature is 71.88 d·℃and 122.51 d·℃.(3) The overwintering larva mainly distributed in 0 to 3cm of soil and litter. 69.1% of them were contained in the soil of 0 to 3 cm and 25.1% gathered in the litter. The overwintering death rate was a little higher with 74%.(4) There are six generations of O.robiniae in the area of Changli, Hebei. The adult occurrence lasts from the end of April to the early August. Most adult emerged in the night and a few happened in the morning and evening but little in the day. Soon after the emergence of male and female adult, they matured and mating. The mating peak of O.robiniae occurred at 7 to 10am in fine days of summer. The longevity of O.robiniae females and males were 50 to 62 hours and 25 to 36hours, respectively. About 50.8% eggs were spawned on the unfolded leaflets and compound leaves, among them about 25.4% eggs were on the back of unexpanded leaflets. Eggs on petioles and old leaves and other parts are about 6.8%. The amount of O.robiniae adult egg carrying was between 100 and 170, the posthumous volume of eggs was 70 to 80, and spawning rate was 53%.2. The morphological characteristics and biology of Platygaster robiniae(1) The adult body length of P. robiniae was 1 ~ 1.3mm, and was black and lustrous. Females were slightly larger than the males.(2) P. robiniae occurred six generations a year in the area of Changli, synchronizing with its host, O.robiniae.The research in the laboratory suggested that the eclosion peak of P. robiniae appeared in 06:00, 08:00 and 18:00. Soon after the emergence of male and female adult, they matured and mating. And the adult mating time lasts 25 to 59 seconds. Males can mating many times in its life,the generally, female mating only once.(3)The research in the field suggested that the P. robiniae oviposition peak appeared in 7:30~10:30 and 15:30~18:00,oviposition amounts were at the range of 47~98. P. robiniae has certain selectivity to the host, the O.robiniae eggs that on the leaflets and unfolded leaves and not parasitic are the favorite. |
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