| Hoplia spectabilis Medvedev (Coleoptera: Scarabaeoidea: Hopliidae) is one of serious shrub pestsand breakouts in the counties of Haixi,Haibei and Hainan municipality in Qinghai Lake Basin in latestyears. It endangers the plants, such as sea-buckthorn, Hippophae rhamnoides, etc. This pest has severelythreatened the local ecological environment and ecological protection of Qinghai Lake. Until now, thereare few research documents about this pests, let alone systematic research report. So, based on this, thisdissertation systematically studied the morphological characters of adult, egg, larva and pupa of the pest,as well as living habits, occurrence law and life history in Buha River area, Tianjun County, QinghaiProvince. Environmental factors of this area were investigated. All of these will provide thefundamental research data for making the sustainable management strategies. The main results are asfollows:1. Morphological characteristics of the adult, egg, larva and pupa were described systematically.Among them, distinctive features of male and female, some partial subtle feature, such as antennae,labial palpus, pronotum, pretarsus and Hind tibiae, male genitalia, morphology of larva and pupa weredescribed for the first time. The corresponding photos of these characters were all presented.2. Biological characteristics and occurrence law of the scarab were ascertained.The scarab adult has the characteristics of feign death, gregariousness, taxis to yellow color andhost selectivity, such as seabuckthorn preference. The sex ratio of male and female adults is1.3:1. Theadults take knapsack mating, with the mating time from20to50minutes. They mate more than once.Female adults lay eggs in soil on higher topography with sunny light and herbage and shrubs where isnot easy to pond. Eight to ten eggs scattered in depth of8～12㎝underground, and the depth of layingeggs varies according to the moisture and texture of soil. The adult begin appearance at9:00, the peak at16:00, and disappear at20:00in a day. The populations have2peaks per year, they are at the end ofmiddle and at the end of late of July, respectively. The beginning period full, full period and endingperiod full are on July16～17, July26and August5, respectively.Larvae have three instars and live underground. They live from8to20cm underground fromsummer to autumn, feeding the plants’ young root. They move downward in late autumn to over winter.In spring, they go upwards for feeding. Mature larvae pupate in earth nest.Early pupa is milk-white color. The color of pupa is changed from milk-white to yellow and finallyto brown as they grow.Life history: One generation per year; the adult emerges in late June and lay eggs in middle July;eggs hatch in early August. The2ndand3rdinstar larvae begin to overwintering in early October. Theypupate in the following spring.3. The spatial distribution of adult population is aggregation in the field.4. Based on the investigation and analysis, this dissertation also pointed out the occurrence and harmindex caused by adult of Hoplia spectabilis. The finding was:43adults per plant was the mildoccurrence; from43to170per plant was moderate; more than171was severe. We initially confirmed that the control threshold was43adults per plant. The studies also revealed that the control efficiencyreached67.9%with manual trap.5. We also summarized the ecological environment of Tianjun County, proposing some technicalstrategies of effectively controlling this pest for sustainable perspective. |
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