A Research On Laws Of Host Selection Migration And Optimum Period Of Chemical To Monolepta Hieroglyphica(Motschulsky)

Monolepta hieroglyphica(Motschulsky)is a kind of polyphagous pests,which widely distribute among China and cause numerous economic losses.In recent years,the insects play an active role in Northeast China,and have been intensified.In this paper,the field survey on the dynamic growth of the adults of Monolepta hieroglyphica in 12 families and 31 kinds,was carried out.By the host selection of the tests of olfactory and epohagy,the migration laws of in distinct periods were determined,which provide theoretical guidance for scientific and rational control of the insects.To begin with,In Jilin Province,the insects reproduce one generations every year,damage adult pests from mid June,display the flourishing period in mid August;but the quantities began to fall at the beginning of September,until the end of the end of September when the disadvantage disappears.The majority of adults are the leaves,flower spikes and fresh fruits of the Leguminosae,Gramineae,Cruciferae,mallow and Solanaceae,of which spot surrounding weeds of fields.In July,the pests gradually excessively increase,and transfer to field crops,of which hosts are corns and rices of the poaceae.In August,there is a the submit period,when the main attacking subjects are cottons of the malvaceae.In September,the related activities witness a decreasing trendency,and the Polygonum aviculare is encroached.Afterwards,the adults die away by degree.And then,the host selection test of Monolepta hieroglyphica by the olfactory selection method,it was found that in the 10 families and 12 kinds of subjects,the cotton of the carapace family made a strong luring and collective effect on the Monolepta hieroglyphica,of which the number of adult worms was excessive.The research,on the main host feeding behavior of the Monolepta hieroglyphica,was experimented,with the method of disk leaf and grid.It was found that there was a remarkable intake preference to host plants including cotton and ramie of the malvaceae,corn and rice of the poaceae,cabbage of the crucifer,soybean of the leguminous,and cucumber of the cucurbitaceae.Next,Monolepta hieroglyphica was inclined to cotton,soybean and cruciferous vegetables.With various crops growing up,the young hosts were chosen,and different hosts were endangered,due to constant migrations.At the beginning of the occurrence,Monolepta hieroglyphica was mainly concentrated on the following spots,including the weeds,the cotton along with soybean representing the field crops,and cabbages and eggplants standing for the vegetable crops.During the period of peak,it moved from the former hosts to the field crops,of which the amount of occurrence was generally higher.Also,it mainly remained on the vegetable crops of cruciferous cabbages and broccoli.However,it unceasingly damaged the weeds of Echinochloa crusgalli and Polygonum aviculare.Lastly,from early July to mid-July,the medical spray on major host plants,provided by beta cypermethrin,contributed to the positive effect on adults of Monolepta hieroglyphica.