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Studies On The Population Dynamics Of Aphis Glycines And Controlling Effect Of Its Dominant Natural Enemies In Northern China

Posted on:2006-12-11Degree:MasterType:Thesis
Country:ChinaCandidate:J MiaoFull Text:PDF
GTID:2133360155452203Subject:Agricultural Entomology and Pest Control
Abstract/Summary:PDF Full Text Request
The soybean aphid is one of the most important insect of soybean, Glycine max (L.) Merrill, it is a small, light- yellow or yellowish-green aphid with two distinct black cornicles. A combination of body color, black cornicles and its colonization on soybean (and buckthorn) distinguishes it from other aphid species. A field survey of soybean aphid, Aphis glycines Matsumura, and its natural enemies was conducted during summer 2003 and 2004 in Langfang, hebei province (116.4°E; 39.3°N). Aphids colonized soybean when plants were still small in early July. After a lag of 2 wk, aphid density increased rapidly in mid-July, reaching a peak of 401.3 ± 79 aphids per ten soybean plants on 17 July 2003 and 375.15±30 aphids per ten soybean plants on 28 July 2004. The population declined to a plateau immediately after this peak, although the density increased again starting in late July 2003 and mid-August 2004, the aphid seemed to be limited by natural enemies after the first peak.The main species of natural enemy were the aphid parasitoid Lysiphlebus sp, Syrphophagus aphidivorus, Trioxys glycines, and Aphelinus sp while major predators included in Propylaea japonica, Orius similes, Chrysopa septempunctata, Chrysopa sinica, Deraeocoris punctulatus, Metasyrphus corollae, Epistrophe balteata, and Erigonidium graminicola.In a field exclosure experiment, A. glycines density in small-mesh cages peaked 2-fold higher than in large-mesh cages and 4-fold higher than on uncaged plants in 2003, and A. glycines density in small-mesh cages peaked 2.4-fold higher than in mid-mesh cages, 8-fold higher than in large-mesh cage and 75-fold higher than on uncaged plants in 2004, indicating that natural enemies did indeed limit aphid density.The study evaluated the functional response of the predator P. japonica on soybean aphids, both species associated with Glycine max (L.) Merrill. The experiment was carried out in laboratory conditions: (25 ± 1) ℃; (80 ± 5) %, RH; 14 h, photoperiod. Great different were found to exist between the larvae at different...
Keywords/Search Tags:A. glycines, natural enemies, population dynamics, P. japonica Thunberg, functional response, density interference effect
PDF Full Text Request
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