The Experiment Population Of Two Species Ladybirds And Toxoptera Aurantii Boyer

This paper dealt with the major pest Toxoptera aurantii Boyer and its natural enemies Coccinella septempunctata Linnaeus and Menochilus sexmaculata Fabricius in organic tea garden of Zherong in Fujian, China. The morphological differences of each stage between the two ladybirds and their predation responds on Toxoptera aurantii were studied. The preferences of two ladybirds to the four aphids on organic tea garden and its surrounding envirement, the hatchability of two ladybirds'eggs at the low temperature and the impact of the four commonly used biological pesticides to the two ladybirds were also studied. The results were as follows:(1) egg: Their eggs had similar size, showing spindle-shaped, light yellow, surface smooth. The surface showed clear signs of black stripe before the hatch of eggs; larva: The first instar larvae of the two ladybirds were not significantly different. The number and color of surface stains of the 2nd to 4th instar larvae had significant differences; pupa: The number of surface stains of the two kinds of pupae had significant differences; adult: The body of early adult emergence was soft, yellow and their coleoptera stains had markedly different.(2) The predation function response of larvae and adults female of C. septempunctata and M. sexmaculata to T. aurantii belonged to HollingII. The functional coefficient and the most predatory amount of the 1st to 4th instar larvae and adults female of C. septempunctata were 1.1361,1.1666,1.2923,1.2908,1.3368, respectively and 24.8,83.3,212.8,434.8,384.6, respectively. The functional coefficient and the most predatory amount of the 1st to 4th instar lavae and adults female of M. sexmaculata were 1.3644,1.0448,1.4416,1.4081,1.4083, respectively and 28.7,32.2,158.7,434.8,357.1, respectively; As the prey density increased, the searching efficiency of the 1st to 4th instar lavae and adults female of C. septempunctata and M. sexmaculata were to reduce.(3) Under the coexistence of four kinds of aphids with the same total aphid number of each test, both the 4th instar larva and adult female of C. septempunctata were preferred to T. aurantii and Aphis gossypii Glover. The 4th instar larva of C. septempunctata had a negative conversion behavior to T. aurantii and Aphis Gossypii. The adult female of C. septempunctata only had negative conversion behavior to A. Gossypii; Under the same conditions the 4th instar larva of M. sexmaculata were preferred to T. aurantii , A. Gossypii and Aphis glycines. But the adult female of M. sexmaculata were preferred to T. aurantii and A. gossypii with negative conversion behavior.(4) The relationship between predation efficiency and individual interference of C. septempunctata and M. sexmaculata was fitted with Hassell model. The interference coefficient of the 1st to 4th lavae and adult female of C. septempunctata were -0.2940,-0.4940,-0.6481,-0.7056,-0.7025, respectively; The interference coefficient of the 1st to 4th lavae and adult female of M. sexmaculata were -0.2919,-0.4034,-0.6535,-0.6773,-0.7092,-0.7025, respectively.(5) The best low temperature storages of the eggs of both C. septempunctata and M. sexmaculata were 4d with 10℃.(6) In the conventional pesticide concentration range, 1.8% pyrethrins matrine had the stronger lethality with the highest calibration mortality, 0.2% angled bittersweet was followed, and the influence of 0.6% oxymatrine prosular was weakest to the two ladybirds.