Studies On Population Dynamics Of Main Pests And Their Non-Contaminated Control Technique On Leaf Vegetable In Nanning

In this article, it was reported the population dynamics and damage condition of the main pests on leaf vegetable in Nanning suburb, the community and population dynamics of the pests on Edible amaranth, the efficiency of several kinds of vegetables intercropping each other and several kinds of non-contaminated pesticides to control the main pests on leaf vegetable. The main results were listed as follows.1. There were 40 species of pests and 5 species of detrimental animals on vegetable inNanning suburb. There were 7 serious pests found around the year, including Diamond backmoth (Plutella xylostella) of Plutellidae, Beet armyworm (Laphygma exigua) and Tobaccocutworm (Prodenia litura) of Noctuidae, Cabbage butterfly (Pieridae), Striped flea beetle(Phyllotreta striolata ) of Chrysomelidae; Green peach aphid (Myzus persicae) and Mustardaphid (Lipaphis erysimi) of Aphididae. The systemic research was conducted on the leafmustard showed that P. xylostella and P. striolata could occur and cause damage in allyear, but L. exigua occurred from April to December, the injured level were P. striolata > P.xylostella > L. exigua. Their population fluctuations were all the pattern of double peaks. Thepopulation peak of P. xylostella occurred from January to March and from May to June, themost population density was found in May. The population peak of P. striolata occurredfrom April to May and September to January next year, the more population density wasfound in May and in November, and the population density of L. exigua was in June, Julyand October. The species and population of pests on Swamp cabbage are less than which inmustard family vegetable, but P. litura, L. exigua and Taiwania circumdata (Herbst) could causeserious damage. The population peaks of P. litura and L. exigua occurred all in June andJuly, and the more population density of T. circumdata was in August and September. Lettuce,Spinach and Anise were hardly damaged, expect by L. exigua in November once in a while.The residue of pesticide on Leaf mustard and Swamp cabbage in Anji vegetable base inNanning was detected by rapid test every month in 2004, the rate of pesticide residuepreponderating over the state standard was over 50% in leaf mustard, but there was only one time that the pesticide residue exceeding the state standard in Swamp cabbage. There was one new pest which its specific name await for being identified could cause seriously damage onChinese cabbage crops. It needs look for effective control measures.2. There were 8 families 11 species pests and two species of them were new pests on Edible amaranth (Amaranthus mangostanus) in Nanning. One of them was Beet flea beetle (Chaetocnema (Tlanoma) discreta) another was one species of Pyralidae (its specific name await for being identified). The research results showed that the diversity indices and the evenness index of the community structure of pests on Edible amaranth were high, the centrality probability index was low. C. discreta was the dominant species in Edible amaranth pests, but its dominant degree was not prominence, the dominant species of the community varied from different season. From May to July, the dominant species were Taiwania obticsata (Boheman) and snails, from July to October it was C. discreta, and from October to December it was American leaf miner (Liriomyza sativae Blanch). The species of main pests and the population of the dominant species varied from different season as well. Several peaks were found in July, September and December, respectively. There were 4~5 species of main pests and the population was more most abundance from August to December. The pests on Edible amaranth now, with the planting area widened, need controlling, but not before.3. The following results of intercropping with different vegetables each other were obtained from field experiments. (1) Fennel intercropping with mustard family vegetables could prominently reduce the population of P. xylostella, Fennel intercropping with Leaf mustard and Chinese cabbage, the density of P. xylostella decline...