Analysis of Occurrence Dynamics of Allothrombium ovatum and Melon Aphids in Facility Watermelon
SHE Xiaoling1，WANG Shaoli2，ZHOU Chengxian1，WU Dan1，HE Jiting1，LYU Yang1，LIU Lijuan3*
1 Beijing Yanqing District Agricultural Technology Extension Station，Beijing 102100，China；2 State Key Laboratory of Vegetable Biobreeding，Institute of Vegetables and Flowers，Chinese Academy of Agricultural Sciences，Beijing 100081，China；3 Beijing Yanqing District Agricultural Science and Technology Service Center，Beijing 102100，China
Abstract：Melon aphid（Aphis gossypii）is an important limiting factor for facility watermelon production．During field survey，we discovered in spring facility cultivation there was a certain amount larva of Allothrombium ovatum ．Whether these larvae could inhibit the population of melon aphid? It was currently unclear．This study conducted monitoring on larva of Allothrombium ovatum and contemporaneous population of melon aphid ，in 2 watermelon plastic-covered tunnels without chemical application at Yanqing district of Beijing；and also analyzed their occurrence dynamics．The results showed that in Yanqing plastic-covered tunnel and watermelon fields the main occurrence stage for Allothrombium ovatum was from May 19th to June 15th．These mites were either free crawling or parasitic on the body of melon aphids．In 2 watermelon plasticcovered tunnels the naturally occurring mite strain rates could reach as high as 26.67% and 33.33%．The number of mites per hundred stains could reach 83.33 heads and 100 heads．Meanwhile，the highest rate of aphid was 26.67% in the same period. Subsequently，the melon aphid populations declined．The exponential population growth trend under suitable environment was not yet presented，indicating that in spring facility watermelon plastic-covered tunnel Allothrombium ovatum could suppress the population of melon aphid in suitable climate years．Attention should be paid to the protection and utilization in production．
