The occurrence of leafminers and their parasitoids on vegetables and weeds in Hangzhou area, Southeast China

Leafminers are the mostimportant insect pests of vegetables inHangzhou area, Zhejiang province, SoutheastChina as well as in the rest of China, but havenever been investigated for speciescomposition, relative abundance and theirassociated parasitoids. A survey was conductedin four localities of Hangzhou area during 1998–2000to determine the distribution ofleafminers and their parasitoids on vegetablecrops and weeds in the field. Over 20,000leafminers were collected and reared. Theleafminer species found were Liriomyzasativae, L. chinensis and Chromatomyia horticola, with C.horticola and L. sativae the mostabundant in spring and autumn, respectively.About 11,000 parasitoid adults were reared fromthe leafminers collected. In total 14hymenopteran species of four families (onebraconid, 10 eulophids, one megaspilid and onepteromalid) were found. Eleven species werereared from C. horticola, nine from L. sativae and seven from L. chinensis.Opius caricivorae and Chrysocharispentheus were the dominant species. Sevenspecies were recorded from L. chinensisfor the first time. Eleven parasitoid specieswere reared from leafminers on two weeds (Veronica undulata and Sonchusoleraceus). Parasitoids caused 48.5–68.8%parasitism on leafminers on crops and 83.7%parasitism on leafminers on weeds in the latergrowing season of vegetable crops. The resultssuggest that leafminer populations areregulated to a certain extent by their naturalenemies in the field.