Diversity,distribution and role of wild crucifers in major cabbage and kale growing areas of Kenya
Species diversity,distribution and role of wild crucifers on DBM and its parasitoids were explored in repeated surveys in four major crucifer-growing areas of Kenya. Thirty fields were selected at each site and presence of wild crucifers within fields and in the surrounding area were recorded quarterly for one year.Presence of DBM larvae and pupae was evaluated and all specimens taken to the lab for parasitoid emergence.Eleven species of wild crucifem in nine genera were collected.Vegetation richness,diversity and evenness varied with season and location.Cabbage growing areas had significantly higher species richness(＞5.25)than kale growing areas(0.75).DBM was recorded from five species；Raphanus raphanistrum was the most preferred(1.22 and 0.99 DBM/plant in Naro Moru and Kinangop,respectively). The parasitoid fauna comprised of six species. Temporal and spatial niche separation was observed with Apanteles sp.and Brachymeria sp.collected only from Erucastrum arabicum in Athi River.Diadegma semiclausum was the most prevalent parasitoid （25.7％and 22.4％parasitism on R.raphanistrum in Kinangop and Naro Moru,respectively),followed by Diadegma moUipla(16.9％in Athi River). The Shannon Diversity Index of parasitoid species(0.87)and species evenness(1.05)was highest on E.Arabicum in the mid-altitude semi-arid areas of Athi River.Species richness was also higher in kale growing areas.We conclude that wild cmcifers in the field act as alternative hosts for diamondback moth. They provide refuge to the pest and its parasitoids in the absence of cultivated crops and help in recolonization of cultivated crops by parasitoids. They also act as potential refuge to the parasitoids and aid in recolonisation of the crop after local extinction due to pesticide application.
Ruth Kahuthia-Gathu Bernhard L(o)hr Hans-Michael Poehling Paul K.Mbugua
International Center of Insect Physiology and Ecology,P.O.Box 30772,Nairobi University of Hannover,P International Center of Insect Physiology and Ecology,P.O.Box 30772,Nairobi University of Hannover,P.O.Box 30419,Hannover,Germany Kenyatta University,Dept.Biological Sciences,P.O.Box 48344,Nairobi
国际会议
北京
英文
148-160
2006-10-24（万方平台首次上网日期，不代表论文的发表时间）