Department of Plant, Soil and Entomological Sciences, University of Idaho, P.O. Box 442339, Moscow, ID 83844-2339, USA.
J Econ Entomol. 2010 Jun;103(3):691-7. doi: 10.1603/ec09388.
The pea leaf weevil, Sitona lineatus (L.) (Coleoptera: Curculionidae), has been a major pest of pea, Pisum sativum L., in eastern Washington and northern Idaho since its introduction to the region in the early 1970s. Eggs are deposited in the spring on the soil surface and first instars hatch and move to pea root nodules, where larvae feed before they pupate and adults emerge in mid- to late summer. No-tillage practices are known to reduce pea leaf weevil colonization in pea, but the effects of tillage on larval densities and subsequent adult emergence have not been examined. During 2005, 2006, and 2007, we compared densities of colonizing adult and immature pea leaf weevils on pea plots grown using conventional tillage and no-tillage. In 2005 and 2006, emergence of adult pea leaf weevil was monitored in the same plots. Densities of colonizing adult and immature pea leaf weevil were significantly higher in conventional tillage plots. Larvae in conventional tillage were further along in development than larvae in no-tillage plots during June and July. Densities of emerging adult pea leaf weevil were significantly greater from conventional tillage than no-tillage plots. Based on densities of colonizing and subsequent emerging adults, survival of weevils from egg through adult was greater in conventional tillage plots. Soils under no-tillage are cooler, resulting in later emergence of the pea crop and delayed root nodule development, possibly affecting the ability of first-instar pea leaf weevil to locate host plant roots. Our results indicate no-tillage fields are less suitable for pea leaf weevil colonization and survival than conventional tillage fields.
豌豆叶象甲， Sitona lineatus（L.）（鞘翅目：象甲科），自 20 世纪 70 年代初引入该地区以来，一直是华盛顿东部和爱达荷州北部豌豆 Pisum sativum L. 的主要害虫。春季将卵产在土壤表面，初孵幼虫孵化并移至豌豆根瘤，在那里幼虫取食，然后化蛹，成虫于夏末至初秋出现。免耕措施已知可减少豌豆叶象甲在豌豆中的定殖，但耕作对幼虫密度和随后成虫出现的影响尚未得到检验。在 2005 年、2006 年和 2007 年，我们比较了使用传统耕作和免耕种植的豌豆田中定殖的成年和未成年豌豆叶象甲的密度。在 2005 年和 2006 年，在相同的地块中监测了成年豌豆叶象甲的出现情况。传统耕作地块中成年和未成年豌豆叶象甲的定殖密度明显更高。6 月和 7 月，传统耕作中的幼虫发育程度比免耕中的幼虫更深入。从传统耕作地块中出现的成年豌豆叶象甲的密度明显大于免耕地块。根据定殖和随后出现的成虫密度，从卵到成虫的象甲存活率在传统耕作地块中更高。免耕土壤较凉爽，导致豌豆作物的出现延迟和根瘤发育延迟，这可能影响初孵幼虫寻找宿主植物根系的能力。我们的结果表明，免耕地块比传统耕作地块更不适合豌豆叶象甲的定殖和生存。
