玉米象蛀蚀对稻谷品质的影响

以5种籼稻为试验对象,在温度25℃±1℃、相对湿度50%~60%条件下,研究不同虫口密度和侵染时间下玉米象蛀蚀对稻谷品质的影响。结果表明:稻谷在受到玉米象侵染后,其品质的变化是由虫口密度和侵染时间共同作用造成的;所有品种的电导率、脂肪酸值和丙二醛含量与侵染时间呈极显著正相关;所有品种整精米率和米饭综合评分与侵染时间呈极显著负相关;所有品种千粒重与虫口密度呈显著或极显著负相关;采用主成分分析法对玉米象侵染后的5种籼稻品质进行评价,综合得分从高到低依次为虾稻1号、粤农丝苗、荃优鄂丰丝苗、隆两优534、黄华占。

沼气储粮对玉米象害虫控制效果的研究

[目的]探究沼气储粮对储粮害虫玉米象的控制效果。[方法]利用沼气进行粮食储存,研究了在甲烷浓度分别为70%、50%、30%的储存条件下种子中玉米象的出虫率和死亡率,研究了水分含量对种子出虫的影响,并考察了沼气储存对玉米种子发芽的影响。[结果]粮种的出虫率随甲烷浓度的降低而增加,最大差值为5.91%;而储粮害虫的死亡率随甲烷浓度的降低而降低,最大差值达71.81%,即沼气储粮的效果是很明显的,但杀虫效果在一定程度上受到种子水分等因素的影响;在储粮过程中,沼气并不影响种子发芽,更不会改变种子成分而使其发生变质,甚至还有保鲜作用。[结论]为仓储害虫的有效控制提供了理论依据。

玉米象对破损玉米粒趋性的研究

在黑暗条件下的养虫笼内放入盛有完整玉米粒、破损玉米粒、完整与破损混合的玉米粒以及空白的培养皿,然后接入100头玉米象(Sitophilus zeamais Motschulsky)成虫观察其趋性,重复3次。试验结果表明,与完整玉米粒相比,玉米象对破损玉米粒的趋性更强。取食完整玉米粒的玉米象仅有3.89±0.40头,取食完整与破损混合的玉米粒有29.22±1.44头,取食破损玉米粒的则有47.22±1.74头。取食完整玉米粒的玉米象与取食破损玉米粒的玉米象在数量上存在显著差异,性别上无显著差异。生产中可以使用在诱捕器内放入破损玉米粒的办法减少玉米象对入仓玉米的为害。

Evaluation of spatial and temporal patterns of insect damage and aflatoxin level in the pre-harvest corn fields to improve management tactics

Spatial and temporal patterns of insect damage in relation to aflatoxin contamination in a corn field with plants of uniform genetic background are not well understood. After previous examination of spatial patterns of insect damage and aflatoxin in pre-harvest corn fields, we further examined both spatial and temporal patterns of cob- and kernel- feeding insect damage, and aflatoxin level with two samplings at pre-harvest in 2008 and 2009. The feeding damage by each of the ear/kernel-feeding insects （i.e., corn earworm/fall armyworm damage on the silk/cob, and discoloration of corn kernels by stink bugs） and maize weevil population were assessed at each grid point with five ears. Sampling data showed a field edge effect in both insect damage and aflatoxin contamination in both years. Maize weevils tended toward an aggregated distribution more frequently than either corn earworm or stink bug damage in both years. The frequency of detecting aggregated distribution for aflatoxin level was less than any of the insect damage assessments. Stink bug damage and maize weevil number were more closely associated with aflatoxin level than was corn earworm damage. In addition, the indices of spatial-temporal association （χ） demonstrated that the number of maize weevils was associated between the first （4 weeks pre-harvest） and second （1 week pre-harvest） samplings in both years on all fields. In contrast, corn earworm damage between the first and second samplings from the field on the Belflower Farm, and aflatoxin level and corn earworm damage from the field on the Lang Farm were dissociated in 2009.