我国作物病虫害生物防治研究与应用最新进展

本文总结了近5年来我国在作物病虫害生物防治研究和应用方面的最新进展, 包括作物害虫、病害(真菌、细菌和病毒病)和线虫的生物防治、植物免疫和昆虫性信息素的研究和应用, 以及新方法和新技术在作物病虫控制中的应用。同时, 与国外的研究进展进行了比较, 指出了存在的主要问题、发展趋势与对策建议。     

不同防治措施对花椰菜地节肢动物群落结构的影响

【目的】明确不同防治措施对花椰菜地节肢动物群落特征的影响,为花椰菜地害虫防治和天敌保护利用提供理论依据。【方法】设置不施药对照区、生物农药防治区和化学农药防治区,按5点随机取样,记录植株和地面所有节肢动物的数量。在田间定点埋放盛有洗衣粉水溶液的玻璃瓶调查在地表活动的节肢动物种类及数量,根据调查结果分析不同防治措施下花椰菜地节肢动物群落特征的差异。【结果】在广州花椰菜地共调查到节肢动物87种,其中植食性害虫29种,捕食性天敌54种,中性昆虫4种。防治措施明显影响节肢动物群落的物种数及其数量。不施药对照区的捕食性天敌、植食性害虫和中性昆虫的数量均高于其他两种施药防治处理区,不同处理区节肢动物群落物种数及其个体数为不施药对照区生物农药防治区化学农药防治区。花椰菜地植食性昆虫功能类群的优势集中性以花椰菜苗期为最小,成熟期最大;捕食性天敌的优势集中性在不同防治区同样以苗期相对较小,而在不施药防治对照区花椰菜各生育期,其大小接近一致;在施药防治区,捕食性天敌的优势集中性表现出波动现象。在花椰菜不同生育期以及不同防治措施区节肢动物群落的优势种不同。整个生育期优势度指数0.1的有烟粉虱、桃蚜、小菜蛾、菜青虫、前凹狼蛛、拟环纹豹蛛和八斑鞘腹蛛。花椰菜地节肢动物群落多样性指数(H′)在不同防治区和花椰菜各生育期之间均呈现不同程度的差异,各指数之间的变化趋势相似。群落整体多样性指数随花椰菜生长而增大,至中后期达到最大,此结果与田间群落的发展动态相吻合,在不同防治区之间的多样性指数为不施药对照区生物农药防治区化学农药防治区。均匀度指数在不同生育期和防治处理区的变化程度相似。害虫亚群落多样性与群落整体多样性变化趋势相似,其多样性指数在花椰菜生长中后期达到最大。不同防治措施区之间的多样性指数为不施药对照区生物农药防治区化学农药防治区,其中以化学农药防治区花椰菜苗期为最小。均匀度在花椰菜苗期为最大,而后随花椰菜生长而减小。捕食性天敌亚群落多样性在花椰菜各个生育期和防治处理之间变化相对平稳。地表节肢动物的调查表明,两种药剂处理区所施药剂对地表节肢动物的杀伤较大。同时,从地表节肢动物数量和捕食性天敌的数量动态来看,地表中性昆虫对捕食性天敌前期的定殖有一定的作用。蜘蛛与植食性昆虫、中性昆虫以及捕食性昆虫具有极显著的相关性,捕食性昆虫与中性昆虫之间也具极显著的相关性,表明这些功能团之间在数量上具有较好的跟随效应。捕食性昆虫与植食性昆虫之间相关未能达到显著水平。【结论】药剂防治措施虽然能有效降低害虫的种群数量,但也使天敌数量相应减少。地表中性昆虫对捕食性天敌前期的定殖有一定的作用,药剂防治能影响花椰菜地节肢动物群落特征,生物农药对花椰菜地节肢动物群落影响小于化学农药。     

Evaluation of a new strategy to modulate skeletal development in Thoroughbred performance horses by imposing track-based exercise during growth

REASON FOR PERFORMING STUDY: No data exist on the intensity of exercise required or on possible harmful effects of increasing exercise in foals over the natural level when free at pasture. OBJECTIVES: To investigate whether an increase in workload over free pasture exercise in the period from directly after birth to the start of training is tolerated by Thoroughbred (TB) foals without increasing injury rate or producing other undesired side effects. METHODS: Thirty-three TB foals were allocated to one of 2 exercise groups directly after birth. One group (PASTEX) was raised on pasture and the other (CONDEX) kept under identical circumstances, but was additionally subjected to an exercise protocol of gradually increasing intensity. Foals were monitored periodically and scored for the presence of clinical signs related to the musculoskeletal system (joint effusion, pain at flexion, occurrence of physeal swelling), and radiographs taken at the end of the conditioning phase. Also, behavioural studies were performed to detect any changes in behaviour related to the exercise programme. Cortisol levels were measured in both groups, to assess the level of stress. RESULTS: Workload in the CONDEX group was significantly higher than in the PASTEX group (approximately 30%). Conditioning increased the likelihood for joint effusion in the antebrachiocarpal joint, but reduced tarsocrural effusion and physeal swelling at the lateral distal radius, the third metacarpal bone (medial aspect) and lateral and medial aspects of the third metatarsal bone. CONCLUSIONS: The 30% increase in workload did not affect the animals' welfare, effects of conditioning exercise on clinical musculoskeletal health were few and there were no adverse effects. POTENTIAL RELEVANCE: This study supports the feasibility of imposing early conditioning exercise in horses and is a benchmark for its effects on the development of equine musculoskeletal tissues.     

Ability of heifers to discriminate between familiar herdmates and members of an unfamiliar group: preference test and operant conditioning test

Using a preference test and operant conditioning in a Y-maze, this experiment examined the ability of heifers to discriminate between their own familiar herdmates and member(s) of an unfamiliar group. Sixteen Danish Friesian heifers, eight older animals (360.6 ± 24.2 days of age) and eight younger ones (190.1 ± 14.1 days of age) were used. Each age group was further divided into two experimental groups. Members of each of these groups were housed together in small pens before the experiments began. In experiment 1, each of the 16 animals was allowed to approach either a familiar or an unfamiliar individual in the Y-maze. The test was repeated 12 times, with a different unfamiliar subject for each test. In experiment 2, eight heifers were individually tested in a conditioning experiment to examine whether they could learn to discriminate between a group of their three herdmates and a group of three unfamiliar heifers. Test animals were rewarded when they chose their own group. In experiment 1, heifers did not show a preference between familiar and unfamiliar individuals. Interestingly the younger stimulus heifers but not the test animals showed an ability to discriminate between unfamiliar animals by vocalizing. In experiment 2, four of the eight test animals achieved the criterion for successful discrimination between the familiar and unfamiliar group ( P  < 0.003: binomial law). There was no age group difference in the ability to discriminate between familiar and unfamiliar animals. In conclusion, heifers did not show a preference toward familiar or unfamiliar individuals; but after conditioning, some heifers could learn to discriminate between familiar and unfamiliar groups.     

Effects of 2 training methods on stress-related behaviors of the dog (Canis familiaris) and on the dog–owner relationship

Instrumental learning plays an important role in dog–human interactions. The recent demand for pet dog training has resulted in the development of various training methods. The present exploratory study aims to compare the effects of 2 training methods on both the behavioral welfare of the dog and the dog–owner relationship: the first method is based on positive reinforcement (appearance of an appetitive stimulus), whereas the second method is based on negative reinforcement (disappearance of an aversive stimulus). The study compared behaviors linked to signs of stress and attentive behaviors toward the owner in 2 dog training schools, which used different methods. Walking on-leash activity and obeying the “sit” command were studied. The results show that dogs from the school using a negative reinforcement–based method demonstrated lowered body postures and signals of stress, whereas dogs from the school using a positive reinforcement–based method showed increased attentiveness toward their owner. However, neither method affected avoidance behaviors. This exploratory study reveals the differential effects of the 2 training methods on dogs' behaviors; it suggests that training methods based on positive reinforcement are less stressful and potentially better for their welfare.     

Evaluation of a new strategy to modulate skeletal development in racehorses by imposing track-based exercise during growth: the effects on 2- and 3-year-old racing careers

REASON FOR PERFORMING STUDY: No data exist on the effects of conditioning exercise at foal age on workload and subsequent clinical injury rate during their 2- and 3-year-old racing careers. OBJECTIVES: To investigate the effects of subjecting TB foals to conditioning exercise prior to the start of race training on: the workload required to reach a level of fitness sufficient to compete; and the prevalence of orthopaedic injury during the first 2 seasons of their racing careers. METHODS: Twenty 18-month-old TBs, 12 subjected to conditioning exercise at foal age (CONDEX) and 8 exercised spontaneously at pasture only (PASTEX) were trained and entered in competitive events. Workload was quantified using the cumulative workload index (the product of average velocity and distance at a specific gait) and the animals were monitored clinically and radiographically for signs of musculoskeletal disorders. RESULTS: Workload to reach the desired fitness level was similar for CONDEX and PASTEX. CONDEX performed more prerace training sessions as 2-year-olds (P<0.05). The incidence of orthopaedic injuries was low in both groups and there were no differences in the occurrence of orthopaedic ailments. PASTEX animals tended to show signs of musculoskeletal disorders earlier than CONDEX animals. This time difference was significant for metacarpophalangeal joint pain on flexion, reduced carpal flexion and hindlimb lameness (P<0.05). CONCLUSIONS: Subjecting TB foals to conditioning exercise early in life does not have adverse effects on racing careers at ages 2 and 3 years, and does not influence the workload needed to reach a fitness level that is sufficient for racing. POTENTIAL RELEVANCE: The lack of negative effects and the indications of some positive effects of early conditioning exercise in the Thoroughbred encourage further large-scale comparative studies.     

A note on the diet and feeding selectivity of juvenile riverbream,Acanthopagrus berda (Forskal, 1775), in a subtropical mangrove creek

The diet and food selectivity of juvenile (< 100 mm S.L.) Acanthopagrus berda were investigated in Beachwood creek, north of Durban. Fish and benthic samples were taken from November 1986 to September 1987. The diet of juvenile A. berda was varied but crustaceans, mainly amphipods, were the dominant prey item. Ivlev's (1961) electivity index revealed a positive selection for amphipods, tanaids and fish scales.     

饲料粉碎粒度和调质温度对肉鸡养分消化率及生长性能的影响

饲料制粒可以提高采食量和缩短采食时间,以提高肉鸡生长性能和饲料转化率.而原料的粉碎和调质是制粒过程中非常重要的环节,不仅直接影响到饲料的营养价值和肉鸡的消化吸收,还会影响加工成本和产品质量.粉碎粒度过大会导致混合不均匀、颗粒品质欠佳等不利影响,并且对动物的采食及采食后的物理性消化产生影响,粒度过小则会对动物健康产生不利影响.调质过程主要是使饲料受到水热作用,使其蛋白质变性、淀粉糊化等,调质温度是调质环节的关键参数,温度的高低对蛋白质变性及淀粉糊化程度有直接影响,从而间接影响到动物的生长性能和养分消化利用率.同时,调质温度过高会导致饲料中添加的酶制剂及维生素等严重失活,反而会降低饲料的营养价值.本文综述了肉鸡饲料粉碎粒度和调质温度的研究进展,阐述了粉碎粒度、调质温度与肉鸡生长性能和养分消化率的重要关系.