Survey and Assessment of the Natural Enemies of Water Hyacinth,Eichhornia crassipes

Abstract

In northern Queensland, the addition of 2,4,5‐T butyl ester was found to be unnecessary to maintain the control of Echinochloa colona (L.) Link and Cyperus Iria L. In dry seeded rice when propanil rates were reduced below the registered rate of 4 kg a.i. ha^?1. Adequate weed control was obtained with 1.3 kg a.i. ha^?1 propanil alone. No adverse effects on rice yield were found with any of the propanil × 2,4,5‐T treatments. Low rates of propanil, 1.3 and 0.72 kg a.i. ha^?1, compared favourably with pre‐emergence treatments of thiobencarb, butachlor, oxyfluorfen and pretilachlor (plus a safener) when weed yields were low. Where water management was poor and Ischaemum rugosum Salisb. was the dominant weed, oxyfluorfen applied pre‐emergence at 0.96 kg a.i. ha^?1 produced a higher rice and a lower weed yield than the low rates of propanil. In three of the five experiments, weed growth was insufficient to depress rice yields significantly.     

溴氰菊酯对南方小花蝽捕食番茄潜叶蛾能力的影响

为探究溴氰菊酯对南方小花蝽Orius similis捕食番茄潜叶蛾 Tuta absoluta能力的影响,本研究以溴氰菊酯对南方小花蝽的致死中浓度为处理浓度,采用药膜法处理南方小花蝽成虫,然后让存活的南方小花蝽取食番茄潜叶蛾卵及1龄幼虫,分析溴氰菊酯对其捕食功能反应及捕食行为的影响。结果表明,经致死中浓度的溴氰菊酯处理后,南方小花蝽捕食番茄潜叶蛾的能力及行为均受到影响,功能反应模型仍符合Holling Ⅱ模型,但南方小花蝽处理猎物的时间延长,控害效能降低,搜寻效应下降, 成虫对卵和1龄幼虫的日最大捕食量分别下降了47.37粒/皿、9.47头/皿;而处理1粒番茄潜叶卵和1头1龄幼虫所用的时间分别延长了777.6 s和3 456.0 s,同时南方小花蝽搜寻、行走、捕食番茄潜叶蛾卵的行为时间分别缩短了444.2、750.2、919.6 s,静止和梳理时间则分别延长了1 677.6、403 s,对番茄潜叶蛾卵和1龄幼虫的捕食量分别降低了4头和1头。因此,溴氰菊酯对南方小花蝽捕食能力产生了抑制作用,在田间防控番茄潜叶蛾时应延长溴氰菊酯与南方小花蝽使用的间隔时间,更好地协调化学与生物防治。     

空间场所对斑痣悬茧蜂选择不同龄期甜菜夜蛾幼虫行为的影响

实验室条件下以甜菜夜蛾各龄期幼虫为寄主,在大观察罩内的盆栽植物上模拟低龄（1～2龄）和高龄幼虫（3～5龄）在田间的分布特点接虫,在小观察罩内同质空间内混合各龄幼虫,分别观察斑痣悬茧蜂的寄主选择行为。研究结果表明,空间大小对斑痣悬茧蜂选择寄主龄期的行为具有很大影响。在大观察罩中,斑痣悬茧蜂对甜菜夜蛾低龄幼虫（1～2龄）的遭遇和放弃行为比例均大于高龄（3～5龄）幼虫,而在小观察罩内的表现则相反。虽然斑痣悬茧蜂的寄主处理时间随寄主龄期的增大而延长,但在大观察罩内斑痣悬茧蜂花费的寄主处理时间比在小观察罩内长。在小观察罩内,寄生蜂对低龄幼虫的再次攻击间隔时间（653.17s）长于高龄幼虫（171.32s）,但在大观察罩内则相反。在大观察罩内低龄幼虫的被寄生率（23.24%～38.54%）高于小观察罩内（7.88%～21.43%）,但是小观察罩内高龄幼虫（4龄）的被寄生率（34.65%）大于大观察罩（16.86%）。最后,就空间大小影响斑痣悬茧蜂寄主选择行为的机理进行了探讨。     

营养和寄主密度对斑痣悬茧蜂搜寻行为的影响

以斜纹夜蛾Spodoptera litura幼虫为寄主,观察了不同补充营养处理（饥饿、饲喂清水、饲喂30%糖水）和寄主密度等因素对斑痣悬茧蜂Meteorus pulchricornis的搜寻效率和寄生选择行为的影响。结果显示,不同寄主密度对斑痣悬茧蜂的搜寻效率和选择偏好有显著影响,寄生蜂明显倾向于选择高密度寄主斑块。未发现补充营养显著影响斑痣悬茧蜂的搜寻时间,说明补充营养对斑痣悬茧蜂的搜寻效率没有显著影响,但对其寄生的寄主数量具有显著影响,在5头.叶-1与15头.叶-1的寄主斑块之间具有显著差异。     

Lethal and sub-lethal effects of spinosad on bumble bees (Bombus impatiens Cresson)

Recent developments of new families of pesticides and growing awareness of the importance of wild pollinators for crop pollination have stimulated interest in potential effects of novel pesticides on wild bees. Yet pesticide toxicity studies on wild bees remain rare, and few studies have included long-term monitoring of bumble bee colonies or testing of foraging ability after pesticide exposure. Larval bees feeding on exogenous pollen and exposed to pesticides during development may result in lethal or sub-lethal effects during the adult stage. We tested the effects of a naturally derived biopesticide, spinosad, on bumble bee (Bombus impatiens Cresson) colony health, including adult mortality, brood development, weights of emerging bees and foraging efficiency of adults that underwent larval development during exposure to spinosad. We monitored colonies from an early stage, over a 10-week period, and fed spinosad to colonies in pollen at four levels: control, 0.2, 0.8 and 8.0 mg kg(-1), during weeks 2 through 5 of the experiment. At concentrations that bees would likely encounter in pollen in the wild (0.2-0.8 mg kg(-1)) we detected minimal negative effects to bumble bee colonies. Brood and adult mortality was high at 8.0 mg kg(-1) spinosad, about twice the level that bees would be exposed to in a 'worst case' field scenario, resulting in colony death two to four weeks after initial pesticide exposure. At more realistic concentrations there were potentially important sub-lethal effects. Adult worker bees exposed to spinosad during larval development at 0.8 mg kg(-1) were slower foragers on artificial complex flower arrays than bees from low or no spinosad treated colonies. Inclusion of similar sub-lethal assays to detect effects of pesticides on pollinators would aid in development of environmentally responsible pest management strategies.     

Impact of alpha-cypermethrin on honey bees foraging on spring oilseed rape (Brassica napus) flowers in field conditions

BACKGROUND: Cruciferous oil-bearing crops have gained in importance worldwide. The expansion of the growing area of these crops has caused a proliferation of pests. Exposure to organophosphate, carbamate and pyrethroid insecticides has been associated with bee poisoning in food crops. This study examines the repellent effect of alpha-cypermethrin on the number of foraging honey bees, Apis mellifera L., on fields of spring oilseed rape, Brassica napus L. var. oleifera. RESULTS: The first experiment was conducted on differently sprayed 10 m(2) experimental plots where alpha-cypermethrin was applied at different times. Another experiment was conducted on a 4 ha seed production field divided into two parts: one part was treated with alpha-cypermethrin and the other was not treated with this insecticide. The results show that there was no difference in the number of honey bees between alpha-cypermethrin-treated and untreated patches. The result persisted through three observation years, regardless of varying flower and honey bee densities. CONCLUSION: No repellent effect of the insecticide on honey bees was found even 24 h after spraying. The density of oilseed rape flowers most likely played a major role in choosing the foraging area.     

α -三联噻吩对红火蚁Solenopsis invicta觅食行为和触角功能的影响

通过研究光活化杀虫活性成分 α -三联噻吩( α -T)对红火蚁 Solenopsis invicta Buren工蚁觅食行为和触角识别功能的影响,探讨了光活化成分用于控制红火蚁的可行性。用Potter喷雾法将100 μg/mL的 α -T丙酮水溶液喷施于红火蚁中型工蚁体表,再经紫外(UVA)光照射30 min,在处理后5、10、15、20和30 min时,试蚁对火腿肠的识别率分别为20.00%、25.00%、38.33%、40.00% 和41.67%,对杀虫剂饵料的识别率分别为3.33%、0、0、3.33%和0,聚集率分别为17.50%、38.33%、 32.50%、45.00%和48.33%;经100 μg/mL的 α -T涂抹试蚁触角再经紫外光照处理30 min后,触角对丙酮反应的电位值为-0.177 mV,可正常行走的工蚁比率为75.00%;以100 μg/mL的 α -T涂抹试蚁触角并经紫外光照射30 min后10 h,红火蚁的死亡率为27.50%;上述结果均与 α -T黑暗处理、对照(CK)光照处理和CK黑暗处理结果差异显著。 α -T对红火蚁工蚁食物识别和探路行走能力均具有良好的光活化抑制作用,以其防治红火蚁具有良好可行性。     

作物根活性格局及其在农田科学管理中的应用

综述了根活性格局的概念、测定方法及其在农田科学管理中的应用，并对相关研究进行了展望。根的活性格局是根的功能学指标，反映根系各个部位对其总体吸收能力的贡献大小，它与活性根的格局在本质上存在着区别，与根的形态格局常具有不一致性。在根活性格局测定方法中，^32P土壤注入法应用最为广泛，土壤水分消耗法主要限于干旱半干旱地区。根活性格局在农田科学管理甲的应用主要表现在：在土壤-植物水分运移模拟中，根活性格局对根系吸水能力的描述更为真实；通过调查作物根活性的高值区和高峰期，可确定施肥的最佳位置和时间；利用不同作物根活性时空分布特点指导物种和种植方式的选择．可实现作物在资源利用上的互补性，发挥某些作物的安全网和营养泵功能。进行作物根活性格局的不同同位素示踪研究、建立各种常见作物物种肋根活性格局数据库等工作还需进一步加强。     

Lethal and sublethal side-effect assessment supports a more benign profile of spinetoram compared with spinosad in the bumblebee Bombus terrestris

BACKGROUND: This study was undertaken to identify the potential side effects of the novel naturalyte insecticide spinetoram in comparison with spinosad on the bumblebee Bombus terrestris L. The potential lethal effects together with the ecologically relevant sublethal effects on aspects of bumblebee reproduction and foraging behaviour were evaluated. Bumblebee workers were exposed via direct contact with wet and dry residues under laboratory conditions to spinetoram at different concentrations, starting from the maximum field recommended concentration (MFRC) and then different dilutions (1/10, 1/100, 1/1000 and 1/10 000 of the MFRC), and compared with spinosad. In addition, the side effects via oral exposure in supplemented sugar water were assessed. RESULTS: Direct contact of B. terrestris workers with wet residues of spinosad and spinetoram showed spinetoram to be approximately 52 times less toxic than spinosad, while exposure to dry residues of spinetoram was about 8 times less toxic than exposure to those of spinosad. Oral treatment for 72 h (acute) indicated that spinetoram is about 4 times less toxic to B. terrestris workers compared with spinosad, while exposure for a longer period (i.e. 11 weeks) showed spinetoram to be 24 times less toxic. In addition, oral exposure to the two spinosyns resulted in detrimental sublethal effects on bumblebee reproduction. The no observed effect concentration (NOEC) for spinosad was 1/1000 of the MFRC, and 1/100 of the MFRC for spinetoram. Comparison between the chronic exposure bioassays assessing the sublethal effects on nest reproduction, with and without allowing for foraging behaviour, showed that the respective NOEC values for spinosad and spinetoram were similar over the two bioassays, indicating that there were no adverse effects by either spinosyn on the foraging of B. terrestris workers. CONCLUSION: Overall, the present results indicate that the use of spinetoram is safer for bumblebees by direct contact and oral exposure than the use of spinosad, and therefore it can be applied safely in combination with B. terrestris. Another important conclusion is that the present data provide strong evidence that neither spinosyn has a negative effect on the foraging behaviour of these beneficial insects. However, before drawing final conclusions, spinetoram and spinosad should also be evaluated in more realistic field‐related situations for the assessment of potentially deleterious effects on foraging behaviour with the use of queenright colonies of B. terrestris. Copyright © 2011 Society of Chemical Industry     

A laboratory evaluation to determine the compatibility of microbiological control agents with the pollinator Bombus terrestris

BACKGROUND: This study was undertaken to identify any potential adverse side effects of the use of seven microbiological control agents (MCAs) on the bumblebee, Bombus terrestris L., in the context of combined use in integrated pest management (IPM). AQ10^® (Ampelomyces quisqualis), Binab‐T‐vector^® (Hypocrea parapilulifera + T. atroviride; 1/1), Prestop‐Mix^® (Gliocladium catenulatum J1446), Serenade^® (Bacillus subtilis QST713), Trianum‐P^® (Trichoderma harzianum T22), Botanigard^® (Beauveria bassiana GHA) and Granupom^® (Cydia pomonella granulovirus), comprising five biofungicides and two bioinsecticides, were investigated. Bumblebee workers were exposed under laboratory conditions to each MCA at its maximum field recommended concentration (MFRC) via three different routes of exposure: dermal contact and orally via either treated sugar water or pollen. RESULTS: The tested MCAs were found to be safe for workers of B. terrestris, with the exception of Botanigard^® and Serenade^®. Exposure to Botanigard^® via contact at its MFRC caused 92% mortality after 11 weeks, while the 1/10 MFRC killed 46% of exposed workers. For Serenade^®, topical contact and oral delivery via sugar water resulted in 88 and 100% worker mortality respectively. With lower concentrations (1/2, 1/5 and 1/10 MFRC) the toxicity decreased, but the effect depended on the route of exposure. In addition to lethal effects, nests were also evaluated for sublethal effects after treatment with the seven MCAs at their respective MFRCs over 11 weeks. In these bioassays, only Botanigard^® and Serenade^® gave rise to a significant (P < 0.05) decrease in drone production. Sublethal effects on foraging behaviour were also evaluated, and only Botanigard at its MFRC delivered via treated sugar water induced negative effects. CONCLUSION: The results demonstrated that most of the MCAs tested can be considered safe for use in combination with B. terrestris, based on the International Organisation for Biological Control of Noxious Animals and Plants (IOBC) classification. However, some can be harmful, such as the biofungicide Serenade^® and the bioinsecticide Botanigard^®. Therefore, it is recommended that all should be tested before use in combination with pollinators. In this context, it is also advisable that these MCAs should be evaluated in more realistic field situations for the assessment of potentially deleterious effects on foraging behaviour. Copyright © 2009 Society of Chemical Industry     

Exploiting chemical ecology to manage hyperparasitoids in biological control of arthropod pests

Insect hyperparasitoids are fourth trophic level organisms that commonly occur in terrestrial food webs, yet they are relatively understudied. These top‐carnivores can disrupt biological pest control by suppressing the populations of their parasitoid hosts, leading to pest outbreaks, especially in confined environments such as greenhouses where augmentative biological control is used. There is no effective eco‐friendly strategy that can be used to control hyperparasitoids. Recent advances in the chemical ecology of hyperparasitoid foraging behavior have opened opportunities for manipulating these top‐carnivores in such a way that biological pest control becomes more efficient. We propose various infochemical‐based strategies to manage hyperparasitoids. We suggest that a push‐pull strategy could be a promising approach to ‘push’ hyperparasitoids away from their parasitoid hosts and ‘pull’ them into traps. Additionally, we discuss how infochemicals can be used to develop innovative tools improving biological pest control (i) to restrict accessibility of resources (e.g. sugars and alternative hosts) to primary parasitoid only or (ii) to monitor hyperparasitoid presence in the crop for early detection. We also identify important missing information in order to control hyperparasitoids and outline what research is needed to reach this goal. Testing the efficacy of synthetic infochemicals in confined environments is a crucial step towards the implementation of chemical ecology‐based approaches targeting hyperparasitoids. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Weed seed predation rate in cereals as a function of seed density and patch size,under high predation pressure by rodents

Weed seed predation is an ecosystem service, influencing weed population dynamics. The impact of weed seed predation on weed population dynamics depends on how predators respond to seed patches at the field scale. Seed predation will be most effective if the proportion of seeds predated increases with increasing size and seed density of patches. Density‐dependent rodent seed predation was measured by varying seed density and patch size in four irrigated conventionally managed cereal fields in north eastern Spain. Artificial weed seed patches were created by applying a range of Lolium multiflorum seed densities from 0 to 7500 seeds m^?2 in 225 m² patches (2008) or in patches that varied in size from 1 to 9 m² (2009). Seed predation was estimated using seed cards and seed frames. The granivorous rodents Mus spretus and Apodemus sylvaticus caused high seed predation rates (92%) in three fields, whereas in a fourth field, it was lower (47%). Rodents responded in an inversely density‐dependent manner, but this had little biological meaning as even in patches seeded with the highest density, the input to the soil seedbank was reduced by 88%. For the period of time this experiment lasted, hardly any new seeds would have entered the seedbank.     

Impact of Bacillus thuringiensis strains on survival,reproduction and foraging behaviour in bumblebees (Bombus terrestris)

BACKGROUND: Bacillus thuringiensis (Bt) and its protein crystals are used worldwide, either as a spray or when expressed in transgenic crops, for the control of pest insects. However, owing to their intensive use, there exists a debate regarding the involvement of this microbial insecticide in bee colony losses. In this study, in a tiered approach using laboratory microcolonies, an evaluation was made of the potential lethal and sublethal hazards on colony reproduction and foraging behaviour of workers of the bumblebee Bombus terrestris (L.) of two commercial Bt strains: kurstaki (Dipel^®) and aizawai (Xentari^®). Bumblebees, like honey bees, are intensively used in modern agriculture for pollination and fulfil a crucial role in the natural ecosystem. RESULTS: Exposure of bumblebees dermally or via treated pollen to either of the two Bt formulations at their field recommended rates (0.1%) caused no reduction in survival. However, when applied in the feeding sugar water, aizawai killed all workers at a concentration of 0.1%, but this lethal effect was lost at 0.01%. With respect to reproductive effects, kurstaki was harmless, while aizawai at 0.1% delivered in the feeding sugar water and pollen reduced reproduction by 100 and 31% respectively. Lower doses of 0.01% aizawai in the sugar water showed no more effect. In addition, kurstaki at 0.1% and aizawai at 0.01% in the feeding sugar water did not impair the foraging behaviour, resulting in normal nest colony performance. CONCLUSION: The results with kurstaki and aizawai demonstrated that, in general, the Bt strains are safe to B. terrestris bumblebees, although in some cases there were detrimental effects that depended on strain and route of exposure. In addition, the authors believe that to draw firm conclusions regarding the hazards of Bt to bumblebees would require more information on relevant concentrations of Bt products in the environment. Hence, routine testing for lethal and sublethal effects is recommended to ascertain combined use of Bt products and bumblebees in modern agriculture. Copyright © 2009 Society of Chemical Industry     

塔里木河下游胡杨对水分条件变化的响应

通过对塔里木河下游应急输水河畔胡杨样枝的年轮分析,结果表明:第3次应急输水后,喀尔达依断面胡杨的横向响应范围达到离河1 000 m;应急输水后不同断面、不同离河距离,地下水埋深梯度、过水时间梯度随着离河道和大西海子水库距离增加,胡杨生长量减少;输水量大的年份胡杨生长量明显大于输水量少的年份,在相同输水量和输水时间前提下,春秋季持续输水对胡杨生长恢复效果要优于夏秋季输水;在持续输水后,胡杨生长量增长幅度减小,其大小逐步趋于近似.     

环境条件变化下汾河水库沉积物中重金属形态分布特征及潜在生态风险评价

对汾河水库沉积物中重金属的污染特征和潜在生态风险评价结果表明:汾河水库沉积物中Cd含量为11.42±2.84mg/kg,高于中国湖泊底泥重金属含量背景值。沉积物中Cd的单项潜在生态风险系数远大于其它重金属,高达2346.57,具有极强的生态危害性;而Zn、Cr和Cu只显示出轻微的生态危害性,故Cd是导致汾河水库沉积物中重金属的潜在生态风险增强的主要贡献者。室内模拟沉积物经历好氧和厌氧等环境条件下,并用EDTA铵盐溶液单一提取法和BCR连续提取法分别研究了汾河水库沉积物中Cd、Zn、Cr和Cu等重金属的形态分布特征;结果表明:在好氧条件下,Cd的形态分布特征变化最为明显,具有潜在环境效应的Cd含量所占总量的比例上升至52.15%;用EDTA单一提取法测定结果表明:生物有效态Cd含量占总量的比例(B/T)在好氧处置后最高,达30.37%;上述试验结果进一步证明了沉积物中Cd具有强烈的潜在生态风险和较高的生物有效性。