Relative toxicity of insecticides to the crucifer pests Plutella xylostella and Myzus persicae and their natural enemies

The widespread and intensive use of conventional pesticides, particularly insecticides, presents a major risk to natural enemies of target pests, as well as to the environment in general. The aim of this study was to investigate the differential intrinsic toxicity of insecticides to two key pests of crucifers, Plutella xylostella and Myzus persicae and their respective hymenopteran parasitoids, Cotesia vestalis and Aphidius colemani. Such knowledge can help inform effective integration of insecticides and biological control in IPM systems. Three insecticides generally regarded as being compatible with natural enemies (abamectin, spinosad and indoxacarb) and one compound regarded as harmful to natural enemies (lambda-cyhalothrin) were examined. A comparative measure of the intrinsic toxicity of fresh deposits of insecticides on Chinese cabbage leaf discs was determined for both pest and parasitoids species after exposure to insecticide for 24 h and 120 h, and after 24 h exposure to insecticide plus 96 h on untreated leaf discs. Differences in the susceptibility of pests and parasitoids to different insecticides were marked for P. xylostella and C. vestalis, LC₅₀ values being significantly lower for the pest species. Such differences were not observed for M. persicae and A. colemani. There was a direct relationship between dose, exposure time and toxicity for all insecticides tested. All insecticides tested showed lower toxicity to both parasitoids compared with P. xylostella, which suggests that for this pest species side-effects on parasitoids can be minimised through IPM practices that reduce exposure time to such non-target organisms.     

The role of parasitic Hymenoptera in integrated pest management in fruit orchards

Parasitic Hymenoptera are some of the most abundant natural enemies of all fruit pests. Their role is rather variable in relation to the type of agroecosystem. Several approaches (introduction of exotic species, inoculative and inundative releases, measures for conservation of the existing species, etc.) can be implemented to increase the role of the parasitoids in controlling pest species. Classical biological, when applicable, as against several citrus pests, is still the most ecologically and economically sound method. The role parasitoids play in the regulation of pest populations remains uncertain, but much evidence for its importance as a regulatory factor comes from biological control programs.     

Effect of Different Wheat-Based Diets and Corn Meal Addition on Development Parameters of Ephestia kuehniella (Zeller, 1879) (Lepidoptera: Pyralidae)

The expansion of Integrated Pest Management (IPM), including biological control, has had several positive consequences for the agricultural environment and participants in the production chain. To enable successful operation and applications of biological control, production of insects used for rearing natural enemies (parasitoids and predators) must be optimized to reduce time and costs and improve production both qualitatively and quantitatively. The present study evaluated the effect of wheat varieties, the main component of artificial diets for Ephestia kuehniella, on the reproductive performance and biological parameters of this flour moth, which is used for mass production of Trichogramma spp. (Hymenoptera: Trichogrammatidae) and other parasitoids and predators. Four varieties of wheat were compared: BRS 327, BRS Marcante, BRS Parrudo, and KBR, with and without the addition of corn E. kuehniella reared on 97% BRS 327 wheat flour + 3% nutritional yeast had the best biological parameters and substitution of corn for about half of the wheat increased the number of eggs per female.     

Factors determining adoption of integrated pest management by vegetable growers in Nakhon Ratchasima Province,Thailand

Widespread use of highly toxic pesticides primarily for agricultural purpose has generated increasing concerns about the negative impact of pesticides on human health and the environment. Integrated pest management (IPM) usually seeks to minimize the use of pesticides and can be utilized to solve pest problems while minimizing risks to people and the environment. A total of 220 vegetable farmers in Nakhon Ratchasima Province of Thailand was interviewed with the objective of investigating the factors determining their adoption or non-adoption of IPM practices. The findings demonstrated that farmers had different uncompromising reasons for determining the use of IPM for their insect pest management. Higher costs of insecticides (91%), adverse effects of insecticides on human health and the environment (80%), and a greater risk of insect pests developing resistance to insecticides (28%) were the primary reasons for the adoption of IPM by vegetable growers in the study area. The reasons for the rejection of IPM practice were unsuitability of IPM for a large farm (52%), implementation difficulties (80%) and a greater belief in synthetic insecticides and their efficacy for target pest control (39%). A comparison between the IPM and the non-IPM farmers showed a significant difference (P < 0.01) in farmers' knowledge of pest management, which influenced IPM adoption or non-adoption. The IPM farmers had greater knowledge about identifying natural enemies and their beneficial role in controlling insect pests, about plant extracts and their efficacy in controlling insect pests and about sticky traps and their efficacy in monitoring natural enemies and controlling insect pests. For example, 24% of IPM farmers had knowledge of natural enemies whereas it was only 4% for the non-IPM farmers. A logistic regression model was fitted which showed that lower cost of pest management, better knowledge on IPM after training and availability of extension services were the factors which influenced farmers' adoption of IPM practice. The non-IPM farmers rejected adoption of IPM due to the common belief that natural enemies would not be effective in controlling insect pests and yields of vegetables would not be increased by practicing IPM.     

云南河口芒果主要病虫害发生规律调查及害虫天敌种类研究

通过对湿热地区云南河口县芒果园内的5种主要病虫害发生规律进行调查,根据调查情况对芒果白粉病、炭疽病,芒果横线尾夜蛾、芒果切叶象甲、桔小实蝇等5种发生程度较重的病虫害进行发生危害情况的相关分析,同时对云南河口地区芒果害虫天敌进行搜集、调查及鉴定,调查鉴定结果表明：共有天敌昆虫24种,其中寄生性天敌11种,分属于2目5科;捕食性天敌昆虫21种,分属于5目8科。调查结果对于生产上科学制定芒果病虫害防治措施具有重要的意义。     

Current control methods for diamondback moth and other brassica insect pests and the prospects for improved management with lepidopteran-resistant Bt vegetable brassicas in Asia and Africa

The diamondback moth (DBM), Plutella xylostella (L.), remains a major pest of brassica crops worldwide. DBM has been estimated globally to cost US$ 1 billion in direct losses and control costs. Chemical control of this pest remains difficult due to the rapid development of resistance to insecticides and to their effect on natural enemies. These problems are especially severe in South Asia and Africa where lack of knowledge, limited access to newer and safer insecticides, and a favourable climate result in DBM remaining a serious year-round pest which substantially increases the cost and uncertainty of crop production. Despite these problems, application of synthetic insecticides remains overwhelmingly the most common control strategy. Biologically-based efforts to control DBM in Africa and Asia have focused strongly on parasitoid introductions. However, despite the identification and deployment of promising parasitoids in many regions, these efforts have had limited impact, often because farmers continue early-season spraying of broad-spectrum insecticides that are lethal to parasitoids and thus exacerbate DBM outbreaks. A significant driver for this pattern of insecticide use is the presence of aphids and other pests whose appearance initiates inappropriate spraying. Despite often extensive training of producers in farmer field schools, many growers seem loath to discard calendar or prophylactic spraying of insecticides. The introduction of an IPM technology that could replace the use of broad-spectrum insecticides for DBM and other key Lepidoptera is crucial if the benefits of parasitoid introduction are to be fully realised. The deployment of DBM-resistant brassicas expressing proteins from Bacillus thuringiensis could help to break this cycle of insecticide misuse and crop loss, but their deployment should be part of an integrated pest management (IPM) package, which recognises the constraints of farmers while addressing the requirement to control other Lepidoptera, aphids and other secondary pests.     

海南草地贪夜蛾寄生蜂调查与基础生物学观察

海南省是我国草地贪夜蛾入侵地之一,为了掌握草地贪夜蛾在海南的发生与防控情况,2019年4—7月,中国热带农业科学院环境与植物保护研究所专家对海南省18个市县主要玉米种植区的草地贪夜蛾天敌开展了实地调查。本研究将调查区采集到的被寄生卵块、幼虫和蛹置于实验室条件下饲养观察,共发现5种寄生蜂天敌,其中卵寄生蜂为夜蛾黑卵蜂和螟黄赤眼蜂,幼虫寄生蜂为淡足侧沟茧蜂,蛹寄生蜂为霍氏啮小蜂,卵-幼虫寄生蜂为台湾甲腹茧蜂,并报道了这5种寄生蜂的主要鉴别特征和基本生物学特性。掌握海南本地草地贪夜蛾寄生蜂天敌的种类,初步探究了其对这种外来入侵害虫的自然控制作用,为筛选防治草地贪夜蛾的优势天敌提供参考。     

天敌昆虫低温贮藏研究进展

在农业生产中由于化学农药的长期不合理使用,导致"3R"问题持续存在和人类赖以生存的环境日益恶化,生物防治产品及技术在有害生物综合治理中的作用越发重要。天敌昆虫的生长发育及存活期往往很短,探索其储存技术是天敌昆虫规模化生产中的关键性环节。低温贮藏可以延长天敌昆虫的寿命,进而可以为生物防治提供充足、稳定的天敌产品。因此,天敌昆虫低温贮藏一直是生物防治领域研究的热点。本文围绕天敌昆虫低温贮藏这一环节,就低温诱导天敌昆虫滞育虫态、冷驯化对昆虫低温贮藏效果的影响、低温贮藏对天敌昆虫适合度(寿命、羽化率、性比、个体尺寸大小、飞行扩散能力等)的影响等方面进行综述,以期为天敌昆虫产品的规模化生产及应用技术提供参考。     

Effects of training on acquisition of pest management knowledge and skills by small vegetable farmers

Effects of farmer field school (FFS) and the conventional (classroom lectures) training on acquisition of pest management knowledge and skills by small vegetable farmers were studied in Yunnan province, China from 2003 to 2007. There were significant gains of knowledge about vegetable pests, natural enemies, insect and disease ecology and pest management among the FFS farmers, but were no significant improvements of knowledge among the conventional trained farmers. Vegetable FFS enabled farmers to learn simple knowledge as well as complex IPM knowledge. In contrast, the conventional training only improved vegetable farmers' simple knowledge. The potential and limitations of FFS as a unique extension tool to disseminate the complex knowledge of IPM to smallholder farmers were demonstrated.     

Natural enemies of the bagworm, Metisa plana Walker (Lepidoptera: Psychidae) and their impact on host population regulation

The bagworm, Metisa plana (Lepidoptera: Psychidae) is an important pest of oil palm, capable of being present as outbreak, which could cause a crop loss of up to 44%. Circumstantial evidence has long indicated that natural enemies play an important role in the population regulation of this pest. However, direct field data on the enemies themselves has been lacking.

A field study on a population of M. plana was made at PORIM Kluang, Johor, Malaysia from September 1988 to December 1992. The population of bagworm was initially high (late 1988, up to 38 larvae/frond, and in early 1990, up to 30 larvae/frond) but remained extremely low in the subsequent period (< 10 larvae/frond).

The population of M. plana was affected by both primary and secondary parasitoids and predators. Among the primary parasitoids, Dolichogenidea metesae was the most pronounced larval parasitoid of M. plana. This parasitoid was commonly attacked by hyperparasitoids, particularly Pediobius anomalus and Pediobius imbreus. A hypothetical life table constructed from the mortality figures of the declining part of the population during late 1988 confirmed that the natural enemies played a key role in suppressing the bagworm population.

The present study confirmed that overlapping generations were vital for the persistence of parasitoids of M. plana. The paper also suggested a possible need of alternative hosts. An active predator, Callimerus arcufer was also commonly encountered.     

Aphidophagous Parasitoids can Forage Wheat Crops Before Aphid Infestation,Parana State,Brazil

Aphid parasitoids are common in Brazilian wheat fields, and parasitize aphids at the wheat tillering stage. However, there is little information available about when this natural enemy occurs in wheat crops. This study investigated the initial occurrence of aphid parasitoids in four commercial wheat crops in northern Paraná during the 2009 crop season. We installed two Malaise traps at each wheat farm, and 400 tillers were assessed weekly in each field for aphid abundance. During this study, we captured 4,355 aphid parasitoids and 197 aphids. Three species of braconid parasitoids were identified, including Aphidius colemani (Viereck 1912), Lysiphlebus testaceipes (Cresson 1880), and Diaeretiella rapae (McIntosh 1855). The aphids species identified were Rhopalosiphum padi (Linnaeus 1758) and Sitobion avenae (Fabricius 1775). This study showed that aphid parasitoids are present in wheat crops even when aphid densities are low, and in one farm, occurred before the aphids colonization. These reports can justified the high efficiency of these natural enemies against aphids in wheat fields.     

Trials of an integrated pest management programme based on selective pesticides in English apple orchards

An integrated pest management (IPM) programme for apple involving selective insecticides applied in response to monitoring and using non-acaricidal fungicides was compared with a routine ‘calendar’ broad-spectrum programme over a 5-year period. This IPM system optimized the effect of natural enemies. From the second season onwards the predacious phytoseiid mite, Typhlodromus pyri, reached sufficient numbers to regulate Panonychus ulmi at low, non-damaging numbers. T. pyri also suppressed apple rust mite, Aculus schlechtendali, over most of this period. No acaricides were required on the IPM plots in the last 3 years of the trial. Small reductions in the number of insecticide/acaricide applications were made on the IPM plots but insect damage to fruit, especially by lepidopterous larvae, was higher than on the broad-spectrum plots. Several pests now rarely seen in commercial orchards built up on IPM plots and required specific treatments. The results are discussed in relation to further development of a commercially applicable IPM system.     

Non-target effects of dimethoate and acephate against Eusieus tularensis Congdon and Aphytis melinus DeBach on lemons in California

Understanding the non-target effects on pesticides used in crop production systems is essential for the development of IPM programmes in those systems. Two organophosphates for control of citrus thrips in citrus were compared at commercial field rates in a lemon orchard for their effect against a predacious mite and a parasitic wasp, both of which have a significant role in coastal lemon IPM. Dimethoate and acephate greatly reduced populations of both beneficial insects, holding them to below detectable levels for 8 weeks post-treatment. Moreover, citrus red mite, a secondary pest, developed beyond the economic treatment threshold in both the dimethoate and acephate plots 10 weeks and 4 weeks post-treatment, respectively. In addition to predatory mite mortality, hormoligosis is suspected in both instances, and especially with acephate, of causing this secondary pest problem.     

Insecticide susceptibility and carboxylesterase activity in leafminers (Diptera: Agromyzidae) and their associated hymenopteran parasitoids

Laboratory cultures of three dipteran leafminers, Liriomyza trifolii, Liriomyza sativae and Chromatomyia horticola, and their four most common hymenopteran parasitoids in Japan, Diglyphus isaea, Chrysocharis pentheus, Neochrysocharis formosa and Hemiptarsenus varicornis, were evaluated for their susceptibility to three conventional insecticides following topical application. All the leafminers were far less sensitive to malathion and moderately less sensitive to permethrin compared with the parasitoids. The marked disparity in insecticide susceptibility convincingly explains the increased abundance of leafminers in the field after applications of these insecticides. L. trifolii and C. horticola were also less sensitive to emamectin-benzoate than the parasitoids, although L. sativae was as sensitive as the parasitoids. We also evaluated the susceptibility of a more minor parasitoid species attacking leafminers in Japan, Halticoptera circulus, to malathion and it was less sensitive than the four more common parasitoid species and may, therefore, be suitable for augmentative biological control of leafminers in IPM programmes that include insecticides. In addition, carboxylesterase activity of each insect species was determined and correlations with their insecticide susceptibility discussed.     

Field Borders Provide Winter Refuge for Beneficial Predators and Parasitoids: A Case Study on Organic Farms

Semi-natural field borders are frequently used in midwestern U.S. sustainable agriculture. These habitats are meant to help diversify otherwise monocultural landscapes and provision them with ecosystem services, including biological control. Predatory and parasitic arthropods (i.e., potential natural enemies) often flourish in these habitats and may move into crops to help control pests. However, detailed information on the capacity of semi-natural field borders for providing overwintering refuge for these arthropods is poorly understood. In this study, we used soil emergence tents to characterize potential natural enemy communities (i.e., predacious beetles, wasps, spiders, and other arthropods) overwintering in cultivated organic crop fields and adjacent field borders. We found a greater abundance, species richness, and unique community composition of predatory and parasitic arthropods in field borders compared to arable crop fields, which were generally poorly suited as overwintering habitat. Furthermore, potential natural enemies tended to be positively associated with forb cover and negatively associated with grass cover, suggesting that grassy field borders with less forb cover are less well-suited as winter refugia. These results demonstrate that semi-natural habitats like field borders may act as a source for many natural enemies on a year-to-year basis and are important for conserving arthropod diversity in agricultural landscapes.     

Perspectives of integrated pest management

Integrated pest management (IPM) programmes require joint interdisciplinary scientific efforts to assemble sound information about: (1) the ecological basis of the pest problem; (2) factors in the agroecosystem that can be manipulated to make the crop environment unfavourable for pests; (3) pest and natural enemy population trends to determine if and when pesticide treatments are necessary; and (4) the benefits and risks of the IPM strategy for agriculture and society. The IPM technology is complex and this is partly why implementation of IPM has been slow. Projections are that if IPM is adopted by agriculture, pesticide use could be reduced by 35–50% from present use levels. Concurrently there would be a reduction in environmental and social problems caused by pesticides.     

我国茶毛虫生物防治研究进展

本文从茶毛虫的捕食性天敌与寄生性天敌、病原微生物、性信息素的合成利用、生物制剂等方面介绍了我国近年来应用生物技术防治茶毛虫的研究进展。     

Identifying an Optimal Screen Mesh to Enable Augmentorium-Based Enhanced Biological Control of the Olive Fruit Fly Bactrocera oleae (Diptera: Tephritidae) and the Mediterranean Fruit Fly Ceratitis capitata (Diptera: Tephritidae)

The augmentorium is a cost-effective screened enclosure designed to receive fruits infested with insect pests, retain the pests inside but let their natural enemies escape to enhance biological control of pest populations. Screen selection is critical to ensure that an augmentorium is effective for a particular system. Here we tested five types of screens with a mini-augmentorium design and measured the escape of four insect species under laboratory conditions: the pests olive fruit fly Bactocera oleae (Rossi) (Diptera: Tephritidae) and Mediterranean fruit fly Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), and the parasitoids Psyttalia lounsburyi (Silvestri) (Hymenoptera: Braconidae) and Psyttalia ponerophaga (Silvestri) (Hymenoptera: Braconidae). The sex ratio of insects that escaped the screens was compared to the sex ratio of insects that could not escape. Results showed that one screen type (‘crystal mesh’) was the best for the purpose of designing a functional augmentorium: it retained 90% of B. oleae adults and 100% of C. capitata adults while letting 72% of Psyttalia lounsburyi adults and 94% of P. ponerophaga adults escape. The other screen types tested were suboptimal, either because they let too many flies freely escape or because they retained too many parasitoids. Sex ratio was almost always similar for insects that managed to escape the screens and insects that were retained, except for P. ponerophaga and the screen type ‘light mesh’. These results are promising for the development of a functional augmentorium against the olive fruit fly and further implementation against Mediterranean fruit fly.     

茶小绿叶蝉生物防治研究进展

本文综述了国内近十多年来对茶小绿叶蝉生物防治的研究进展,包括对茶小绿叶蝉天敌、植物源农药的研究,提出了今后茶小绿叶蝉生物防治的研究重点和发展方向。     

瓜实蝇龄期和密度对蝇蛹金小蜂寄生能力的影响

蝇蛹金小蜂是蝇类害虫重要的蛹期寄生性天敌，为了评价其对蔬菜上重要害虫瓜实蝇的控害潜能，本文就蝇蛹金小蜂对瓜实蝇蛹的寄生潜能进行了研究，建立了功能反应和干扰效应数学模型。结果表明，蝇蛹金小蜂对不同蛹龄瓜实蝇蛹的寄生功能反应均符合 HollingⅡ模型，但不同蛹龄之间的功能反应参数存在差异。蝇蛹金小蜂对 2 日龄、4 日龄和 6 日龄瓜实蝇蛹的模方程分别为 Na = 0.478 0N0/(1+0.010N0)、Na = 0.474 0N0/(1+0.008 6N0) 和 Na = 0.476 4N0/(1+0.009 9N0)。蝇蛹金小蜂自身密度也会对寄生产生一定的干扰效应，用 Hassell-Varley 模型拟合，蝇蛹金小蜂干扰效应方程可表示为：a = 0.071 9P –0.252 6。