Augmentative biological control concerns the periodical release of natural enemies. In commercial augmentative biological control, natural enemies are mass-reared in biofactories for release in large ...numbers to obtain an immediate control of pests. The history of commercial mass production of natural enemies spans a period of roughly 120 years. It has been a successful, environmentally and economically sound alternative for chemical pest control in crops like fruit orchards, maize, cotton, sugar cane, soybean, vineyards and greenhouses. Currently, augmentative biological control is in a critical phase, even though during the past decades it has moved from a cottage industry to professional production. Many efficient species of natural enemies have been discovered and 230 are commercially available today. The industry developed quality control guidelines, mass production, shipment and release methods as well as adequate guidance for farmers. However, augmentative biological control is applied on a frustratingly small acreage. Trends in research and application are reviewed, causes explaining the limited uptake are discussed and ways to increase application of augmentative biological control are explored.
Tritrophic interactions between plants, herbivores, and their natural enemies are an integral part of all terrestrial ecosystems. Herbivore-induced plant volatiles (HIPVs) play a key role in these ...interactions, as they can attract predators and parasitoids to herbivore-attacked plants. Thirty years after this discovery, the ecological importance of the phenomena is widely recognized. However, the primary function of HIPVs is still subject to much debate, as is the possibility of using these plant-produced cues in crop protection. In this review, we summarize the current knowledge on the role of HIPVs in tritrophic interactions from an ecological as well as a mechanistic perspective. This overview focuses on the main gaps in our knowledge of tritrophic interactions, and we argue that filling these gaps will greatly facilitate efforts to exploit HIPVs for pest control.
•Establishment of farmer-managed Natural Enemies Farm Reservoirs (NEFRs) led to an increase in the absolute and average count of A. papayae per leaf.•The rise in A. papayae populations per leaf ...elevated parasitism rates, leading to an overall reduction in the infestation levels of PMB per leaf.•The presense of NEFRs resulted in an increase in the type (species) and number (abundance) of predatory arthropods in the respective treatments.
The papaya mealybug (PMB), Paracoccus marginatus, infests a wide range of plant species, including economically important crops, like papaya, citrus, cassava, and avocado, leading to significant economic losses. The parasitoid, Acerophagous papayae has been shown to manage the pest and was introduced in three coastal counties of Kenya from 2021. Natural Enemies Field Reservoirs (NEFRs), a technology that serves as in-situ production of A.papayae, were established in farmers’ fields in the three counties to assess their effectiveness in controlling the papaya mealybug in Kenya. Three treatments were set up including a. ‘No prior A. papayae release + NEFR’, b. ‘Prior A. papayae release + NEFR’, and c. ‘Prior A. papayae release but no NEFR’ (control). PMB populations decreased by 49.12 % and 62.8 % in treatments a and b, respectively, but increased by 37.6 % in the control. On the other hand, the absolute count of A. papayae increased by 456 %, 190 % and 51.6 % in treatments a, b and c, the control, respectively. Consequently, the parasitism rates increased by 116.7 % and 17.8 % in treatments a, and b, respectively but declined by 10.3 % in the control. The most abundant predators out of ten recovered genera were Cryptolaemus montrouzieri (44.0 %), Tenuisvalvae notata (23.9 %) and Exochomus sp. (19.9 %). The highest abundance and diversity of predators was recorded in treatment b ‘Prior A. papayae release + NEFR’ and the least abundance and diversity in the control. This study sheds light in the critical role of NEFRs in the management of PMB and its underscored potential as an effective, low-cost, farmer managed technology is discussed.
Biological control is an underlying pillar of integrated pest management, yet little focus has been placed on assigning economic value to this key ecosystem service. Setting biological control on a ...firm economic foundation would help to broaden its utility and adoption for sustainable crop protection. Here we discuss approaches and methods available for valuation of biological control of arthropod pests by arthropod natural enemies and summarize economic evaluations in classical, augmentative, and conservation biological control. Emphasis is placed on valuation of conservation biological control, which has received little attention. We identify some of the challenges of and opportunities for applying economics to biological control to advance integrated pest management. Interaction among diverse scientists and stakeholders will be required to measure the direct and indirect costs and benefits of biological control that will allow farmers and others to internalize the benefits that incentivize and accelerate adoption for private and public good.
The role of volatiles in plant communication Bouwmeester, Harro; Schuurink, Robert C.; Bleeker, Petra M. ...
Plant journal,
December 2019, Letnik:
100, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Summary
Volatiles mediate the interaction of plants with pollinators, herbivores and their natural enemies, other plants and micro‐organisms. With increasing knowledge about these interactions the ...underlying mechanisms turn out to be increasingly complex. The mechanisms of biosynthesis and perception of volatiles are slowly being uncovered. The increasing scientific knowledge can be used to design and apply volatile‐based agricultural strategies.
Significance Statement
Volatiles mediate the interaction of plants with pollinators, micro‐organisms, other plants and herbivores and their natural enemies. The increasing knowledge about the role of volatiles in these interactions, the underlying mechanisms, the biosynthesis and perception of volatiles are reviewed and the perspective for volatile‐based agricultural control strategies discussed.
Ecologists and farmers often have contrasting perceptions about the value of natural habitat in agricultural production landscapes, which so far has been little acknowledged in ecology and ...conservation. Ecologists and conservationists often appreciate the contribution of natural habitat to biodiversity and potential ecosystem services such as biological pest control, whereas many farmers see habitat remnants as a waste of cropland or source of pests. While natural habitat has been shown to increase pest control in many systems, we here identify five hypotheses for when and why natural habitat can fail to support biological pest control, and illustrate each with case studies from the literature: (1) pest populations have no effective natural enemies in the region, (2) natural habitat is a greater source of pests than natural enemies, (3) crops provide more resources for natural enemies than does natural habitat, (4) natural habitat is insufficient in amount, proximity, composition, or configuration to provide large enough enemy populations needed for pest control, and (5) agricultural practices counteract enemy establishment and biocontrol provided by natural habitat. In conclusion, we show that the relative importance of natural habitat for biocontrol can vary dramatically depending on type of crop, pest, predator, land management, and landscape structure. This variation needs to be considered when designing measures aimed at enhancing biocontrol services through restoring or maintaining natural habitat.
•Natural habitat can fail to enhance biocontrol and may even enhance pests.•Pest populations may have no effective natural enemies in the region.•Cropland may be more important for biocontrol than natural habitat.•Intensive agricultural practices can override benefits from natural habitat.•Multiple mechanisms from local to landscape scales underlie high biocontrol variation.
•Insecticidal Bt crops were grown on more than 100 million hectares in 2017.•Risk assessment considers exposure and toxicity of natural enemies to Bt proteins.•Bt proteins appear not to harm natural ...enemies.•Reduced insecticide use in Bt crops can enhance the conservation of natural enemies.•Bt technology represents a powerful tool for IPM.
Genetically engineered (GE) crops producing insecticidal proteins from Bacillus thuringiensis (Bt) (mainly Cry proteins) have become a major control tactic for a number of key lepidopteran and coleopteran pests, mainly in maize, cotton, and soybean. As with any management tactic, there is concern that using GE crops might cause adverse effects on valued non-target species, including arthropod predators and parasitoids that contribute to biological control. Such potential risks are addressed prior to the commercial release of any new GE plant. Over the past 20+ years, extensive experience and insight have been gained through laboratory and field-based studies of the non-target effects of crops producing Cry proteins. Overall, the vast majority of studies demonstrates that the insecticidal proteins deployed today cause no unintended adverse effects to natural enemies. Furthermore, when Bt crops replace synthetic chemical insecticides for target pest control, this creates an environment supportive of the conservation of natural enemies. As part of an overall integrated pest management (IPM) strategy, Bt crops can contribute to more effective biological control of both target and non-target pests. The growing use of insecticidal seed treatments in major field crops (Bt or not) may dampen the positive gains realized through reductions in foliar and soil insecticides. Nonetheless, Bt technology represents a powerful tool for IPM.
Fall armyworm (FAW), a voracious agricultural pest native to North and South America, was first detected on the African continent in 2016 and has subsequently spread throughout the continent and ...across Asia. It has been predicted that FAW could cause up to $US13 billion per annum in crop losses throughout sub-Saharan Africa, thereby threatening the livelihoods of millions of poor farmers. In their haste to respond to FAW governments may promote indiscriminate use of chemical pesticides which, aside from human health and environmental risks, could undermine smallholder pest management strategies that depend to a large degree on natural enemies. Agro-ecological approaches offer culturally appropriate low-cost pest control strategies that can be readily integrated into existing efforts to improve smallholder incomes and resilience through sustainable intensification. Such approaches should therefore be promoted as a core component of integrated pest management (IPM) programmes for FAW in combination with crop breeding for pest resistance, classical biological control and selective use of safe pesticides. Nonetheless, the suitability of agro-ecological measures for reducing FAW densities and impact need to be carefully assessed across varied environmental and socio-economic conditions before they can be proposed for wide-scale implementation. To support this process, we review evidence for the efficacy of potential agro-ecological measures for controlling FAW and other pests, consider the associated risks, and draw attention to critical knowledge gaps. The evidence indicates that several measures can be adopted immediately. These include (i) sustainable soil fertility management, especially measures that maintain or restore soil organic carbon; (ii) intercropping with appropriately selected companion plants; and (iii) diversifying the farm environment through management of (semi)natural habitats at multiple spatial scales. Nevertheless, we recommend embedding trials into upscaling programmes so that the costs and benefits of these interventions may be determined across the diverse biophysical and socio-economic contexts that are found in the invaded range.
•Fall armyworm, a voracious agricultural pest, has recently invaded Africa and Asia.•FAW could cause up to $16B in crop losses across Africa annually.•Use of chemical pesticides could undermine pest control through natural enemies.•We review the literature on agro-ecological approaches to control FAW.•Agro-ecological approaches provide proven low-cost options for smallholders.
Ecological research conducted over the past five decades has shown that increasing tree species richness at forest stands can improve tree resistance to insect pest damage. However, the commonality ...of this finding is still under debate. In this review, we provide a quantitative assessment (i.e., a meta-analysis) of tree diversity effects on insect herbivory and discuss plausible mechanisms underlying the observed patterns. We provide recommendations and working hypotheses that can serve to lay the groundwork for research to come. Based on more than 600 study cases, our quantitative review indicates that insect herbivory was, on average, lower in mixed forest stands than in pure stands, but these diversity effects were contingent on herbivore diet breadth and tree species composition. In particular, tree species diversity mainly reduced damage of specialist insect herbivores in mixed stands with phylogenetically distant tree species. Overall, our findings provide essential guidance for forest pest management.
Insects in agroecosystems contend with many stressors – e.g., chemicals, heat, nutrient deprivation – that are often encountered at low levels. Exposure to mild stress is now well known to induce ...hormetic (stimulatory) effects in insects, with implications for insect management, and ecological structure and function in agroecosystems. In this review, we examine the major ecological niches insects occupy or guilds to which they belong in agroecosystems and how hormesis can manifest within and across these groups. The mechanistic underpinnings of hormesis in insects are starting to become established, explaining the many phenotypic hormetic responses observed in insect reproduction, development, and behavior. Whereas potential effects on insect populations are well supported in laboratory experiments, field-based hypothesis-driven research on hormesis is greatly lacking. Furthermore, because most ecological paradigms are founded within the context of communities, entomological agroecologists interested in hormesis need to ‘level up’ and test hypotheses that explore effects on species interactions, and community structure and functioning. Embedded in this charge is to continue experimentation on herbivorous pest species while shifting more focus towards insect natural enemies, pollinators, and detritivores – guilds that play crucial roles in highly functioning agroecosystems that have been understudied in hormesis research. Important areas for future insect agroecology research on hormesis are discussed.
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•Insects are prominent, crucial, and exposed to many stressors in agroecosystems.•Mild chemical, heat, or nutrition stress can stimulate insects hormetically.•Insect herbivores, predators, parasitoids, detritivores and pollinators may be stimulated.•Multiple areas of insect-hormesis-agroecology remain to be explored.
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