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.
Green leaf volatile production by plants Ameye, Maarten; Allmann, Silke; Verwaeren, Jan ...
The New phytologist,
November 2018, Letnik:
220, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Plants respond to stress by releasing biogenic volatile organic compounds (BVOCs). Green leaf volatiles (GLVs), which are abundantly produced across the plant kingdom, comprise an important group ...within the BVOCs. They can repel or attract herbivores and their natural enemies; and they can induce plant defences or prime plants for enhanced defence against herbivores and pathogens and can have direct toxic effects on bacteria and fungi. Unlike other volatiles, GLVs are released almost instantly upon mechanical damage and (a)biotic stress and could thus function as an immediate and informative signal for many organisms in the plant’s environment. We used a meta-analysis approach in which data from the literature on GLV production during biotic stress responses were compiled and interpreted.We identified that different types of attackers and feeding styles add a degree of complexity to the amount of emitted GLVs, compared with wounding alone. This meta-analysis illustrates that there is less variation in the GLV profile than we presumed, that pathogens induce more GLVs than insects and wounding, and that there are clear differences in GLV emission between monocots and dicots. Besides the meta-analysis, this review provides an update on recent insights into the perception and signalling of GLVs in plants.
A catalogue of natural enemies considered and released as biological control (biocontrol) agents against invasive alien plants in South Africa has been maintained for many years, and is updated here ...to include the period 2011-2020. The current catalogue reorders and separates data for exotic natural enemies that have been approved as classical biocontrol agents, from those on exotic natural enemies that have been considered but not released, exotic natural enemies that have been inadvertently introduced into South Africa with host plants that include target weed species, and locally sourced natural enemies that have been considered as bioherbicides. Ninety weed species have been targeted for biocontrol, with 310 exotic natural enemies considered, 136 classified as de jure or de facto classical biocontrol agents, and 92 established in the field on 66 target weeds. Ten of these species were found to have established independently of being released while research on them was in progress. An additional six exotic species have been found established on target weeds, and 11 locally sourced natural enemies have been considered for inundative or augmentative biocontrol, of which two have been developed commercially. Of the exotic natural enemies deliberately established, 35% inflict extensive damage to their host plants. Insects make up the majority of biocontrol agents (90%), with the balance of 8% being fungi and 2%, mites. Both establishment rates and damage levels vary between taxa. Five biocontrol agents previously considered established, have not been found in the field for several years and their persistence is in doubt. Outcomes of biocontrol at a plant population level are indicated for 54 target weeds on which agents have been established for over a decade. The increase in numbers of target weeds considered, as well as biocontrol agents released, over the past decade, has been enabled by continued generous funding and an efficient release-approval process.
As natural enemies, entomopathogenic fungi are essential for controlling certain plant pests, such as whitefly. Many types of entomopathogenic fungi can infect whiteflies, including those from the ...genera Aschersonia, Metarhizium, Beauveria, and Cladosporium. Currently, there is great interest in using entomopathogenic fungi as an environmentally friendly pest control in organic and sustainable agricultural systems. This study aimed to identify entomopathogenic fungus associated with whiteflies. Identification of entomopathogenic fungus was performed morphologically and molecularly using DNA barcoding with ITS-1 and ITS-4 as primers, in addition to sequencing and phylogenetic tree analysis. Whiteflies infected with entomopathogenic fungus were discovered on ornamental plants (Premna serratifolia, Ficus religiosa, and Ficus rumphii) in Denpasar, Bali, Indonesia from January to March 2023. We found that samples from the field had mycelium that was unbranched or sparingly branched with solitary conidiophores arising terminally from ascending hyphae or laterally from plagiotropous hyphae. Samples from PDA media had ramoconidia with darkened septa, straight and conidia in long branched chains, branching in all directions, conidia were obovoid, ovoid to limoniform. The fungal colonies had the characteristics of being grey-olivaceous, olivaceous-black, and the margins were grey-livaceous to white, gray olivaceous in colony center due to abundant sporulation. In addition, based on the BLAST nucleotide sequence from NCBI GenBank, the insect pathogen phylogenetic tree found in Denpasar, Bali, is in the same clade as Cladosporium dominicanum strain SCAU014, accession number KY827344.1. Based on morphological and molecular analysis the fungus that infects whiteflies on ornamental plants is C. dominicanum.
The objective of this study is to inventory and identify the different species of aphids and aphidophages associated with them in citrus orchards in the Chlef region (Algeria) in order to promote ...predation and parasitism interactions for the ultimate purpose of biological control of these formidable pests. Surveys are conducted twice a month for an entire year. For sampling, we used yellow sticky traps, yellow pans, and visual determination. This study allowed us to identify seven species of aphids and 34 species of aphidophages, including 30 predator species and 4 parasitoid species. The most abundant aphids are Aphis spiraecola (Patch, 1914) and Aphis gossypii (Glover, 1877), while the most common aphidophages are Episyrphus balteatus (De Geer, 1776), Chrysoperla carnea (Stephens, 1836), Coccinella septempunctata (Linné, 1758), Aphidoletes aphidimyza (Rondani, 1847) and Lysiphlebus fabarum (Marshall, 1896). In terms of frequency, aphidophages are dominated by ladybugs, followed by lacewings, then syrphids, then bugs, and aphid midges in last place. The diversity of the aphidophages fauna is not very important, but the highest values are observed towards the end of April. Predation activities in the study area extend from the end of March to November. Aphidophages associated with aphids are divided into generalists and specialists. Specialist aphidophages show preferences for certain prey over others, in the case of aphid diversity according to both intrinsic and extrinsic factors.
Plant volatiles are used not only by herbivorous insects to find their host plants, but also by the natural enemies of the herbivores to find their prey. There is also increasing evidence that plant ...volatiles, in addition to species-specific pheromones, help these insects to find mating partners. Plant structures such as flowers, fruit, and leaves are frequently rendezvous sites for mate-seeking insects. Here we propose that the combined use of plant volatiles and pheromones can efficiently guide insects to these sites, where they will have access to both mates and food. This notion is supported by the fact that plant volatiles can stimulate the release of sex pheromones and can render various insects more receptive to potential mates.
Species-specific sex pheromones are commonly considered to be the principle cues leading to successful mating in insects. However, increasing evidence suggests that plant volatiles play an additional and highly important role in the mate location process.
Volatiles released from various plant structures (leaves, flowers, and fruits) may significantly contribute to mate finding by a wide variety of insect species, including herbivores, pollinators, and parasitoids.
By using plant volatiles and pheromones in combination, some insects are expected to be able to find mates in a timely and efficient manner.
In many insects the use of plant volatiles to find food as well as mates may have evolved as an efficient foraging strategy.
Field experiments were conducted during 2019–21 in Varanasi, Mirzapur and Bhadohi districts of Uttar Pradesh, with a view to study validation and economic viability of IPM technology in eggplant ...(Solanum melongena L.) in a farmers’ driven approach. The synthesized improved IPM technology comprising seed treatment with Trichoderma viride @5 g/kg seed; seedling root dip in carbendazim 50 wp @1 g/l followed by chlorantraniliprole 18.5 sc @0.5 ml/l solution against seed borne diseases and shoot and fruit borer, respectively, clipping of borer damaged shoots at weekly interval, installation of pheromone traps @25–30 traps/ha for mass trapping of brinjal shoot and fruit borer (BSFB), need based spray (ETL>5%) of chlorantraniliprole 18.5 sc @0.35 ml/l or emamectin benzoate 5 SG @0.4 g/l or fenpropathrin 30 ec @0.33 ml/l against BSFB, installation of yellow sticky traps, application of Azadirachtin 0.03% @5 ml/l and need based spray of thiamethoxam 25 wg @0.4 g/l or fenpropathrin 30 ec @0.33 ml/l against sucking pests like whiteflies and hoppers, collection and destruction of borer and Phomopsis blight infected fruits, Sclerotinia white rot infected twigs and branches and little leaf affected plants periodically, need based application of carbendazim 50 wp @0.5 g/l for management of Phomopsis blight and white rot, were found effective in reducing the incidence of pests and minimizing the yield losses. The adoption of IPM technology also resulted in reducing the number of chemical sprays to 10 from 21–24 in farmers’ practices (FP) fields in a season with higher fruit yields of 51.1 and 45.3 t/ha in IPM, 39.6 and 33.7 t/ha in FP and 25.7 and 20.4 t/ha in untreated control fields with higher incremental benefit cost (B:C) ratio of 4.61:1 and 4.86:1 in IPM than 3.16:1, 3.24:1 in non-IPM and 2.53:1, 2.42:1 in untreated control plots during 2019–20 and 2020–21, respectively.
Theory predicts that higher biodiversity in the tropics is maintained by specialized interactions among plants and their natural enemies that result in conspecific negative density dependence (CNDD). ...By using more than 3000 species and nearly 2.4 million trees across 24 forest plots worldwide, we show that global patterns in tree species diversity reflect not only stronger CNDD at tropical versus temperate latitudes but also a latitudinal shift in the relationship between CNDD and species abundance. CNDD was stronger for rare species at tropical versus temperate latitudes, potentially causing the persistence of greater numbers of rare species in the tropics. Our study reveals fundamental differences in the nature of local-scale biotic interactions that contribute to the maintenance of species diversity across temperate and tropical communities.
Apparent Competition Holt, Robert D; Bonsall, Michael B
Annual review of ecology, evolution, and systematics,
11/2017, Letnik:
48, Številka:
1
Journal Article
Recenzirano
Most species have one or more natural enemies, e.g., predators, parasites, pathogens, and herbivores, among others. These species in turn typically attack multiple victim species. This leads to the ...possibility of indirect interactions among those victims, both positive and negative. The term apparent competition commonly denotes negative indirect interactions between victim species that arise because they share a natural enemy. This indirect interaction, which in principle can be reflected in many facets of the distribution and abundance of individual species and more broadly govern the structure of ecological communities in time and space, pervades many natural ecosystems. It also is a central theme in many applied ecological problems, including the control of agricultural pests, harvesting, the conservation of endangered species, and the dynamics of emerging diseases. At one end of the scale of life, apparent competition characterizes intriguing aspects of dynamics within individual organisms-for example, the immune system is akin in many ways to a predator that can induce negative indirect interactions among different pathogens. At intermediate scales of biological organization, the existence and strength of apparent competition depend upon many contingent details of individual behavior and life history, as well as the community and spatial context within which indirect interactions play out. At the broadest scale of macroecology and macroevolution, apparent competition may play a major, if poorly understood, role in the evolution of species' geographical ranges and adaptive radiations.
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