scholarly journals Indirect Effect of Pesticides on Insects and Other Arthropods

Toxics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 177
Author(s):  
Francisco Sánchez-Bayo
Keyword(s):  
Natural Enemies ◽  
Indirect Effects ◽  
Species Interactions ◽  
Nutrient Recycling ◽  
Algae Blooms ◽  
Pest Outbreaks ◽  
Ecological Mechanisms ◽  
Periphyton Biomass ◽  
Predatory Insects ◽  
Intended Use

Pesticides released to the environment can indirectly affect target and non-target species in ways that are often contrary to their intended use. Such indirect effects are mediated through direct impacts on other species or the physical environment and depend on ecological mechanisms and species interactions. Typical mechanisms are the release of herbivores from predation and release from competition among species with similar niches. Application of insecticides to agriculture often results in subsequent pest outbreaks due to the elimination of natural enemies. The loss of floristic diversity and food resources that result from herbicide applications can reduce populations of pollinators and natural enemies of crop pests. In aquatic ecosystems, insecticides and fungicides often induce algae blooms as the chemicals reduce grazing by zooplankton and benthic herbivores. Increases in periphyton biomass typically result in the replacement of arthropods with more tolerant species such as snails, worms and tadpoles. Fungicides and systemic insecticides also reduce nutrient recycling by impairing the ability of detritivorous arthropods. Residues of herbicides can reduce the biomass of macrophytes in ponds and wetlands, indirectly affecting the protection and breeding of predatory insects in that environment. The direct impacts of pesticides in the environment are therefore either amplified or compensated by their indirect effects.

scholarly journals Predicting direct and indirect non-target impacts of biocontrol agents using machine-learning approaches

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252448
Author(s):  
Hannah J. Kotula ◽  
Guadalupe Peralta ◽  
Carol M. Frost ◽  
Jacqui H. Todd ◽  
Jason M. Tylianakis
Keyword(s):  
Machine Learning ◽  
Random Forest ◽  
Natural Enemies ◽  
Indirect Effects ◽  
Species Interactions ◽  
Habitat Type ◽  
Indirect Interactions ◽  
Biocontrol Agents ◽  
Biological Pest Control ◽  
Indirect Impacts

Biological pest control (i.e. ‘biocontrol’) agents can have direct and indirect non-target impacts, and predicting these effects (especially indirect impacts) remains a central challenge in biocontrol risk assessment. The analysis of ecological networks offers a promising approach to understanding the community-wide impacts of biocontrol agents (via direct and indirect interactions). Independently, species traits and phylogenies have been shown to successfully predict species interactions and network structure (alleviating the need to collect quantitative interaction data), but whether these approaches can be combined to predict indirect impacts of natural enemies remains untested. Whether predictions of interactions (i.e. direct effects) can be made equally well for generalists vs. specialists, abundant vs. less abundant species, and across different habitat types is also untested for consumer-prey interactions. Here, we used two machine-learning techniques (random forest and k-nearest neighbour; KNN) to test whether we could accurately predict empirically-observed quantitative host-parasitoid networks using trait and phylogenetic information. Then, we tested whether the accuracy of machine-learning-predicted interactions depended on the generality or abundance of the interacting partners, or on the source (habitat type) of the training data. Finally, we used these predicted networks to generate predictions of indirect effects via shared natural enemies (i.e. apparent competition), and tested these predictions against empirically observed indirect effects between hosts. We found that random-forest models predicted host-parasitoid pairwise interactions (which could be used to predict attack of non-target host species) more successfully than KNN. This predictive ability depended on the generality of the interacting partners for KNN models, and depended on species’ abundances for both random-forest and KNN models, but did not depend on the source (habitat type) of data used to train the models. Further, although our machine-learning informed methods could significantly predict indirect effects, the explanatory power of our machine-learning models for indirect interactions was reasonably low. Combining machine-learning and network approaches provides a starting point for reducing risk in biocontrol introductions, and could be applied more generally to predicting species interactions such as impacts of invasive species.

Agro-ecological mechanisms for weed and pest suppression and nutrient recycling in high yielding complex rice systems

2021 ◽  
Vol 313 ◽  
pp. 107385
Author(s):  
Uma Khumairoh ◽  
Egbert A. Lantinga ◽  
Irfan Handriyadi ◽  
Rogier P.O. Schulte ◽  
Jeroen C.J. Groot
Keyword(s):  
Nutrient Recycling ◽  
Ecological Mechanisms ◽  
Pest Suppression

Feedbacks of consumer nutrient recycling on producer biomass and stoichiometry: separating direct and indirect effects

Oikos ◽  
2009 ◽  
Vol 118 (11) ◽  
pp. 1732-1742 ◽  
Author(s):  
Lesley B. Knoll ◽  
Peter B. McIntyre ◽  
Michael J. Vanni ◽  
Alexander S. Flecker
Keyword(s):  
Indirect Effects ◽  
Nutrient Recycling ◽  
Direct And Indirect Effects

scholarly journals Dwarf Mistletoe Infection Interacts with Tree Growth Rate to Produce Opposing Direct and Indirect Effects on Resin Duct Defenses in Lodgepole Pine

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 222 ◽  
Author(s):  
Scott Ferrenberg
Keyword(s):  
Growth Rate ◽  
Natural Enemies ◽  
Indirect Effects ◽  
Annual Ring ◽  
Annual Growth ◽  
Tree Age ◽  
Direct And Indirect Effects ◽  
Dwarf Mistletoe ◽  
Resin Ducts ◽  
Resin Duct

Research Highlights: I sought to disentangle the influences of tree age, growth rate, and dwarf mistletoe infection on resin duct defenses in lodgepole pine, Pinus contorta Douglas ex Loudon, revealing the presence of direct positive and indirect negative effects of mistletoe on defenses. Background and Objectives: For protection against natural enemies, pines produce and store oleoresin (resin) in ‘resin ducts’ that occur throughout the tree. Dwarf mistletoe, Arceuthobium americanum Nutt. ex Engelm. (hereafter “mistletoe”), is a widespread parasitic plant affecting the pines of western North America. Infection by mistletoe can suppress pine growth and increase the probability of insect attack—possibly due to a reduction in resin duct defenses or in the potency of chemical defenses at higher levels of mistletoe infection, as reported in Pinus banksiana Lamb. However, the influence of mistletoe infection on defenses in other pine species remains unclear. I hypothesized that mistletoe infection would induce greater resin duct defenses in P. contorta while simultaneously suppressing annual growth, which was expected to reduce defenses. Materials and Methods: Using increment cores from P. contorta trees occurring in a subalpine forest of Colorado, USA, I quantified tree age, annual growth, annual resin duct production (#/annual ring), and cross-sectional area (mm2 of resin ducts/annual ring). Results: Mistletoe infection increased with tree age and had a direct positive relationship with resin duct defenses. However, mistletoe infection also had an indirect negative influence on defenses via the suppression of annual growth. Conclusions: Through the combined direct and indirect effects, mistletoe infection had a net positive impact on resin duct production but a net negative impact on the total resin duct area. This finding highlights the complexity of pine defense responses to natural enemies and that future work is needed to understand how these responses influence overall levels of resistance and the risk of mortality.

Geographical variation, population structure and gene flow between populations of Chrysophtharta agricola (Coleoptera: Chrysomelidae), a pest of Australian eucalypt plantations

2003 ◽  
Vol 93 (2) ◽  
pp. 137-144 ◽  
Author(s):  
H.F. Nahrung ◽  
G.R. Allen
Keyword(s):  
Gene Flow ◽  
Natural Enemies ◽  
Chemical Control ◽  
Genetic Resistance ◽  
Allelic Diversity ◽  
Native Forest ◽  
Pest Species ◽  
Eucalypt Plantations ◽  
Pest Outbreaks ◽  
High Allelic Diversity

AbstractChrysophtharta agricola (Chapuis) is a pest of commercial eucalypt plantations in Tasmania and Victoria. Vagility of pest populations may result in difficulty predicting temporal and spatial pest outbreaks, and influence genetic resistance to chemical control. Gene flow in this pest species was estimated to assess predicability of attack, the potential efficacy of natural enemies, and the likelihood of resistance build-up. Ten geographic populations of C. agricola (six from Tasmania, one from the Australian Capital Territory, one from New South Wales and two from Victoria) were examined for genetic variation and gene flow using cellulose acetate allozyme electrophoresis. Six enzyme systems (PGI, PGD, PGM, IDH, HEX and MPI) were consistently polymorphic and scorable and were used to quantify estimated gene flow between populations. FST values and analysis of molecular variance indicated that gene flow was restricted between populations. Chrysophtharta agricola exhibited high levels of heterozygosity, probably because of high allelic diversity, and because all loci examined were polymorphic. The southern-most population was the most genetically different to other Tasmanian populations, and may also have been the most recently colonized. Limited gene flow implies that outbreaks of C. agricola should be spatially predictable and populations susceptible to control by natural enemies. Our results also imply that genetic resistance to chemical control may occur under frequent application of insecticide. However, testing population movement between plantations and native forest also needs to be conducted to assess gene flow between forest types.

A question of size and fear: competition and predation risk perception among frugivores and predators

2020 ◽  
Vol 101 (3) ◽  
pp. 648-657
Author(s):  
Daiane Cristina Carreira ◽  
Jedediah F Brodie ◽  
Calebe P Mendes ◽  
Katia Maria P M B Ferraz ◽  
Mauro Galetti
Keyword(s):  
Risk Perception ◽  
Predation Risk ◽  
Indirect Effects ◽  
Species Interactions ◽  
Human Impacts ◽  
Activity Patterns ◽  
Fruit Trees ◽  
Visitation Rates ◽  
Top Predators ◽  
Large Predators

Abstract Mammalian spatial and temporal activity patterns can vary depending on foraging behavior or the perception of predation or competition risk among species. These behaviors may in turn be altered by human influences such as defaunation. Herein, we evaluate whether frugivores avoid areas with high visitation rates by potential predators or competitors, and whether this avoidance changes in areas with different degrees of defaunation. We installed 189 cameras under fruit trees in six areas of the Atlantic Forest, Brazil, that differ in the abundance of top predators and large frugivores. Small predators and small frugivores were more frequent at night while large frugivores were more frequent during the day, but small frugivores visited and spent less time at fruiting trees on brighter nights, unlike large predators and large frugivores. Small frugivores also were less frequent in areas with high visitation by large frugivores and more frequent in highly defaunated areas. Our results suggest that the dynamics among mammalian functional groups varied according to diel patterns, potential competitors, and defaunation. We highlight the importance of understanding how species interactions are changing in areas exposed to strong human impacts to mitigate the indirect effects of defaunation.

scholarly journals Arthropod Diversity Influenced by Two Musa-Based Agroecosystems in Ecuador

Agriculture ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 235
Author(s):  
Daniel Vera-Aviles ◽  
Carmita Suarez-Capello ◽  
Mercè Llugany ◽  
Charlotte Poschenrieder ◽  
Paola De Santis ◽  
...  
Keyword(s):  
Production Systems ◽  
Cropping Systems ◽  
Mixed System ◽  
Mixed Species ◽  
Precipitation Regimes ◽  
Pest Outbreaks ◽  
Ecological Mechanisms ◽  
Arthropod Abundance ◽  
Agricultural Production Systems

Banana and plantain (Musa spp.) are very important crops in Ecuador. Agricultural production systems based on a single cultivar and high use of external inputs to increase yields may cause changes in the landscape structure and a loss in biodiversity. This loss may be responsible for a decrease in the complexity of arthropod food webs and, at the same time, related to a higher frequency and range of pest outbreaks. Very little is known either about the ecological mechanisms causing destabilization of these systems or the importance of the diversity of natural enemies to keep pests under control. Few studies have focused on this issue in tropical ecosystems. Here, we address this problem, comparing two Musa-based agroecosystems (monocultivar and mixed-species plantations) at two sites in Ecuador (La Maná and El Carmen) with different precipitation regimes. The diversity of soil macro fauna, represented by arthropods, was established, as indicators of the abovementioned disturbances. Our ultimate goal is the optimization of pest management by exploring more sustainable cropping systems with improved soil quality. Arthropod abundance was higher in the mixed system at both localities, which was clearly associated with the quality of the soils. In addition, we found Hymenoptera species with predatory or parasitic characteristics over the pests present in the agroecosystems under study. These highly beneficial species were more abundant at the locality of La Maná. The mixed type of production system provides plant diversity, which favors beneficial arthropod abundance and permits lower agrochemical application without yield penalties in comparison to the monoculture. These findings will help in the design of Musa-based agroecosystems to enhance pest control.

scholarly journals Meta-Analysis Suggests Differing Indirect Effects of Viral, Bacterial, and Fungal Plant Pathogens on the Natural Enemies of Insect Herbivores

Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 765
Author(s):  
Ussawit Srisakrapikoop ◽  
Tara J. Pirie ◽  
Mark D. E. Fellowes
Keyword(s):  
Natural Enemies ◽  
Indirect Effects ◽  
Plant Pathogens ◽  
Meta Analysis ◽  
Trophic Levels ◽  
Plant Diseases ◽  
Plant Quality ◽  
Insect Herbivore ◽  
Insect Herbivores ◽  
Fungal Plant Pathogens

Indirect effects are ubiquitous in nature, and have received much attention in terrestrial plant–insect herbivore–enemy systems. In such tritrophic systems, changes in plant quality can have consequential effects on the behavior and abundance of insect predators and parasitoids. Plant quality as perceived by insect herbivores may vary for a range of reasons, including because of infection by plant pathogens. However, plant diseases vary in their origin (viral, bacterial or fungal) and as a result may have differing effects on plant physiology. To investigate if the main groups of plant pathogens differ in their indirect effects on higher trophic levels, we performed a meta-analysis using 216 measured responses from 29 primary studies. There was no overall effect of plant pathogens on natural enemy traits as differences between pathogen types masked their effects. Infection by fungal plant pathogens showed indirect negative effects on the performance and preference of natural enemies via both chewing and piercing-sucking insect herbivore feeding guilds. Infection by bacterial plant pathogens had a positive effect on the natural enemies (parasitoids) of chewing herbivores. Infection by viral plant pathogens showed no clear effect, although parasitoid preference may be positively affected by their presence. It is important to note that given the limited volume of studies to date on such systems, this work should be considered exploratory. Plant pathogens are very common in nature, and tritrophic systems provide an elegant means to examine the consequences of indirect interactions in ecology. We suggest that further studies examining how plant pathogens affect higher trophic levels would be of considerable value.

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