Insect Herbivores of Rice: Their Natural Regulation and Ecologically Based Management

Horgan, Finbarr G.

doi:10.1007/978-3-319-47516-5_12

Cited by 11 publications

(23 citation statements)

References 74 publications

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“…This, together with phenomenal industrial growth in China and India since the early 2000s, has created an environment where agrochemicals are increasingly overused or misused. For example, since 2002, pesticide trade in Asia has increased by over 340% [2,8]. Intensification of rice production has resulted in increased rice harvests over much of Asia; however, for many nations, the rate of yield increase in relation to inputs has declined in recent decades [8].…”

Section: Introductionmentioning

confidence: 99%

Effects of Vegetation Strips, Fertilizer Levels and Varietal Resistance on the Integrated Management of Arthropod Biodiversity in a Tropical Rice Ecosystem

Horgan

Crisol‐Martínez

Stuart

et al. 2019

Insects

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Integrated biodiversity management aims to conserve the beneficial species components of production ecosystems and reduce the impacts of pests. In 2011 and 2013, experiments were conducted at Los Baños, Laguna, Philippines, to compare arthropod communities in rice plots and on levees with and without vegetation strips. Vegetation strips included spontaneous weeds, sesame and okra (2011), or mung bean (2013). The plots were treated with one of three nitrogen levels and in one experiment were planted with planthopper-resistant (IR62) and susceptible (IR64) rice varieties. Parasitoids and predators of lepidopteran pests and of the ricebug, Leptocorisa oratorius, were more abundant in high-nitrogen rice plots where their prey/hosts also had highest densities. Planthoppers and leafhoppers were more abundant in low-nitrogen plots. Weedy and sesame/okra bunds provided habitat for a range of natural enemies including spiders, parasitoids and predatory bugs, but did not have higher pest numbers than cleared bunds. Higher abundances of the predator Cythorhinus lividipennis and higher parasitism of planthopper (Nilaparvata lugens) eggs by Anagrus sp. were associated with sesame/okra bunds in late season rice plots. Mung bean also provided habitat for key predators and parasitoids that spilled over to adjacent rice; however, mung bean was also associated with higher numbers of lepidopteran and grain-sucking pests in the adjacent rice, albeit without increased damage to the rice. For ricebug in particular, damage was probably reduced by higher parasitoid:pest ratios adjacent to the vegetation strips. Varietal resistance and mung bean strips had an additive effect in reducing abundance of the planthopper Sogatella furcifera and the leafhopper Nephotettix virescens. Reduced numbers of these latter pests close to vegetation strips were often compensated for by other plant-sucking bugs, thereby increasing the intensity of potentially stabilizing interspecific interactions such as competition. We highlight the benefits of diversifying rice landscapes and the need to optimize vegetation strips, e.g., by including lepidopteran trap-plants, for intensive rice production systems.

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Section: Introductionmentioning

confidence: 99%

Effects of Vegetation Strips, Fertilizer Levels and Varietal Resistance on the Integrated Management of Arthropod Biodiversity in a Tropical Rice Ecosystem

Horgan

Crisol‐Martínez

Stuart

et al. 2019

Insects

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“…In addition, the presence/abundance of these parasitoids can be explained not only by host presence but also by the diversity of plants and the surrounding habitat. Thus there is also the potential application of ecological engineering to promote these natural enemies, by providing them with additional sources of nectar and refuge (see Dominik et al, 2018;Gurr et al, 2016;Horgan, 2017). A significant finding from our work is that the maximum control on hopper abundance occurs when both predators and parasitoids are present (despite the fact that the predators also prey on the parasitoids).…”

Section: Discussionmentioning

confidence: 74%

Section: Discussionmentioning

confidence: 99%

“…The combination of rice, arthropod herbivore pests, their natural enemies and detritivores constitutes a highly biodiverse ecosystem that recycles organic materials through decomposition, reduces herbivore damage, and pollinates flowers and crops (Horgan, ). As the rice plants grow and develop, herbivores will invade the rice fields and may become pests if not effectively regulated; however, generalist predators consume many of these early herbivore colonists (Settle et al, ; Wilby et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…At the same time, specialist natural enemies like egg parasitoids (Hymenoptera) and egg predators (e.g. Hemiptera: Miridae) begin to colonize the fields and build up numbers (Horgan, ; Settle et al, ). Studies in tropical rice, particularly from Indonesia and the Philippines, focused on the role of natural enemies find strong correlations between planthopper abundance and the abundance of spiders, egg parasitoids, or mirid bugs, suggesting density‐dependent responses are a feature of regulation and an indicator of a healthy rice environment (Dominik, Seppelt, Horgan, Settele, & Vclavk, ; Horgan, ; Kenmore, Perez, Dyck, & Gutierrez, ).…”

Section: Introductionmentioning

confidence: 99%

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Quantifying parasitoid and predator controls on rice hopper eggs using a dynamic stage‐structured model and field data

Kettle

Sann

Marion

2019

Journal of Applied Ecology

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1. Rice hoppers can cause devastation to rice crops in SE Asia via disease spread and direct feeding. Current regulation is through pesticides; however, a more sustainable approach is to use the natural enemies of the hoppers. Here, we show how the combination of a process-based model and field data can give insights into natural pest control, beyond those obtained through direct analysis of the field data.2. We use a stage-structured host-parasitoid model based on time-delay ordinary differential equations (using the r package "stagePop"; Kettle & Nutter, 2015;Methods in Ecology and Evolution 6:1484-1490) to investigate the interactions of four parasitoid genera and an egg predator on the eggs of two hopper hosts: the brown plant hopper (Nilaparvata lugens (Stål)) and the green leaf hopper (Nephottetix spp.).3. Model parameters are derived from 62 (×3) datasets from experiments in the Philippines. In these experiments, hopper eggs on rice plants were exposed in the field for 3 days and then taken back to the laboratory. The number of emerging hopper nymphs and parasitoid adults were then recorded. Single-host and mixed host experiments were performed. 4. The field data are not sufficient to fully constrain the model parameters so our results are given in terms of the value of an unknown parameter (γ; the number of hopper eggs killed per successful parasitism) which may be ascertained via future experiments. Synthesis and applications.Our model experiments suggest that although parasitoids are most likely the main control on hopper egg abundance, and despite the fact that the egg predator also consumes parasitoid eggs, the two-enemy system (parasitoids and predators) is more effective at hopper egg control than if either enemy is present alone. Our results provide evidence in support of ecological engineering approaches that promote both parasitoids and egg predators.

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Assessing Potential Environmental Impacts of Pesticide Usage in Paddy Ecosystems: A Case Study in the Deduru Oya River Basin, Sri Lanka

Chathuri

Yadav

Propper

et al. 2022

Enviro Toxic and Chemistry

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Rice paddies are unique ecosystems that provide rich wetland habitat. Their enduring existence across vast stretches of land has led them to evolve into unique systems serving a diverse assemblage of organisms and sustaining a staple grain for many people. With food demand rising, agricultural intensification through agrochemical application is a common practice used to boost food production in developing countries, including Sri Lanka. The aim of the present study was to assess the concentration of pesticide residues in water in rice ecosystems and discover their potential impacts on both environmental health and the most common fauna groups across a cropping year in Sri Lanka. A total of 270 water samples from waters associated with paddy fields within a watershed were analyzed for 20 commonly used pesticides; in addition, local farm holders were surveyed to assess pesticide usage details in three selected paddy tracts. We then used the Cornell University environmental impact quotient (EIQ) calculator and the ECOTOX Knowledgebase to determine the exposure risk associated with individual pesticides relative to their application rates and aquatic concentrations. Survey results demonstrate that several pesticides were overapplied at rates 1.2–11 times the recommended application, and the EIQ demonstrated high environmental risk of two of the agrochemicals detected, 2‐methyl‐4‐chlorophenoxyacetic and diazinon. Fish, amphibians, insects, and beetles were found to have a wide range of potential adverse outcomes from exposure to diazinon, captan, thiamethoxam, and chlorantraniliprole. To balance the trade‐offs between food security and ecosystem sustainability, the present study recommends that adoption of quantifiable environmental health indicators be considered as part of the national policy regulating pesticide use. Environ Toxicol Chem 2022;41:343–355. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

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Insect Herbivores of Rice: Their Natural Regulation and Ecologically Based Management

Cited by 11 publications

References 74 publications

Effects of Vegetation Strips, Fertilizer Levels and Varietal Resistance on the Integrated Management of Arthropod Biodiversity in a Tropical Rice Ecosystem

Effects of Vegetation Strips, Fertilizer Levels and Varietal Resistance on the Integrated Management of Arthropod Biodiversity in a Tropical Rice Ecosystem

Quantifying parasitoid and predator controls on rice hopper eggs using a dynamic stage‐structured model and field data

Assessing Potential Environmental Impacts of Pesticide Usage in Paddy Ecosystems: A Case Study in the Deduru Oya River Basin, Sri Lanka

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