Arthropods destroy an estimated 18–26 % of annual crop production worldwide, at a value of more than $ 470 billion. The greater proportion of losses (13–16 %) occurs in the field, before harvest, and losses have been heaviest in developing countries. With the Earth’s human population expected to reach 10 billion by the end of the current century, raising agricultural productivity through the prevention of crop losses to pests has assumed considerable urgency. The techniques employed in crop loss assessment provide a framework useful in identifying the causes and magnitude of crop losses, and a basis for the evaluation of control options. Crop losses to arthropods have been reported to be lower in traditional than in modern, industrial agriculture, and are thought to result from the more environmentally sound and sustainable practices employed in traditional agriculture. Many of the pest problems in modern agriculture have arisen through an over-reliance on synthetic chemicals for pest control. More environmentally sound pest control practices not only are more sustainable, but may provide greater economic benefits as well. The return per dollar invested in ecologically-based biological and cultural pest controls has been estimated to range from $ 30 to $ 300, significantly higher than the $ 4 estimated for control based on synthetic pesticides. Crop losses to pests must be reduced in ways that are compatible with sustainable production, which requires pest control to be approached in a holistic manner with a focus on the entire agroecosystem. Key to averting or minimizing crop losses to pests is a commitment, by government or other entities, to collect the data, on which reliable estimates of losses are based.

Crop Losses to Arthropods

The natural enemies of the more important arthropod, nematode and mollusc pests of strawberry in northern and central Europe and their use as biocontrol agents are reviewed. Most pests of strawberry are polyphagous and they and their natural enemies occur on other host plants (especially Rosaceae) as well as on other crops. Strawberry cultivation methods, including protected cultivation and other methods of extending the fruiting season, soil sterilization, polythene mulching and pesticide spray programmes have profound influences on the pest and natural enemy complex, though such effects have not been quantified adequately. All the pests of strawberry reviewed have natural enemies, though some pests (e.g. capsid bugs) have few. A few natural enemy groups are known to act as important natural limiting factors in pest population development in commercial strawberry crops. Two examples are naturallyoccurring phytoseiid predatory mites which regulate pest mite populations, and predatory carabid beetles which...

Review: Natural Enemies and Biocontrol of Pests of Strawberry in Northern and Central Europe

By altering myriad aspects of leaf chemistry, increasing concentrations of CO2 and O3 in the atmosphere derived from human activities may fundamentally alter the relationships between insect herbivores and plants. Because exposure to elevated CO2 can alter the nutritional value of leaves, some herbivores may increase consumption rates to compensate. The effects of O3 on leaf nutritional quality are less clear; however, increased senescence may also reduce leaf quality for insect herbivores. Additionally, changes in secondary chemistry and the microclimate of leaves may render plants more susceptible to herbivory in elevated CO2 and O3. Damage to soybean (Glycine max L.) leaves and the size and composition of the insect community in the plant canopy were examined in large intact plots exposed to elevated CO2 (~550 μmol mol−1) and elevated O3 (1.2*ambient) in a fully factorial design with a Soybean Free Air Concentration Enrichment system (SoyFACE). Leaf area removed by folivorous insects was estimated by digital photography and insect surveys were conducted during two consecutive growing seasons, 2003 and 2004. Elevated CO2 alone and in combination with O3 increased the number of insects and the amount of leaf area removed by insect herbivores across feeding guilds. Exposure to elevated CO2 significantly increased the number of western corn rootworm (Diabrotica virgifera) adults (foliage chewer) and soybean aphids (Aphis glycines; phloem feeder). No consistent effect of elevated O3 on herbivory or insect population size was detected. Increased loss of leaf area to herbivores was associated with increased carbon-to-nitrogen ratio and leaf surface temperature. Soybean aphids are invasive pests in North America and new to this ecosystem. Higher concentrations of CO2 in the atmosphere may increase herbivory in the soybean agroecosystem, particularly by recently introduced insect herbivores.

Effects of elevated CO2 and O3 on leaf damage and insect abundance in a soybean agroecosystem

The purpose of this study was to evaluate the performance of Neoseiulus californicus (McGregor) for the control of Tetranychus urticae Koch in commercial strawberry fields, under greenhouse conditions, in association or not with the use of acaricides. The N. californicus strain used in this study was tolerant or resistant to several pesticides. Three experiments were carried out in the State of Sao Paulo, Brazil. For the first experiment, the initial infestation of T. urticae was 87.1 active stages per leaflet. Two applications of propargite were made on the first and the 14th day of the experiment. Approximately 2 h after each propargite application, N. californicus was released at a rate of 3.0 and 1.9 adult mites per plant, respectively, for each application. The population of T. urticae decreased from 87.1 to 2.8 mites per leaflet in the first three weeks. After this period, the population of T. urticae was maintained at low levels (≤1.5 mites/leaflet) until the end of the experiment (10th week). Propargite and dimethoate sprayed on the strawberry field did not affect significantly the population of this predaceous mite. For the second experiment, the infestation of T. urticae was 29.1 mites per leaflet, when the acaricide chorfenapyr was applied on the strawberry field. The release of N. californicus (2 mites per plant) was made 2 weeks after spraying the acaricide. The population of T. urticae was maintained at low levels (≤2.8 mites/leaflet) for 8 weeks (evaluation period). The T. urticae infestations in plots with N. californicus were significantly lower than in non-release plots, for the experiments 1 and 2. In the third experiment, the initial infestation of T. urticae was 40.5 mites per leaflet (55.5 active stages/leaflet on release plants; 25.5 active stages/leaflet on non-release plants). Three releases of N. californicus (average rate of 3.0 adult mites/plant), without any acaricide application, were not sufficient to reduce significantly the T. urticae population in release plots (release plants + non-release plants) in 6 weeks from the first release, however, the spider mite population decreased from 55.5 to 7.8 active stages per leaflet on release plants, during this period. Interplant dispersal of N. californicus was low in this strawberry field with high infestation of T. urticae. The studies indicate the viability of the use of this strain of N. californicus for the control of T. urticae in strawberry fields under greenhouse conditions, especially in association with selective acaricides.

Management of Tetranychus urticae (Acari: Tetranychidae) in strawberry fields with Neoseiulus californicus (Acari: Phytoseiidae) and acaricides

A key economic pest of strawberries in California is the western tarnished plant bug, Lygus hesperus Knight (Hemiptera:Miridae). Alfalfa (Medicago sativa L.) is a highly attractive plant host to western tarnished plant bug, and we hypothesized that it can be successfully managed as a trap crop for pest suppression in strawberries. Completely randomized design trap cropping experiments were established on an organic strawberry farm from 2002 to 2004. Western tarnished plant bug adults and nymphs were significantly more abundant in alfalfa trap crops than in comparable edge strawberry rows. Over 3 experimental yr, twice-weekly summer vacuuming of alfalfa trap crops with a tractor-mounted vacuuming device reduced adult and nymph abundance by 72 and 90%, respectively, in trap crops. This summer vacuuming of alfalfa trap crops also significantly reduced damage caused by western tarnished plant bug in associated unvacuumed organic strawberries (June and July 2002, June 2003, and June and July 2004) compared with either an untreated control (2003) or the organic strawberry grower's standard whole field vacuuming treatment. Vacuuming of alfalfa trap crops reduces an organic grower's costs (tractor, tractor fuel, and driver time) by 78% compared with current whole field vacuuming practices. An economic analysis of a whole hectare model indicates that a positive return from the use of vacuumed trap crops could be realized in 2004. The overall potential positive net return for the 3 mo of vacuumed alfalfa trap crop treatments in 2004 was calculated at +$1,829/ha.

Control of Western Tarnished Plant Bug Lygus hesperus Knight (Hemiptera: Miridae) in California Organic Strawberries Using Alfalfa Trap Crops and Tractor-Mounted Vacuums

Plant physiological status determines translaminar movement of avermectin B 1 in strawberry leaves, and the resulting noncontact residual kill of twospotted spider mite, Tetranychus urticae Koch. Significant T urticae mortality was obtained upon contact with avermectin B 1 with and without the addition of dormant oil, and with propargite. Noncontact residual kill of T. urticae by avermectin B 1 was greater on fruiting summer-type plants than on plants in winter semidormancy. When avermectin B 1 was applied only to the top surface of leaves, addition of dormant oil enhanced T urticae mortality on lower leaf surfaces of plants in winter semidormancy. T. urticae mortality was not affected by the addition of oil when plants were in either a spring-type vegetative growth state or a summer-type sexual state. The results of this study suggest an explanation for inconsistencies observed in field applications of avermectin B 1 for control of T. urticae.

Effect of Strawberry Plant Physiological Status on the Translaminar Activity of Avermectin B1 and Its Efficacy Against the Twospotted Spider Mite (Acari: Tetranychidae)

Strawberry ( Fragaria x ananassa ) developmental physiology is affected by temperature and photoperiod. Supplemental cold storage treatments of daughter plants of the reproductively day-neutral ‘Selva’, between their harvest from high-elevation propagation nurseries and fall transplant into production fields, stimulated vegetative vigor. In a 3-yr study, the increased vegetative vigor resulting from pretransplant supplemental cold storage treatments reduced susceptibility to infestation by and abundance of twospotted spider mites, Tetranychus urticae Koch, during the subsequent fruit production season. Harvest date of daughter plants had an effect on the size of T urticae populations in the following production season if the plants failed to receive adequate vernalization in the field during winter. Medium versus large daughter-crown diameter at transplant produced no significant differences in susceptibility to spider mite infestation, or in the degree of vegetative vigor or yield. Proper manipulation of daughter-plant chilling treatment may enable strawberry producers to decrease plant susceptibility to T urticae infestation, produce optimum-sized plants, and maximize yield.

Pretransplant Cold Storage of Strawberries: Effects on Plant Vigor, Yield, and Spider Mite (Acari: Tetranychidae) Abundance

Several suction sampling devices were compared with a beating tray and a whole-plant sample for determining population abundance of Lygus hesperus (Knight) as well as some beneficial predatory arthropods (Geocoris spp., Hemerobius spp., Chrysopa camea (Stephens), Orius tristicolor (White), and spiders) in California strawberry fields. The Allen-vac (A-vac) sampler best approximated the whole-plant sample for L. hesperus and beneficials except spiders. The beating tray provided the most consistent though lower estimates, but could provide a useful estimate of L. hesperus and beneficial arthropod abundance in an integrated pest management monitoring program. The D-vac provided a slightly lower estimate of L. hesperus density than did the A-vac samples or beating-tray samples at a greater cost in sampling time. For each regression of relative technique against the corresponding whole-plant estimate, the intercept was not significantly different from 0. Taylor’s power law was used to develop variance-mean models for each sampling type tested.

Sampling for Lygus hesperus (Hemiptera: Miridae) in Strawberries

Yield of day-neutral strawberries, Fragaria × ananassa Duch (‘Selva’), grown in California were evaluated for 7 yr over a range of twospotted spider mite, Tetranchus urticae Koch, population densities. From 1988 through 1994, acaricide treated and untreated plots of Selva were established each fall in Watsonville, Santa Cruz County, CA. T. urticae population densities were calculated on a per midtier leaflet basis every 2 wk as the average number of motile T. urticae counted on 10 midtier leaflets sampled from each plot. Mite-days were calculated from these counts and summed for monthly intervals by using 15 March and 30 August as starting and ending dates, respectively. These calculations provide a standard index of T. urticae feeding pressure on strawberry plants among and within years. Yield loss resulting from T. urticae feeding in untreated plots versus plots treated with acaricides averaged 25%. T. urticae feeding had little or no effect on fruit size but caused a significant reduction in the number of berries produced per plant. The later T. urticae were first detected in winter or spring, the less yield was reduced during the peak fruiting months of June and July. Maximum T. urticae abundance was negatively associated with yield, and greater mite-day accumulations were associated with yield decline. Regression analysis indicated that the 0% yield reduction threshold averaged 30 cumulative mite days during any monthly period. This implies that detectible yield reduction caused by mite feeding occurs at population densities > 1 T. urticae per leaflet. However, late winter and early spring mite feeding resulted in greater yield reductions than mite feeding at equivalent levels of infestation in late spring and summer. Yield reduction resulting from mite feeding is cumulative at relatively low population levels throughout spring and damage resulting from mite feeding plateaus during summer.

Interaction of the Twospotted Spider Mite (Acari: Tetranychidae) with Yield of Day-Neutral Strawberries in California

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Douglas B. Walsh

Author Tools

Chat about Author

Papers

Effect of Strawberry Plant Physiological Status on the Translaminar Activity of Avermectin B1 and Its Efficacy Against the Twospotted Spider Mite (Acari: Tetranychidae)

Pretransplant Cold Storage of Strawberries: Effects on Plant Vigor, Yield, and Spider Mite (Acari: Tetranychidae) Abundance

Sampling for Lygus hesperus (Hemiptera: Miridae) in Strawberries

Interaction of the Twospotted Spider Mite (Acari: Tetranychidae) with Yield of Day-Neutral Strawberries in California