A new classification of lifestyles of phytoseiid mites is proposed based on the findings and suggestions from many studies conducted in the fifteen years since the publication of the lifestyle system by McMurtry & Croft (1997). In this newly proposed classification, Type I (Specialized mite predators) is divided into three subtypes to highlight mite prey specificity: subtype I-a—Specialized predators of Tetranychus species (Tetranychidae); subtype I-b—Specialized predators of web-nest producing mites (Tetranychidae); subtype I-c—Specialized predators of tydeoids (Tydeoidea). Type II (Selective predators of tetranychid mites) remains essentially the same. Type III (Generalist predators) is a huge and diverse group of general feeders; predators in this category are now grouped into five subtypes based on the microhabitat occupied and morphology: subtype III-a— Generalist predators living on pubescent leaves; subtype III-b—Generalist predators living on glabrous leaves; III-c—Generalist predators living in confined spaces on dicotyledonous plants; III-d—Generalist predators living in confined spaces on monocotyledonous plants; III-e—Generalist predators from soil/litter habitats. Type IV (Pollen feeding generalist predators) also remains essentially the same. Two possible additional lifestyles include phytoseiids living on aquatic plants and phytoseiids able to pierce leaf cells. Behavioral and biological information is updated and implications for biological control strategies are discussed.

/pdf/revision-of-the-lifestyles-of-phytoseiid-mites-acari-3kxqrdljb4.pdf

Revision of the lifestyles of phytoseiid mites (Acari: Phytoseiidae) and implications for biological control strategies

Biological control is the suppression of populations of pests and weeds by living organisms. These organisms can provide important protection from invasive species and protect our environment by reducing the need for pesticides. However, they also pose possible environmental risks, so biological control interventions must be undertaken with great care. This book enhances our understanding of biological control interactions by combining theory and practical application. Using a combination of historical analyses, theoretical models and case studies, with explicit links to invasion biology, the authors cover biological control of insects, weeds, plant pathogens and vertebrate animals. The book reflects increasing recognition of risks over the past 20 years, and incorporates the latest technological advances and theoretical developments. It is ideal for researchers and students of biological control and invasion biology.

Biological Control: Ecology and Applications

Effects of chlorpyrifos and sulfur on spider mites (Acari: Tetranychidae) and their natural enemies.

Pesticides are toxic chemicals used to control pests, weeds and pathogens. Three quarters of all pesticides are employed in agricultural production, particularly in developed countries, in an effort to mitigate crop damage endured by intensive agriculture. However, after more than 60 years of worldwide usage, their side-effects on terrestrial ecosystems - even when applied as recommended - are obvious. This chapter examines the ecological problems caused by specific chemicals/groups, so that this awareness may help improve agricultural practices through appropriate risk management. Fungicides alter the microbial-fungi communities responsible for the recycling of nutrients in the soil, and copper fungicides are toxic to earthworms and other animals. The routine application of herbicides has produced a net loss of plant biomass and biodiversity in many landscapes, which indirectly reduces the associated arthropod communities and leads to population declines in many species of birds, and possibly amphibians too, due to lack of food. Insecticides are very toxic to most invertebrates in the soil, birds and small mammals, causing significant reductions in their populations and disturbing the trophic structure of their communities. Persistent pesticides accumulate in soil and concentrate through the trophic chain, causing a plethora of sublethal effects which are negative for the survival of individuals as well as the viability of their populations; the long term effects of DDT and cyclodiene poisoning in birds is still an ecological issue despite more than 30 years of not being applied in most developed countries. While pesticides have increased our agricultural productivity and helped feed the current human population, the price of this productivity is being paid by the Earth's ecosystems at large.

/pdf/impacts-of-agricultural-pesticides-on-terrestrial-ecosystems-5tzo75r745.pdf

Impacts of Agricultural Pesticides on Terrestrial Ecosystems

Spatial scale of benefits from adjacent woody vegetation on natural enemies within vineyards

In 2001 and 2002, we monitored densities of western grape leafhopper, Erythroneura elegantula Osborn, and Virginia creeper leafhopper, Erythroneura ziczac Walsh (Homoptera: Cicadellidae), eggs from June through September in managed and nonmanaged vineyards in Washington state. Anagrus parasitoids (Hymenoptera: Mymaridae) were reared from sampled parasitized leafhopper eggs. Densities of nonparasitized and parasitized E. elegantula eggs, and nonparasitized E. ziczac eggs, were significantly higher in nonmanaged grapevines, although this pattern was not consistent for the latter two groups. Densities of parasitized E. ziczac eggs were consistently low across management regimes. Anagrus erythroneurae S. Trjapitzin & Chiappini, Anagrus daanei S. Triapitsyn, and Anagrus tretiakovae S. Triapitsyn emerged from parasitized E. elegantula eggs, whereas latter two mymarid species also parasitized E. ziczac eggs. Of these species, A. tretiakovae was the most common parasitoid of Erythroneura leafhopper eggs ...

Identity, Abundance, and Phenology of Anagrus spp. (Hymenoptera: Mymaridae) and Leafhoppers (Homoptera: Cicadellidae) Associated with Grape, Blackberry, and Wild Rose in Washington State

Specialist-feeding phytoseiid mites have a well-documented role in biological control of phytophagous spider mites. However, although there is evidence for the importance of generalist-feeding phytoseiid mites in spider mite suppression, their role is less clear than that of specialists. The effectiveness of generalists as biocontrol agents and their interactions with specialists might be directly influenced by canopy structure or indirectly affected by altering plant microclimate. We manipulated densities of generalist phytoseiid mites and canopy size (large and small) in open-field experiments in an abandoned vineyard. In the first experiment, we increased generalist densities by transferring grapevine foliage housing robust generalist populations, whereas in the second experiment, we lowered generalist densities using the broad-spectrum insecticide chlorpyrifos. In both experiments, we also altered canopy size by tying grapevine shoots. Increasing densities of generalists resulted in lower spider mite densities. Generalists initially decreased densities of specialist phytoseiid mites as well, although specialist densities rebounded as spider mite densities increased later in the experiment. Lowering generalist densities appeared to slightly increase densities of both spider and specialist mites, consistent with the first experiment. However, these effects were not statistically significant, possibly because the reduction in generalist densities through chlorpyrifos application was not as dramatic as our generalist augmentation in the first experiment. Canopy size did not significantly affect pest or predatory mite densities in either experiment. These field experiments demonstrate that generalists can slow spider mite population growth in grapes. In contrast, canopy architecture appeared to have little impact on spider mite biocontrol.

https://bioone.org/journals/Environmental-Entomology/volume-35/issue-1/0046-225X-35.1.56/Effects-of-Generalist-Phytoseiid-Mites-and-Grapevine-Canopy-Structure-on/10.1603/0046-225X-35.1.56.pdf

Effects of Generalist Phytoseiid Mites and Grapevine Canopy Structure on Spider Mite (Acari: Tetranychidae) Biocontrol

In 2001 and 2002, grapevines in southcentral Washington were surveyed to assess taxonomic composition, density, and phenology of spider mites and predaceous phytoseiid mites. To determine how management intensity affected the mite fauna we compared mite densities among, 1) non-managed grapevines not exposed to any chemical input, 2) managed vineyards exposed to fungicides and herbicides, and 3) managed vineyards exposed to fungicides, herbicides, insecticides and acaricides. Because the use of non-selective pesticides often results in higher pest densities due to negative effects on predators, our hypothesis was that as chemical input increased, spider mite densities would increase while densities of phytoseiid mites would decrease. Tetranychus mcdanieli McGregor was the most abundant spider mite in our samples. Spider mite densities were lowest in sites receiving no chemical input, while spider mite densities were similar in low and high input managed vineyards. Galendromus occidentalis (Nesbitt...

Impact of management intensity on mites (Acari: Tetranychidae, Phytoseiidae) in Southcentral Washington wine grapes

Unsprayed deciduous trees and shrubs were sampled from August to September in 2001 and 2002 throughout southcentral Washington State to obtain information on the phytoseiid mite fauna and phytoseiid-plant associations. Nine phytoseiid species were identified on 17 plant species. Generalist-feeding phytoseiid mites outnumbered specialist-feeders by approximately 4:1 in 2001 and 5:1 in 2002. Dogwood (Cornus spp.), alder (Alnus spp.), blackberry (Rubus spp.), and maple (Acer spp.) had the highest phytoseiid mite densities. Plants that possess leaves with pit or tuft domatia appeared to have more phytoseiid mites than those without domatia. There was no clear association between ventral leaf pubescence and phytoseiid mite presence. Phytoseiid-plant associations and implications for wine grape biological control are discussed.

Deirdre A. Prischmann

Papers

Effects of chlorpyrifos and sulfur on spider mites (Acari: Tetranychidae) and their natural enemies.

Identity, Abundance, and Phenology of Anagrus spp. (Hymenoptera: Mymaridae) and Leafhoppers (Homoptera: Cicadellidae) Associated with Grape, Blackberry, and Wild Rose in Washington State

Effects of Generalist Phytoseiid Mites and Grapevine Canopy Structure on Spider Mite (Acari: Tetranychidae) Biocontrol

Impact of management intensity on mites (Acari: Tetranychidae, Phytoseiidae) in Southcentral Washington wine grapes

Phytoseiidae (Acari) on unsprayed vegetation in southcentral Washington: implications for biological control of spider mites on wine grapes