Biodiversity In Ecosystem Services Biology Essay

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This research proposes a possible solution to reduce the interruption in ecosystem service overlap by increasing the abundance of beneficial insects through the addition of native, perennial plant communities within agriculturally dominated landscapes. Area (matrix) specific increases in plant biodiversity have the potential to stabilize the protection and proliferation of ecosystem services through conservation of ecosystem services provided by beneficial insects. For this investigation the specific matrix consists of certified organic farms and the insect ecosystem service providers of interest include natural enemies and native pollinators and their faunal association with native, perennial plant communities. (the focus is on implementing landscape management practices that conserve insects which deliver biological control of herbivorous pests and pollination to agricultural landscapes.

What are Ecosystem Services?

Agricultural production of food and fiber that are of value to the human population contribute to, as well as, impact the nature of self-organized ecological systems . Ecosystem services (ES) refers to processes by which natural and modified ecosystems, and the species that exist within, function to sustain and provision human life (Daily 1997, MA 2005, Muller et al. 2005 Swinton et al. 2006, Sandhu et al. 2007, Zhang 2007). In 2004, research conducted by Nations Millennium Ecosystem Assessment grouped ES into four categories defined as: provisioning, regulating, supporting and cultural. The qualitative characteristics of these groups are explained as follows: provisioning ES include the production of crops, wild food, biomass, and water; regulating ES include climate control, disease control and carbon sequestration; supporting ES include primary production; crop pollination and the regulation of nutrient cycles and cultural ES include spiritual benefits, recreational activities and the promotion of scientific discovery (MA 2005). In no way are these categories mutually exclusive and their synergistic overlap is more advantageous compared to the sum of the individual effects. Aspects that promote the sustainability of ES include biodiversity perpetuation combined with the conservation of ecosystem structure and function.

What role does biodiversity play to promote ES?

The fundamental driving force behind ES characteristics is biodiversity; defined as diversity in composition of genes, species, populations, and ecosystems (MEA 2005, Moonen and Barbari 2008) In terms of agriculture the term agrobiodiversity is used; referring to the variety and variability of living organisms that contribute to food and agriculture (Jackson et al. 2007). Agricultural systems depend on supporting and regulating services as inputs for the success of provisioning services (MA 2003, Muller et al 2005, and Zhang et al. 2007). Improving functions of agrobiodiversity that promote provisioning ecosystem services (food, fuel, fiber and fresh water production) receives more attention than the supporting and regulating ecosystem services that provide inputs making provisioning services possible. This imbalance may be due to the fact that humans can better relate to something that provides them with a physical outcome, especially when the results are life sustaining resources like foods. In contrast, the regulating and provisioning services which that determine the quality provisioning services consist of intricate processes involving collections of species and associated feeding guilds (Zhang et al. 2007). The supply of ES fostered by biodiversity is generally determined by the diversity of the populations producing the services (Luck et al. 2003). This research focuses on insect populations as providers and vectors of ES specific to crop production.

What ecosystem services (ES) are mediated by insects?

In general terms, ecosystem service providers (ESP), are considered to be any species or population that provides specific ecosystem services. There are many organisms that mediate the delivery of ES specific to cropping systems and beneficial insects are among the most important. Beneficial insect assemblages, especially at robust population levels, provide an array of ES to agricultural systems triggered by density dependent processes including functional and numerical responses (Elliot et al. 2002). Insect mediated ES (IMES) of focus here include pollination and biological control. Delivery of these regulating and supporting services are examples of the aforementioned inputs upon which provisioning ES rely. In contrast to the IMES that assist successful crop production, several insect species are pestiferous and impede successful crop production. Zhang et.al (2007) has termed productivity loss, increased production costs, and competition for resources as a result of herbivorous pest feeding behaviors ecosystem dis-services (ED).

What are beneficial insects?

Beneficial insects, specific to agricultural systems, enhance the ecological stability and resilience of cropping systems and maintain crop yield (Landis et al. 2005). These insects are categorized by feeding guilds and include entomophagous predators, parasitoids, and pollinators. Functional traits associated with trophic systems are a measure of ecosystem performance determined by the strength of interactions among species (MEA 2005). Entomophagous predators and parasitoids, commonly referred to as natural enemies, can account for __insert percentage here__ of pest removal from crops. When natural enemy populations are significant; pest mortality increases which decreases crop damage and pesticide inputs on conventional farms can be reduced. However, certified organic farms depend on natural pest regulation. Approaches related to organic and more sustainable agriculture generally increase beneficial insect populations as well as pest population due to increased biodiversity (Snyder et al. 2007). Land management plans are just as important in more diverse cropping systems as they are in monoculture systems indicating a need to focus on aspects of biodiversity that conserve and attract beneficial insects. Managed and unmanaged bees are the main contributors to crop pollination. The importance of pollination via non-managed bees has been receiving more attention in recent years due to the reduction in honey bee colonies by Colony Collapse Disorder. Beneficial insects, their functional traits, and their required resources will be discussed with more detail in upcoming sections.

How do land management practices influence the success of insect mediated ecosystem services (IMES)?

Just as IMES affect agricultural productivity, agricultural productivity affects IMES. The delivery of IMES in agriculturally dominated landscapes depend on land management strategies that preserve the diversity, composition, and function of remaining natural ecosystems as associated species(MA 2005, Zhang et al. 2007). If management is aimed at supporting biodiversity for the fulfillment of the desired agroecosystem functions it results in species adapted to the chosen objectives which can increase the magnitude of the desired process (Moonen and Barberi 2008). A growing body of research regarding land cover management which promotes ESP for the regulation of pest outbreaks indicates that fewer outbreaks occur when agricultural fields are surrounded vegetation that provides resources for insect ESP. Studies of this type, conducted in the Midwest, documented that soybean fields surrounded by less annual cropland and more perennial vegetation witnessed the suppression of soybean aphid populations due to the increased presence of desired insect predators such as ladybeetles (taken from grant).

Landscape alteration that reduces biodiversity effects insect species distribution causing local extinction, loss of a species from a local area, and functional extinction, reduction of a species to the extent where it is no longer able to play a significant role in ecosystem function (MEA 2005). The extent to which modern farming practices reduce biodiversity affects the assemblages of insect ESP and their delivery of IMES. Systems that use pesticides, especially broad-spectrum insecticides, have non-target effects on beneficial insect populations (Harwood et al. 2009). Extensive monocultures simplify agricultural landscapes by reducing the diversity of prey species and plant species has several negative consequences on beneficial insects. When landscapes are altered in this way, prior ecosystems tend to be highly fragmented or completely replaced (Wilkenson and Landis from Wackers et al. 2005). Oversimplification results in the uneven spatial and temporal distribution of resources that beneficial insect populations require to persist and effectively deliver ES to crops (Landis et al. 2005). It has been recognized that species which are unable to persist in these disturbed areas are often replaced with species that are able to thrive in the altered landscape and the replacements are often invasive, pest species. This creates and imbalance in favor of ED. Therefore, it is important to consider the life cycle, habitat needs, and behavior of ESP outside of predation or pollination periods (Swinton et al. 2006).

However, part of the functioning system must include planned agrobiodiversity which refers to the crops and livestock selected by farmers while the other part of the system includes associated agrobiodiversity which refers to the biota colonizing the system and its ability to be robust local management and local environment (Jackson et al. 2007). Augmenting associated agrobiodiversity can impede interruptions regarding ES delivered to agroecosystems. Patches of uncultivated biotypes offer insect ESP: habitat, nutrition, refuge from harsh management practices, nesting sites, and over-wintering sites. As agricultural practices continue to simplify landscapes, these patches become less frequent contributing to the degradation of ecological infrastructure that permits dispersal of beneficial insects (Bjorklund et al. 1999). Having access to patches of non-crop plant species facilitate the ability of beneficial insect to persist near agricultural fields before, during, and after periods of IMES are needed by the cultivated species (Coll and Guershon 2002). The capability of insects to disperse long distances varies and infrequent, unconnected patches of non-crop habitats may impede IMES to crops due to increased travel risks and energy budgeting constraints. In upcoming paragraphs specific resource needs will be grouped and discussed in terms of the feeding guilds that deliver IMES.

What causes ES to be interrupted?

Unfortunately, the stability of ES has been interrupted by human disturbances in response to the demands that increasing population sizes impose on the ecosystem. The MEA (2005) emphasizes habitat change due to land use change is the most important direct driver of biodiversity reduction and these changes have occurred more rapidly in the past 50 years than any other time in human history. Agricultural has been identified as a major contributor to world-wide loss of biodiversity due to physical manipulation of land and inputs (Sandhu et al. 2007). Agricultural science has made enormous progress in the advancement of technology to increase the production of crops, however the current challenge is to meet the food demands of a growing population without further damaging the allocation of ES (Sandhu et al. 2007) Intensive agricultural practices including tillage, drainage, planting, monocropping, harvesting, crop rotation and pesticide use cause a reduction in the diversity of native, natural habitat and impacts wild species (McLaughlin and Mineua 1995). Likewise, dependence on high-yielding varieties, genetically modified crops and agrochemical inputs may be detrimental to human, animal and environmental health (Jackson et al. 2007). Fundamental and potentially irreversible losses in ecosystem function become more likely as more of the original land cover is lost to commodity production (Fisher et al. 2006). Intensive agriculture accounts for 10% of the global land use and an additional 17% is under extensive use associated with fewer artificial inputs (Jackson et al. 2007). Agriculture both produces and consumes ES and it is important to create a balance between these two aspects to promote long-term farm sustainability (Sandhu et al. 2010). However, as biodiversity decreases so does the resiliency of agroecosystems.

Why is it important to improve ES?

Restoring biodiversity aids in agroecosystem functioning by fostering assemblages of species that impose complementary effects on ecosystem functioning via the delivery of ES. A biodiversity based paradigm for sustainable agriculture may be a potential improvement in "damage recovery" (Jackson et al. 2007). Increased attention in the area of landscape ecology has led to an appreciation of the role of spatial structure of land cover, including the recognition that habitat patch size and connectivity are often critical to sustaining synergistic metapopulations of ESP (Swinton et al. 2006). Organic farming systems have been considered one of the production systems that aim to achieve this balance by utilizing and balancing ES (Sandhu et al. 2010). However, management practices utilized by neighboring conventional farmers may influence organic efforts on a larger scale. In other words, the biodiversity driving ES located within habitats located on organic farms are affected by the additional impacts exerted by surrounding landscapes. Given the strong evidence for both field and landscape level influence on the provision of pest suppression and pollination services, these services can be managed and conserved by manipulating the diversity of plant communities (Swinton et al. 2006). Increasing plant species richness, even at low levels, may have the largest effects on improving ecosystem processes (Jackson et al. 2007 FROM LOREAU 2002). Diversification strategies include the implementation of polycultures, cover crops, ground cover, within crop refuge habitats, perennial intercropping and buffer strips (Wilkinson and Landis 2005 from Wackers et al. 2005). Here the focus is the species composition of buffer strips to optimize the delivery of IMES to organic agricultural systems in particular.

The majority of research proposing that land management practices that aim to increase biodiversity can positively impact IMES, particularly pest suppression, uses conventional farming systems as a model landscape. With the recent growth and interest in organically grown crops, the worldwide market for organic products is increasing every year. (Between 2004 and 2005, the United States contributed to the largest market increase of $1.5 billion in regards to organic products, which is almost half of the worldwide market (Zehnder et al. 2007). Growing organic practices and farms transitioning to organic practices present the need for integrated management techniques that foster prolonged sustainability to replace immediate, reactive decision making (Zehnder et al. 2007). In the case of organic farms, implementing perennial, vegetative buffer strips to enhance IMES such as top-down trophic interactions and pollination does not have the same implications compared to conventional farms. Organic farmers would not have to take land out of production, which may reduce profits, but can increase the abundance of ESP by enhancing the composition and diversity of their already required buffer zones with resources that support insect ESP.

In the state of Iowa the USDA requires organic farms to establish distinct, defined boundaries and buffer zones to be certified as organic. Buffer zones prevent the drift of unintended substance, chemical and genetic, which may be used in adjoining crop land. Required buffer zones, the lack of chemical inputs, and the willingness of organic farmers to try progressive approaches that improve IMES allow organic systems to be a favorable matrix. However, there are presently no standards for the size and composition of plant species of these federally required buffer zones. Certain vegetation has the potential to encourage the colonization of ESP and perennial species possess the characteristics to support the colonization. Moreover, native perennial species are adapted to local conditions and require less maintenance than annual species. Previous studies recognize many benefits of riparian buffers including: erosion reduction, water filtration and wildlife resources; all of which are services maintaining ecosystem sustainability. In agroecosystems, we can exploit these benefits while promoting the fitness and productivity of interdependent plant communities and reduce the need for human intervention. What has yet to be resolved is the species composition of perennial buffer strips required to support the optimal abundance and diversity of insect ESP (Landis). An in depth discussion about the plant communities in buffer strips that are commonly used by Iowa organic farms and alternative species selected for the potential improvement of buffer strips will be discussed in upcoming paragraphs. (in the plant community section)

VERY IN PROGRESS!!!!!!!

Beneficial insects of interest and their requires resources to enhance IMES

Under field conditions, the resources required for beneficial insects to maintain proper fitness can be depleted, limited and fragmented. Many organisms depend on more than one resource during their life cycle for proper development (Banks, Bommarco and Ekbon 2008). Evidence shows that the abundance and diversity of beneficial insects increases on sites with greater land complexity, due to the accessibility of food sources and habitat when compared to less complex, monoculture landscapes. (Zhang et al. 2007). The on-farm diversity of plant species, regarding crop species as well as non-crop species, drives the success of IMES by providing distinct niche partitioning (Snyder et al. 2007). The greater amount niches that are able to be occupied by beneficial insect provide resources and reduce competition allowing beneficial insects from different feeding guilds to colonize local landscapes. Natural enemies from diverse feeding guilds are theoretically most effective in pest control due to different phenologies that ensure the pest is attacked throughout the growing season (Holland et al. 2008). Insect feeding guilds of interest here include predators, parasitoids, herbivores, pollinivors or nectivores. Land practices that offer resources for these feeding guilds are likely to receive more ES.

Natural Enemy - predators

Predatory feeding guilds are commonly identified as biological control agents due to predatory, carnivorous feeding habits on herbivorous pest insects causing pest mortality. Entomophagous predators are usually larger than their prey and are able to consume many prey. Research shows that most predatory insects involved in biological control are actually omnivores because they also feed on plant-derived foods to acquire carbohydrates (Wackers et al. 2008). Exploitation of sugar by predatory insects can be a life history attribute or can occur on a temporal basis (Wackers et al. 2008). Regardless of these distinctions, feeding on nectar, extrafloral nectar, honeydew or pollen effects survival, reproduction, physical activity, metabolic upkeep and overall fitness which influences carnivore-herbivore dynamics (Wackers et al. 2008). In addition to supplementing primary prey with plant derived food, some predators are unable to achieve optimal fitness when limited by the variety of available prey items. Harwood et al. (2009) explains that predators need to optimize nutrient intake, balance ingested nutrients and avoid prey toxins by feeding on diverse species of prey. Furthermore, providing beneficial insects with multiple prey species result in increased herbivore suppression, fosters the emergence of complementary predators that have a preference for certain species or life stages of prey, and reduces the effects of intraguild predation (Snyder et al. 2007). Field experiments conducted by Ostman et al. (2004) exhibited a positive correlation regarding the availability of alternative prey for generalist predators and removal of aphid pest prey. Overall, diet quality and availability effects behavioral and physiological attributes that maintain the communities of entomophagous predators in order to suppress herbivorous pest populations to avoid crop damage.

Charts?

Major players (predators) and their resource association :

Taxonomy : Coleoptera : Coccinellidae

Transient predator (adult) Resident predator (larva 3 and 4) (Costamagna et al.2008)

Nutrition

Primary

Prey

Aphididae spp. mites, scales, lepidoptera eggs, leafhoppers, intraguild spp.

Secondary / Alternative (plant derived)

Components

Evidence and Physiological benefits

Nectar (sugars)

Nectar contains three times the carbohydrates compared to prey (Michaud and Quershi 2006, Lundgren 2009)

Many species feed on sap for hydration which is not necessary when feeding on prey , H. annuus (sunflower), Kochia scoparia L. and Amaranthus palmeri S. Wats (weed spp) (Michaud and Quershi 2006)

Sugar resources can help increase survival when prey is scarce, reduce weight loss and reduce eggs sorption during reproductive diapauses (Lundgren 2009)

Provides energy source for continued foraging for preferred prey (Michaud and Quershi 2006)

Extra Floral Nectar

41 spp. of adults feed on EF nectarines (Landis 2005)

Contains less secondary defense chemicals than floral nectar (Lundgren 2009)

Pollen (sugar, protein and all essential amino acids)

39 spp. consume more than 88 species of pollen which consists of (12%-61%) protein by weight and is used to fuel migration (Lundgren 2009)

Honeydew (sugary exudates)

Frequently encountered, high energy source which extends survival, allows modest reproduction and intensifies foraging of larvae and adult (Lundgren 2009)

Mixed diets

(prey + plant)

Physiological benefits

female fitness 5-10 fold when suitable prey is encountered

termination of reproductiove diapause

development on pollen may reduce adult fitness

oviposition near prey for successful larval development

prey contains more substantial amounts of lipids and protein

pollen as a solitary food source does not support egg maturation (except Coleomegilla maculata) (Lundgren 2009)

adding sugar to prey substantially improved adult performance and increases reproduction capacity pollen is important for spermatogenesis and combined with prey it promotes reproduction (Lundgren 2009)

Habitat Requirements : OW requires wooded or semi-natural areas (Elliot et al. 2002)

Taxonomy: Coleoptera : Carabidae (in progress)

Diets with mixed prey species resulted in increased weight, shorted mean egg development time, continued egg production over time compared to the single prey diets

Require a diversity of prey including non-pest herbivores (Harwood et al. 2009)

Larvae are almost all predaceous; adults of most species consume a mixture of plant and animal food (Helyer, Brown and Cattlin 2003).

Habitat Requirements

Owing in grassy strips, grasslands, hedgerows or field margins enhances abundance, fecundity and species diversity (Landis et al. 2005)

Taxonomy: Tachyporus spp. (Coleoptera : Staphylinidae) (in progress)

Prey includes insect eggs, larvae and pupae, as well as small soft-bodied insects such as aphids

Taxonomy : Orius insidiosus Say (Hemiptera : Anthocoridae)

Resident predator - Life Stages: Nymph and Adult

Nutrition

Primary

Prey

Aphididae spp., spider mites, insect eggs, leafhoppers, insect spp

Secondary / Alternative (plant derived)

Componants

Evidence and Physiological benefits

Nectar (sugars)

When diet lack vitellogenin precursors, one of which is carbohydrates, egg production is decreased (Ferkovich and Shapiro 2004)

Extra Floral Nectar

Pollen (sugar, protein and all essential amino acids)

Attracted to / colonize pollen producing plants and feed on pollen which increases their performance (Coll and Guershon 2002)

Positive correlation between diets supplemented with pollen and amount of eggs laid (Ferkovich and Shapiro 2004)

Honeydew (sugary exudates)

Mixed diets

(prey + plant)

Physiological benefits

Other Hemipteran predators (in progress)

Miridae - Plagiognathus species including P. politus, predator of leaf beetles (Helyer, Brown and Cattlin 2003) C. associatus (adults)predators of aphids (Helyer, Brown and Cattlin 2003 and Costamagna et al.2008)

Nabidae sp. (nymph and adult) (Costamagna et al.2008) predators of aphids, leafhoppers, catapillars, and mites (Helyer, Brown and Cattlin 2003

Found to be more abundant in grass-infested alfalfa fields than in pure stands (Elliot et al. 2002)

Pentatomidae - P. maculiventris species are predatory told from other species by the dark spot

Lygaeidae

Reduviidae

Taxonomy : Nueroptera : Chrysopidae and Hemerobiidae

Resident predator - Life Stages : Larvae and Adult

Nutrition

Primary

Prey

Aphididae spp., leafhoppers

Secondary / Alternative (plant derived)

Componants

Evidence and Physiological benefits

Nectar (sugars)

(Wackers et al. 2008, Robinson et al. 2007)

Increased longevity in the absence of prey, at low prey density the pre-oviposition is decreased and the daily oviposition rate increased, increase in fecundity creating larger larval populations (also predatory)

(Robinson et al. 2007)

Extra Floral Nectar

(Wackers et al. 2008, Robinson et al. 2007)

Pollen (sugar, protein and all essential amino acids)

(Wackers et al. 2008, Robinson et al. 2007

Honeydew (sugary exudates)

(Wackers et al. 2008, Robinson et al. 2007

Mixed diets

(prey + plant)

Physiological benefits

Taxonomy: Diptera : Syrphidae

Life Stages : Larvae - Predatory, Adult - Nectivorous and Polliniferous

Nutrition

Primary

Prey (Larvae)

Aphididae spp. - (Only Syrphids in the subfamily Syrphinae (Helyer, Brown and Cattlin 2003))

Secondary / Alternative (plant derived)

Plant componants

Evidence and Physiological benefits

Nectar (sugars)

Wackers et al. 2008, Robinson et al. 2007

Extra Floral Nectar

Pollen (sugar, protein and all essential amino acids)

Wackers et al. 2008, Robinson et al. 2007

Honeydew (sugary exudates)

Wackers et al. 2008, Robinson et al. 2007

Mixed diets

(prey + plant)

Physiological benefits

Adults feed solely on nectar and pollen but oviposit in response to cues from aphids (Robinson et al. 2007)

Taxonomy: Diptera : Empididae

Life Stages : Larvae - Predatory, Adult - Nectivorous, Polliniferous, and predatory

Parasitoids - in progress

Parasitoids are similar to parasite in that they live on or in a host at the expense of the host organism. Characteristic that separate parasitoids from parasites and predators include: the parasitic behavior is expressed only during the larval stage, the adult is free living with few exceptions, the parasitoid larva kills and consumes it's host, the parasitoid typically consumes only one host (Gordh et al. 1999). The larva completes its development inside the host and emerges as a free living adult that feeds on nectar, honeydew and pollen. Adult parasitoids then continue the cycle by ovipositing in or on their associated host. Many species of parasitoids target hosts that are considered agricultural pests. However, due annual crop cycles that are synchronized with temporal pest occurrences, parasitoids do not always have hosts available……………………………….. insert info from peer reviews in parasitoid file here…………………………………………………………..

Major players (parasitoids) and their resource association -

Hymenoptera :

Ichneumonidae

Braconidae - Aphids and caterpillars, including European corn borer, armyworms, hornworms, diamondback moth, and corn rootworm, and leafminers (Gardiner et al. / MSU extension bulletin E2942 date)

Aphidiidae

(Chalcidoidea) : Aphelinidae and other families in this group parasitize aphids and other insect eggs

Host / Nutrition

Primary

Prey

Secondary / Alternative (plant derived)

Plant components

Evidence and Physiological benefits

Nectar (sugars)

Adults feed solely on nectar, pollen and honeydew, but when food deprived adults are not as receptive to host associated cues and without sugar their net reproduction is too low to maintain populations even with abundant hosts (Wackers et al. 2008)

Parasitoids require nectar and honeydew for survival and egg maturation (Vollhardt et al. 2009)

Extra Floral Nectar

Pollen (sugar, protein and all essential amino acids)

Wackers et al. 2008

Honeydew (sugary exudates)

Parasitoids use honeydew as a host location karimone and oviposition stimulus which simplifies their search task when seeking prey for oviposition (Wackers et al. 2008)

Mixed diets

(prey + plant)

Physiological benefits

Aphidiidae - In the absence of flowers and honeydew excretions from aphids; aphid parasitoids (Aphidiidae) starve. When only 1% of field is allocated to flowering species, the longevity of these parasitoids increased to 34% (with flowers located in the field margins), 51% ( when flowers were located within intercropping strips, and 97% (when flowers were located at random throughout the field.

With aphids present most of their time spent parasitizing and feeding on honeydew. (Vollhardt et al. 2009)

Other reasons to provide enough resources for a variety of insect ESP (especially biological control agents) to utilize:

Pollinators - in progress

It is estimated that one third of crops used for human food and 90% of flowering plants rely on pollination via animals for reproduction and the majority of this pollination is provided by insect species (Buchmann and Nabhan 1996). Insect mediated crop pollination is a valued ES and pollination services are delivered by managed honey bees, native bumble bees and a variety of wild native bees. Tuell et al. (2008) reports that 87 out of 115 crops raised for fruit, vegetable, or seed production are depend on insect pollinators for the dissemination of genetic material . In terms of dollar values, pollination services are assessed at $15 billion dollars for managed honey bees and $3.07 for non-managed bees. Crops known to benefit from hardy, native bee populations include alfalfa, apples, blueberries, canola, cherries, cranberries, cucumbers, pears, prunes, pumpkins, soybeans, squash, sunflowers (seeds), tomatoes, vegetables (seeds), and watermelons (USDA agroforestry bulletin 2006)

******The high demand for crop pollination has resulted in increased rental costs of honey bee colonies initiating the need for alternative or supplemental pollination services.

There is an estimated 4000 species of native bees that nest in the ground, twigs, wood, stems, cavities and plant residues (Ley and NAPPC). In order to ensure robust and functional populations of native pollinators at agricultural sites certain resources must be available during and beyond the growing season. Flowers provide nectar , containing sugar and required amino acids, and pollen, containing protein, making up vital components of a bee's diet. Integrating a variety of native, perennials in buffer strips and non-crop areas near cultivated cropland should include species that bloom at different times throughout the season providing bees with different phonologies the nutritional resources that synchronize with their seasonal activity. Along with nutritional needs, a variety of flowering species have the ability to attract diverse pollinator species by providing protective canopy layers, assorted flower architecture which compliments differences in mouthpart morphology, a variety of colors and fragrances, and nesting sites. ****** The combination of these landscape features enhance not only the abundance of pollinators for crop pollination, but boost the functionality, movement, longevity, and fecundity of individual bees.***********

Pollinators - Major players and their resource association -

PLANTS - in progress

Question: What plant species are currently used in buffer strips?

Preliminary research conducted at Iowa State University produced a survey of what plant species organic growers currently maintain in their buffer strips. The results of the survey show that these growers primarily use perennial grass species within buffer strips which provides limited habitat for beneficial insects. This information indicates that the potential ES that can be derived from these buffer strips is not fully realized and improvements can be made to foster the abundance of insect ESP (taken from grant).

Table 1. Common plant types used in organic buffer strips*

Plant category** Row crop*** Horticulture All

Grasses 52.5% 92.9% 60.0%

Legumes 34.4% 57.1% 38.7%

Shrubs/Trees 6.6% 28.6% 13.3%

Prairie/CRP 14.8% 7.1% 6.7%

Row Crop 9.8% 0.0% 12.0%

Other 4.9% 14.3% 6.7%

*The summarized answers are in response to the question "What do you plant and maintain in your buffer strips?"

**Plants used by growers within buffer strips were summarized by the most general category used in producer descriptions. Percentages within a column exceed 100% as producers may have listed multiple species.

(Other questions to consider) in progress

Question: What research provides evidence that buffer strips can be improved?

Many researchers and conservation agencies conducted tests to determine insect attractiveness and phonological associations with native, perennial plants. Planting native, perennial species have advantages

Question: What aspects require further investigation?

The combination of the most attractive species from Landis study.

Do all the most attractive need to be included (reduction plots)

Even though evidence suggests BI abundance increases with plant species diversity and continuous flowering resources, the function of prey removal showed variation is several studies. It is proposed that natural enemies may aggregate to areas with alternative prey abundance, but this does not always correlate with higher predation rates of pest prey due to favorable consumption of alternative prey and arrestment due to abundant food (Ostman 2004). Note to self - This may be evident in the reduction plots that provide "enough" resources to attract inset ESP and support populations when preferred pest prey is scarce, but limit resources just enough to promote migration to pests at damaging, out-break populations. In other words: aggregation versus mobility.

Question: How does the level of disturbance among different landscapes affect insect ESP and IMES? (objective 2)

Along with the quality of the habitat, the diversity of insect ESP at a given site also depends on the structure of the surrounding landscape (Dauber et al. 2003).In Iowa, organic farms are located within a landscape dominated by large-scale conventional farms and each type of farm differs regarding the level of habitat disturbance. In highly disturbed, conventional, agricultural landscapes pest outbreaks occur at with greater intensity due to the abundance of host plants. Since most of the natural enemies associated with biological control of pests utilize mixed diets by consuming prey and plant resources it is necessary to understand how natural enemies respond to the separation of resources assuming that less disturbed landscapes provide more plant related resources and highly disturbed areas provide more prey. Studies have shown that a low frequency of natural and semi-natural areas in agricultural landscapes inhibit the dispersal of species and functional groups of insects from the undisturbed areas into crops (Jackson et al. 2007). However, the implementation of a resource rich buffer strip, located between agricultural systems with high and low disturbance regimes, may act as a corridor for insect ESP. Landscape structure may influence the source-sink dynamics of insect ESP by facilitating or inhibiting the movement of the desired species which may have affect the evenness of IMES at a particular target site.

"The question of whether intensive or extensive agriculture best optimizes the various trade-offs associated with provision is an important issue requiring targeted research" ( Zhang et al. 2007)

Studies have shown that aphid ptoid - Aphidiidae exhibited a 9 fold increase in longevity achieving 97% of max life span (in absence of aphids and honeydew) when flowering resources were randomly assigned in field, compared to flower arranged in marginal strips and intercropping strips ((Vollhardt et al. 2010)

Random placement function as isles for sugar intake increasing energy for aphid search in the field. In the strip simulation, the ptoids starved because of their need to disperse to find hosts for oviposition they did not stay near flowers and aphids were absent. Even at really low aphid densities, ptoids found enough honey dew to survive. SO….

Does this occur with other natural enemies, will the more random resources at organic farms support ptoids and facilitate host parasitism or will abundant hosts in nearby conventional systems "steal" the ptoids.

Introduce specific projects here - ESA format for peer review

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Exams can be one of the most stressful experiences you’ll ever have! Revision is key, and we’re here to help. With custom created revision notes and exam answers, you’ll never feel underprepared again.