Designing landscapes to accommodate both humans and nature poses huge challenges but is increasingly recognised as an essential component of conservation and land management. The land-sparing land-sharing approach has been proposed as a tool to address this challenge. However, its focus on an ideal landscape configuration leaves a gap on what step-wise management decisions are needed to transform the existing landscape to reach that ideal endpoint. We provide a new conceptual framework amenable to the application of structured decision-making to identify the step-wise pathways between the present landscape and a desired landscape given a defined objective and fixed budget. The model can be parameterised for specific systems using information about: the current state of the landscape, the rates of change between landscape states, and the cost and effectiveness of taking actions. To demonstrate this, we apply it to three different landscape types and find that investment into one of three management actions (varying degrees of management and restoration) can move the system towards more biodiversity or more managed land depending on the objectives of the stakeholders. The dynamic and flexible nature of the framework makes it useful for decision-making in a land sparing land sharing context.

Agricultural systems have been continuously intensified to meet rising demand for agricultural products. However, there are increasing concerns that larger, more connected crop fields and loss of seminatural areas exacerbate pest pressure, but findings to date have been inconclusive. Even less is known about whether increased pest pressure results in measurable effects for farmers, such as increased insecticide use and decreased crop yield. Using extensive spatiotemporal data sampled every 2 to 3 d throughout five growing seasons in 373 cotton fields, we show that pests immigrated earlier and were more likely to occur in larger cotton fields embedded in landscapes with little seminatural area (<10%). Earlier pest immigration resulted in earlier spraying that was further linked to more sprays per season. Importantly, crop yield was the lowest in these intensified landscapes. Our results demonstrate that both environmental conservation and production objectives can be achieved in conventional agriculture by decreasing field sizes and maintaining seminatural vegetation in the surrounding landscapes.

Aedes aegypti (Linnaeus) was once highly prevalent across eastern Australia, resulting in epidemics of dengue fever. Drought conditions have led to a rapid rise in semi-permanent, urban water storage containers called rainwater tanks known to be critical larval habitat for the species. The presence of these larval habitats has increased the risk of establishment of highly urbanised, invasive mosquito vectors such as Ae. aegypti. Here we use a spatially explicit network model to examine the role that unsealed rainwater tanks may play in population connectivity of an Ae. aegypti invasion in suburbs of Brisbane, a major Australian city. We characterise movement between rainwater tanks as a diffusion-like process, limited by a maximum distance of movement, average life expectancy, and a probability that Ae. aegypti will cross wide open spaces such as roads. The simulation model was run against a number of scenarios that examined population spread through the rainwater tank network based on non-compliance rates of tanks (unsealed or sealed) and road grids. We show that Ae. aegypti tank infestation and population spread was greatest in areas of high tank density and road lengths were shortest e.g. cul-de-sacs. Rainwater tank non-compliance rates of over 30% show increased connectivity when compared to less than 10%, suggesting rainwater tanks non-compliance should be maintained under this level to minimize the spread of an invading Ae. aegypti population. These results presented as risk maps of Ae. aegypti spread across Brisbane, can assist health and government authorities on where to optimally target rainwater tank surveillance and educational activities.

Grasslands are valuable non-crop habitats in the world's agricultural regions, providing more than simply forage for grazing domestic and wild animals. They provide refuge and resources that support high levels of arthropod biodiversity, most importantly for natural enemies that provide vital biological control services to the surrounding cropped landscape. Ideally, farmers could manage and manipulate grasslands to boost their biocontrol services, although to achieve this, knowledge of the ecological function of these habitats is essential. Unfortunately, grasslands are often bundled together with other habitat types, such as scrubland and forest, under the label 'non-crop habitats', and little is known about the contribution that these specific habitats make towards landscape pest suppression. While recent research has been investigating the importance of other non-crop habitat such as native vegetation remnants, the contribution that grassland habitats may make towards landscape pest suppression remains a significant knowledge gap in biocontrol research. Here, the current understanding of grassland habitats as biological control service providers in the world's mixed farming systems is reviewed. Limited research into whether grassland habitats support natural enemies, and thus contribute biological control services to the adjacent surrounding cropped landscape, has returned inconclusive, even conflicting, results. Potential explanations for this inconsistency are explored, including the lack of studies, inadequate estimates of predator impact and the variety of different grassland habitat types studied, including their diversity in composition and management practices. Conclusions drawn from these studies are discussed, and suggestions for management are recommended, including increasing grassland floristic diversity, limiting intensive management practices and implementing weed control. Future research directions are proposed, along with the need to develop a universal grassland classification system for research, management and conservation purposes, using grassland type, floristic diversity and management practices as key axes for classification.

AbstractBACKGROUNDThe whitefly Bemisia tabaci is an important vector of virus diseases, impacting cassava production in East Africa. To date, breeding efforts in this region have focused on disease resistance. Here we use a spatially‐explicit simulation model to explore how breeding strategies for whitefly resistance will influence the population dynamics of whitefly in the context of regional variation in cassava crop management practices.RESULTSSimulations indicated that regions with a short cropping cycle and two cropping seasons per year were associated with high whitefly abundance. Nymph mortality and antixenosis resistance mechanisms were more effective than mechanisms that lead to longer whitefly development times. When spatial variation was introduced in heterogeneous landscapes, however, negative consequences of the antixenosis effect were observed in fields containing whitefly susceptible varieties, unless the proportion of whitefly resistant variety in the landscape was low (~10%) or the amount of matrix in the landscape was high (~75%).CONCLUSIONWe show the importance of considering cropping regime and landscape management context when developing and deploying whitefly‐resistant cassava varieties. Recommendations differ significantly between regions. There may also be unintended negative consequences of higher whitefly densities for whitefly susceptible varieties if uptake of the new variety in a landscape is high, depending on the mechanism of resistance and the landscape context. Furthermore, we show that in some cases, such as where there is substantial fallow combined with a short single‐season crop, the management characteristics of the existing cropping regime alone may be effective at controlling whitefly populations. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Designing landscapes to accommodate both humans and nature poses huge challenges, but is increasingly recognised as an essential component of conservation and land management. The land-sparing land-sharing framework has been proposed as a tool to address this challenge. However, it has been largely criticised for its simplicity. We provide a new conceptual framework amenable to the application of structured decision-making that moves beyond the dichotomy of land-sparing or land-sharing. Using this new framework, we present a general system model that can be used to make land management decisions for the conservation of species, ecosystem services and production land at different spatial scales. The model can be parameterised for specific systems using information about: the current state of the landscape, the rates of change between landscape states, and the cost and effectiveness of taking actions. To demonstrate the utility of the model we apply it to three different landscape types. Across our three case studies, we show that investment into one of three management actions (varying degrees of management and restoration) can move the system towards more biodiversity or more managed land depending on the objectives of the land manager. We show that the dynamic and flexible nature of the landscape is important to take into account rather than a static snapshot in time. Rather than focusing on establishing the perfect landscape with a set proportion dedicated to production and to biodiversity conservation, we argue that a more useful approach is to establish incremental movements towards a landscape that meets the goals of multiple objectives. Our framework can be used to illustrate to decision makers the costs and trade-offs of different actions and help them determine land management policy.

Arthropod predators and parasitoids support the health and functioning of the world's ecosystems, most notably by supplying biological control services to agricultural landscapes. Quantifying the impact that these organisms have on their prey can be challenging, as direct observation and measurement of arthropod predation is difficult. The use of sentinel prey is one method to measure predator impact; however, despite widespread use, few studies have compared predation on different prey types within a single experiment. This study evaluated the predation rates on four sentinel prey items in grass and wheat fields in south-east Queensland, Australia. Attack rates on live and dead Helicoverpa armigera eggs, and dead H. armigera larvae and artificial plasticine larvae, were compared and the predators that were attracted to each prey type were documented with the use of field cameras. There was no significant difference in predation rates between sentinel eggs, while dead larvae were significantly more attacked than artificial larvae. Prey were attacked by a diverse range of predators, including ants, beetles, various nymph and juvenile insects and small mammals. Different predators were active in grass and crop fields, with predator activity peaking around dawn and dusk. The same trends were observed within and between the two habitats studied, providing a measure of confidence in the sentinel prey method. A range of different sentinel prey types could be suitable for use in most comparative studies; however, each prey type has its own benefits and limitations, and these should be carefully evaluated to determine which is most suitable to address the research questions.

Area-wide integrated pest management (AW-IPM) of insect pests relies on surveillance and communication to estimate wild population size, guide targeted control, and determine the effectiveness of any pest control action.However, knowing where and when pests arrive in real-time, communicating the information quickly, and delivering insect pest control in a coordinated manner are potential barriers to achieving areawide management.Agricultural technology is creating opportunities to remove these barriers, which in turn will facilitate the adoption of AW-IPM.Technology advances in insect surveillance (detection and monitoring), data flow and information communication are being realized, and increasingly becoming commercially available.This technological change is largely being driven by macro-economic trends of increased cost of labour, international agricultural trade and shifting consumer demands, and a confluence of new hardware technologies that free computation from the desktop.As professionals and practitioners of pest management, there is an opportunity to shape technological solutions to remove barriers to AW-IPM, and to achieve sustainable pest management across commodities and pests.Yet, the success of the technological solution and its area-wide implementation will depend on the way that we think about the problem (innovation), and the solutions (engineering).

Despite decades of study, conservation biocontrol via manipulation of landscape elements has not become a mainstream strategy for pest control. Meanwhile, conservation groups and governments rarely consider the impacts of land management on pest control, and growers can even fear that conservation biocontrol strategies may exacerbate pest problems. By finding leverage points among these actors, there may be opportunities to align them to promote more widespread adoption of conservation biological control at the landscape-scale. But are ecologists measuring the right things and presenting the right evidence to enable such alignment? We articulate key concerns of growers, conservation groups, and governments with regards to implementing conservation biological control at the landscape scale and argue that if ecologists want to gain more traction, we need to reconsider what we measure, for what goals, and for which audiences. A wider set of landscape objectives that ecologists should consider in our measurements include risk management for growers and co-benefits of multifunctional landscapes for public actors. Ecologists need to shift our paradigm toward longer-term, dynamic measurements, and build cross-disciplinary understanding with socioeconomic and behavioral sciences, to enable better integration of the objectives of these diverse actors that will be necessary for landscape management for conservation biocontrol to achieve its full potential.

To enhance biological pest control in crop fields, it is recommended to increase semi-natural area on farm and decrease insecticide spraying. While the benefits of semi-natural area for biocontrol in unsprayed fields are often demonstrated, it remains largely unknown if there are any benefits in real-world, commonly sprayed crops. Here, we explored the combined effects of semi-natural field margins and insecticide spraying on pest (cotton bollworm) egg predation in 53 Australian cotton fields and semi-natural field margins across 2 years. We used predation experiments close to field edges to exclude functional groups of predators depending on their spatio-temporal activity (diurnal vs. nocturnal and ground vs. canopy dwelling) and digital cameras to record natural enemy taxa responsible for predation. Ground predation was substantially higher than canopy predation and its magnitude in unsprayed crops with semi-natural margins was similar to that within semi-natural areas. In contrast, semi-natural field margins did not benefit biocontrol in sprayed crop fields and did not influence recovery rate of biocontrol after spraying. Within ground-dwelling predators, one dominant taxon contributed the most to biocontrol at a particular time and place. However, the dominant predator-prey interactions changed between day and night and fields with and without margins, thus indicating increased importance of additional predator taxa with increasing spatio-temporal scales. Synthesis and applications. Our results show that semi-natural margins benefit pest control only in unsprayed fields. Spraying at different time (e.g. during night) would not reduce the negative effects of insecticides because it would affect complementary group of nocturnal natural enemies that exert equally high biocontrol as diurnal ground-dwelling predators. We highlight the need for management recommendations to simultaneously consider pros and cons of within-field spraying and surrounding semi-natural habitats to maximize their benefits in high-input conventional production systems.

Urban landscape features play an important role in the distribution and population spread of mosquito vectors. Furthermore, current insecticide and novel rear-and-release strategies for urban mosquito management rarely consider the spatial structure of the landscape when applying control practices. Here, we undertake a mark-recapture experiment to examine how urban features influence the movement and distribution of Australian container-inhabiting Aedes vectors. We pay attention to the role of semipermanent water storage containers, called rainwater tanks, and the influence of movement barriers, such as roads, on the spread and distribution of vector populations. Results suggest that Aedes aegypti (Linnaeus) (Diptera: Culicidae) were more likely to be captured around rainwater tanks, and that released males travel throughout residential blocks but do not cross roads. Conversely, female Aedes notoscriptus (Skuse) (Diptera: Culicidae) movement was uninhibited by roads and rainwater tanks did not influence female distribution or oviposition behavior. Using an isotropic Gaussian kernel framework, we show that vector movement is likely to be greater when applying a temporal effect, than when estimated by traditional methods. We conclude that a greater understanding on the role of urban features on vector movement will be important in the new age of rear-and-release mosquito control strategies, particularly those where estimations of movement are important for ensuring efficacy of application.

While pest management tends to focus on pests that are already present in crops, non‐crop hosts may play a crucial role in supporting pest populations outside the crop growing season. Non‐crop hosts may allow pest populations to persist throughout the year, build‐up and colonise crops after emergence. Here, we assess the hosts of the Rutherglen bug, Nysius vinitor Bergroth, which is a polyphagous native insect pest of growing economic importance in Australia. We conducted a literature review on the occurrence of N. vinitor on crop and non‐crop hosts and analysed field survey data on N. vinitor abundance from two independent field studies in three agricultural regions of Australia. We differentiated between juvenile (nymph) and adult stages to consider the function of plants as reproduction sites. The literature review resulted in reports of N. vinitor on 44 crop species from 18 plant families. Pigweed Portulaca oleracea and capeweed Arctotheca calendula were the most cited weed hosts. In the field study, N. vinitor was primarily found on exotic weeds and grasses within pastures, Lucerne and degraded native vegetation remnants. While N. vinitor was found on a total of 16 weed plant families, juvenile stages of N. vinitor were most often observed on fleabane ( Conyza spp.), goosefoot Chenopodium pumilio (Amaranthaceae) and plants of the Asteraceae family, indicating that these are important host plants for N. vinitor reproduction. Grasses appear to be an important but understudied host plant group; citations in the literature do not reflect the extent to which N. vinitor was found on grasses in the field. In contrast, the field survey indicated that very few native plant species supported N. vinitor , which was consistent across regions and confirms findings from the literature review. Our findings suggest that exotic weeds and grasses (but not native plants) play a key role in supporting N. vinitor populations in Australian agricultural landscapes. Reducing exotic weeds in pastures and non‐crop habitats may limit breeding opportunities of N. vinitor and may be an important component in the area‐wide management of this polyphagous pest.

New technologies for insect pest management, such as Sterile Insect Technique (SIT), present an opportunity to reduce chemical use in agricultural landscapes. However, they require socio-economic and ecological evaluation to ensure they are effective. We present a decision-making framework for sterile Queensland fruit fly \u0027Qfly\u0027 (Bactrocera tryoni) release informed by both economic and biophysical models as part of an area-wide management (AWM) program with SIT. The conceptual framework presented here guided the development of economic and biophysical models to meet the objective of informing management strategies. Our economic modelling has provided an important assessment of the feasibility and opportunities for AWM and SIT at the scale of three case study regions in southern Australia (Sunraysia, Murray/Goulburn valley (MGV) and Riverland). We found that there are three potential economically-viable implementation strategies for AWM of Qfly including SIT: Outbreak eradication (and potentially maintenance of area freedom, should legislation allow); direct substitution for existing management techniques in spatially-isolated contexts (including in support of industry-specific market access); and more effective management in an urban context than existing ad hoc approaches. In terms of releases of sterile males, our biophysical research has generated valuable risk maps for three case study regions. An understanding of the spatial and temporal risk of Qfly occurrence for a given target region is essential to the development of a future tool or system for planning sterile fly releases, as well as for ongoing management and monitoring programs. As a minimum, knowledge of the land use, climatic suitability and host phenology in a region is required. Ideally, this should incorporate the construction of risk maps that can inform decision-making for releases. The spatial simulation modelling showed that complex landscapes, containing a higher diversity of fruiting hosts across different seasons, will pose greater challenges in achieving population suppression and adoption of AWM strategies in readiness for SIT. Urban areas pose a significant challenge, as these areas provide a reservoir of flies throughout the year with potential to move into nearby crops. Therefore, it is important that they are managed as part of an AWM approach (potentially employing SIT) in order to effectively suppress flies across a landscape. The model identifies potential hotspots and bottlenecks in space and time which can be used to develop more targeted and effective SIT release strategies. We show that an urban treatment is most effective when reducing populations in late winter/early spring before they can move into the agricultural area. Our work highlights the importance of a conceptual framework that provides a broad consideration of the economic, social, and biological feasibility of a SIT program prior to the release of sterile flies using modelling approaches, as well as an ongoing need to consider the socioeconomic and biophysical components of the system for sterile Qfly releases to be successful. This work led to the development of online guidelines for area-wide management (AWM) of Qfly incorporating Sterile Insect Technique (SIT) in Australia www.area-wide-management.com.au.

A key determinant of insect persistence in marginal habitats is the ability to tolerate environmental extremes such as temperature. Aedes aegypti is highly invasive and little is known about the physiological sensitivity of the species to fluctuating temperature regimes at the lower critical threshold for development. A temperature that may limit the establishment and persistence of the species in sub-optimal regions. Daily winter temperatures were measured in common Australian larval habitats, replicated in environmental chambers and used to investigate the effect of fluctuating temperatures on the development and survival of tropical and subtropical strains of Australian Ae. aegypti. Development was slow for all treatments but both strains were able to complete development to the adult stage, suggesting previous models underestimate the potential for the species to persist in eastern Australia. Results suggested that thermal buffering in large volume habitats, and water that persists for greater than 32 days, will facilitate completion of the life cycle during sub-tropical winters. Furthermore, we provide a non-linear estimate of the lower critical temperature for Ae. aegypti development that suggests the current threshold may be incorrect. Our study demonstrates that the current re-introduction of water storage containers such as rainwater tanks, into major Australian population centres will increase the risk of Ae. aegypti establishment by permitting year-round development in locations south of its current distribution.

Context Animal population dynamics are shaped by their movement decisions in response to spatial and temporal resource availability across landscapes. The sporadic availability and diversity of resources can create highly dynamic systems. This is especially true in agro-ecological landscapes where the dynamic interplay of insect movement and heterogeneous landscapes hampers prediction of their spatio-temporal dynamics and population size. Objectives We therefore systematically looked at population-level consequences of different movement strategies in temporally-dynamic resource landscapes for an insect species whose movement strategy is slightly understood: the Queensland Fruit Fly ( Bactrocera tryoni ) Methods We developed a spatially-explicit model to predict changes in population dynamics and sizes in response to varying resources across a landscape. We simulated the temporal dynamics of fruit trees as the main resource using empirical fruiting dates. Movement strategies were derived from general principles and varied in directedness of movement and movement trigger. Results We showed that temporal continuity in resource availability was the main contributing factor for large and persistent populations. This explicitly included presence of continuous low-density resources such as fruit trees in urban areas. Analysing trapping data from SE Australia supported this finding. We also found strong effects of movement strategies, with directed movement supporting higher population densities. Conclusions These results give insight into structuring processes of spatial population dynamics of Queensland Fruit Fly in realistic and complex food production landscapes, but can also be extended to other systems. Such mechanistic understanding will help to improve forecasting of spatio-temporal hotspots and bottlenecks and will, in the end, enable more targeted population management.

Around the world, several pest tephritids are extending their ranges from warm tropical or Mediterranean climates into cooler temperate regions. The ability to tolerate climatic diversity is uncommon among insects, and understanding the population phenology drivers of such species across different parts of their range will be critical for their management. Here, we determined the role of temperature versus fruit availability on the population phenology of Queensland fruit fly, Bactrocera tryoni. Using a field site located at the subtropical/temperate interface, with host fruits continuously available, we monitored the development times and abundance of B. tryoni, a species which has invaded temperate Australia from the tropics. From fruit samples held at ambient and controlled conditions, the abundance of emerging flies was highly variable among collection dates, but the variance did not reflect the observed changes in temperature. For most samples, the survival rate of flies in a field site was lower than predicted by a day-degree population model fitted with mean daily field temperatures. The development time of the immature stage in the field was prolonged, presumably due to cooler ambient conditions, but the fitted day-degree population model consistently over-predicted estimated development times. Our results indicate that at the subtropical/temperate interface, the decline in B. tryoni populations during winter is only partly driven by temperature and host availability. We classify B. tryoni as a climate generalist, which likely employs physiological as well as behavioural mechanisms to achieve broad climatic tolerance ranges.

The idea that noncrop habitat enhances pest control and represents a win-win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win-win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies.

Semi-natural areas surrounding field crops are generally shown to enhance natural enemies of pests and biocontrol services within field crops worldwide. However, most of the evidence comes from work conducted in temperate regions of the northern hemisphere and it remains unclear to what extent these conclusions hold true in other parts of the world. Here, we provide an overview of the research in Australia investigating the link between populations of pests and their natural enemies and the type, quality, quantity and spatial arrangement of non-crop habitats surrounding field crops. There is strong evidence in Australia that exotic weeds support multiple pest species, but the link between weediness of semi-natural habitats and biological pest control within field crops remains to be investigated. Further, woody vegetation in good condition (not grazed, with mid- and under-story and good ground cover) appears to supports multiple natural enemies that move into crops, especially when in close proximity to the crop. The role of grasslands is less conclusive, and in some cases, other crops, such as lucerne, may play a major role for biocontrol within neighbouring crops. At the landscape scale, proportion of non-crop vegetation had opposing results at different spatial scales and for different natural enemies. However, the research investigating landscape composition is scarce, particularly in relation to biological pest control. We conclude that non-crop vegetation in a good condition is critical for developing solutions for improving biological pest control and reducing risk of pest outbreaks, but more research is needed to understand the mechanisms and develop reliable recommendations.

Early-season immigration into arable fields by natural enemies is key for effective biocontrol, but little is known about the mechanisms underlying immigration processes.