Field evaluation of female- and male-targeted traps for Ceratitis capitata (Diptera: Tephritidae).

Mediterranean fruit fly (Medfly) Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is a globally significant economic pest for which lure based trapping can be used to monitor established populations and for surveillance. Either female- or male-targeted traps can be used; however, recommendations on which to apply are inconsistent and many programs rely on male-targeted traps. Here, we compare the performance of male-targeted traps (Lynfield Trap with Trimedlure) and female-targeted traps (Biotrap Globe trap with the 3-component lure-TMA Plus) in apple orchards in south-west Western Australia over 2 years (September 2019 to September 2021). Male-targeted traps caught more Medflies overall than female-targeted traps, although the difference was minor. However, female-targeted traps were better at attracting Medfly early in the season when populations were small; and were more likely to capture at least one fly when their paired male-targeted trap caught none. Conversely, male-targeted traps were more likely to capture Medflies late in the season and were more likely to catch high numbers of Medflies. Consequently, female-targeted traps may be better at detecting Medfly early in the season, and male-targeted traps may be better at detecting Medfly abundance late in the season, at least in apple orchards. Our results suggest that either or both trap-types could be used for monitoring Medfly populations, with the optimal solution being dependent on the intended application.

Simulation to investigate site-based monitoring of pest insect species for trade.

Pest insect surveillance using lures is widely used to support market access requirements for traded articles that are hosts or carriers of quarantine pests. Modeling has been used extensively to guide the design of surveillance to support pest free area claims but is less commonly applied to provide confidence in pest freedom or low pest prevalence within sites registered for trade. Site-based surveillance typically needs to detect pests that are already present in the site or that may be entering the site from surrounding areas. We assessed the ability of site-based surveillance strategies to detect pests originating from within or outside the registered site using a probabilistic trapping network simulation model with random-walk insect movement and biologically realistic parameters. For a given release size, time-dependent detection probability was primarily determined by trap density and lure attractiveness, whereas mean step size (daily dispersal) had limited effect. Results were robust to site shape and size. For pests already within the site, detection was most sensitive using regularly spaced traps. Perimeter traps performed best for detecting pests moving into the site, although the importance of trap arrangement decreased with time from release, and random trap placement performed relatively well compared to regularly spaced traps. High detection probabilities were achievable within 7 days using realistic values for lure attractiveness and trap density. These findings, together with the modeling approach, can guide the development of internationally agreed principles for designing site-based surveillance of lure-attractant pests that is calibrated against the risk of non-detection.

Radiographic areal density measurements on the OMEGA EP laser system.

We describe two orthogonal radiography geometries at the OMEGA EP laser facility, which we refer to as side-on and face-on radiography. This setup can be used to determine quantitative information about the areal densities in solid, particulate, or liquid samples. We show sample images from these two different platforms that use the radiography diagnostic, one of material microjetting by the Richtmeyer-Meshkov instability and one of a deforming tin sample by the Rayleigh-Taylor instability, demonstrating the versatile applicability of such measurements in the field of high-energy density physics. The analytical methodology behind the quantitative Rayleigh-Taylor face-on radiography is also demonstrated and can be applied to other types of samples.

Lifecycle of the invasive omnivore, Forficula auricularia, in Australian grain growing environments.

BACKGROUND: The European earwig, Forficula auricularia (L.) (Dermaptera: Forficulidae), is regarded as an important beneficial in many orchard environments but has the potential to be a plant pest in other systems, including to grain crops. Due to its agricultural importance, the lifecycle of F. auricularia has been widely studied in North America and Europe. However, much less is known in the southern hemisphere, including Australia where F. auricularia has been present for over 170 years. RESULTS: To elucidate the lifecycle of F. auricularia, we monitored five sites in grain-growing areas of southern Australia using two different trap types. Adults were found year-round, but most prevalent from late-spring to mid-winter. First instars were typically found from mid to late winter. Second, third and fourth instars occurred from winter through to late spring. The seasonal development of F. auricularia in Australia may be much earlier than observed in comparable North American studies. Degree day modelling highlights variation in development times across the active season for F. auricularia across our sites. CONCLUSION: Forficula auricularia is well adapted to the Australian grain growing environments. The timing of egg hatching aligns closely with crop emergence, juveniles then develop alongside the crop, and adult development occurs by harvest time in late spring. These findings are important given that many of these crops (canola, lucerne, pulses) are vulnerable to attack by F. auricularia during emergence and development. They also suggest a phenotypic capacity of this species to adapt different phenology after introduction into a novel environment. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

A streaked parabolic crystal imaging diagnostic at the Orion laser.

We report on a novel scheme for the imaging of soft X-rays using a parabolic crystal coupled to a fast X-ray streak camera. The merits of parabolic, and more generally aspheric imaging, are discussed in relation to conventional spherical schemes and calculations used to show the advantages. An example of such a system has been designed and built at the Orion laser, AWE Aldermaston, UK. The system's parameters are set out, and the approaches to the operational challenges are presented. The system has been used on high-energy density physics experiments to measure the release isentrope of warm dense matter states. Time-integrated and temporally resolved results are shown, demonstrating 5 µm spatial resolution (6 µm across a 200 µm field-of-view) and 10 ps temporal resolution. A discussion of the resolution-limiting factors is presented, along with possible applications and future improvements.

Climate, human influence and the distribution limits of the invasive European earwig, Forficula auricularia, in Australia.

BACKGROUND: By modelling species-environment relationships of pest species, it is possible to understand potential limits to their distributions when they invade new regions, and their likely continued spread. The European earwig, Forficula auricularia, is a non-native invasive species in Australia that has been in the country for over 170 years. However, in the last few decades it has invaded new areas. Unlike in other countries, F. auricularia is a pest species of grain production in Australia. In this study we detail the Australian distribution of this species, adding new samples focused around grain-growing regions. Using this information, we build global species distribution models for F. auricularia to better understand species-environment relationships. RESULTS: Our models indicate that the distribution of F. auricularia is strongly associated with temperate through to semi-arid environments, a high winter rainfall and pronounced temperature seasonality. We identified regions that hold suitable, but as yet vacant, niche space for Australian populations, suggesting further potential for range expansion. Beyond climate, an index describing human influence on the landscape was important to understand the distribution limits of this pest. We identified regions where there was suitable climate space, but which F. auricularia has not occupied, probably due to low levels of human impact. CONCLUSION: Modelling the global distribution of a non-native pest species aided understanding of the regional distribution limits within Australia and highlighted the usefulness of human impact measures for modelling globally invasive insect species. © 2018 Society of Chemical Industry.

Assessing the current and future biological control potential of Trichogramma ostriniae on its hosts Ostrinia furnacalis and Ostrinia nubilalis.

BACKGROUND: Understanding interactions between biocontrol agents and their pest hosts under climate change should assist implementation of biocontrol strategies, by identifying appropriate biocontrol agents for release or determining the optimal timing of releases. Species distribution models (SDMs) were applied to evaluate the distributions of Trichogramma ostriniae and its native host, Ostrinia furnacalis, in southeastern Asia, and a non-native host, Ostrinia nubilalis, in a novel range, North America, using MAXENT and CLIMEX modelling approaches. RESULTS: The models led to similar predictions about the expected distribution of the two species in Asia, and emphasized likely mismatches between host and natural enemy. Trichogramma ostriniae was predicted to occur in the summer corn region of China, with distribution limits linked to its sensitivity to cold, seasonality of radiation and precipitation. The modelled Ostrinia nubilalis distribution overlapped with the main corn production areas of the northeastern USA and Canada; temporary/seasonal suitable habitat was also predicted across the southeastern USA. Climate change scenarios are predicted to favour T. ostriniae over its hosts in northeastern China and North America. CONCLUSION: The modelling approaches used here proved useful for assessing environmental factors linked to an egg parasitoid and its lepidopteran hosts and identifying areas potentially suitable for inundative releases. © 2017 Society of Chemical Industry.

Broad spectrum pesticide application alters natural enemy communities and may facilitate secondary pest outbreaks.

BACKGROUND: Pesticide application is the dominant control method for arthropod pests in broad-acre arable systems. In Australia, organophosphate pesticides are often applied either prophylactically, or reactively, including at higher concentrations, to control crop establishment pests such as false wireworms and earth mite species. Organophosphates are reported to be disruptive to beneficial species, such as natural enemies, but this has not been widely assessed in Australian systems. Neither has the risk that secondary outbreaks may occur if the natural enemy community composition or function is altered. METHODS: We examine the abundance of ground-dwelling invertebrate communities in an arable field over successive seasons under rotation; barley, two years of wheat, then canola. Two organophosphates (chlorpyrifos and methidathion) were initially applied at recommended rates. After no discernible impact on target pest species, the rate for chlorpyrifos was doubled to elicit a definitive response to a level used at establishment when seedling damage is observed. Invertebrates were sampled using pitfalls and refuge traps throughout the experiments. We applied measures of community diversity, principal response curves and multiple generalised linear modelling techniques to understand the changes in pest and natural enemy communities. RESULTS: There was large variability due to seasonality and crop type. Nevertheless, both pest (e.g., mites and aphids) and natural enemy (e.g., predatory beetles) invertebrate communities were significantly affected by application of organophosphates. When the rate of chlorpyrifos was increased there was a reduction in the number of beetles that predate on slug populations. Slugs displayed opposite trends to many of the other target pests, and actually increased in numbers under the higher rates of chlorpyrifos in comparison to the other treatments. Slug numbers in the final rotation of canola resulted in significant yield loss regardless of pesticide application. DISCUSSION: Organophosphates are a cost-effective tool to control emergent pests in broad-acre arable systems in Australia. We found risks associated with prophylactic application in fields under rotation between different crop types and significant changes to the community of pests and natural enemy. Disrupting key predators reduced effective suppression of other pests, such as slugs, and may lead to secondary outbreaks when rotating with susceptible crops such as canola. Such non-target impacts are rarely documented when studies focus on single-species, rather than community assessments. This study represents a single demonstration of how pesticide application can lead to secondary outbreaks and reinforces the need for studies that include a longer temporal component to understand this process further.

Divergent thermal specialisation of two South African entomopathogenic nematodes.

Thermal physiology of entomopathogenic nematodes (EPN) is a critical aspect of field performance and fitness. Thermal limits for survival and activity, and the ability of these limits to adjust (i.e., show phenotypic flexibility) depending on recent thermal history, are generally poorly established, especially for non-model nematode species. Here we report the acute thermal limits for survival, and the thermal acclimation-related plasticity thereof for two key endemic South African EPN species, Steinernema yirgalemense and Heterorhabditis zealandica. Results including LT50 indicate S. yirgalemense (LT50 = 40.8 ± 0.3 °C) has greater high temperature tolerance than H. zealandica (LT50 = 36.7 ± 0.2 °C), but S. yirgalemense (LT50 = -2.4 ± 0 °C) has poorer low temperature tolerance in comparison to H. zealandica (LT50 = -9.7 ± 0.3 °C), suggesting these two EPN species occupy divergent thermal niches to one another. Acclimation had both negative and positive effects on temperature stress survival of both species, although the overall variation meant that many of these effects were non-significant. There was no indication of a consistent loss of plasticity with improved basal thermal tolerance for either species at upper lethal temperatures. At lower temperatures measured for H. zealandica, the 5 °C acclimation lowered survival until below -12.5 °C, where after it increased survival. Such results indicate that the thermal niche breadth of EPN species can differ significantly depending on recent thermal conditions, and should be characterized across a broad range of species to understand the evolution of thermal limits to performance and survival in this group.

Niche overlap of congeneric invaders supports a single-species hypothesis and provides insight into future invasion risk: implications for global management of the Bactrocera dorsalis complex.

BACKGROUND: The invasive fruit fly, Bactrocera invadens, has expanded its range rapidly over the past 10 years. Here we aimed to determine if the recent range expansion of Bactrocera invadens into southern Africa can be better understood through niche exploration tools, ecological niche models (ENMs), and through incorporating information about Bactrocera dorsalis s.s., a putative conspecific species from Asia. We test for niche overlap of environmental variables between Bactrocera invadens and Bactrocera dorsalis s.s. as well as two other putative conspecific species, Bactrocera philippinensis and B. papayae. We examine overlap and similarity in the geographical expression of each species' realised niche through reciprocal distribution models between Africa and Asia. We explore different geographical backgrounds, environmental variables and model complexity with multiple and single Bactrocera species hypotheses in an attempt to predict the recent range expansion of B. invadens into northern parts of South Africa. PRINCIPAL FINDINGS: Bactrocera invadens has a high degree of niche overlap with B. dorsalis s.s. (and B. philippinensis and B. papayae). Ecological niche models built for Bactrocera dorsalis s.s. have high transferability to describe the range of B. invadens, and B. invadens is able to project to the core range of B. dorsalis s.s. The ENMs of both Bactrocera dorsalis and B. dorsalis combined with B. philipenesis and B. papayae have significantly higher predictive ability to capture the distribution points in South Africa than for B. invadens alone. CONCLUSIONS/SIGNIFICANCE: Consistent with other studies proposing these Bactrocera species as conspecific, niche similarity and overlap between these species is high. Considering these other Bactrocera dorsalis complex species simultaneously better describes the range expansion and invasion potential of B. invadens in South Africa. We suggest that these species should be considered the same-at least functionally-and global quarantine and management strategies applied equally to these Bactrocera species.