Forest Insect Biosecurity: Processes, Patterns, Predictions, Pitfalls

Using eDNA to play whack-a-mole with invasive species in green yard waste

As large cities begin to overrun their landfill capacities, they begin to look for alternative locations to handle the waste stream. Seeing an opportunity to bring in revenue, rural communities offer to handle municipal waste in their landfills. However, many rural communities are also places of agricultural production, which are vulnerable to attacks by invasive insect species, which could be present in green yard waste, the component of municipal waste most likely to contain agriculturally harmful insect species. We used environmental DNA (eDNA) to determine whether green yard waste could be a pathway for invasive insect species to enter and establish in the landfill-receiving agricultural community. We identified several target species that could be in green yard waste coming from Vancouver, BC, Canada, to Central Washington State, USA. We sampled green yard waste from 3 sites every 2 weeks from June to October in 2019 and 2020. DNA was extracted from the nearly 400 samples and subjected to amplification with COI barcoding primers followed by sequencing to identify target insects in the samples. Sequence analyses identified 3 species from the target list: 2 species that are pests of deciduous tree fruits and a generalist root-feeding crop pest. This eDNA technique was useful in identifying potential invasive species in green yard waste and may prove to be an important tool informing policy on the movement of biological material across borders and stemming the spread of invasive species.

Risk of spread of the Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Liviidae) in Ghana

The impact of invasive species on biodiversity, food security and economy is increasingly noticeable in various regions of the globe as a consequence of climate change. Yet, there is limited research on how climate change affects the distribution of the invasive Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera:Liviidae) in Ghana. Using maxnet package to fit the Maxent model in R software, we answered the following questions; (i) what are the main drivers for D. citri distribution, (ii) what are the D. citri-specific habitat requirements and (iii) how well do the risk maps fit with what we know to be correctly based on the available evidence?. We found that temperature seasonality (Bio04), mean temperature of warmest quarter (Bio10), precipitation of driest quarter (Bio17), moderate resolution imaging spectroradiometer land cover and precipitation seasonality (Bio15), were the most important drivers of D. citri distribution. The results follow the known distribution records of the pest with potential expansion of habitat suitability in the future. Because many invasive species, including D. citri, can adapt to the changing climates, our findings can serve as a guide for surveillance, tracking and prevention of D. citri spread in Ghana.

The pyrexia channel remodels egg-laying of Liriomyza huidobrensis in response to temperature change

BACKGROUND

The pea leafminer, Liriomyza huidobrensis, is one of the most important insect pests on vegetables and ornamentals. The survival and egg-laying behavior of leafminers are markedly affected by the environment temperature. However, the mechanisms underlying the relationship between egg-laying and temperature are still largely unknown.

RESULTS

Here, we find that leafminers have evolved an adaptive strategy to overcome the stress from high or low temperature by regulating oviposition-punching plasticity. We further show that this oviposition-punching plasticity is mediated by the expression of pyx in the ovipositor when subjected to disadvantageous temperature. Specifically, down-regulation of pyx expression in leafminers under low temperature stress led to a significant decrease in the swing numbers of ovipositor and puncture area of the egg spot, and consequently the lower amount of egg-laying compared to leafminers at ambient temperature. Conversely, activation of pyx expression under high temperature stress increased the swing numbers and puncture area, still resulting in a reduction of egg-laying amount.

CONCLUSION

Thereby, leafminers are able to coordinate pyx channel expression level and accordingly depress the oviposition. Our study uncovers a molecular mechanism underlying the adaptive strategy in insects that can avoid disadvantageous temperature for reproducing offspring. © 2024 Society of Chemical Industry.

Optimal allocation of resources among general and species-specific tools for plant pest biosecurity surveillance

This paper proposes a surveillance model for plant pests that can optimally allocate resources among survey tools with varying properties. While some survey tools are highly specific for the detection of a single pest species, others are more generalized. There is considerable variation in the cost and sensitivity of these tools, but there are no guidelines or frameworks for identifying which tools are most cost-effective when used in surveillance programs that target the detection of newly invaded populations. To address this gap, we applied our model to design a trapping surveillance program in New Zealand for bark- and wood-boring insects, some of the most serious forest pests worldwide. Our findings show that exclusively utilizing generalized traps (GTs) proves to be highly cost-effective across a wide range of scenarios, particularly when they are capable of capturing all pest species. Implementing surveillance programs that only employ specialized traps (ST) is cost-effective only when these traps can detect highly damaging pests. However, even in such cases, they significantly lag in cost-effectiveness compared to GT-only programs due to their restricted coverage. When both GTs and STs are used in an integrated surveillance program, the total expected cost (TEC) generally diminishes when compared to programs relying on a single type of trap. However, this relative reduction in TEC is only marginally larger than that achieved with GT-only programs, as long as highly damaging species can be detected by GTs. The proportion of STs among the optimal required traps fluctuates based on several factors, including the relative pricing of GTs and STs, pest arrival rates, potential damage, and, more prominently, the coverage capacity of GTs. Our analysis suggests that deploying GTs extensively across landscapes appears to be more cost-effective in areas with either very high or very low levels of relative risk density, potential damage, and arrival rate. Finally, STs are less likely to be required when the pests that are detected by those tools have a higher likelihood of successful eradication because delaying detection becomes less costly for these species.

Emerging advances in biosecurity to underpin human, animal, plant, and ecosystem health

One Biosecurity is an interdisciplinary approach to policy and research that builds on the interconnections between human, animal, plant, and ecosystem health to effectively prevent and mitigate the impacts of invasive alien species. To support this approach requires that key cross-sectoral research innovations be identified and prioritized. Following an interdisciplinary horizon scan for emerging research that underpins One Biosecurity, four major interlinked advances were identified: implementation of new surveillance technologies adopting state-of-the-art sensors connected to the Internet of Things, deployable handheld molecular and genomic tracing tools, the incorporation of wellbeing and diverse human values into biosecurity decision-making, and sophisticated socio-environmental models and data capture. The relevance and applicability of these innovations to address threats from pathogens, pests, and weeds in both terrestrial and aquatic ecosystems emphasize the opportunity to build critical mass around interdisciplinary teams at a global scale that can rapidly advance science solutions targeting biosecurity threats.

A CNN-Based Method for Enhancing Boring Vibration with Time-Domain Convolution-Augmented Transformer

Recording vibration signals induced by larvae activity in the trunk has proven to be an efficient method for detecting trunk-boring insects. However, the accuracy of the detection is often limited because the signals collected in real-world environments are heavily disrupted by environmental noises. To deal with this problem, we propose a deep-learning-based model that enhances trunk-boring vibration signals, incorporating an attention mechanism to optimize its performance. The training data utilized in this research consist of the boring vibrations of Agrilus planipennis larvae recorded within trunk sections, as well as various environmental noises that are typical of the natural habitats of trees. We mixed them at different signal-to-noise ratios (SNRs) to simulate the realistically collected sounds. The SNR of the enhanced boring vibrations can reach up to 17.84 dB after being enhanced by our model, and this model can restore the details of the vibration signals remarkably. Consequently, our model's enhancement procedure led to a significant increase in accuracy for VGG16, a commonly used classification model. All results demonstrate the effectiveness of our approach for enhancing the detection of larvae using boring vibration signals.

Citizen science can enhance strategies to detect and manage invasive forest pests and pathogens

Incorporating a citizen science approach into biological invasion management strategies can enhance biosecurity. Many citizen science projects exist to strengthen the management of forest pest and pathogen invasions within both pre- and post-border scenarios. Besides the value of citizen science initiatives for early detection and monitoring, they also contribute widely to raising awareness, informing decisions about eradication and containment efforts to minimize pest and pathogen spread, and even finding resistant plant material for restoration of landscapes degraded by disease. Overall, many projects actively engage citizens in the different stages of forest pest and pathogen invasions, but it is unclear how they work together across all stages of the entire biological invasion process to enhance biosecurity. Here we provide examples of citizen science projects for each stage of the biological invasion process, discuss options for developing a citizen science program to enhance biosecurity, and suggest approaches for integrating citizen science into biosecurity measures to help safeguard forest resources in the future.

When the Beetles Hit the Fan: The Fan-Trap, an Inexpensive, Light and Scalable Insect Trap under a Creative Commons License, for Monitoring and Experimental Use

Monitoring is an important component in pest management, to prevent or mitigate outbreaks of native pests and to check for quarantine organisms. Surveys often rely on trapping, especially when the target species respond to semiochemicals. Many traps are available for this purpose, but they are bulky in most cases, which raises transportation and deployment issues, and they are expensive, which limits the size and accuracy of any network. To overcome these difficulties, entomologists have used recycled material, such as modified plastic bottles, producing cheap and reliable traps but at the cost of recurrent handywork, not necessarily possible for all end-users (e.g., for national plant-protection organizations). These bottle-traps have allowed very large surveys to be conducted, which would have been impossible with standard commercial traps, and we illustrate this approach with a few examples. Here, we present, under a Creative Commons BY-SA License, the blueprint for a fan-trap, a foldable model, laser cut from a sheet of polypropylene, which can rapidly be produced in large numbers in a Fab lab or by a commercial company and could be transported and deployed in the field with very little effort. Our first field comparisons show that fan-traps are as efficient as bottle-traps for some Scolytinae species and we describe two cases where they are being used for monitoring.