Monitoring insect numbers and biodiversity with a vertical-beam entomological radar.

Concerns about perceived widespread declines in insect numbers have led to recognition of a requirement for long-term monitoring of insect biodiversity. Here we examine whether an existing, radar-based, insect monitoring system developed for research on insect migration could be adapted to this role. The radar detects individual larger (greater than 10 mg) insects flying at heights of 150-2550 m and estimates their size and mass. It operates automatically and almost continuously through both day and night. Accumulation of data over a 'half-month' (approx. 15 days) averages out weather effects and broadens the source area of the wind-borne observation sample. Insect counts are scaled or interpolated to compensate for missed observations; adjustment for variation of detectability with range and insect size is also possible. Size distributions for individual days and nights exhibit distinct peaks, representing different insect types, and Simpson and Shannon-Wiener indices of biodiversity are calculated from these. Half-month count, biomass and index statistics exhibit variations associated with the annual cycle and year to year changes that can be attributed to drought and periods of high rainfall. While species-based biodiversity measures cannot be provided, the radar's capacity to estimate insect biomass over a wide area indicates utility for tracking insect population sizes. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.

Delivering on a promise: futureproofing automated insect monitoring methods.

Due to rapid technological innovations, the automated monitoring of insect assemblages comes within reach. However, this continuous innovation endangers the methodological continuity needed for calculating reliable biodiversity trends in the future. Maintaining methodological continuity over prolonged periods of time is not trivial, since technology improves, reference libraries grow and both the hard- and software used now may no longer be available in the future. Moreover, because data on many species are collected at the same time, there will be no simple way of calibrating the outputs of old and new devices. To ensure that reliable long-term biodiversity trends can be calculated using the collected data, I make four recommendations: (1) Construct devices to last for decades, and have a five-year overlap period when devices are replaced. (2) Construct new devices to resemble the old ones, especially when some kind of attractant (e.g. light) is used. Keep extremely detailed metadata on collection, detection and identification methods, including attractants, to enable this. (3) Store the raw data (sounds, images, DNA extracts, radar/lidar detections) for future reprocessing with updated classification systems. (4) Enable forward and backward compatibility of the processed data, for example by in-silico data 'degradation' to match the older data quality. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.

Geometric morphometrics and machine learning as tools for the identification of sibling mosquito species of the Maculipennis complex (Anopheles).

Geometric morphometrics allows researchers to use the specific software to quantify and to visualize morphological differences between taxa from insect wings. Our objective was to assess wing geometry to distinguish four Anopheles sibling species of the Maculipennis complex, An. maculipennis s. s., An. daciae sp. inq., An. atroparvus and An. melanoon, found in Northern Italy. We combined the geometric morphometric approach with different machine learning alghorithms: support vector machine (SVM), random forest (RF), artificial neural network (ANN) and an ensemble model (EN). Centroid size was smaller in An. atroparvus than in An. maculipennis s. s. and An. daciae sp. inq. Principal component analysis (PCA) explained only 33% of the total variance and appeared not very useful to discriminate among species, and in particular between An. maculipennis s. s. and An. daciae sp. inq. The performance of four different machine learning alghorithms using procrustes coordinates of wing shape as predictors was evaluated. All models showed ROC-AUC and PRC-AUC values that were higher than the random classifier but the SVM algorithm maximized the most metrics on the test set. The SVM algorithm with radial basis function allowed the correct classification of 83% of An. maculipennis s. s. and 79% of An. daciae sp. inq. ROC-AUC analysis showed that three landmarks, 11, 16 and 15, were the most important procrustes coordinates in mean wing shape comparison between An. maculipennis s. s. and An. daciae sp. inq. The pattern in the three-dimensional space of the most important procrustes coordinates showed a clearer differentiation between the two species than the PCA. Our study demonstrated that machine learning algorithms could be a useful tool combined with the wing geometric morphometric approach.

A novel vehicle-mounted sticky trap; an effective sampling tool for savannah tsetse flies Glossina morsitans morsitans Westwood and Glossina morsitans centralis Machado.

BACKGROUND: Black screen fly round (BFR) is a mobile sampling method for Glossina morsitans. This technique relies on the ability of operator(s) to capture flies landing on the screen with hand nets. In this study, we aimed to evaluate a vehicle-mounted sticky panel trap (VST) that is independent of the operator's ability to capture flies against BFR, for effective and rapid sampling of G. m. morsitans Westwood and G. m. centralis Machado. We also determined the influence of the VST colour (all-blue, all-black or 1:1 blue-black), orientation and presence of odour attractants on tsetse catch. METHODOLOGY/PRINCIPAL FINDINGS: Using randomised block design experiments conducted in Zambia, we compared and modelled the number of tsetse flies caught in the treatment arms using negative binomial regression. There were no significant differences in the catch indices of the three colour designs and for in-line or transversely oriented panels for both subspecies (P > 0.05). When baited with butanone and 1-octen-3-ol, VST caught 1.38 (1.11-1.72; P < 0.01) times more G. m. centralis flies than the un-baited trap. Attractants did not significantly increase the VST catch index for G. m. morsitans (P > 0.05). Overall, the VST caught 2.42 (1.91-3.10; P < 0.001) and 2.60 (1.50-3.21; P < 0.001) times more G. m. centralis and G. m. morsitans respectively, than the BFR. The VST and BFR took 10 and 35 min respectively to cover a 1 km transect. CONCLUSION/SIGNIFICANCE: The VST is several times more effective for sampling G. m. morsitans and G. m. centralis than the BFR and we recommend its use as an alternative sampling tool.

A Review of Insect Monitoring Approaches with Special Reference to Radar Techniques.

Drastic declines in insect populations are a vital concern worldwide. Despite widespread insect monitoring, the significant gaps in the literature must be addressed. Future monitoring techniques must be systematic and global. Advanced technologies and computer solutions are needed. We provide here a review of relevant works to show the high potential for solving the aforementioned problems. Major historical and modern methods of insect monitoring are considered. All major radar solutions are carefully reviewed. Insect monitoring with radar is a well established technique, but it is still a fast-growing topic. The paper provides an updated classification of insect radar sets. Three main groups of insect radar solutions are distinguished: scanning, vertical-looking, and harmonic. Pulsed radar sets are utilized for all three groups, while frequency-modulated continuous-wave (FMCW) systems are applied only for vertical-looking and harmonic insect radar solutions. This work proves the high potential of radar entomology based on the growing research interest, along with the emerging novel setups, compact devices, and data processing approaches. The review exposes promising insect monitoring solutions using compact radar instruments. The proposed compact and resource-effective setups can be very beneficial for systematic insect monitoring.

Multi-instrumental techniques for evaluating butterfly structural colors: A case study on Polyommatus bellargus (Rottemburg, 1775) (Lepidoptera: Lycaenidae: Polyommatinae).

Color is an important communication channel for day-flying butterflies. Chemical (pigmentary) coloration is often supplemented by physical color generated by photonic nanostructures. These nanoarchitectures - which are characteristic for a given species - exhibit wavelength ranges in which light propagation is forbidden. The photonic nanoarchitectures are located in the lumen of the wing scales and are developed individually by each scale during metamorphosis. This self-assembly process is governed by the genes in the nucleus of the scale producing cell. It is crucial to establish well-defined measurement methods for the unambiguous characterization and comparison of colors generated in such a complex manner. Owing to the intricate architecture ordered at multiple levels (from centimeters to tens of nanometers), the precise quantitative determination of butterfly wing coloration is not trivial. In this paper, we present an overview of several optical spectroscopy measurement methods and illustrate techniques for processing the obtained data, using the species Polyommatus bellargus as a test case, the males of which exhibit a variation in their blue structural color that is easily recognizable to the naked eye. The benefits and drawbacks of these optical methods are discussed and compared. Furthermore, the origin of the color differences is explained in relation to differences in the wing scale nanomorphology revealed by electron microscopy. This in turn is tentatively associated with the unusually large genetic drift reported for this species in the literature.

Development of Tenebrio molitor (Coleoptera: Tenebrionidae) on Poultry Litter-Based Diets: Effect on Chemical Composition of Larvae.

In order to investigate a low-cost and sustainable food source, the present study evaluated the use of poultry litter for rearing Tenebrio molitor Linnaeus, 1758 (Coleoptera: Tenebrionidae). The experiment was performed with five diets containing increasing levels of poultry litter (0, 25, 50, 75, and 100%) replacing the control diet and five replicates with 50 larvae per sample unit. Larval growth and development were evaluated and the chemical compositions of diet and T. molitor larvae were determined. Larval development and reproduction efficiency of T. molitor were similar in all treatments. The sole use of poultry litter to feed T. molitor reduced the crude protein of flour by only 8%. Including 50% or more poultry litter in the standard diet is the best-suited formulation for larvae production and incorporation of minerals in the larvae. Mealworm can be grown successfully on diets composed by poultry litter, the diet did not affect survival, growth, and development; however, studies spanning several insect generations should be performed to determine the effects of diet composition on adult fecundity. The knowledge acquired using poultry litter to feed T. molitor will be useful to carry out new research, in addition to evidencing the possibility of low-cost mass rearing of these larvae.

Deep learning and computer vision will transform entomology.

Most animal species on Earth are insects, and recent reports suggest that their abundance is in drastic decline. Although these reports come from a wide range of insect taxa and regions, the evidence to assess the extent of the phenomenon is sparse. Insect populations are challenging to study, and most monitoring methods are labor intensive and inefficient. Advances in computer vision and deep learning provide potential new solutions to this global challenge. Cameras and other sensors can effectively, continuously, and noninvasively perform entomological observations throughout diurnal and seasonal cycles. The physical appearance of specimens can also be captured by automated imaging in the laboratory. When trained on these data, deep learning models can provide estimates of insect abundance, biomass, and diversity. Further, deep learning models can quantify variation in phenotypic traits, behavior, and interactions. Here, we connect recent developments in deep learning and computer vision to the urgent demand for more cost-efficient monitoring of insects and other invertebrates. We present examples of sensor-based monitoring of insects. We show how deep learning tools can be applied to exceptionally large datasets to derive ecological information and discuss the challenges that lie ahead for the implementation of such solutions in entomology. We identify four focal areas, which will facilitate this transformation: 1) validation of image-based taxonomic identification; 2) generation of sufficient training data; 3) development of public, curated reference databases; and 4) solutions to integrate deep learning and molecular tools.

TRsandflies: A Web-Based Software for the Morphometric Identification of Sand Flies in Turkey.

Sand flies are vector of several diseases, mostly cutaneous and visceral leishmaniasis (CL and VL). Also, 29 sand fly species have been identified in previous fauna studies carried out in 40 provinces of Turkey. Totally, 24 sand flies species belonging to Phlebotomus (Ph.) (Diptera: Psychodidae) genus have been proven or reported as possible vector species. This study aimed to develop a new software which could contribute to researchers' decision making about the identification of sand flies with obtained data from entomological surveys conducted before in Turkey. Developed software called TRsandflies included 35 textbox created with parameters obtained from caught sand flies specimens by the above-mentioned surveys. It also contained 130 photos and distribution maps related to 24 sand flies species. In addition, C# language and MYSQL database were used in the program. TRsandflies had three different forms (pages) allowing the user to compare the specimens and known species. In the species identification trials with three repetitions carried out in the program, except for the specimens belonging to the Transphlebotomus Artemiev & Neronov, 1984 subgenus, morphometric data of all previously collected sand fly species specimens were included. The process of running the morphometric measurement results of predetermined specimens in the program provided us with an accurate prediction rate of 86.66% in male specimens and 71.66% in female specimens. We concluded that the web-based software developed could play an important role in reducing the rate of possible errors that might be encountered by conventional identification methods.

Sampling Efficacy and Survival Rates of Labarrus pseudolividus (Coleoptera: Scarabaeidae) and Onthophagus taurus (Coleoptera: Scarabaeidae) Using Flotation and Sieve-Separation Methodology.

Understanding collection methodologies and their limitations are essential when targeting specific arthropods for use in habitat restoration, conservation, laboratory colony formation, or when holistically representing local populations using ecological surveys. For dung beetles, the most popular collection methodology is baited traps, followed by light traps and unbaited flight-intercept traps during diversity surveys. A less common collection method, flotation, is assumed to be laborious and messy, and so only a handful of papers exist on its refinement and strengths. Our purpose was threefold: First, we tested the recovery and survival rates of Labarrus (=Aphodius) pseudolividus (Balthasar) and Onthophagus taurus (Schreber) when floating beetle-seeded dung pats to determine potential collection and safety issues. We collected 72.4 and 78% of the seeded L. pseudolividus and O. taurus, respectively, with >95% survival rating. Second, we developed a flotation-sieving technique that enables users to rapidly collect and passively sort dung beetles with less time and effort. Specifically, we often collected 50-100 g of wild dung beetles within a couple of hours of gathering dung and sorted them in a couple more by allowing dung beetles to sort themselves by size within a series of sieves; Third, we reviewed flotation-based advantages and disadvantages in comparison to other methodologies.

Using Visual and Digital Imagery to Quantify Horn Fly (Diptera: Muscidae) Densities.

The horn fly, Haematobia irritans L. (Diptera: Muscidae), is a persistent pest of cattle globally. A threshold of 200 flies per animal is considered the standard management goal; however, determining when that threshold has been exceeded is difficult using visual estimates that tend to overestimate the actual fly densities and are, at best, subjective. As a result, a more reliable and durable method of determining horn fly densities is needed. Here, we describe the methods commonly used to quantify horn fly densities including visual estimates and digital photography, and provide examples of quantification software and the prospect for computer automation methods.

Methods for Surveying Stable Fly Populations.

Stable flies are among the most important pests of livestock throughout much of the world. Their painful bites induce costly behavioral and physiological stress responses and reduce productivity. Stable flies are anthropogenic and their population dynamics vary depending on agricultural and animal husbandry practices. Standardized sampling methods are needed to better identify the factors controlling stable fly populations, test novel control technologies, and determine optimal management strategies. The current study reviewed methods used for a long-term study of stable fly population dynamics in the central Great Plains. An additional study compared the relative size of flies sampled from the general population with that of flies sampled emerging from substrates associated with livestock production. Flies developing in livestock associated substrates are significantly larger than those in the general population indicating that other types of developmental sites are contributing significant numbers of flies to the general population. Because efforts to identify those sites have yet to be successful, we speculate that they may be sites with low densities of developing stable flies, but covering large areas such as croplands and grasslands. The stable fly surveillance methods discussed can be used and further improved for monitoring stable fly populations for research and management programs.

'Drone-Netting' for Sampling Live Insects.

Drones have become valuable tools for biodiversity studies by providing aerial photographs; however, for most entomological studies, images, in particular those taken remotely, are usually insufficient; rather sampling of specimens is required. We equipped a cheap off-the-shelf drone with a net bag, flew it over the ground, sweeping the vegetation, and sampled adult and larval insects as well as spiders. 'Drone-netting' proved to be a versatile method for general insect sampling, particularly in inaccessible terrains. It is time- and cost-effective, minimally invasive, and adaptable for many research tasks in entomofaunistics; it shows a degree of representativeness similar to hand-netting, and caught specimens stay alive and can be released if not needed.

Saving time maintaining reliability: a new method for quantification of Tetranychus urticae damage in Arabidopsis whole rosettes.

BACKGROUND: The model species Tetranychus urticae produces important plant injury and economic losses in the field. The current accepted method for the quantification of the spider mite damage in Arabidopsis whole rosettes is time consuming and entails a bottleneck for large-scale studies such as mutant screening or quantitative genetic analyses. Here, we describe an improved version of the existing method by designing an automatic protocol. The accuracy, precision, reproducibility and concordance of the new enhanced approach are validated in two Arabidopsis accessions with opposite damage phenotypes. Results are compared to the currently available manual method. RESULTS: Image acquisition experiments revealed that the automatic settings plus 10 values of brightness and the black background are the optimal conditions for a specific recognition of spider mite damage by software programs. Among the different tested methods, the Ilastik-Fiji tandem based on machine learning was the best procedure able to quantify the damage maintaining the differential range of damage between accessions. In addition, the Ilastik-Fiji tandem method showed the lowest variability within a set of conditions and the highest stability under different lighting or background surroundings. Bland-Altman concordance results pointed out a negative value for Ilastik-Fiji, which implies a minor estimation of the damage when compared to the manual standard method. CONCLUSIONS: The novel approach using Ilastik and Fiji programs entails a great improvement for the quantification of the specific spider mite damage in Arabidopsis whole rosettes. The automation of the proposed method based on interactive machine learning eliminates the subjectivity and inter-rater-variability of the previous manual protocol. Besides, this method offers a robust tool for time saving and to avoid the damage overestimation observed with other methods.

Highlights in Medical Entomology, 2019: Familiar Foes and New Frontiers.

The 2019 Entomological Society of America annual meeting was held in St. Louis, Missouri, just blocks away from the iconic Gateway Arch. Representing a 'gateway to the West', this inspired the theme of the Highlights in Medical Entomology to reflect on the accomplishments of the past year as we move into a 'new frontier' of vector biology research. Papers were selected broadly across arthropods that influence public health, focusing on topics ranging from West Nile virus transmission, ticks and tick-borne disease, to advances in genetics and 'big data' studies. This included current perspectives on West Nile virus ecology and epidemiology, which has now been endemic in the United States for 20 yr. Additional topics such as the advantages of citizen science and the importance of scientific communication were also discussed. Together, these papers demonstrate the achievements of the vector community while emphasizing the challenges that we collectively face to reduce the burden of vector-borne disease.

Highlights of Veterinary Entomology, 2019.

Research in the field of veterinary entomology is dominated by studies concerning arthropods that affect animal health. In 2019, this research primarily addressed the overwhelming industry need to manage detrimental species such as biting flies and ticks and the ongoing problems caused by insecticide/acaricide resistance evolution in these pests. Research also included evidence supporting the need for the conservation of beneficial species, such as biological control organisms. Many studies in a variety of pest systems have demonstrated the potential detrimental effects of insecticide use on nontarget organisms, and those of veterinary importance are no exception. An emphasis also was placed on research regarding alternative management strategies for veterinary pests. The presentation herein provides a descriptive summary of selected research that contributed greatly to the body of knowledge regarding arthropods of veterinary importance. This included several studies that will pave the way towards more effective veterinary pest management in an effort to improve animal health and welfare and, therefore, the sustainability of animal agriculture.

Urban Entomology Highlights From 2019 Help Create Integrated Pest Management Plans.

Urban insect pests such as ants, termites, cockroaches, and bed bugs are more than just nuisances; they often negatively impact structures, landscapes, animal health, commercial food production, food safety, and public health (mental, physical, and financial). Due to the tremendous burden these insects can inflict, researchers, manufacturers, and pest management professionals work to create solutions that effectively manage urban and structural pests. One solution that has proven useful in agriculture is the development of an integrated pest management (IPM) plan; i.e., a science-based approach to pest control that utilizes multiple tactics such as preventative tools, chemical control (sprays, fumigation, and baits), biological control, and exclusion. There are many permutations of urban IPM plans, but in general they consist of five components: 1) identifying the pest, 2) monitoring the pest, 3) developing an intervention plan (including prevention and control techniques), 4) implementing the program, and 5) recording and evaluating the results. The objectives of the current publication were to 1) highlight urban entomology research published in 2019 and 2) show how the results from these publications help pest management professionals create and implement IPM plans.

Novel Experimental Methods for the Investigation of Hermetia illucens (Diptera: Stratiomyidae) Larvae.

Large-scale insect rearing for food and feed production can be improved by understanding diet digestion and host-microbe interactions. To examine these processes in black soldier fly (Hermetia illucens L.; Diptera: Stratiomyidae) larvae, two protocols were developed. Protocol 1 describes a method to produce viable, sterile black soldier fly larvae and a gentle method for diet sterilization. Sterile black soldier fly larvae can be used to study the diverse role of microbes in larval development. Nutrient requirements of sterile black soldier fly larvae are met only through diet. Viable sterile black soldier fly larvae were consistently generated using a four-step treatment with alternating immersions of eggs for 2 min each in ethanol (70%) and sodium hypochlorite (0.6%), over two cycles. A nonthermal method of diet sterilization, namely high-energy electron beam (HEEB) treatment, was introduced. Subsequently, growth of sterile black soldier fly larvae was observed on the HEEB-treated diets (40, 60, and 40% of replicates with poultry feed, liver pie, and an artificial diet, respectively) but not on autoclaved diets. In Protocol 2, we propose a novel method to collect frass from individual larvae. We then measured the metabolites in frass, using high-pressure liquid chromatography. Results on metabolites confirmed the influence of digestion. For instance, succinate increased from 1 to 2 and 7 µmol/g sample from diet to gut homogenate and frass, respectively. The collection method is a promising tool to estimate the diet and nutrient requirements of black soldier fly larvae, thus increasing the performance and reliability of black soldier fly larvae rearing. We discuss in detail the possible applications and limitations of our methods in black soldier fly larvae research.

A Guide and Toolbox to Replicability and Open Science in Entomology.

The ability to replicate scientific experiments is a cornerstone of the scientific method. Sharing ideas, workflows, data, and protocols facilitates testing the generalizability of results, increases the speed that science progresses, and enhances quality control of published work. Fields of science such as medicine, the social sciences, and the physical sciences have embraced practices designed to increase replicability. Granting agencies, for example, may require data management plans and journals may require data and code availability statements along with the deposition of data and code in publicly available repositories. While many tools commonly used in replicable workflows such as distributed version control systems (e.g., 'git') or script programming languages for data cleaning and analysis may have a steep learning curve, their adoption can increase individual efficiency and facilitate collaborations both within entomology and across disciplines. The open science movement is developing within the discipline of entomology, but practitioners of these concepts or those desiring to work more collaboratively across disciplines may be unsure where or how to embrace these initiatives. This article is meant to introduce some of the tools entomologists can incorporate into their workflows to increase the replicability and openness of their work. We describe these tools and others, recommend additional resources for learning more about these tools, and discuss the benefits to both individuals and the scientific community and potential drawbacks associated with implementing a replicable workflow.