Male Beetles Research Articles

Phenotypic Assortment Changes the Landscape of Selection.

Social interactions with conspecifics can dramatically affect an individual's fitness. The positive or negative consequences of interacting with social partners typically depend on the value of traits that they express. These pathways of social selection connect the traits and genes expressed in some individuals to the fitness realized by others, thereby altering the total phenotypic selection on and evolutionary response of traits across the multivariate phenotype. The downstream effects of social selection are mediated by the patterns of phenotypic assortment between focal individuals and their social partners (the interactant covariance, Cij', or the multivariate form, CI). Depending on the sign and magnitude of the interactant covariance, the direction of social selection can be reinforced, reversed, or erased. We report estimates of Cij' from a variety of studies of forked fungus beetles to address the largely unexplored questions of consistency and plasticity of phenotypic assortment in natural populations. We found that phenotypic assortment of male beetles based on body size or horn length was highly variable among subpopulations, but that those differences also were broadly consistent from year to year. At the same time, the strength and direction of Cij' changed quickly in response to experimental changes in resource distribution and social properties of populations. Generally, interactant covariances were more negative in contexts in which the number of social interactions was greater in both field and experimental situations. These results suggest that patterns of phenotypic assortment could be important contributors to variability in multilevel selection through their mediation of social selection gradients.

Metabolomics and transcriptomics of pheromone biosynthesis in an aggressive forest pest Ips typographus

Eurasian spruce bark beetle, Ips typographus, is a destructive pest in spruce forests. The ability of I. typographus to colonise host trees depends on its massive aggregation behaviour mediated by aggregation pheromones, consisting of 2-methyl-3-buten-2-ol and cis-verbenol. Other biologically active compounds such as ipsdienol and verbenone have also been detected in the beetle. Biosynthesis of 2-methyl-3-buten-2-ol and ipsdienol de novo from mevalonate and that of cis-verbenol from α-pinene sequestrated from the host have been reported in preliminary studies. However, knowledge on the molecular mechanisms underlying pheromone biosynthesis in this pest is currently limited. In this study, we performed metabolomic and differential gene expression (DGE) analysis for the pheromone-producing life stages of I. typographus. The highest amounts of 2-methyl-3-buten-2-ol (238 ng/gut) and cis-verbenol (23 ng/gut) were found in the fed male gut (colonisation stage) and the immature male gut (early stage), respectively. We also determined the amount of verbenyl oleate (the possible storage form of cis-verbenol), a monoterpenyl fatty acid ester, to be approximately 1604 ng/mg in the immature stage in the beetle body. DGE analysis revealed possible candidate genes involved in the biosynthesis of the quantified pheromones and related compounds. A novel hemiterpene-synthesising candidate isoprenyl-di-phosphate synthase Ityp09271 gene proposed for 2-methyl-3-buten-2-ol synthesis was found to be highly expressed only in the fed male beetle gut. Putative cytochrome P450 genes involved in cis/trans-verbenol synthesis and an esterase gene Ityp11977, which could regulate verbenyl oleate synthesis, were identified in the immature male gut. Our findings from the molecular analysis of pheromone-producing gene families are the first such results reported for I. typographus. With further characterisation of the identified genes, we can develop novel strategies to disrupt the aggregation behaviour of I. typographus and thereby prevent vegetation loss.

Identification of Components of the Aggregation Pheromone of the Guam Strain of Coconut Rhinoceros Beetle, Oryctes rhinoceros, and Determination of Stereochemistry

The coconut rhinoceros beetle, Oryctes rhinoceros (Linnaeus 1758) (Coleoptera: Scarabaeidae: Dynastinae) (CRB), is endemic to tropical Asia where it damages both coconut and oil palm. A new invasion by CRB occurred on Guam in 2007 and eradication attempts failed using commonly applied Oryctes rhinoceros nudivirus (OrNV) isolates. This and subsequent invasive outbreaks were found to have been caused by a previously unrecognized haplotype, CRB-G, which appeared to be tolerant to OrNV. The male-produced aggregation pheromone of the endemic, susceptible strain of O. rhinoceros (CRB-S) was previously identified as ethyl 4-methyloctanoate. Following reports from growers that commercial lures containing this compound were not attractive to CRB-G, the aim of this work was to identify the pheromone of CRB-G. Initial collections of volatiles from virgin male and female CRB-G adults from the Solomon Islands failed to show any male- or female-specific compounds as candidate pheromone components. Only after five months were significant quantities of ethyl 4-methyloctanoate and 4-methyloctanoic acid produced by males but not by females. No other male-specific compounds could be detected, in particular methyl 4-methyloctanoate, 4-methyl-1-octanol, or 4-methyl-1-octyl acetate, compounds identified in volatiles from some other species of Oryctes. Ethyl 4-methyloctanoate elicited a strong electroantennogram response from both male and female CRB-G, but these other compounds, including 4-methyloctanoic acid, did not. The enantiomers of ethyl 4-methyloctanoate and 4-methyloctanoic acid were conveniently prepared by enzymatic resolution of the commercially-available acid, and the enantiomers of the acid, but not the ester, could be separated by gas chromatography on an enantioselective cyclodextrin phase. Using this approach, both ethyl 4-methyloctanoate and 4-methyloctanoic acid produced by male CRB-G were shown to be exclusively the (R)-enantiomers whereas previous reports had suggested male O. rhinoceros produced the (S)-enantiomers. However, re-examination of the ester and acid produced by male CRB-S from Papua New Guinea showed that these were also the (R)-enantiomers. In field trapping experiments carried out in the Solomon Islands, both racemic and ethyl (R)-4-methyloctanoate were highly attractive to both male and female CRB-G beetles. The (S)-enantiomer and the corresponding acids were only weakly attractive. The addition of racemic 4-methyloctanoic acid to ethyl 4-methyloctanoate did significantly increase attractiveness, but the addition of (R)- or (S)-4-methyloctanoic acid to the corresponding ethyl esters did not. Possible reasons for the difference in assignment of configuration of the components of the CRB pheromone are discussed along with the practical implications of these results.

Bioinspired bowl-array enabled angle-independent and fast responsive photonic colors for environmental sensing

Bioinspired adaptive coloring strategies advance the investigation of responsive photonic crystal (PC) colors for environmental visual sensing, but are being encumbered by inherent strong angle-dependent structural colors of their highly ordered photonic microstructures. Herein, imitating hexagonal pit array on the elytral surface of a male beetle- Chlorophila obscuripennis and utilizing optically isotropic features of the unique concave axisymmetric geometry, biomimetic micro-sized bowl-array enabled angle-independent and flexible one-dimensional PC colors are first demonstrated based on transfer printing technique which is certified as a facile, energy efficient and universal nanofabrication strategy. The photonic films assembled by functional copolymers and inorganic oxides are successfully transferred onto bowls on the surface of polydimethylsiloxane, exhibiting flexible and brilliant pixel array-like non-iridescent colors. Even after being twisted and stretched, water-washing and rubbing, the nanomaterial-based photonic films on the bowls still show glossy and stable angle-independent colors, presenting powerful strengths for practical visual sensing. In practical terms, functional copolymers based PC films on the bowls are developed as humidity and organic solvents colorimetric sensors free of angles with desirable sensitivity, remarkable durability and repeatability. And integrating photonic multilayered films with different response features, multi-mode pattern displays are realized. The remarkable sensing and display applications reflect the high values of the novel bowls enabled angle-independent photonic color building strategy.

Study of the possibility of using pheromones to control the number of polyphagous soybean (Glycine max) pests

The soybean is an economically important crop for Krasnodar krai. The biological control of polyphagous soybean pests is necessary for organic farming. The aim of our study was to study the possibility of using a synthetic analogs of sex pheromones to control the number of polyphagous soybean pests (Glycine max). The present investigation consisted in the fact that as a primary means of regulation of the number of click beetles (Coleoptera: Elateridae), such as Agriotes gurgistanus Heyden, A. tauricus (Faldermann) and A. sputator (L.) and the cotton bollworm Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae), methods of mass capture of males (elimination) and disruption of chemical communication (disorientation) were used on soybeans.. The studies were carried out in the soybean plot with an area of 8 hectares (GPS: 45.03° N 38.52° E; FSBSI FRCBZR, Krasnodar), and in the experimental plot “Zolotaya Niva” with an area of 10 hectares (GPS: 45.13°N 39.35°E Voronezhskaya village, Krasnodar Krai). Preparative forms of pheromones were made on specially designed technological equipment at FSCBPP. Glue traps for monitoring and mass catching of cotton bollworms (type “Attracon”) were also manufactured using FSCBPP technological equipment. Estrontype pheromone traps were purchased from the manufacturer. To determine the dynamics of flight and the number of pests, pheromone traps were placed on experimental plots at the rate of one trap per 1–3 hectares. In experiments on mass trapping of insects (elimination), traps were placed in the amount of 5–10 traps per hectare. The effectiveness of the method was determined by the fertilization of females in control and experiment. Females click beetles were captured using the lure method and LED traps.It was found that the effectiveness of the method of elimination of male click beetles (Agriotes gurgistanus, A. tauricus and A. sputator) was 89–95%, and the level of impaired chemical communication (disorientation) reached 91–99%. The disorientation effect for the cotton moth H. armigera was 92%, with the damage to plants and soybeans not exceeding 2.0%. The effectiveness of this method was 88.6–94.5%, during disorientation of three representatives of Elateridae family and cotton moth H. armigera (Lepidoptera: Noctuidae) it was found that the effectiveness of this method was 91.0–99.6% for Elateridae, and 92.0% for H. armigera. This work has presented a novel approach to the possibility of using pheromones as not only the main means of monitoring phytophages, but also a method for controlling polyphagous pests of soybeans, which is important in the development of protection for organic farming systems.

Microbiome Associated with the Mycangia of Female and Male Adults of the Ambrosia Beetle Platypus cylindrus Fab. (Coleoptera: Curculionidae).

Simple SummaryThe ambrosia beetle Platypus cylindrus is a major cork oak pest in Portugal. Beetles have different roles in host tree colonization and are equipped with specific structures (mycangia) for fungal transportation. The information on bacterial composition associated with mycangia is scarce. The bacterial community present in the mycangia of P. cylindrus male and female beetles collected from cork oak galleries was investigated. Mycangia anatomical structure was also explored using histological and 3D imaging techniques to highlight evidence of biological sexual dimorphism. A diverse bacterial community with few gender-specific bacteria was shown and histology revealed connections linking external and internal tissues only in females, providing the first insights into sexual differentiation for bacteria in a Platypodinae beetle species.The ambrosia beetle Platypus cylindrus Fab. (Coleoptera: Curculionidae) is a major cork oak pest in Portugal. Female and male beetles have different roles in host tree colonization and are both equipped with prothoracic mycangia for fungal transportation. Despite a known beneficial role of bacteria in ambrosia beetles, information on bacterial composition associated with prothoracic mycangia structures is scarce. Bacterial community from mycangia of P. cylindrus male and female beetles collected from cork oak galleries was investigated by means of 16S metagenomics. Mycangia anatomical structure was also explored with histological techniques and X-ray computed microtomography to highlight evidence supporting biological sexual dimorphism. A bacterial community with highly diverse bacterial taxa with low abundances at the genus level was revealed. Lactobacillales, Leptotrichia, Neisseria, Rothia, and Sphingomonadaceae were significantly more abundant in males, while Acinetobacter, Chitinophagaceae, Enterobacteriaceae, Erwiniaceae, Microbacteriaceae, and Pseudoclavibacter were more abundant in females. Additionally, a core bacteriome of five genera was shared by both sexes. Histological examination revealed visible connections linking external and internal tissues in females, but none in males. Overall, these results provide the first insights into sexual differentiation for bacteria in a Platypodinae beetle species, identifying key patterns of bacteria distribution in the context of beetle ecology and functional behavior.

When perception isn’t reality: allometric variation in the exaggerated mandibles of male stag beetles (Coleoptera: Lucanidae)

Abstract A variety of protocols have been used to study allometric variation in size of the exaggerated mandibles on male stag beetles. Many of these protocols entail logarithmic transformation of the original measurements followed by numerical analysis of the transformations by linear regression or some conceptual extension thereof. I reanalysed data from four such studies to show how these protocols can lead investigators to conclusions that are not well supported by the original observations. One of the data sets was originally reported to conform to simple loglinear allometry, with untransformed observations that presumably follow the path of a two-parameter power function; one was said to represent biphasic, loglinear allometry, with two distinctive morphs having different scaling relationships on the arithmetic scale; and two were originally described as cases of discontinuous, loglinear allometry caused by dimorphisms. My analyses, which were based on graphical analysis and nonlinear regression of untransformed observations, revealed that all the data sets form S-shaped distributions and that each of the distributions is well described by a four-parameter sigmoid function. None of the bivariate distributions reveals a discontinuity or dimorphism. Thus, the original authors unknowingly offered descriptions and interpretations for patterns of variation that do not exist in their data.

Assessment of the Attraction Range of Sex Pheromone Traps to Agriotes (Coleoptera, Elateridae) Male Click Beetles in South-Eastern Europe.

Simple SummaryClick beetles are the adults of wireworms, soil-dwelling larvae that damage multiple arable crops. The attraction range of YATLORf pheromone traps to click beetles of four species of Agriotes wireworms was studied to provide additional information about the implementation of integrated pest management against these harmful pests in Europe. This should allow a significant reduction in insecticide use. Male click beetles were marked and released at different distances from a pheromone trap. Recapture rate, maximum sampling ranges, and effective sampling areas were calculated. The recapture rate was significantly affected by distance, species, and wind direction and decreased as distance increased. The majority of beetles were caught from short distances (up to 10 m) within the first five days. The estimated attraction range was low for all the considered Agriotes species, suggesting that pheromone traps were unsuitable for use as mass trapping instruments to disrupt mating. However, after results and previous research outputs were evaluated, it seems possible to use the traps not only as monitoring tools, but also as attract-and-kill strategies for most beetle populations.The attraction range of YATLORf pheromone traps to adults of four species of Agriotes (A. brevis, A. sordidus, A. litigiosus, and A. ustulatus) was studied to provide additional information about the most harmful Agriotes species in Europe. Male click beetles were marked and released at different distances from a pheromone trap. The recapture rate was calculated and analyzed using analysis of variance. The recapture rate was significantly affected by distance, species, and wind direction. The recapture rate decreased as distance increased. The majority of beetles were caught from short distances (up to 10 m) within the first five days. A. brevis, a mainly crawling species, showed the lowest recapture rate. The wind direction affected the recovery rate, with a significantly lower number of beetles moving downwind from the release points. Maximum sampling ranges and effective sampling areas were calculated. The obtained estimations were low (53 to 86 m and 509 to 2602 m2, respectively) for all the considered Agriotes species, suggesting that they were unsuitable for use as mass trapping instruments to disrupt mating. However, it seems possible to use the traps not only as monitoring tools, but also as attract-and-kill strategies for most beetle populations.

Histochemical Studies on the Male Accessory Glands of the Tenebrionid Beetle Blaps polychresta (Coleoptera, Tenebrionidae)

The aim of the presnt study is to describe the male accessory glands of the tenebrionid beetle Blaps polychresta using histochemical methods and to detect the nature of their secretions. In the adult male tenebrionid beetle Blaps polychresta, there is one pair of bean – shaped and other pair of long tubular accessory reproductive glands. Each bean – shaped gland consists of a single layer of secretory columnar epithelium, surrounded by a muscular coat which is highly tracheated and innervated. Each tubular gland consists of one type of secretory columnar epithelium, surrounded by thin muscular coat which is innervated and highly tracheated. The nuclei of secretory cells in both glands are situated in the basal zone. Histochemical tests of the bean – shaped glands indicate that the secretion of these glands is mainly composed of neutral mucopolysaccharide, glycogen, proteins and lipids. Histochemical tests of the tubular glands indicate the presence of neutral mucopolysaccharide and scanty acidic mucopolysaccharide secretion inside the lumen of these glands, the positive reaction for glycogen and proteins in the cells and secretion inside the lumen of these glands indicate the glycoprotein nature of the secretion.

Rapid Genomic Evolution Drives the Diversification of Male Reproductive Genes in Dung Beetles.

The molecular basis for the evolution of novel phenotypes is a central question in evolutionary biology. In recent years, dung beetles have emerged as models for novel trait evolution as they possess distinct precopulatory traits such as sexually dimorphic horns on their head and thorax. Here, we use functional and evolutionary genomics to investigate the origins and the evolution of postcopulatory reproductive traits in male dung beetles. Male ejaculates that underlie postcopulatory sexual selection are excellent candidates to study novel trait evolution as they are complex, fast evolving, and often highly divergent in insects. We assemble de novo transcriptomes of male accessory glands and testes of a widespread dung beetle, Catharsius molossus, and we perform an evolutionary analysis of closely and distantly related insect genomes. Our results show there is rapid innovation at the genomic level even among closely related dung beetles. Genomic expansion and contraction drive the divergence of male reproductive traits and their functions. The birth of scores of completely novel reproductive genes is reinforced by the recruitment of these genes for high expression in male reproductive tissues, especially in the accessory glands. We find that male accessory glands of C. molossus are specialized for secretory function and express female, egg, and embryo-related genes as well as serine protease inhibitors, whilst the testes are specialized for spermatogenesis and sperm function. Finally, we touch upon putative functions of these evolutionary novelties using structure-function analysis as these proteins bear no homology to any other known proteins.

Taxonomic revision of Australasian diving beetles in the genus Leiodytes Guignot, 1936 (Coleoptera: Dytiscidae, Bidessini).

Bidessus migrator Sharp, 1882, so far assigned to Clypeodytes Régimbart, 1894, and widely distributed in Australia and New Guinea, is re-described. Based on morphological and molecular evidence, it is here transferred to Leiodytes Guignot, 1936. Bidessus loriae Régimbart, 1892 is found to be a junior subjective synonym of L. migrator. We describe the following new species: Leiodytes surianiae sp. nov. (eastern New Guinea, northeast coast of Queensland), and Leiodytes wattsi sp. nov. (southern New Guinea and Darwin area to northern Queensland). We delineate the species using characters such as male genital structure and beetle size, shape and color pattern. Mitochondrial Cox1 data for 27 individuals, representing all three Australasian species, were generated and revealed clusters congruent with the morphological evidence. In Australia Leiodytes only occurs in the tropical and subtropical northern part of the continent. None of the species is endemic to Australia. The species are mainly lentic, occurring in seasonal swamps, flooded meadows and pools of intermittent rivers and temporary creeks.

Nickel oxide nanoparticles induce genotoxicity and cellular alterations in the ground beetle Blaps polycresta (Coleoptera: Tenebrionidae).

Nickel nanoparticles (Ni-NPs) have advantageous applications in the industry; however, little is known of their adverse effects on biological tissues. In the present study, the ground beetle Blaps polycresta was employed as a sensitive indicator for nickel oxide nanoparticles (NiO-NPs) toxicity. Adult male beetles were injected with six dose levels of NiO-NPs (0.01, 0.02, 0.03, 0.04, 0.05, and 0.06 mg/g body weight). Mortality was reported daily over 30 days under laboratory conditions to establish an LD50. Nickel was detected in the testicular tissues of the beetles using X-ray analysis and transmission electronic microscopy. Beetles treated with the sublethal dose of 0.02 mg/g were selected to observe molecular, cellular, and subcellular changes. Gene transcripts of HSP70, HSP90, and MT1 were found to be increased >2.5-, 1.5-, and 2-fold, respectively, in the treated group compared with the controls. Decreased gene expression of AcPC01, AcPC02, and AcPC04 (≤1.5-, ≤2-, and < 2.5-fold, respectively, vs. controls) also were reported in the treated group. Under light microscopy, various structural changes were observed in the testicular tissues of the treated beetles. Ultrastructure observations using scanning and transmission electron microscopy showed severe damage to the subcellular organelles as well as deformities of the heads and flagella of the spermatozoa. Therefore, the present study postulated the impact of NiO-NPs in an ecological model.

Effect of semiochemical exposure on flight propensity and flight capacity of Dendroctonus ponderosae in laboratory bioassays

During flight, insect herbivores respond to volatile organic compounds (VOCs) released by host and non-host plants or conspecifics. Dendroctonus ponderosae uses chemical cues including host and non-host VOCs, as well as aggregation pheromones to navigate through the environment and find a suitable reproductive host. The dispersal flight distance of D. ponderosae from its natal host to its reproductive host varies widely, even within populations of beetles. Beetle energetics do not entirely explain this flight variation. In this study, we test the effect of beetle exposure to semiochemical cues before and during flight on subsequent flight propensity (the likelihood of flight initiation) and flight capacity (the distance and velocity of flight) using computer-linked flight mills. Exposure to host volatiles before flight interacts with beetle pre-flight weight to influence subsequent flight capacity of female but not male beetles. Female beetles flew further and faster following exposure to their aggregation pheromone, trans-verbenol. Flight of female beetles was reduced when they were exposed to volatiles from the non-host, Populus tremuloides, during flight. This study is the first to indicate that semiochemical cues not only influence beetle orientation during flight but also flight capacity of D. ponderosae. These results provide baseline information on the effect of environmental cues on dispersal by flight of D. ponderosae.

Sexual deception of a beetle pollinator through floral mimicry

Sexual mimicry is a complex multimodal strategy used by some plants to lure insects to flowers for pollination.1-4 It is notable for being highly species-specific and is typically mediated by volatiles belonging to a restricted set of chemical compound classes.3,4 Well-documented cases involve exploitation of bees and wasps (Hymenoptera)5,6 and flies (Diptera).7-9 Although beetles (Coleoptera) are the largest insect order and are well known as pollinators of both early and modern plants,10,11 it has been unclear whether they are sexually deceived by plants during flower visits.12,13 Here we report the discovery of an unambiguous case of sexual deception of a beetle: male longhorn beetles (Chorothyse hessei, Cerambycidae) pollinate the elaborate insectiform flowers of a rare southern African orchid (Disa forficaria), while exhibiting copulatory behavior including biting the antennae-like petals, curving the abdomen into the hairy lip cleft, and ejaculating sperm. The beetles are strongly attracted by (16S,9Z)-16-ethyl hexadec-9-enolide, a novel macrolide that we isolated from the floral scent. Structure-activity studies14,15 confirmed that chirality and other aspects of the structural geometry of the macrolide are critical for the attraction of the male beetles. These results demonstrate a new biological function for plant macrolides and confirm that beetles can be exploited through sexual deception to serve as pollinators.

Nutrient Composition of Cashew Stem Girdler Analeptes trifasciata (Coleoptera: Cerambycidae) and Its Suitability for Feed and as Food

Global demand for high-quality animal protein is expected to increase astronomically by 57 % come 2050 and meeting this demand will be quite challenging. However, insect as food is a safe alternative considering the fact that most insects have dietary quality. This is due to their rich protein content which is comparable with conventional animal sources of protein. In Nigeria, the pest Analeptes trifasciata is one of the edible insects, which is consumed among others such as grasshoppers, locusts, termites, palm weevils and crickets in most rural communities. The nutritive composition of adult male and female cashew stem girdler beetles (A. trifasciata) were analysed by proximate analysis to determine the crude protein, crude fibre, ash content, ether extract, dry matter and moisture content. Also minerals such as calcium, magnesium, sodium, phosphorus, iron, cadmium, zinc and manganese and vitamin (A, B, C, D, E and K) contents were analysed using standard methods. Student t-test was used for the statistical analysis. The crude protein (39.63 ± 0.04 %), crude fibre (0.43 ± 0.01 %) and water content (53.03 ± 0.01 %) of males were significantly higher than that of females. Females recorded higher values of dry matter compared to males. Males recorded significantly higher vitamin content than females, for vitamin B1 (0.216 ± 0.001 mg/100 g), vitamin B2 (0.058 ± 0.001 mg/100 g), vitamin B12 (1.37 ± 0.01 mg/100 g) and vitamin C (0.89 ± 0.01 mg/100 g). Females recorded significantly higher (P < 0.05) contents of vitamins A (725.3 ± 0.12 µg/100 g), D (189.5 ± 0.12 mg/100 g), E (266.7 ± 0.12 mg/100 g) and K (31.8 ± 0.12 mg/100 g). Females had higher mineral contents of Ca2+, Na+, P+, Fe2+ and Mn–. The results show that A. trifasciata has high protein content making the beetle a cheap and excellent source of protein. The micronutrients are in favourable proportions and the beetle can be explored as a strategy for tackling nutritional deficiencies.

Narrow‐spectrum artificial light silences female fireflies (Coleoptera: Lampyridae)

AbstractThe rapid spread of artificial light at night (ALAN) poses myriad problems for nocturnal biodiversity.Bioluminescent taxa that communicate via glowing lures, warning signals, or courtship advertisements may have their signals obscured by artificial illumination, unless the added light is spectrally tuned to reduce its impact.Previous research has demonstrated that broad‐spectrum white light inhibits the production of courtship advertisements by male firefly beetles, yet the impact of varying wavelengths of artificial light on both members of the courtship dialogue is largely unknown.We exposed courting pairs ofPhotinus obscurellusfireflies to five colours of downwelling illumination, at two intensities, and recorded changes in male flash rate and flash intensity, female responsiveness, and the flash pattern composition of both sexes.All artificial light treatments significantly suppressed courtship activity.Bright amber light had the greatest impact, suggesting that ALAN which most overlaps the spectrum of firefly bioluminescence will most disrupt firefly courtship.Our findings contradict similar investigations of non‐bioluminescent taxa and raise concerns about the possibility of a universal standard for ecologically sustainable ALAN.

Fertility and mortality impacts of thermal stress from experimental heatwaves on different life stages and their recovery in a model insect.

With climate change creating a more volatile atmosphere, heatwaves that create thermal stress for living systems will become stronger and more frequent. Using the flour beetle Tribolium castaneum, we measure the impacts of thermal stress from experimental heatwaves in the laboratory on reproduction and survival across different insect life stages, and the extent and pace of any recovery. We exposed larvae, pupae, juvenile and mature adult male beetles to 5-day periods of heat stress where temperatures were maintained at either 40°C or 42°C, a few degrees above the 35°C optimum for this species' population productivity, and then measured survival and reproduction compared with controls at 30°C. Mortality due to thermal stress was greatest among juvenile life stages. Male reproductive function was specifically damaged by high temperatures, especially if experienced through pupal or immature life stages when complete sterility was shown at reproductive maturity; larval exposure did not damage adult male fertility. High temperatures impaired testis development and the production of viable sperm, with damage being strongest when experienced during pupal or juvenile adult stages. Despite this disruption, males recovered from heat stress and, depending on the stage of exposure, testis size, sperm production and fertility returned to normal 15–28 days after exposure. Our experiments reveal how thermal stress from heatwave conditions could impact on insect survival and reproduction across different life stages, and the potential and timescales of recovery.

Choosier small hive beetle males miss out when females score nutritious bee jelly

Gorging on stored honey, pollen and developing brood, parasitic small hive beetles (Aethina tumida) can decimate a beehive in a matter of weeks. And even though infested bee colonies fight back, by incarcerating the intruders in crevices guarded by sentries without food for months, the cunning interlopers are able to deceive their custodians into passing on snacks. Posing as nurse and worker bees, the intruder beetles rub their mandibles and antennae against the heads of their captors in hope of receiving a sip of nectar or honey from their benefactor's crop. However, the ruse is not without risk. Sixty percent of beetle approaches end in assault, which made Christian Pirk and colleagues from the University of Pretoria, South Africa, and the University of Graz, Austria, wonder whether the beetles more often tried their luck with younger, docile young bees than older, more aggressive workers.After fashioning impromptu beetle jails from transparent Petri dishes, Zoë Langlands, from the University of Pretoria, incarcerated small groups of the beetles with three bees – a newly emerged bee, a 6- to 7-day-old nurse bee and an older forager – recording the insects’ interactions for 2 h. Filming the beetles approach their captors in search of food, the team was surprised that the male beetles were much more discerning than the females. They preferred to approach the youngest bees, while the females were equally as likely to approach a crabby forager, a nurse or a gentle newly emerged bee. And when the beetles hoodwinked their gaolers into providing them with a snack, the male beetles only sipped from the youngest bee groups, while the females fed from elderly and young bees alike, taking the longest draughts from the feisty nurses. In addition, when the researchers checked the bees’ reactions to their inmates, they found that the youngest bees had the mildest manners, rarely attempting to sting the impudent beetles, while the nurses stood their ground, stabbing at the begging beetles almost 200 times. Yet the bees allowed the beetles to dine for twice as long as members of their own community.So, why were the female beetles prepared to gamble their chances on a sip from feisty nurse bees when the odds of an assault were stacked against them? ‘Nurse bees are the workers that digest pollen and produce a protein-rich jelly that they feed to the larvae’, says Ezette du Rand. Were the nurses providing their inmates with more than just a sip of honey to make the risk worthwhile? Langlands injected nurse bees with a radioactive amino acid, and staged more beetle/nurse beg-offs to determine whether the beetles were supping on the nurses’ protein-rich jelly. And when she measured the amount of radioactivity in the beetles’ bodies, 43% of the female beetles were ‘hot’, while only 31% of the males had consumed a protein-packed meal.Female small hive beetles are better at persuading their captors to part with their nutritious jelly, which is usually reserved for the queen and her brood, probably because the females need the protein boost most when preparing to lay the eggs of the next generation of hive-busting beetle parasites.

Limoniic Acid - Major Component of the Sex Pheromones of the Click Beetles Limonius canus and L. californicus.

Wireworms, the larvae of click beetles (Coleoptera: Elateridae), are soil-dwelling insect pests inflicting major economic damage on many types of agricultural crops worldwide. The objective of this work was to identify the female-produced sex pheromones of the Pacific Coast wireworm, Limonius canus LeConte, and the sugarbeet wireworm, L. californicus (Mannerheim) (Coleoptera: Elateridae). Headspace volatiles from separate groups of female L. canus and L. californicus were collected on Porapak Q and analyzed by gas chromatography with electroantennographic detection (GC-EAD) and GC-mass spectrometry. GC-EAD recordings revealed strong responses from male L. canus and male L. californicus antennae to the same compound, which appeared below GC detection threshold. The structure of this candidate pheromone component was deduced from the results of micro-analytical treatments of extracts, retention index calculations on four GC columns, and by syntheses of more than 25 model compounds which were assessed for their GC retention characteristics and electrophysiological activity. The EAD-active compound was identified as (E)-4-ethyloct-4-enoic acid, which we name limoniic acid. In field experiments in British Columbia and Alberta, Canada, traps baited with synthetic limoniic acid captured large numbers of male Limonius click beetles, whereas unbaited control traps captured few. Compared to traps baited with the analogue, (E)-5-ethyloct-4-enoic acid, traps baited with limoniic acid captured 9-times more male L. californicus, and 6.5-times more male western field wireworms, L. infuscatus Motschulsky, but 2.3-times fewer male L. canus. Limoniic acid can now be developed for detection, monitoring and possibly control of L. californicus, L. infuscatus and L. canus populations.

Influence of ultrasound on juvenile hormone titers in Monochamus alternatus Hope (Coleoptera: Cerambycidae)

Abiotic stress factors can significantly affect insects. In particular, the stressful effects of exposure to ultrasound on insects are considered important. In the present study, we investigated the effects of ultrasound on the important global pest Monochamus alternatus (Coleoptera: Cerambycidae), which is the main vector of the pinewood nematode. We exposed M. alternatus adults (aged 1 day, 3 days, and 5 days) to ultrasound at different frequencies (using two ultrasonic devices, i.e., LHC20 with a mixture of frequencies at 35 kHz, 70 kHz, and 105 kHz; and GFG-8016G at two separate frequencies of 30 kHz and 60 kHz) for different periods of time (1 h, 12 h, and 24 h), before evaluating the juvenile hormone III (JHIII) titers. All of the ultrasound treatments significantly decreased the JHIII titers in M. alternatus adults. The decreases in the JHIII titers due to ultrasound exposure did not differ according to sex, but the effects on beetles of different ages differed significantly depending on the duration of exposure. The decreases in the JHIII titers were highest in male and female beetles after exposure to ultrasound for 12 h. Following exposure to ultrasound for any time period, the decreases in the JHIII titers were lower in adults aged 3 days than those aged 1 day and 5 days. The different ultrasonic frequencies led to variable decreases in the JHIII titers in M. alternatus adults, where the greatest decreases occurred in beetles exposed to ultrasound at 60 kHz. Our results indicate that ultrasound can negatively affect the normal JHIII levels and it may further disrupt sexual maturation by M. alternatus adults.