Predatory Beetles Research Articles

A Viral Pathogen from Pine Processionary Moth, Thaumetopoea pityocampa (Denis & Schiffermuller, 1775) (Lepidoptera: Notodontidae)

Pine processionary moth, Thaumetopoea pityocampa (Den. & Schiff.) is a serious defoliator in pine forests. Its larvae cause defoliation by eating leaves mainly on coniferous species, Pinus brutia, P. nigra, P. pinaster, and P. pinea in Turkey. Cypovirus is the most common entomopathogen in T. pityocampa populations. In this study, the ultrastructure of the cypovirus of T. pityocampa was observed in the intestine lumen of the predatory beetle, Calasoma sycophanta L. (Coleoptera: Carabidae), which supports the hypothesis of possible transmission of the virus to T. pityocampa populations by the predatory beetle. Polyhedral occlusion bodies (OBs) and virions were examined by electron microscopy. OBs of the virus were of irregular shape and 2.1 µm (1.2-3) in diameter, and each of them included up to 50 virions in a cross-section. Virions were icosahedral and 78.3 (65-90) nm in size and each virion had surface spikes. Smaller OBs, larger virions and a high number of virions per cross-section were the main features of the cypovirus in T. pityocampa. Our observations make us conclude that the predator beetle, C. sycophanta, may disseminate OBs of cypovirus when preying upon infected T. pityocampa larvae.

Influence of Three Aphid Species for Determining the Stage-specific Functional Response of the Coccinellid Beetle Menochilus sexmaculatus (F.)

Coccinellids are common predators of aphids, including Aphis nerii, Diuraphis noxia and Lipaphis erysimi. The zigzag ladybird beetle, Menochilus sexmaculatus, is an effective predator against various aphid species. In the present study, different stages of M. sexmaculatus were evaluated for their functional response against A. nerii, D. noxia, and L. erysimi. Functional response at different densities of aphids was calculated over a period of 24h at 25 ± 5 °C and 65 ± 5% RH. Roger's Random Predator equation was used to calculate the parameters of a functional response. All the predatory stages showed Type II functional response. Attack rate was highest in the fourth instar for all aphid species (4.5171, 2.5894 and 2.8853, respectively), while the shortest handling time of the fourth instar was recorded for A. nerii (0.0175h) and L. erysimi (0.0159h). In the case of D. noxia, the shortest handling time was observed in the first instar (0.0175h). The fourth instar of M. sexmaculatus consumed more prey, followed by the third instar. These results indicate that the fourth instar of M. sexmaculatus was the most effective stage against its prey, followed by the third instar, adult females and males. Further field experiments must be carried out to corroborate the efficacy of these predatory beetles under natural conditions.

Glyphosate exposure disturbs the bacterial endosymbiont community and reduces body weight of the predatory ladybird beetle Harmonia axyridis (Coleoptera: Coccinellidae)

The predatory ladybird beetle, Harmonia axyridis, is a predominant natural enemy of pest insects in cotton fields. Commercialization of genetically modified crops has promoted the increased use of the herbicide glyphosate. In this study, to assess potential negative effects of glyphosate on beneficial non-target organisms in cotton fields, we first examined how glyphosate exposure affected the development and endosymbiotic bacterial community of H. axyridis. The results showed that the survival rate, development duration, pupation rate and emergence rate of H. axyridis under low and high concentrations of glyphosate exposure were not significantly changed, but glyphosate did significantly reduce the body weight of H. axyridis. Based on 16S rRNA sequencing, there were no significant differences in the diversity or richness of the endosymbiotic bacteria of H. axyridis before and after glyphosate exposure. The dominant bacterial phyla Firmicutes and Proteobacteria and genera Staphylococcus and Enterobacter remained the same regardless of treatment with glyphosate, however the abundance and copy number of these bacteria were altered. Glyphosate treatment significantly reduced the abundance and gene copy number of Staphylococcus and increased the abundance and gene copy number of Enterobacter. This is the first report demonstrating that glyphosate can reduce the body weight H. axyridis and alter the bacterial endosymbiont community by affecting the abundance and gene copy number of dominant bacteria.

Field Borders Provide Winter Refuge for Beneficial Predators and Parasitoids: A Case Study on Organic Farms.

Semi-natural field borders are frequently used in midwestern U.S. sustainable agriculture. These habitats are meant to help diversify otherwise monocultural landscapes and provision them with ecosystem services, including biological control. Predatory and parasitic arthropods (i.e., potential natural enemies) often flourish in these habitats and may move into crops to help control pests. However, detailed information on the capacity of semi-natural field borders for providing overwintering refuge for these arthropods is poorly understood. In this study, we used soil emergence tents to characterize potential natural enemy communities (i.e., predacious beetles, wasps, spiders, and other arthropods) overwintering in cultivated organic crop fields and adjacent field borders. We found a greater abundance, species richness, and unique community composition of predatory and parasitic arthropods in field borders compared to arable crop fields, which were generally poorly suited as overwintering habitat. Furthermore, potential natural enemies tended to be positively associated with forb cover and negatively associated with grass cover, suggesting that grassy field borders with less forb cover are less well-suited as winter refugia. These results demonstrate that semi-natural habitats like field borders may act as a source for many natural enemies on a year-to-year basis and are important for conserving arthropod diversity in agricultural landscapes.

Seasonal dynamics of bean aphids and its relationship with the abundance of Lady Bird Beetles

The seasonal dynamics of aphid Aphis craccivora Koch (Hemiptera: Aphididae) on four bean species namely country bean Lablab purpureus, yard long bean Vigna sesquipedalis, hyacinth bean Dolichos lablab and bush bean Phaseolus vulgaris were studied from September to December 2017 in the experimental field of the Department of Entomology, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh. The study also investigated the relationship between the abundance of aphid and its predatory insect lady bird beetle. Aphid abundance on the bean species showed increasing trend from the 4th week of September and reached to the peak during the 2nd week of November and then declined. Bush bean and yard long bean, respectively depicted the higher and lower abundances of aphid throughout the study. Relationship between the abundance of aphid and lady bird beetle on the bean species were positively correlated. Aphid showed negatively correlation with temperature and rainfall, and positive correlation with relative humidity, and the correlations were not significant. Multiple regression equation showed that temperature had the highest effect which contributed 16.1 - 19.2% role on the population of aphid.
 Bangladesh J. Zool. 48(2): 357-363, 2020

<p><strong>Spatial distribution and sequential sampling of aphid and their natural enemies on wheat</strong></p>

Although many pests attack wheat, the damage due to wheat aphids has been on rise due to climate change phenomenon. Population of aphids increases during February to March and so the ladybird beetles to devour on aphids. With the aim of facilitating conservation of ladybird beetles, predator conditioned sampling plans were worked out. Wheat aphids, Rhopalosiphum padi L. and Sitobion avenae F. were observed infesting wheat. Major predatory coccinellid beetles, Cheilomenes sexmaculata (Fabricius) and Coccinella septempunctata (Linnaeus) were also found feeding on the wheat aphids. Spatial distribution of mixed population of the aphids and coccinellid beetles was analyzed using variance-mean ratio and regression models such as Taylor’s power law and Iwao’s mean crowding regression. The aphids and its predatory beetles were counted at different crop age. The mean population for wheat aphid was 7.88/plant and 0.72/ plant at 75 and 106 days after sowing (DAS), respectively. Variance-mean ratio indicated regular to aggregated distribution of aphids on the crop. Taylor’s power law aggregation parameter (b = 2.62) and density contagiousness co-efficient (β = 1.20) of Iwao’s mean crowding regression also revealed aggregated distribution of the wheat aphids. The mean population of coccinellid beetles varied from 0.72 to 1.43/plant during 68 to 100 DAS. Taylor’s power law aggregation parameter (b = 3.64) and density contagiousness co-efficient (β = 2.09) of Iwao’s mean crowding regression revealed aggregated distribution of the predators on the wheat crop. Sequential sampling plans were developed for wheat aphid management with and without predator’s effect through Taylor’s power law and Iwao’s mean crowding regression. Inclusion of predator effect in the regression models increased aphid population levels which necessitates need for management measures at higher population levels. Thus, the sequential sampling plans with predator effect are useful in avoiding unnecessary pesticide application on wheat crop for the aphid management.

Predatory beetles on seeds, fruits, and flower buds in a tropical forest of Panama

Fruit and seed predators determine plant populations dynamics and community structure of tropical forests. Its impact can have drastic consequences on the development of plants and their ability to reproduce. Among the main causes of damage to fruits, and seeds, Coleoptera of the Curculionidae and Bruchidae families and other groups of beetles stand out. The research was carried out in the Metropolitan Natural Park (PNM), considered as the "lung of the City of Panama" which has deciduous trees that reach up to 36 m in height and an average annual temperature of 28° C. The work consisted of collecting samples of fruits and seeds of all plant species encountered in the fruiting condition in the park from August 2015 to July 2016. Additionally, flower buds of Anacardium excelsum L. attacked by two species of Anthonomus Germar, 1817 were also included in the analyses. A total of 797 beetles were collected from 3091 samples (seeds, fruits, flower buds) reared at environmental conditions. The Curculionidae and Bruchidae families presented the highest abundance of individuals and species richness. One species of Hypothenemus Westwood, 1836 (Scolytinae), was the most abundant within the Curculionidae family and in the Bruchidae family one species of Acanthoscelides Schilsky, 1905. Tree species such as Oenocarpus mapora H. Karst. 1857 and Guazuma ulmifolia Lam presented higher predation of their fruits or seeds. On average only 5% of dissected seeds were predated across 32 host plant species. In total, 31 genera of beetles were reared from flower buds, seeds, and fruits of 17 plant species. Host-specificity was moderated, with 47% of flower bud, fruit and seed predator genera associated with just one plant species. Sixty one percent of the coleopterans were collected in the dry season (December to March).

Prey removal in cotton crops next to woodland reveals periodic diurnal and nocturnal invertebrate predation gradients from the crop edge\xa0by birds and bats

Factors influencing the efficacy of insectivorous vertebrates in providing natural pest control services inside crops at increasing distances from the crop edge are poorly understood. We investigated the identity of vertebrate predators (birds and bats) and removal of sentinel prey (mealworms and beetles) from experimental feeding trays in cotton crops using prey removal trials, camera traps and observations. More prey was removed during the day than at night, but prey removal was variable at the crop edge and dependent on the month (reflecting crop growth and cover) and time of day. Overall, the predation of mealworms and beetles was 1-times and 13-times greater during the day than night, respectively, with predation on mealworms 3–5 times greater during the day than night at the crop edge compared to 95 m inside the crop. Camera traps identified many insectivorous birds and bats over crops near the feeding trays, but there was no evidence of bats or small passerines removing experimental prey. A predation gradient from the crop edge was evident, but only in some months. This corresponded to the foraging preferences of open-space generalist predators (magpies) in low crop cover versus the shrubby habitat preferred by small passerines, likely facilitating foraging away from the crop edge later in the season. Our results are in line with Optimal Foraging Theory and suggest that predators trade-off foraging behaviour with predation risk at different distances from the crop edge and levels of crop cover. Understanding the optimal farm configuration to support insectivorous bird and bat populations can assist farmers to make informed decisions regarding in-crop natural pest control and maximise the predation services provided by farm biodiversity.

Assessing the laboratory mass rearing of Predator Beetle Rhizophagus grandis Gyll. (Coleoptera: Monotomidae)

The aim of this study was to determine the progeny production of predator beetle Rhizophagus grandis (Gyllenhal) (Coleoptera: Monotomidae) under laboratory conditions. Different numbers of male and female predators introduced into breeding logs and the numbers of new progenies and their sex ratios were determined in the early and late spring periods. A total of 8776, 13,402, 5742 and 7864 R. grandis individuals were reared in 60, 109, 128 and 56 breeding logs in four consecutive years, respectively. Of the prepupae that have dropped from breeding logs to enter the sand in experimental basins, 81.4 % of them have emerged as adults at the end of the experimental periods. The average number of R. grandis per log was 146.2, 123, 44.9 and 140.4 according to experimental years, and 181.7 and 93.2, 123, 62.4 and 32.9, 163.8 and 101.5 according to the early and late spring periods in the experimental years, respectively. In the second year of the experiments, only early spring rearings have been performed that have yielded 123 R. grandis per log on average. Progeny production of a female R. grandis was 18.3, 18.7, 5.8 and 17.6 on average, 2004, 2005, 2006 and 2007 respectively. Different numbers of predator females and males were used in early and late spring experiments in the study. Progeny production was higher in early spring when the experiments were performed with 6 females and 2 males. Of the 35,784 R. grandis individuals that were obtained from the experiment, 16.4 %, 28.3 % and 55.3 % were collected from the first, second and third part of the sand environment where the breeding logs kept during experiment.

Alien and native tree species having extrafloral nectaries as favorite hunting area for arboreal endemic Philippine tiger beetles (Coleoptera: Cicindelidae) in human-disturbed habitat in Lanao del Sur Province, Mindanao, Philippines.

To document a relation between abundance of arboreal, predatory tiger beetles, their ant prey, and extrafloral nectaries attracting the ants, we gathered data from more than 10 species of native and introduced trees and large, tree‐like perennial plants in Lanao del Sur Province, Mindanao, Philippines. All specimens of tiger beetles (two Tricondyla and two Neocollyris species, all endemic to the country) were noted on five tree species characterized by presence of extrafloral nectaries, including three alien/invasive and two native ones. Invasive Spathodea campanulata and native Hibiscus tiliaceus were the most inhabited ones (respectively, 56% and 19% of beetles). Presence of tiger beetles on these trees most probably depends on high abundance of ants, which are typical prey for arboreal Cicindelidae, while occurrence of ants can result from presence of extrafloral nectaries on different parts of the plants. This suggests a new mutualistic insect–plant interaction between native and invasive species.

New insights into the phylogeny and evolution of lady beetles (Coleoptera: Coccinellidae) by extensive sampling of genes and species

Ladybirds (family Coccinellidae) are one of the most diverse groups of beetles and globally comprise over 6000 species. Despite their scientific and economic significance, the taxonomy of Coccinellidae remains unstable, and we still know little about their evolutionary history. By using a small number of genes, previous phylogenetic analyses have not reliably resolved the relationships among major ladybird lineages. In this study, we sequenced 94 nuclear protein-coding genes for 214 species of Coccinellidae and 14 outgroups, covering 90 genera and 35 tribes. We found that nucleotide compositional heterogeneity is present among ladybird tribes so that phylogenetic inference at the amino acid level is more reliable than at the DNA level. Based on the maximum likelihood analyses of the amino acid dataset, we recognize three subfamilies in Coccinellidae: Microweiseinae, Monocoryninae stat. nov., and Coccinellinae. The subfamily relationships are strongly supported as (Microweiseinae, (Monocoryninae stat. nov., Coccinellinae)). The tribes of ladybirds are mostly monophyletic, except Ortaliini, Sticholotidini, Scymnini, and Coccidulini. The phylogenetic relationships among tribes of Coccinellinae are still not well resolved, with many nodes weakly supported. Our divergence time analysis suggests that the crown group of extant lady beetles arose in the Early Cretaceous ~ 143 million years ago (Mya) and experienced a rapid diversification during the Late Cretaceous (120–70 Mya). We hypothesize that the boom of angiosperms in the Late Cretaceous promoted the diversification of herbivorous Sternorrhyncha insects, especially aphids, which in turn drove the rapid radiation of predatory lady beetles. In summary, our work provides a comprehensive time-calibrated phylogeny of Coccinellidae that provides a sound framework for revising their classification and understanding the origin of their biodiversity.

Establishment of the predator Laricobius nigrinus, introduced as a biological control agent for hemlock woolly adelgid in Virginia, USA

Laricobius nigrinus Fender (Coleoptera: Derodontidae), a predatory beetle native to western North America, has been released since 2003 for management of hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae), a non-native pest killing hemlocks in eastern North America. Over 420,000 L. nigrinus have been released in the eastern USA from field and lab-reared sources, 14,000 of which were deployed in the Commonwealth of Virginia, USA. In order to determine the establishment rates of L. nigrinus in Virginia, surveys were conducted in 2017 and 2018 at all release sites within this state. During the study, stand-level HWA densities were estimated, and hemlock tree health and predator–prey ratios were quantified. The identification of Laricobius spp. recoveries were made using microsatellite analysis. During the period of the study, L. nigrinus were found to have established at 82% of Virginia release sites and were the primary species recovered (80%). Both Laricobius rubidus (18%) and hybrids (2%) were also recovered. Stand-level HWA densities varied greatly over sites and years but showed a general decline in year two of the study. Establishment at such a high percentage of release sites suggests that the climate in Virginia is suitable for the predator and the insect is adaptable to the wide variety of site conditions where hemlocks typically grow.

Іле-Алатау МҰТП қаттықанаттылары (Coleoptera) (Оңтүстік-Шығыс Қазақстан)

The article presents the results of research conducted by the authors on the territory of the Ile-Alatau State National Natural Park in 2020-2021. Research works are devoted to the fauna, biology and ecology of beetles or beetles on the territory of this natural park. Coleoptera are the largest group of insects, which is of great practical importance. They are distributed on the territory of the IleAlatau GNPP. Most of the beetle species are zoophages, and phytophages also predominate. When collecting the material, standard entomological methods were used-collection with an entomological filter, collection with an artificial light source, manual collection, etc. As a result of the conducted research, 47 species from 10 families of the coleoptera order were collected on the territory of the Ile-Alatau State National Natural Park: Meloidae, Curculionidae, Buprestidae, Chrysomelidae (out of 8 species, 17%), Tenebrionidae, Cerambycidae, Scarabaeidae (of 3 species, 7%), Coccinellidae, Silphidae, Сarabidae (of 2 species, 4%). In this order, predatory beetles are nutritionally related: representatives of the family Coccinellidae, Carabidae, the remaining species from 8 families (Meloidae, Curculionidae, Buprestidae, Chrysomelidae, Tenebrionidae, Cerambycidae, Scarabaeidae, Silphidae) are phytophages. Coleoptera are divided into zoophages (4 species), phytophages (41 species), coprophages (1 species), saprophages (1 species) by nutritional connection. Coleoptera on the territory of the Ile-Alatau State National Natural Park differ into chortobionts (27), dendrobionts (17 species), herpetobionts (3 species). Beetles in the park are ecologically mesophilic species.

Барсакелмес қорығы қаттықанаттыларының (Coleoptera) күзгі фаунасы

Coleoptera are the most diverse and species-rich order of insects. Biologically, coleoptera are very diverse. Beetle nutrition is also extremely diverse. Among them there are predators, phytophages, saprophages, necrophages. Predatory beetles prey on various small invertebrates, mainly other insects. Herbivorous beetles feed not only on the green parts of a wide variety of plants, but also on wood. Beetles are found everywhere (in water, on land, on plants, in soil) and are essential in the circulation of substances in nature. The research was carried out in October 2021 in the section of the Syrdarya River delta, up to the Koksarai dam, Amanatkol Lake, Shobankol Lake, Alakol Lake, Akshatau Lake, Shomishkol lake, okr. village. Shomishkol, Kolshykkan lake. Conventional entomological traditional methods were used in the conducted research. As a result of the field work, representatives from the Insect class (Insecta) of the order Coleoptera, or beetles (Coleoptera) were identified. A total of 24 species from 4 families are represented. The sem stands out for its species diversity. Tenebrionidae (12 species), Carabidae (3 species), in the other 2 families, only 1 species are noted. Studies in 2021 have shown a decrease in the number and faunal change of dominant species. Since the studies were conducted in October, many invertebrates have already gone to winter.

Seasonal dynamics of dominant species of soil predators (Coleoptera: Carabidae, Staphylinidae) in agrolandscapes and their potential gluttony

We studied the seasonal change in the number of dominant species of predatory beetles on vegetable crops and determined their potential gluttony. A total of 1,472 beetles were collected, belonging to 22 species of ground beetles (Carabidae) and 27 species of rove beetles (Staphylinidae). The dominant species are: Harpalus rufipes (De Geer, 1774) (17.6% dominance), Amara fulva (De Geer) (13.28%), Bembidion properans (Stephens, 1828) (10.39%), Trechus quadristriatus (Schrank, 1781) (6.20%), Calathus melanocephalus (Linnaeus, 1758) (5.39%), Poecilus cupreus Linnaeus, 1758 (5.3%), Bembidion femoratum Sturm, 1825 (5.10%), Aleochara bilineata, (Gyllenhaal, 1810) (17.6%), Aloconota gregagia (Erichson, 1839) (10.21%), Amischa analis (Gravenhorst, 1802) (6.01%), Amischa bifoveotata (Mannerheim, 1830) (5.41%). During the season, there is a change in dominant species. At the beginning of the season, smaller species dominate, while larger species dominate in the second half of the plant vegetation. The maximum number of predators are observed in June and August. The periods of the maximum abundance of ground beetles and rove beetles do not coincide in time, which is the evolutionary adaptation of two groups of predators that coexist. In laboratory experiments, when pest eggs were offered as food, Aleochara bilineata and Bembidion femoratum were the most voracious. Larger predator species showed high voracity when larvae of flies were offered as food.

Flower strips as a bridge habitat facilitate the movement of predatory beetles from wheat to maize crops.

Generalist predators play a key role in the biocontrol of insect pests in agricultural systems. However, predators are subject to frequent mortality events due to periodic disturbance regimes such as crop planting and harvest, which inevitably affect the population development of predators. Conservation of predators in this critical period is important for double-cropping systems such as winter wheat and summer maize, the most widely used cropping system in North China. Planting Cnidium monnieri flower strips at field borders could not only serve as a bridge habitat to conserve the dominant predator Propylaea japonica in wheat fields during harvest but also help the predator immigrate to adjacent maize fields. The predator abundance was 7-fold higher on flower strips than that on natural vegetation strips during the wheat postharvest period and before the maize plant emergence for about a month, and its abundance in maize fields planted with flower strips was nearly 2-fold higher than that in maize fields planted with natural vegetation strips. Moreover, 77.56% of predators that entered maize fields were proven to originate from flower strips. Our findings provided evidence that manipulating flower strips as a bridge habitat in wheat-maize rotation fields could conserve P. japonica during crop phenophase changes, and we quantitatively testified that the proportion of this predator in maize fields derived from flower strips. In practice, such a strategy may also be applied in other double-cropping and triple-cropping systems. © 2020 Society of Chemical Industry.

Comparison of biological methods to control Aphis fabae Scopoli (Hemiptera: Aphididae) on kalanchoe crops in East Africa

Aphids cause considerable damage to numerous crops all over the world and insecticides are the main means of controlling them, despite their detrimental impacts on human and environmental health. This study assessed the effectiveness of the parasitoid Aphidius colemani Viereck (Hymenoptera: Braconidae), a mixture of predatory ladybird beetles, Hippodamia variegata Goeze, Chilocorus calvus Chiccl, and Cheilomenes propinqua Mulsant (Coleoptera: Coccinellidae), and an entomopathogenic strain of Aspergillus flavus Link (Eurotiales: Trichocomaceae), collected locally in Tanzania, to control Aphis fabae Scopoli (Hemiptera: Aphididae). After assessing the predation and parasitism rates of these natural enemies at different aphid densities in laboratory experiments, their ability to control aphids on kalanchoe was assessed in a greenhouse experiment over two seasons. The largest number of A. fabae parasitized or consumed in the laboratory was found at a density of 160 aphids per predator, or parasitoid. At that density, an adult female of A. colemani parasitized 114 A. fabae per day, on average, and adults of C. calvus, H. variegata, and C. propinqua consumed 75, 72, and 85 aphids per day, respectively. A. flavus spores applied at 1 × 107 spores ml−1 reduced the aphid population by 7.9 and 12.6 times within 10 days in the first and second seasons of the greenhouse experiments, respectively, as opposed to 2.8 and 2.5 times by releasing a mixture of the ladybirds at a rate of 5 adults/m2, and by 3.3 and 9.5 times by releasing A. colemani at a rate of 2 adults/m2. This study confirmed the potential of these locally collected bio-control agents for controlling A. fabae. However, use of the isolated A. flavus strain was undermined by its production of aflatoxin. Further research is therefore required to tap into the potential of a non-toxic strain of A. flavus and/or other entomopathogenic fungi.

Functional investigation of monoterpenes for improved understanding of the relationship between hosts and bark beetles

AbstractSpruce bark beetle (Ips typographus L.) is the most destructive insect pest of spruce forests in Eurasia. However, contact toxicity, in vivo metabolism, and ecological functions of host monoterpenes are poorly understood at the spruce tree–bark beetle–predator tritrophic level. Spruce monoterpenes including S‐(–)‐α‐pinene, R‐(+)‐α‐pinene, and myrcene showed contact toxicity to I. typographus, with LD50 values ranging from 22–32 μg/mg. When topically treated with S‐(–)‐α‐pinene or R‐(+)‐α‐pinene, the amounts of volatile metabolites, including 4S‐(–)‐cis‐verbenol, 4S‐(+)‐/4R‐(–)‐trans‐verbenol, R‐(+)‐/S‐(–)‐verbenone and 1R‐(–)‐/1S‐(+)‐myrtenol, in the hindgut extracts of I. typographus varied significantly between sexes, and their quality (enantiomeric composition) varied significantly with the chirality of α‐pinene. More importantly, S‐(–)‐α‐pinene induced male adults to produce large amounts of 4S‐(–)‐cis‐verbenol and S‐(–)‐verbenone. When topically treated with myrcene, the expected semiochemicals such as E‐myrcenol, ipsenol and ipsdienol were not detected in the beetle hindguts, indicating that the pheromone biosynthetic system of I. typographus does not participate in the metabolism of host myrcene. In trap tests, S‐(–)‐α‐pinene and R‐(+)‐α‐pinene increased the catches of I. typographus and its predator Thanasimus substriatus in pheromone‐baited traps, whereas myrcene exhibited a strong repellent (or inhibitory) effect on I. typographus but not on its predator. I. typographus seems to adopt different ecological strategies (e.g. avoidance to myrcene and preference for α‐pinene) to adapt to and tolerate different host monoterpenes. Extensive investigation of these monoterpenes will help us understand their roles in manipulating the arms race between host trees and bark beetles, and potentially improve the efficacy of controlling I. typographus via the push‐pull strategy using host kairomones.

Forest cover and heterogeneous pastures shape the diversity of predatory rove beetles in tropical riparian habitats

In tropical landscapes, forest remnants have been reduced to narrow strips of vegetation along rivers and streams surrounded by agricultural land that affects biodiversity, depending on the habitat and landscape characteristics. To assess the effect of riparian forest loss on the diversity of Staphylininae predatory rove beetles, we considered two habitat conditions (river sites with riparian vegetation and sites with heterogeneous pastures) within two micro-basin types (with >70% and <40% forest cover) in a tropical montane cloud forest landscape, Mexico. Beetles were collected using baited pitfall traps during the rainy season of 2014. No differences were found between micro-basin types and, although species richness (0D) was similar between habitat conditions, when the diversity of common (1D) and dominant (2D) species was considered, sites with heterogeneous pastures were almost twice as diverse as those with riparian vegetation. All diversity measurements were greater in sites with heterogeneous pastures of either micro-basin type. Air temperature and canopy cover were the environmental variables that best explained the variation in beetle species composition. The greatest environmental differences related to species composition were detected between habitat conditions and were more evident in sites with heterogeneous pastures and low forest cover in the surroundings. The results suggest that replacing riparian vegetation with heterogeneous pastures, within micro-basins that lost between 30% and 60% of their forest cover, does not significantly reduce the diversity of predatory rove beetle but rather modifies the beetle composition. Effective formulation of management strategies to mitigate the impact of land use modification therefore requires an understanding of the interaction between vegetation remnants and landscape characteristics.

Fluctuating Asymmetry as a Method of Assessing Environmental Stress in Two Predatory Carabid Species within Mediterranean Agroecosystems

Fluctuating asymmetry (FA) is used in assessing the effect of environmental stress on the development stability of individuals by measuring small random deviations from perfect bilateral symmetry. Here, we checked for FA on two predatory carabid beetles, Pterostichus melas and Poecilus koyi, in order to evaluate species response to agricultural practices within Mediterranean agroecosystems, as well as FA as a method. The samples were collected in vineyards and olive groves, both under integrated pest management (IPM) and ecological pest management (EPM), and in pristine habitats in the Mediterranean region of Croatia. Geometric morphometrics (GMMs) were used to analyze the pronotum and abdomen shape variations and left–right asymmetries of each population. In respect to the FA measurements, analyzed species responded differently, with P. koyi displaying a lower intensity of FA than P. melas. On the other hand, P. melas beetles from vineyards showed a higher intensity of FA compared with populations from pristine habitats and olive groves. Accordingly, FA pointed out olive groves as potentially less adverse habitats to predatory carabids, keeping in mind the different levels of asymmetry between the two species. Our study singled out P.melas as a more suitable species for further research, in the effect that different agricultural practices can have their impact on non-target invertebrates analyzed by measuring the FA.