Important Forest Pest Research Articles

Potential applicability of SPLAT® Verb for management of European spruce bark beetle, Ips typographus (L.)

AbstractThe European spruce bark beetle, Ips typographus (L.), is the most important forest pest in Europe due to the profound impacts of periodic outbreaks on ecosystem goods and services. Herein, we evaluated the responses of I. typographus to different doses of verbenone (SPLAT® Verb, 10% (−)‐verbenone by weight; ISCA Inc., Riverside, CA, USA) in traps baited with its aggregation pheromones. Results are based on 1,492,289 I. typographus collected in five experiments over 3 years. SPLAT® Verb inhibited the response of I. typographus to baited traps out to 14 m from the point of release (dollop) and for >80 days at a dose of 75 g per dollop. Reductions in trap catch ranged from 34% to 93% depending on the dose of verbenone, age of SPLAT® Verb dollops, distance from dollops and the environment. In forest stands, significant reductions in trap catch were observed at distances up to 14 m from the point of release, with the largest reductions observed at 0 m (93%) and 2 m (64%). In an open area, significant reductions in trap catch were observed at distances up to only 2 m from the point of release, with the largest reduction observed at 0 m (66%). The much lower active inhibitory range of verbenone in the open area appears to be explained by less stable accumulations of verbenone in the surrounding air. There was a significant negative correlation between trap catch and the amount of verbenone measured in air in the vicinity of traps. We also observed inhibition of the sixtoothed spruce bark beetle, Pityogenes chalcographus (L.), another important forest pest in Europe, at all doses (20, 40, 75 and 100 g) of SPLAT® Verb that were evaluated. The implications of these and other results to the management of I. typographus are discussed.

Phylogeography and bioclimatic models revealed a complicated genetic structure and future range shifts of Lymantria monacha L.

AbstractThe phylogeography of economically important forest pests is important for understanding their demographic and evolutionary history. Linking the genetic data obtained with the bioclimatic models helps reveal future demographic trends of the pest species studied. Lymantria monacha is a polyphagous species that feeds on numerous coniferous and deciduous trees throughout the Palaearctic and is known to cause catastrophic defoliation, particularly in Europe. In addition, data from various mapping programmes over the last decade have revealed changes in the distribution of L. monacha. Therefore, in this study, we decided to clarify the evolutionary and demographic history of this important forest species using genetic data complemented by bioclimatic modelling. Our results confirmed the systematic status and monophyly of L. monacha. However, the lack of a geographical pattern between the studied regions suggests that the current genetic structure may be the result of recent dispersal events. Moreover, we found that the areas of high genetic diversity are consistent with potential past range shifts and survival of changes in climate and host plant availability. These two main variables also seem to determine the future range of L. monacha. Also, our modelling confirmed a poleward shift in its range and with a significant retraction from its current southern edge of distribution.

Fungi associated with ambrosia beetle Xylosandrus germanus in Slovakia

The black timber bark beetle (Xylosandrus germanus) is a strongly invasive ambrosia beetle and an important forest pest in Slovakia. This pest is closely associated with symbiotic fungi used as its food source. We investigated the fungi associated with X. germanus adults in Slovakia. In this study, Beauveria bassiana, B. pseudobassiana, Clonostachys rosea, Fusarium oxysporum, Ophiostoma quercus, Phaeoacremonium scolyti, and Talaromyces amestolkiae were isolated and identified by morphological and molecular analyses. The fungus Ophiostoma quercus was most frequently isolated from living beetles, while the entomopathogenic Beauveria bassiana was the most commonly isolated from dead beetles. The morphological descriptions of fungi based on isolates from the surface of X. germanus adults are provided.

Morphological, Molecular Identification and Virulence of Entomopathogenic Fungi Isolated From Dendroctonus micans (Kugelann,1794) (Coleoptera: Curculionidae)

In this study, to determine an effective fungal agent against Dendroctonus micans (Kugelann, 1794) (Coleoptera: Curculionidae), which causes significant economic losses in forested areas, Picea orientalis (L.) Link in Artvin between 2021-2022. Dendroctonus micans larvae and adults were collected from the trees, and 18 fungi were isolated from larvae and adult insects. Morphological (infection type, colony morphology, spore form) and molecular (ITS1-5.8S ITS2 gene region) characterization determined that the isolates were Metarhizium anisopliae (Metschn.) Sorokin, 1883 (Hypocreales: Clavicipitaceae), M. robertsii, M. pinghaense and Clonostachys rosea Samuels & Rossman, 1999 (Hypocreales: Bionectriaceae). Isolates M. robertsii (OZM4) and M. pinhaense (OZM9) have been isolated from this pest for the first time. As a result of insecticidal activity tests performed on D. micans larvae and adults of 1x107spore/ml spore suspension, the larvae, M. anisopliae (OZM2), showed a mortality rate of 92% within 7 days and adults mortality was determined 100% at the end of the experiment, and mycosis rates were found to be consistent with mortality rates. These results show that isolates with high virulence are promising in microbial and integrated control applications against important forest pests.

The Diversity of Parasitoids and Their Role in the Control of the Siberian Moth, Dendrolimus sibiricus (Lepidoptera: Lasiocampidae), a Major Coniferous Pest in Northern Asia.

The Siberian moth, Dendrolimus sibiricus Tschetv., 1908 (Lepidoptera: Lasiocampidae) is a conifer pest that causes unprecedented forest mortality in Northern Asia, leading to enormous ecological and economic losses. This is the first study summarizing data on the parasitoid diversity and parasitism of this pest over the last 118 years (1905-2022). Based on 860 specimens of freshly reared and archival parasitoids, 16 species from two orders (Hymenoptera and Diptera) were identified morphologically and/or with the use of DNA barcoding. For all of them, data on distribution and hosts and images of parasitoid adults are provided. Among them, the braconid species, Meteorus versicolor (Wesmael, 1835), was documented as a parasitoid of D. sibiricus for the first time. The eastern Palaearctic form, Aleiodes esenbeckii (Hartig, 1838) dendrolimi (Matsumura, 1926), status nov., was resurrected from synonymy as a valid subspecies, and a key for its differentiation from the western Palaearctic subspecies Aleiodes esenbeckii ssp. esenbecki is provided. DNA barcodes of 11 parasitoid species from Siberia, i.e., nine hymenopterans and two dipterans, represented novel records and can be used for accurate molecular genetic identification of species. An exhaustive checklist of parasitoids accounting for 93 species associated with D. sibirisus in northern Asia was compiled. Finally, the literature and original data on parasitism in D. sibiricus populations for the last 83 years (1940-2022) were analysed taking into account the pest population dynamics (i.e., growth, outbreak, decline, and depression phases). A gradual time-lagged increase in egg and pupal parasitism in D. sibiricus populations was detected, with a peak in the pest decline phase. According to long-term observations, the following species are able to cause significant mortality of D. sibiricus in Northern Asia: the hymenopteran egg parasitoids Telenomus tetratomus and Ooencyrtus pinicolus; the larval parasitoids Aleiodes esenbeckii sp. dendrolimi, Cotesia spp., and Glyptapanteles liparidis; and the dipteran pupal parasitoids Masicera sphingivora, Tachina sp., and Blepharipa sp. Their potential should be further explored in order to develop biocontrol programs for this important forest pest.

The weak genetic structure of Melolontha melolontha (L.) and Melolontha hippocastani (Fabr.), two important forest pests, indicates their large population sizes and effective gene flow

Abstract Cockchafers Melolontha spp. are polyphagous root pests and outbreak species of considerable economic importance to forestry in Europe. Knowledge of genetic diversity within and between cockchafer populations is largely unexplored but could lead to more effective monitoring and management strategies of these pests. In this study, we fill several gaps in the knowledge of the genetic population structure of Melolontha melolontha and Melolontha hippocastani. Using microsatellite loci and over 200 individuals per species, we examined the genetic structure of Melolontha spp. populations collected from three primary outbreak areas in central and southeastern Poland. We demonstrated that our focal species share some common genetic patterns, such as considerable genetic diversity within subpopulations (within sampling sites) with minor effects of past bottlenecks possibly masked by current population sizes. The estimates of effective population sizes, although subject to wide credibility intervals, indicated a large number of individuals contributing to further generations of the population. The migration rates exceed the threshold of one per generation required for gene flow and maintenance of population equilibrium, indicating limited impact from forest management practices on either cockchafer species. While genetic differentiation was observed in M. melolontha populations, supported by various indices (fixation index, principal coordinate analysis, assignment tests), the M. hippocastani populations were genetically similar. This disparity may hint at the potential historical divergence between these species. In this aspect, more detailed phylogeographic and population genetic studies covering a large area of the Palaearctic distributions of both species are required. Our findings constitute one of the initial efforts aimed at delineating the genetic diversity, differentiation, population structure, gene flow, and migration patterns within Melolontha spp. This exploration is especially significant for M. hippocastani, given its completely unexplored genetic population structure.

A new sawfly Cephalcia koreana (Hymenoptera: Pamphiliidae), the pest of Manchurian fir Abies holophylla in Korea

The genus Cephalcia Panzer in the sawfly family of Pamphiliidae Cameron is widely distributed in the Holarctic. However, very little is known about the Korean species. Here, we describe Cephalcia koreana Park & Jung, sp. nov. in Korea. Its larvae seriously defoliated leaves of Abies holophylla plantations in Hwacheon-gun, Gangwon Province during 2020–2022. It is newly recognized as an important forest insect pest. We provide taxonomic information including a new key for identifying and separating five Korean species and photographs of diagnostic characters with biological notes and genetic data of the new species.

SMRT Sequencing Technology Was Used to Construct the Batocera horsfieldi (Hope) Transcriptome and Reveal Its Features.

Batocera horsfieldi (Hope) (Coleoptera: Cerambycidae) is an important forest pest in China that mainly infests timber and economic forests. This pest primarily causes plant tissue to necrotize, rot, and eventually die by feeding on the woody parts of tree trunks. To gain a deeper understanding of the genetic mechanism of B. horsfieldi, this study employed single-molecule real-time sequencing (SMRT) and Illumina RNA-seq technologies to conduct full-length transcriptome sequencing of the insect. Total RNA extracted from male and female adults was mixed and subjected to SMRT sequencing, generating a complete transcriptome. Transcriptome analysis, prediction of long non-coding RNA (lncRNA), coding sequences (CDs), analysis of simple sequence repeats (SSR), prediction of transcription factors, and functional annotation of transcripts were performed in this study. The collective 20,356,793 subreads (38.26 G, clean reads) were generated, including 432,091 circular consensus sequences and 395,851 full-length non-chimera reads. The full-length non-chimera reads (FLNC) were clustered and redundancies were removed, resulting in 39,912 consensus reads. SSR and ANGEL software v3.0 were used for predicting SSR and CDs. In addition, four tools were used for annotating 6058 lncRNAs, identifying 636 transcription factors. Furthermore, a total of 84,650 transcripts were functionally annotated in seven different databases. This is the first time that the full-length transcriptome of B. horsfieldi has been obtained using SMRT sequencing. This provides an important foundation for investigating the gene regulation underlying the interaction between B. horsfieldi and its host plants through gene editing in the future and provides a scientific basis for the prevention and control of B. horsfieldi.

Functional importance of groups I and II chitinases in cuticle chitin turnover during molting in a wood-boring beetle, Monochamus alternatus

Insects must periodically replace their old cuticle/exoskeleton with a new one in a process called molting or ecdysis to allow for continuous growth through sequential developmental stages. Many RNA interference (RNAi) studies have demonstrated that certain chitinases (CHTs) play roles in this vital physiological event because knockdown of these CHT genes resulted in developmental arrest during the ensuing molting period in several insect species. In this research we analyzed the functions of group I (MaCHT5) and group II (MaCHT10) CHT genes in molting of the Japanese pine sawyer, Monochamus alternatus, an important forest pest known as a major vector of the pinewood nematode. Real-time qPCR revealed that these two CHT genes differ in their expression patterns during late stages of development. Depletion of either MaCHT5 or MaCHT10 transcripts by RNAi resulted in lethal larval-pupal and pupal-adult molting defects depending on the double-stranded RNA (dsRNA) injection timing during development. The insects were unable to shed their old cuticle and died. Furthermore, transmission electron microscopic analysis revealed that, unlike dsEGFP-treated controls, dsMaCHT5- and dsMaCHT10-treated pharate adults exhibited a failure of degradation of the endocuticular layer of their old pupal cuticle, retaining nearly intact horizontal chitinous laminae and vertical pore canal fibers. Both enzymes were indispensable for complete turnover of the chitinous old endocuticle, which is critical for insect molting. The possible functions of two spliced variants of MaCHT10, namely, MaCHT10a and MaCHT10b, are also discussed. Our results add to the knowledge base for further functional studies of insect chitin catabolism by revealing the relative importance of both MaCHT5 and MaCHT10 in chitin turnover with subtle differences in their action. These essential genes and their encoded proteins are potential targets to manipulate for controlling populations of M. alternatus and other pest insects.

Two decades of epidemiological surveillance of the pine wood nematode in France reveal its absence despite suitable conditions for its establishment

Key messageThis study takes stock of the first 20 years (2000–2019) of monitoring the pine wood nematode (PWN) in metropolitan France. While PWN was never found in the wild during this period, it was reported in some wood-based commodities entering or circulating on French territory. This stresses the importance of remaining extremely vigilant, as the conditions found in France, especially weather conditions, could be particularly suitable for the pest’s establishment.ContextThe pine wood nematode (PWN) Bursaphelenchus xylophilus, responsible for pine wilt disease (PWD), is one of the most important forest tree pests worldwide. It is thus the focus of many monitoring programmes. In the European Union, for example, it is categorised as a priority quarantine pest, so each member state is obliged to monitor the PWN on its territory.AimsThe first objective of this paper was to describe PWN monitoring in metropolitan France, namely how it is organised and whether it has led to the nematode’s detection. Secondly, we wished to investigate what the levels of PWD expression for host pines infected by B. xylophilus would be in France. Thirdly, we wanted to find out whether other Bursaphelenchus species had been found on French territory during these two decades of PWN monitoring.MethodsWe analysed data from samples collected in the framework of the monitoring programme between 2000 and 2019 to track the PWN in its host pines, its insect vector (Monochamus spp.) and in wood-based commodities imported into or circulating in metropolitan France. We also generated risk maps of PWD expression based on an evapo-transpiration model using climate data for the period 2000–2019.ResultsThis monitoring, which was regularly reinforced from 2000 to 2019, consisted of sampling and analysing around 18,000 wood samples and 66,000 insects over this period. Although the PWN was not detected in pine stands or within its insect vector, some wood-based commodities were found to be contaminated. Risk maps of PWD expression show that in the most recent years (2015–2019), the weather conditions in a large fraction of metropolitan France were suited to PWD expression, mostly with a delay (i.e., latency) between infection and observable wilt symptoms. PWN monitoring has also revealed the presence of other Bursaphelenchus species, most of which were discovered for the first time in metropolitan France and are described herein.ConclusionWhile metropolitan France is still free of the PWN, this study emphasises the need to remain cautious as the French territory appears particularly suitable for this pest’s establishment. Furthermore, our research has led us to propose some ideas on how to improve PWN monitoring.

Integrated forest protection

In forestry science and profession, continuous efforts are being made to implement forest protection, the most perfect, most efficient and most complex dynamic systems of interconnected and inextricably linked parts of living and non-living nature, against all harmful abiotic and biotic factors, integrally and in an organized manner. Integral forest protection implies versatile and maximum, continuous, application of protective measures in order to ensure unhindered growth and growth of trees, and the creation of the highest quality wood volume. The dangers that threaten mature forest trees are numerous. Maintaining the vitality of forest plant species, from seedlings to trees of different age classes, is a long-term process during which they can be exposed for a longer or shorter time, to harmful biotic or abiotic factors, which sometimes cause long-term pathological processes, with unforeseeable environmental and economic consequences. Their sources lie, on the one hand, in the ecosystem itself, and on the other, in the activities of man, who consciously or unconsciously stimulates them. Any intervention in natural forests must take into account that they are regulated communities of the living beings and that the laws of its maintenance and renewal must be respected, if its regulatory mechanisms are not to be disrupted. Integral forest protection, as well as its most important part related to integrated pest management (IPM), requires a conceptual approach to knowing the complexity of forest ecosystems and the role of man in maintaining their good health and vitality. Integral protection must be used in a broad context, as a set of all available activities that prevent economic damage, with as little disturbance of biocenotic balance, as little environmental pollution and as low costs as possible, that is, as much economy as possible. This implies the unification of numerous activities, aimed at eliminating the causes of damage and preserving their stability, and through a strategy of protection against all adverse factors, not just the currently most aggressive. Prevention in IPM, requires an ecological approach to problems in the forestry business. The protection of natural and anthropogenic stands should be based primarily on preventive measures. Prevention in IPM is an ecological approach to problems in the forestry business. In order to decide on the necessity of applying repressive measures, it is necessary to determine, for each species and area, specific harmfulness thresholds, as well as risk assessment, which usually includes characterization of biological control means, definition of possible ecological and health risk and efficiency. The application of pesticides in forests has always been the subject of, sometimes very heated, discussion by the scientific and professional public. The main controversy was over whether natural enemies are powerful enough to keep a certain type of harmful organism in natural numbers, that is, below the threshold of harmfulness. Management of pesticides and their use in the fight against the most economically important forest pests, includes a detailed analysis of the benefits and risks of this method of IPM. Pesticides are used only when this is the only solution, to prevent the occurrence of absolutely unacceptable damage. The use of pesticides cannot be justified if the costs of control, or potential damage to the environment, are greater than the estimated loss of wood mass. Therefore, monitoring, whose task is to detect harmful organisms and assess the infestation of forest ecosystems, should be part of the overall forest management plan. Long-term monitoring of individual species and taking appropriate forestry measures reduce or eliminate the need for repressive pesticide control measures.

The transcriptomic response of Hyphantria cunea (Drury) to the infection of Serratia marcescens Bizio based on full-length SMRT transcriptome sequencing.

Hyphantria cunea (Drury) is a globally important forest pest. We found that the Serratia marcescens Bizio strain SM1 had insecticidal activity against H. cunea, but the transcriptomic response of H. cunea to SM1 were not clear. Therefore, we performed full-length sequencing of the transcriptomes of H. cunea larvae infected with SM1 and the control group. A total of 1,183 differentially expressed genes (DEGs) were identified by comparing the group infected with SM1 and the control group, including 554 downregulated genes and 629 upregulated genes. We found many downregulated genes in metabolic pathways. Furthermore, some of these downregulated genes were involved in cellular immunity, melanization, and detoxification enzymes, which showed that SM1 weakened H. cunea immunity. In addition, genes in the juvenile hormone synthesis pathway were upregulated, which was detrimental to the survival of H. cunea. This research analyzed the transcriptomic response of H. cunea to SM1 by high-throughput full-length transcriptome sequencing. The results provide useful information to explore the relationship between S. marcescens and H. cunea, and theoretical support for the application of S. marcescens and the control of H. cunea in the future.

Cradle for the newborn Monochamus saltuarius: Microbial associates to ward off entomopathogens and disarm plant defense.

The Japanese pine sawyer, Monochamus saltuarius, as a beetle vector of Bursaphelenchus xylophilus (pine wood nematode), is an economically important forest pest in Eurasia. To feed on the phloem and xylem of conifers, M.saltuarius needs to overcome various stress factors, including coping with entomopathogenic bacteria and also various plant secondary compounds (PSCs). As an important adaptation strategy to colonize host trees, M.saltuarius deposit eggs in oviposition pits to shield their progeny. These pits harbor bacterial communities that are involved in the host adaptation of M.saltuarius to the conifers. However, the composition, origin, and functions of these oviposition pit bacteria are rarely understood. In this study, we investigated the bacterial community associated with M.saltuarius oviposition pits and their ability to degrade PSCs. Results showed that the bacterial community structure of M.saltuarius oviposition pits significantly differed from that of uninfected phloem. Also, the oviposition pit bacteria were predicted to be enriched in PSC degradation pathways. The microbial community also harbored a lethal strain of Serratia, which was significantly inhibited. Meanwhile, metatranscriptome analysis indicated that genes involved in PSCs degradation were expressed complementarily among the microbial communities of oviposition pits and secretions. Invitro degradation showed that bacteria cultured from oviposition pits degraded more monoterpenes and flavonoids than bacteria cultured from uninfected phloem isolates. Disinfection of oviposition pits increased the mortality of newly hatched larvae and resulted in a significant decrease in body weight in the early stages. Overall, our results reveal that M.saltuarius construct oviposition pits that harbor a diverse microbial community, with stronger PSCs degradation abilities and a low abundance of entomopathogenic bacteria, resulting in the increased fitness of newly hatched larvae.

Host association, environment, and geography underlie genomic differentiation in a major forest pest.

Diverse geographic, environmental, and ecological factors affect gene flow and adaptive genomic variation within species. With recent advances in landscape ecological modelling and high-throughput DNA sequencing, it is now possible to effectively quantify and partition their relative contributions. Here, we use landscape genomics to identify determinants of genomic differentiation in the forest tent caterpillar, Malacosoma disstria, a widespread and irruptive pest of numerous deciduous tree species in North America. We collected larvae from multiple populations across Eastern Canada, where the species experiences a diversity of environmental gradients and feeds on a number of different host tree species, including trembling aspen (Populus tremuloides), sugar maple (Acer saccharum), red oak (Quercus rubra), and white birch (Betula papyrifera). Using a combination of reciprocal causal modelling (RCM) and distance-based redundancy analyses (dbRDA), we show that differentiation of thousands of genome-wide single nucleotide polymorphisms (SNPs) among individuals is best explained by a combination of isolation by distance, isolation by environment (spatial variation in summer temperatures and length of the growing season), and differences in host association. Configuration of suitable habitat inferred from ecological niche models was not significantly related to genomic differentiation, suggesting that M.disstria dispersal is agnostic with respect to habitat quality. Although population structure was not discretely related to host association, our modelling framework provides the first molecular evidence of host-associated differentiation in M.disstria, congruent with previous documentation of reduced growth and survival of larvae moved between natal host species. We conclude that ecologically mediated selection is contributing to variation within M.disstria, and that divergent adaptation related to both environmental conditions and host association should be considered in ongoing research and management of this important forest pest.

Comprehensive comparison of treatments for controlling the large pine weevil (Hylobius abietis) in Central Europe

Adults of the large pine weevil (Hylobius abietis) cause serious damage to coniferous seedlings and are among the most important forest pests in Europe. Seedling protection by chemicals is gradually being restricted or banned for environmental reasons, and non-chemical alternatives are therefore needed. In this 3-year study, we compared the following five treatments for protecting Norway spruce seedlings against H. abietis in the Central European mountains where the weevil is especially abundant: alpha-cypermethrin sprays (the only chemical treatment); coating with sprayed glue (Vermifix); wax coating with C and F types (Norsk Wax); and physical protection with collars. The same block design was set up at a clear-cut site and at a nursery site to compare seedling mortality and wax quality under “wild conditions” with pests and under “ideal conditions” without pests. Repeated application of alpha-cypermethrin was the most effective and least expensive method to protect seedlings against H. abietis. Among the four non-chemical methods, repeated application of glue was the most effective. Because collars were moderately effective but not cost-effective, we do not recommend the use of collars. Wax was inexpensive and environmentally safe but protected seedlings for only 1 year; the newer F type of wax performed better than the C type of wax, and perhaps the F type can be improved. In general we found that seedlings at sites with high numbers of H. abietis require protection for at least 3 years. We conclude by providing an overview of all methods currently available for managing H. abietis in forests.

Research Progress on the Dendrolimus spp. Pheromone: From Identification to Molecular Recognition.

Dendrolimus species (Lepidoptera, Lasiocampidae), are the most serious phytophagous pests of coniferous forests worldwide. Dendrolimus feed intensively on needles, leading to considerable economic loss and ecological damage. Notably, the outbreak of Dendrolimus is a somewhat periodic pattern, and those outbreaks cause rapid and large-scale destruction of pine forests, with those forests observed to look like “Fire without smoke”. Sex pheromones play an important role during insect mating and reproduction, and there has been extensive research into the pheromone of Dendrolimus. The pheromone components of several Dendrolimus have been identified, and functions of two most important pheromone recognition genes, pheromone-binding proteins (PBPs) and pheromone receptors (PRs), were clarified. The evolution of PBP gene sequences is in good agreement with the trends in structural changes of the sex pheromone components in several Dendrolimus species, and it is interesting that PRs of Dendrolimus spp. occupy a novel lineage of PRs tuned to Type I pheromones in Lepidoptera. We present the current state of research into the sex pheromone of these important forest pests and highlight the emerging topics, to clarify future urgent work into Dendrolimus.

3‐Methylcyclohex‐2‐en‐1‐one reduces the aggregation of Dendroctonus pseudotsugae barragani and corresponding mortality of Pseudotsuga menziesii in northern Mexico

Abstract Dendroctonus pseudotsugae is the most important forest insect pest of Douglas‐fir Pseudotsuga menziesii in North America. Two subspecies of Douglas‐fir beetle are recognized: D. pseudotsugae pseudotsugae, which inhabits southwestern Canada and western United States, and Dendroctonus pseudotsugae barragani, which occurs in northern Mexico. This study aimed to determine the effectiveness of 3‐methylcylohex‐2‐en‐1‐one (MCH) in reducing aggregation of D. pseudotsugae barragani, and corresponding Douglas‐fir mortality by this insect. Two field experiments were conducted: the first consisted of three doses of MCH in bubble caps (plus a control treatment) applied within 16 0.5 ha plots. The second consisted of three doses of MCH disrupt micro‐flakes (plus a control treatment) applied within 16 1.0 ha plots. MCH bubble caps at 28.8 and 44.0 g AI/ha and MCH disrupt micro‐flakes at 185.3 and 741 g AI/ha significantly reduced the aggregation of D. pseudotsugae barragani. When applying MCH as bubble caps, only the highest dose (44.0 g AI/ha) significantly reduced the number of successfully attacked trees. However, MCH micro‐flake doses of 185.3 and 741 g AI/ha reduced the number of successfully attacked trees to zero.

Activation of the Host Immune Response in Hyphantria cunea (Drury) (Lepidoptera: Noctuidae) Induced by Serratia marcescens Bizio.

Simple SummaryHyphantria cunea (Drury) is a quarantine pest, due to its extensive host, leading to serious economic losses in the agricultural and forestry industries. To control this pest, it is increasingly important to use microbial pesticides because they are biologically active and ecologically safe. Serratia marcescens Bizio (SM1) is a potential biocontrol bacterium. Although SM1 has a pathogenic role in H. cunea, H. cunea self-defense reduces the pathogenic effect of SM1. In this study, immune-related differentially expressed genes (DEGs) in H. cunea were first identified after SM1 infection, and the immune regulation mode of H. cunea in response to SM1, including antimicrobial peptide synthesis pathways, melanization and cellular immunity, was revealed. According to the analysis, the immune system of H. cunea was induced by SM1. In summary, our study demonstrates how the immune systems of the H. cunea work to resist the infection of SM1, which provides the theoretical basis for researching more efficient microbial pesticides for H. cunea.Host–pathogen interactions are essential to our understanding of biological pesticides. Hyphantria cunea (Drury) is an important forest pest worldwide. The immune mechanism of the interaction between H. cunea and Serratia marcescens Bizio (SM1) is unclear. First, transcriptome sequencing and quantitative real-time PCR (qRT-PCR) analysis described the H. cunea immune response to SM1. A total of 234 immune-related differentially expressed genes (DEGs) were found. Many immune regulatory genes in three classical pathways were found. Antimicrobial peptides, including attacin B, cecropin A, gloverin, lebocin and diapausin, are involved in defending against SM1 challenge, and are mainly produced by Toll and immune deficiency (IMD) pathways. Some melanization genes were changed in H. cunea, which suggested that H. cunea melanization was activated by SM1. Furthermore, phagocytosis, autophagolysosome and apoptosis pathways in cellular immunity were activated in H. cunea against SM1. Finally, the expression patterns of 10 immune genes were analyzed systematically by qRT-PCR, and most of the genes were upregulated compared to the control. Our studies provide useful information about the immune response of H. cunea under the stress of SM1, which is important to understand how SM1 affects the immune system of H. cunea and provides new ideas to control H. cunea by using SM1.

New records of pyraloid moths (Lepidoptera: Pyraloidea) in the Andaman and Nicobar Islands, India

Data on the distribution of 20 species of moths from the families Crambidae and Pyralidae in the Andaman and Nicobar Islands, India, are presented, with notes on their host plants and general distribution. Of these, 19 species, as well as the genus Pseudosacada Singh, Kirti et Ranjan, 2020, are recorded for the region for the first time. Agrioglypta excelsalis (Walker, 1866) is recorded for the first time for India. Most of the listed species are important agricultural and forest pests.

Reference Gene Selection for Normalizing Gene Expression in Ips Sexdentatus (Coleoptera: Curculionidae: Scolytinae) Under Different Experimental Conditions.

Ips sexdentatus (Coleoptera: Curculionidae: Scolytinae) is one of the most destructive and economically important forest pests. A better understanding of molecular mechanisms underlying its adaptation to toxic host compounds may unleash the potential for future management of this pest. Gene expression studies could be considered as one of the key experimental approaches for such purposes. A suitable reference gene selection is fundamental for quantitative gene expression analysis and functional genomics studies in I. sexdentatus. Twelve commonly used reference genes in Coleopterans were screened under different experimental conditions to obtain accurate and reliable normalization of gene expression data. The majority of the 12 reference genes showed a relatively stable expression pattern among developmental stages, tissue-specific, and sex-specific stages; however, some variabilities were observed during varied temperature incubation. Under developmental conditions, the Tubulin beta-1 chain (β-Tubulin) was the most stable reference gene, followed by translation elongation factor (eEF2) and ribosomal protein S3 (RPS3). In sex-specific conditions, RPS3, β-Tubulin, and eEF2 were the most stable reference genes. In contrast, different sets of genes were shown higher stability in terms of expression under tissue-specific conditions, i.e., RPS3 and eEF2 in head tissue, V-ATPase-A and eEF2 in the fat body, V-ATPase-A and eEF2 in the gut. Under varied temperatures, β-Tubulin and V-ATPase-A were most stable, whereas ubiquitin (UbiQ) and V-ATPase-A displayed the highest expression stability after Juvenile Hormone III treatment. The findings were validated further using real-time quantitative reverse transcription PCR (RT-qPCR)-based target gene expression analysis. Nevertheless, the present study delivers a catalog of reference genes under varied experimental conditions for the coleopteran forest pest I. sexdentatus and paves the way for future gene expression and functional genomic studies on this species.