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The current knowledge of morphology and chaetotaxy of the different developmental stages within the subfamily Scolytinae presents an information deficit that needs to be addressed. Thus, the objective of the present study was to describe, the chaetotaxy and morphology of larvae and pupae, and determine the number of larval instars, the sexual dimorphism in adults, and the development time in Phloeosinus tacubayae. The number of larval instars was determined using traditional morphometry of cephalic capsule and multivariate analysis; description of morphology and chaetotaxy of larvae and pupae, and sexual dimorphism in adults was based on light microscopy and scanning electron microscopy photographs; finally, we quantified development time by mean reviews of 10 gallery systems selected randomly in infested logs, in the laboratory. Morphometric analysis of the cephalic capsule allowed the recognition of 3 different instars. Our results showed that the larvae of P. tacubayae have unique attributes in the body that differentiate them from other genera of the subfamily for example the epicranial suture is not marked, and differentiated from Phloeosinus canadensis, such as a smaller number of setae in the maxillae and without a tergal plate. The pupa had a smaller number of setae on the whole body. The most useful morphological characters to identify a sexual dimorphism in adults were found in the shape and relative position of the seventh and eighth tergites; development time lasted 40 days in total, being the pupal stage the one that took the longest to complete.

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Jamaica produces coffee marketed as Blue Mountain and high mountain (grown outside the Blue Mountains). Since the discovery of the coffee berry borer (CBB; Hypothenemus hampei) in Jamaica in 1978, chemical control has traditionally been the primary approach used to protect the crop from the pest. However, in the last 20 years, there has been an effort to shift towards more sustainable management strategies. The study was conducted to determine CBB activity (trap catch) and field infestation on coffee farms in the high mountains and Blue Mountains of Jamaica, over a crop cycle. A total of 27,929 and 12,921 CBBs were captured at high mountain and Blue Mountain farms, respectively. Peak CBB activity occurred in April in the high mountain region (365 CBBs/trap/month) and February in the Blue Mountain region (129 CBBs/trap/month). The highest levels of infestation were in November (33%) and October (34%) in the high mountain region and Blue Mountain region, respectively. There was no significant difference in the patterns of CBB activity and infestation between the study locations, and neither were related to the temperature or relative humidity. However, there was a significant relationship with rainfall. These data suggest that the population dynamics of the CBB may involve complex interactions among weather conditions, berry development, and agronomic practices.

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Rahnella sp. ChDrAdgB13 is a dominant member of the gut bacterial core of species of the genus Dendroctonus, which is one of the most destructive pine forest bark beetles. The objectives of this study were identified in Rahnella sp. ChDrAdgB13 genome the glycosyl hydrolase families involved in carbohydrate metabolism and specifically, the genes that participate in xylan hydrolysis, to determine the functionality of a putative endo-1,4-ß-D-xylanase, which results to be bifunctional xylanase-ferulic acid esterase called R13 Fae and characterize it biochemically. The carbohydrate-active enzyme prediction revealed 25 glycoside hydrolases, 20 glycosyl transferases, carbohydrate esterases, two auxiliary activities, one polysaccharide lyase, and one carbohydrate-binding module (CBM). The R13 Fae predicted showed high identity to the putative esterases and glycosyl hydrolases from Rahnella species and some members of the Yersiniaceae family. The r13 fae gene encodes 393 amino acids (43.5 kDa), containing a signal peptide, esterase catalytic domain, and CBM48. The R13 Fae modeling showed a higher binding affinity to ferulic acid, α-naphthyl acetate, and arabinoxylan, and a low affinity to starch. The R13 Fae recombinant protein showed activity on α-naphthyl acetate and xylan, but not on starch. This enzyme showed mesophilic characteristics, displaying its optimal activity at pH 6.0 and 25°C. The enzyme was stable at pH from 4.5 to 9.0, retaining nearly 66-71% of its original activity. The half-life of the enzyme was 23 days at 25°C. The enzyme was stable in the presence of metallic ions, except for Hg2+. The products of R13 Fae mediated hydrolysis of beechwood xylan were xylobiose and xylose, manifesting an exo-activity. The results suggest that Rahnella sp. ChDrAdgB13 hydrolyze xylan and its products could be assimilated by its host and other gut microbes as a nutritional source, demonstrating their functional role in the bacterial-insect interaction contributing to their fitness, development, and survival.

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Dendroctonus-bark beetles are natural agents contributing to vital processes in coniferous forests, such as regeneration, succession, and material recycling, as they colonize and kill damaged, stressed, or old pine trees. These beetles spend most of their life cycle under stem and roots bark where they breed, develop, and feed on phloem. This tissue is rich in essential nutrients and complex molecules such as starch, cellulose, hemicellulose, and lignin, which apparently are not available for these beetles. We evaluated the digestive capacity of Dendroctonusrhizophagus to hydrolyze starch. Our aim was to identify α-amylases and characterize them both molecularly and biochemically. The findings showed that D. rhizophagus has an α-amylase gene (AmyDr) with a single isoform, and ORF of 1452 bp encoding a 483-amino acid protein (53.15 kDa) with a predicted signal peptide of 16 amino acids. AmyDr has a mutation in the chlorine-binding site, present in other phytophagous insects and in a marine bacterium. Docking analysis showed that AmyDr presents a higher binding affinity to amylopectin compared to amylose, and an affinity binding equally stable to calcium, chlorine, and nitrate ions. AmyDr native protein showed amylolytic activity in the head-pronotum and gut, and its recombinant protein, a polypeptide of ~53 kDa, showed conformational stability, and its activity is maintained both in the presence and absence of chlorine and nitrate ions. The AmyDr gene showed a differential expression significantly higher in the gut than the head-pronotum, indicating that starch hydrolysis occurs mainly in the midgut. An overview of the AmyDr gene expression suggests that the amylolytic activity is regulated through the developmental stages of this bark beetle and associated with starch availability in the host tree.

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Los descortezadores Dendroctonus frontalis (Coleoptera: Scolytidae) son un grupo de coleópteros estrechamente ligado a las masas forestales y son una de las plagas más dañinas en México, ocasionando que la cobertura forestal se reduzca considerablemente. Adicionalmente factores como el cambio climático, favorecen el aumento en las poblaciones de escarabajos descortezadores del género Dendroctonus. Por lo anterior es conveniente conocer la variación poblacional de descortezadores, particularmente de Dendroctonus frontalis, cuyas poblaciones dependen de la variabilidad climática que influye en su abundancia. Teniendo como hipótesis que la altitud y las variables ambientales afectan el comportamiento en la abundancia de D. frontalis, se planteó como objetivo estimar la variación espacio-temporal de poblaciones de D. frontalis en bosques de pino a diferentes altitudes. El estudio se realizó en la comunidad de Durango, Zimapán, Hidalgo, México. Se utilizó un diseño experimental de parcelas apareadas con dos tratamientos, de feromona y testigo. Se colocaron siete trampas con ambos tratamientos en un rango de 1 568 a 2 117 m.s.n.m. para determinar la abundancia altitudinal de D. frontalis. El muestreo se llevó a cabo de enero a diciembre 2015. Se obtuvo una relación positiva entre la abundancia de D. frontalis y el gradiente altitudinal y respecto a la abundancia de D. frontalis y la temperatura se observó una relación moderada, pero no significativa; de la misma forma para la precipitación media anual. La relación con la temperatura media máxima y el balance de precipitación de primavera/verano fueron estadísticamente significativos. Se presentó una tendencia positiva en la abundancia de D. frontalis de acuerdo al índice anual de aridez, por lo cual se espera que con el aumento de las temperaturas el estrés en la vegetación de los bosques sea mayor, favoreciendo el incremento de las poblaciones de escarabajos descortezadores.

The bark beetles Dendroctonus frontalis (Coleoptera: Scolytidae) are a group of coleoptera closely linked to forest masses, and one of the most harmful pests in Mexico, causing the forest cover to be considerably reduced. Additionally factors such as climate change, favor the increase in populations of bark beetles of the genus Dendroctonus. Taking as a hypothesis that altitude and environmental variables affect the behavior in the abundance of D. frontalis, the objective was to estimate the temporary-spatial variation of D. frontalis populations in pine forests at different altitudes. The study was conducted in the community of Durango, Zimapán, Hidalgo, Mexico. An experimental design of paired plots with two treatments was used, pheromone and control. Seven traps were placed with both treatments in a range of 1 568 to 2 117 m.a.s.l. to determine the altitudinal abundance of D. frontalis. The sampling was realized from January to December 2015. A positive relationship was observed between the abundance of D. frontalis and the altitudinal gradient. About the abundance of D. frontalis and the temperature, a moderate but not significant relationship was observed in the same way for the average annual precipitation. The relation with the maximum average temperature and the spring summer precipitation balance were statistically significant. There was a positive trend on the abundance of D. frontalis according to the annual aridity index, which is why it is expected that the increase of temperatures the stress in the vegetation of the forests will be greater, favoring the increase of bark beetles populations.

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Dendroctonus bark beetles (Scolytinae) are one of the most important disturbance agents of coniferous forests in North and Central America. These beetles spend their lives almost entirely under the tree bark, and their survival and reproductive success depend on their ability to overcome the toxic effect of the trees' oleoresin. The cytochromes P450 (CYPs) are associated with the detoxification process of xenobiotics, as well as other physiological processes. Different cytochromes (families 4, 6, and 9) in the Dendroctonus species have been expressed under several experimental conditions; nevertheless, the expression time-course of these genes is unknown. To explore the induction speed of CYPs, we evaluated the relative expression of the CYP6BW5, CYP6DG1, CYP6DJ2, CYP9Z18, and CYP9Z20 genes at the early hours of drilling and settling into a tree (1, 2, 4, 6, 8, 12, 18 h) both in females and males, solitary or paired, of the bark beetle Dendroctonus rhizophagus Thomas and Bright. Our findings show that the five genes were rapidly overexpressed in the early hours (1 to 6 h) in both sexes and in solitary and paired conditions, suggesting their participation in the detoxification process. Additionally, the CYPs expression shows up- and down-regulation patterns through these short times, suggesting their probable participation in other physiological processes as the biosynthesis of hormones, pheromones or compounds related to reproduction.

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Spruce beetle, Dendroctonus rufipennis Kirby, is associated with forest mortality in Colorado and across western North America, yet it is not well understood how thermal variability affects basic population processes such as flight phenology. However, phenology-temperature relationships are important for understanding patterns of ecosystem disturbance, especially under projected climate warming. Here, we use a multiyear trapping study to test the hypothesis that spruce beetle flight synchrony, timing, and fitness traits (body size) are affected by variation in regional temperature and physiography. Large quantities of co-colonizing scolytines (Polygraphus convexifrons) (Coleoptera: Curculionidae, Scolytinae) and predatory beetles (Thanasimus undulatus) (Coleoptera: Cleridae) that may affect D. rufipennis populations also responded to spruce beetle synthetic pheromone lures. Relationships between flight patterns and environmental conditions were also analyzed for these species. The winter of 2018 was warmer and drier than winter 2017 and was associated with earlier flight for both scolytine species across most sites. The most important environmental factor driving D. rufipennis flight phenology was accumulated growing degree-days, with delayed flight cessation under warmer conditions and larger beetles following a warm winter. Flight was consistently more synchronous under colder growing season conditions for all species, but synchrony was not associated with winter temperatures. Warmer-than-average years promoted earlier flight of D. rufipennis and associated species, and less synchronous, prolonged flight across the region. Consequently, climate warming may be associated with earlier and potentially extended biotic pressure for spruce trees in the Rocky Mountain region, and flight phenology of multiple scolytines is plastic in response to thermal conditions.

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Extensive outbreaks of bark beetles have affected not only large parts of coniferous forests in the Northern Hemisphere, but also - largely absent from global attention - native pine forests of Central America. As such outbreaks frequently spark management debates among residents, land managers, forest owners and the public, the social acceptance of bark beetle control measures has become crucial for modern land management. However, the sociological and psychological determinants of the preference for specific bark beetle control measures outside protected areas remain unclear. To determine the acceptability of bark beetle control measures in El Salvador, we assessed how demographic variables, attitude towards the bark beetle, education, and self-reported knowledge affected the preference for different bark beetle control measures in a survey of government employees and local forest owners using a quantitative questionnaire survey. Cumulative link mixed models revealed that the general preference for control measures increased with increasing self-reported knowledge about the bark beetle but decreased with increasing level of respondent education and an increasing positive attitude towards the bark beetle. Respondents generally preferred beetle control measures on small areas than on large areas. Preferences for control measures did not differ between government employees and forest owners, with controlled burning and chemical control significantly less accepted than stand thinning or salvage logging. We discuss the most preferred control measures considering recent scientific evidence of their efficacy and conclude that the current bark beetle outbreak should be controlled through logging of pines weakened by fire in the short-term and by stand thinning in the medium-term to prevent further outbreaks.

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BACKGROUND: Ceratocystis fimbriata recognized among the species that induce mango sudden decline (MSD), causes plant death within a short period. The beetles Hypocryphalus mangiferae and Xyleborus affinis (Curculionidae: Scolytinae) are the vectors of MSD. Thorough understanding of the spatial distribution of the pest is crucial to designing control techniques and drawing up sampling plans. This study aimed to identify the beetles and their dispersal pattern in mango trees in MSD-infected commercial orchards, and the association with the severity of the C. fimbriata infestation. RESULTS: Beetle attacks were observed to be maximal on mango tree trunks revealing severe infestation. From the geostatistical analysis, an aggregated pattern was evident as galleries in the trunks and branches of mango trees. CONCLUSION: This is the first study to employ geostatic tools on a plant scale in MSD-infested mango orchards and to study the incidence of beetle attack. The results may prove a highly effective tool for mango growers, with respect to the management of beetles and MSD, as this will facilitate the monitoring of specific sites where the frequency of beetles and MSD is high. © 2018 Society of Chemical Industry.

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The death of trees is an ecological process that promotes regeneration, organic matter recycling, and the structure of communities. However, diverse biotic and abiotic factors can disturb this process. Dendroctonus bark beetles (Curculionidae: Scolytinae) are natural inhabitants of pine forests, some of which produce periodic outbreaks, killing thousands of trees in the process. These insects spend almost their entire life cycle under tree bark, where they reproduce and feed on phloem. Tunneling and feeding of the beetles result in the death of the tree and an alteration of the resident microbiota as well as the introduction of microbes that the beetles vector. To understand how microbial communities in subcortical tissues of pines change after they are colonized by the bark beetle Dendroctonus rhizophagus, we compare both the bacterial and fungal community structures in two colonization stages of Pinus arizonica (Arizona pine) employing Illumina MiSeq. Our findings showed significant differences in diversity and the dominance of bacterial community in the two colonization stages with Shannon (P = 0.004) and Simpson (P = 0.0006) indices, respectively, but not in species richness with Chao1 (P = 0.19). In contrast, fungal communities in both stages showed significant differences in species richness with Chao1 (P = 0.0003) and a diversity with Shannon index (P = 0.038), but not in the dominance with the Simpson index (P = 0.12). The ß-diversity also showed significant changes in the structure of bacterial and fungal communities along the colonization stages, maintaining the dominant members in both cases. Our results suggest that microbial communities present in the Arizona pine at the tree early colonization stage by bark beetle change predictably over time.

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