Biology,demography and community interactions of Tarsonemus (Acarina: Tarsonemidae) mites phoretic on Dendroctonus frontalis (Coleoptera: Scolytidae)

1 Dendroctonus frontalis, the southern pine beetle, is associated with a diverse community of fungi and mites that are phoretic on the adult beetles. Tarsonemus ips, T. kranzti and T. fusarii (Acarina: Tarsonemidae) may interact within this community in ways that link the population dynamics of D. frontalis, the mites and three dominant species of fungi. We explored species associations by comparing the dietary suitability of different fungi for Tarsonemus spp. 2 All three mite species fed and reproduced at high rates when feeding on the bluestain fungus, Ophiostoma minus, which is an antagonist of D. frontalis larvae. 3 Mites also had positive population growth rates when feeding upon Ceratocystiopsis ranaculosus, one of the mycangial fungi, but could barely reproduce when feeding upon Entomocorticium sp. A, the mycangial fungus that is most suitable for D. frontalis. 4 During the time from colonization of a tree by D. frontalis adults until departure from the tree of their progeny (≈ 40 d at 30 °C), mite populations feeding upon O. minus can increase by factors of up to 209 (T. fusarii), 173 (T. ips) or 384 (T. krantzi). These high growth rates are allowed by rapid development (age of first reproduction = 8–9 d), high fecundity (≈ 1 egg/d) and high longevity (> 28 d). 5 Precocious mating increases the chance that females are mated prior to colonizing a new tree and arrhenotokous parthenogenesis permits reproduction by unmated females. 6 Tarsonemus mites may introduce negative feedback into D. frontalis population dynamics by generating indirect interactions between D. frontalis and O. minus.     

Synergistic effects of α-pinene and exo-brevicomin on pine bark beetles and associated insects in Arizona

The southern pine beetle (Dendroctonus frontalis) and western pine beetle (Dendroctonus brevicomis) cause significant mortality to pines in the southern and western United States. The effectiveness of commercial lures at capturing these bark beetles in Arizona has not been tested and may vary from other regions of their distribution. We conducted experiments using baited Lindgren funnel traps to investigate (i) if D. frontalis is more attracted to the standard commercial lure for D. brevicomis (frontalin + exo‐brevicomin + myrcene) than the D. frontalis lure (frontalin + terpene blend), (ii) whether replacement of myrcene with α‐pinene changes trap catches of Dendroctonus and associated insects, and (iii) whether the attraction to these lures varies across the geographical range of ponderosa pine forests throughout Arizona. In 2005, we tested various combinations of frontalin, exo‐brevicomin, myrcene and α‐pinene to D. frontalis, D. brevicomis and associated species. Dendroctonus frontalis, D. brevicomis and the predator Temnochila chlorodia were most attracted to lures with exo‐brevicomin. The replacement of the myrcene component with α‐pinene in the D. brevicomis lure resulted in the capture of twice as many bark beetles and Elacatis beetles. However, T. chlorodia did not differentiate between monoterpenes. In 2006, traps were set up in 11 locations around Arizona to test the relative attraction of lure combinations. In 9 out 11 locations, the D. brevicomis lure with α‐pinene was more attractive than the lure with myrcene or a terpene blend. These results suggest that the D. brevicomis lure with α‐pinene rather than myrcene is more effective lure to capture D. brevicomis and D. frontalis in Arizona. However, geographical variation in attractiveness to lures is evident even within this region of the beetles’ distributions. Differential attraction of Dendroctonus and their predators to these lures suggests potential use in field trapping and control programmes.     

华山松大小蠹及其伴生蓝变真菌对华山松木质部危害的解剖学特征

为揭示华山松大小蠹和伴生蓝变真菌引起秦岭华山松枯萎的机制,选择秦岭北坡沣峪林场境35年树龄的健康华山松Pinus armandi为研究对象,对接种华山松大小蠹Dendroctonus armandi及与其伴生的蓝变真菌Ceratocystis polonica引起的寄主树木木质部形态变化进行了解剖观察。结果表明：接种致病性蓝变真菌C. polonica 1周后的4株华山松 的木质部组织内,蓝变区域显著增加,4～6周后蓝变区域不再增加; 而在接种无菌琼脂的2株对照华山松的木质部组织内,没有检测到蓝变区域。研究结果提示蓝变真菌C. polonica是致死秦岭华山松的重要病原菌,该伴生菌随华山松大小蠹入侵健康寄主华山松木质部组织,在木质部定居并分解木质部,堵塞树脂道,致使寄主华山松树脂代谢和水分代谢紊乱。该研究结果表明,虽然华山松大小蠹长期以来被认为是致死华山松的毁灭性小蠹虫,但是其共生蓝变真菌C. polonica对成熟华山松的致害作用不应该被忽视。     

Phoretic mites and nematode associates of Scolytus multistriatus and Scolytus pygmaeus (Coleoptera: Scolytidae) in Austria

Abstract 1 The species assemblages and abundance of phoretic mites and nematodes associated with the elm bark beetles, Scolytus multistriatus and Scolytus pygmaeus, were studied in Austria. 2 A total of 3922 individual mites were recorded from 144 adults of S. multistriatus and 178 adults of S. pygmaeus. The species spectrum was identical and the relative abundance of mites was very similar for both species of scolytids. Nine mite species, Pyemotes scolyti, Pseudotarsonemoides eccoptogasteri, Trichouropoda bipilis, Tarsonemus crassus, Proctolaelaps eccoptogasteris, Proctolaelaps scolyti, Chelacheles michalskii, nr. Eueremaeus sp. and Elattoma sp. were detected. Two of the nine species, nr. Eueremaeus sp. and Elattoma sp., are documented here as new associates of Scolytus spp. 3 Pyemotes scolyti was the most frequent mite species, and Ps. eccoptogasteri and T. bipilis were relatively common, whereas the other mites occurred occasionally or were rare. 4 The trophic roles of most of the mites associated with S. multistriatus and S. pygmaeus are poorly known, but they may include fungivores, parasitoids of bark beetle broods, predators of bark beetle broods and/or mites and/or nematodes. 5 Besides phoretic mites, two nematode associates were seen on the investigated insects. A species of Cryptaphelenchus occurred under the elytra of both scolytid species, whereas the adults of a Neoparasitylenchus sp. were present inside abdomens of S. multistriatus, but absent from S. pygmaeus.     

Macrochelid mite fauna in the eastern part of the Lesser Sunda Islands, with description of two new species

Thirteen species in four genera of mites of the family Macrochelidae phoretic on dung beetles were collected in the eastern part of the Lesser Sunda Islands, Indonesia, providing the first record of the family for that area. Of these, two species, Macrocheles entetiensis Hartini and Takaku, sp. nov. and Macrocheles sumbaensis Hartini and Takaku, sp. nov., are new to science. The remaining 11 species are Glyptholaspis fimicola, Holostaspella bifoliata, Macrocheles baliensis, Macrocheles sp. aff. glaber, M. hallidayi, M. kraepelini, M. krantzi, M. limue, M. merdarius, M. oigru and Neopodocinum sinicum.     

Bacteria in oral secretions of an endophytic insect inhibit antagonistic fungi

Abstract.  1. Colonisation of host trees by an endophytic herbivore, the spruce beetle, Dendroctonus rufipennis , is accompanied by invasion of its galleries by a number of fungal species. Four of these associated species were identified as Leptographium abietinum , Aspergillus fumigatus , Aspergillus nomius , and Trichoderma harzianum .
2.  Trichoderma and Aspergillus significantly reduced spruce beetle survival and reproduction in controlled assays.
3. A previously undescribed behaviour was observed, in which spruce beetle adults exuded oral secretions, especially within fungus-pervaded galleries.
4. These oral secretions inhibited the growth of fungi except A. nomius , and disrupted the morphology of the latter. Administration of these secretions indicated a dose-dependent inhibitory effect.
5. Oral secretions cultured on microbiological media yielded substantial bacterial growth.
6. Filter-sterilised secretions failed to inhibit fungal growth, evidence that the bacteria are responsible for the antifungal activity.
7. Nine bacterial isolates belonging to the Actinobacteria, Firmicutes, Gammaproteobacteria, and Betaproteobacteria taxa were obtained from the secretions.
8. Bacterial isolates showed species-specific inhibitory activity against the four fungi antagonistic to spruce beetle. The bacterium with the strongest fungal inhibition activity was the actinomycete Micrococcus luteus .
9. The production of bark beetle secretions containing bacteria that inhibit fungal growth is a novel finding. This suggests an additional level of complexity to ecological associations among bark beetles, conifers, and microorganisms, and an important adaptation for colonising subcortical tissue.     

Resistance to Bark Beetle Attack in Caribbean Pine: Potential Role of 4‐Allylanisole1

In the Neotropics, Caribbean pine is subject to epidemic attack by southern pine beetle. We found significantly higher levels (>2.5%) of 4‐allylanisole in the monoterpenoid fraction of the oleoresin of trees in stands with high beetle‐induced mortality, and a negative association between magnitude of attack and levels of 4‐allylanisole in individual trees. Results also suggest that individual trees with low 4‐allylanisole levels may escape attack if they occur in stands characterized by high levels of this compound.     

Role of the entomogenous fungus, Neozygites floridana, in population declines of the twospotted spider mite, Tetranychus urticae, on field corn

In field plots in which populations of predaceous species were suppressed using carbaryl, populations of the twospotted spider mite, Tetranychus urticae Koch, on field corn declined in association with aerial dispersal of the mites or with epizootics of the entomogenous fungus, Neozygites floridana Weiser & Muma. The relative importance of these two factors varied from year to year depending on environmental conditions. When moist weather conditions induced epizootics of N. floridana before corn plants became heavily infested with mites, the pathogen appeared to be the major factor causing mite population declines. When dry weather conditions allowed mite populations to expand unchecked until corn plants became entirely infested, mite aerial dispersal was the major factor associated with mite population declines. In every field in which there was an epizootic of N. floridana, routine applications of the fungicide maneb delayed epizootics and reduced or delayed the impact of the pathogen on mite populations. The total number of Neozygites-infected mites produced in maneb-treated plots throughout the test period was significantly greater than that in untreated plots when epizootics were initiated during periods of mite population growth. Fewer total infected mites were produced in maneb-treated plots compared to untreated plots when epizootics were initiated during periods of mite population decline.

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Résumé Dans des parcelles de maïs dont les populations d'espèces prédatrices avaient été éliminées par du carbaryl, des populations de T. urticae ont régressé en fonction de la dispersion aérienne des acariens ou d'épizooties provoquées par N. floridana. L'importance relative de ces deux causes varie d'année suivant les conditions écologiques. Le pathogène paraissait la principale cause de déclin des populations quand le temps humide a induit les épizooties par N. floridana avant que le maïs n'ait été largement contaminé par les acariens. Quand le temps sec a permis aux populations d'acariens de se développer sans frein jusqu'à contamination totale du maïs, la dispersion aérienne des acariens était la principale cause de déclin des populations d'acariens. Dans tous les champs où il y avait eu épizootie de N. floridana, des traitements de routine avec le fongicide meneb ont retardé les épizooties et réduit ou retardé l'impact du pathogène sur les populations d'acariens. Pendant toute la période d'étude, le nombre total d'acariens infestés par Neozygites était significativement plus élevé dans les parcelles traitées au maneb que dans les parcelles non traitées, lorsque les épizooties étaient provoquées pendant la période de croissance des populations d'acariens. Quand les épizooties ont été déclenchées pendant la période de déclin des populations d'acariens, un nombre plus faible d'acariens infestés était observé dans les parcelles traitées au maneb que dans les parcelles sans traitement.

     

Physiological and biochemical analysis of overwintering and cold tolerance in two Central European populations of the spruce bark beetle, Ips typographus

Overwintering success is one of the key aspects affecting the development and outbreaks of the spruce bark beetle, Ips typographus (L.) populations. This paper brings detailed analysis of cold tolerance, and its influence on overwintering success, in two Central European populations of I. typographus during two cold seasons. Evidence for a supercooling strategy in overwintering adults is provided. The lower lethal temperature corresponds well to the supercooling point that ranges between −20 and −22 °C during winter months. The supercooled state is stabilized by the absence of internal ice nucleators and by seasonal accumulation of a mixture of sugars and polyols up to the sum concentration of 900 mM. The cryoprotective function of accumulated metabolites is probably based on increasing the osmolality and viscosity of supercooled body fluids and decreasing the relative proportion of water molecules available for lethal formation of ice nuclei. No activity of thermal hysteresis factors (stabilizers of supercooled state) was detected in hemolymph. Lethal times for 50% mortality (Lts50) in the supercooled state at −5, −10 or −15 °C are weeks (autumn, spring) or even months (winter), suggesting relatively little mortality caused by chill injury. Lts50 at −15 °C are significantly shorter in moist (6.9 days) than in dry (>42 days) microenvironment because there is higher probability of external ice nucleation and occurrence of lethal freezing in the moist situation.     

Description of Medwayella independencia (Siphonaptera,Stivaliidae), a new species of flea from Mindanao Island,the Philippines and their phoretic mites,and miscellaneous flea records from the Malay Archipelago

Medwayella independencia, a new species of flea, is described from the tupaiid host Urogale everetti (Thomas) from Mindanao Island, Philippines. Several other species of fleas are also recorded from the Philippines including a single male of Lentistivalius philippinensis Hastriter and Bush, 2013 (previously known only from two males), the bat fleas Thaumapsylla breviceps orientalis Smit and Thaumapsylla longiforceps Traub, a single unidentified female species of Macrostylophora Ewing collected from the murid Bullimus bagobos Mearns, and a pair of Medwayella robinsoni ssp. from Sundasciurus hoogstraali (Sanborn) from Busuanga Island, Philippines. Representatives of Medwayella Traub, 1972 and Macrostylophora have not previously been recorded from the Philippines. A key to the male sex of Medwayella is provided. Phoretic mites of the genus Psylloglyphus (family Winterschmidtiidae) were present under the abdominal sclerites of several male and female specimens of M. independencia. This is the second report of a phoretic mite on a species of Medwayella Traub. The co-evolutionary implications between phoretic mites and fleas are discussed.     

Horizontal and vertical transmission of viruses in the honey bee, Apis mellifera

The most crucial stage in the dynamics of virus infections is the mode of virus transmission. In general, transmission of viruses can occur through two pathways: horizontal and vertical transmission. In horizontal transmission, viruses are transmitted among individuals of the same generation, while vertical transmission occurs from mothers to their offspring. Because of its highly organized social structure and crowded population density, the honey bee colony represents a risky environment for the spread of disease infection. Like other plant and animal viruses, bee viruses use different survival strategies, including utilization of both horizontal and vertical routes, to transmit and maintain levels in a host population. In this review, we explore the current knowledge about the honey bee viruses and transmission routes of bee viruses. In addition, different transmission strategies on the persistence and dynamics of host-pathogen interactions are also discussed.     

Occurrence, characterization and development of two different types of microbodies in the nematophagous fungus Arthrobotrys oligospora

Abstract The occurrence of microbodies in different cells of the nematophagous fungus Arthrobotrys oligospora has been investigated. In the predacious phase this organism forms complex 3-dimensional network traps. Mature trap cells generally were crowded with "special" microbodies which possessed an electron dense matrix and were surrounded by a membrane of approx. 9 nm. These organelles developed during the early stages of trap formation and were derived from specialized regions of the endoplasmic reticulum. Cytochemical staining experiments revealed that the electron-dense microbodies contained catalase and d -amino acid oxidase and thus must be considered peroxisomal in nature. Electron-dense bodies were absent in normal vegetative cells of the fungus. These cells contained "normal" microbodies which developed from each other by the separation of small organelles from mature ones. As in yeasts, the metabolic function of these latter organelles was dependent upon environmental conditions.     

Ultrastructure of spermatogenesis in the sea star,Asterina minor

The ultrastructural features of spermatogenesis were investigated in the hermaphroditic sea star Asterina minor. The primordial germ cells in the genital rachis contain small clusters of electron-dense material (nuage material) and a stack of annulate lamellae. They also have a flagellum and basal body complex situated close to the Golgi complex. After the development of the genital rachis into the ovotestis, spermatogenic cells increase in number and differentiation begins. Nuage material is observed in spermatogonia, but it gradually disappears in spermatocytes. The annulate lamellae do not exist beyond the early spermatogonial stage. By contrast, a flagellum and basal body complex are found throughout spermatogenesis. The Golgi-derived proacrosomal vesicles appear in the spermatocyte and coalesce to form an acrosomal vesicle in the early spermatid. The process of acrosome formation is as follows: (1) a lamella of endoplasmic reticulum (ER) continuous with the outer nuclear membrane encloses the posterior portion of the acrosomal vesicle; (2) the vesicle attaches to the cell membrane with its anterior portion; (3) periacrosomal material accumulates in the space between the acrosomal vesicle and the ER; (4) the nucleus proper changes its features to surround the acrosome; (5) amorphous, electron-dense material is deposited under the electron-dense disk; and (6) the nucleus forms a hollow opposite the electron-dense material.     

Progress, spread and natural transmission of Bahia bark scaling of citrus in Brazil

Progress, spread and natural transmission of Bahia bark scaling of citrus were evaluated in a trial where 240 screenhouse‐nursed nucellar grapefruit plants –‘Clason’, ‘Little River Seedless’, ‘Red Blush’, ‘Reed’ and ‘Howell Seedless’ cvs – were planted alongside and 5 m apart from a 10‐year‐old symptomatic ‘Marsh Seedless’ grapefruit orchard. Plants were distributed in 16 rows of 15 trees, with three plants of each cultivar per row. Eight trial plants were kept in screen cages. Incidence of symptomatic plants was assessed at 3‐months intervals, for 5 years, and for further 2 years at irregular intervals. Cumulative maps of disease incidence were produced for each assessment date and used in all analyses. Temporal progress was analysed by nonlinear fitting of three disease progress models. Spread was characterised in three levels of spatial hierarchy by the following analyses: ordinary runs, binomial dispersion index, binary power law fitting, isopath mapping and nonlinear fitting of disease gradient models. The first symptomatic plant was detected 2 years after planting. In the last disease assessment, 5 years after the first, 98% of the unprotected plants were symptomatic. None of the screen‐caged trees showed any symptoms. Bahia bark scaling progress was polyetic and best described by the logistic model. Ordinary runs analysis showed little if any evidence of transmission between adjacent trees. Diseased plants showed a very aggregated pattern inside quadrats (D > 5 and b > 1.53). Isopath mapping showed that main spread was only because of the primary inoculum source. Secondary foci were also observed, but they were never dissociated from main initial disease focus. Disease gradient followed wind direction, starting near the original inoculum source and was best described by exponential model. These results support a hypothesis of Bahia bark scaling transmission by air‐borne vectors with limited dispersion ability.     

Molecular detection of various rickettsiae in mites (acari: trombiculidae) in southern Jeolla Province, Korea

This study revealed the presence of various rickettsial agents in mites from wild rodents collected in Southern Jeolla Province, Korea, by nested polymerase chain reaction (PCR) and sequence analysis of a partial citrate synthase and rickettsia outer membrane protein B genes. Rickettsial agents closely related to the Rickettsia species TwKM02, R. australis, and the Rickettsia species Cf15 were successfully identified in this study, for the first time in Korea, and R. japonica, R. akari, R. conorii, R. felis, and R. typhi were also detected, as previously described. The data presented in this paper extend knowledge on the geographic distribution of SFG rickettsiae in eastern Asia and it may necessary to consider the role of mites in rickettsial transmission.     

Biosynthesis of the widely distributed hydrocarbon (Z,Z)-6,9-heptadecadiene in astigmatid mites

ABSTRACT

Using a crude enzyme solution prepared from astigmatid mites, the conversion reaction to (Z,Z)-6,9-heptadecadiene (6,9-C17) using linoleyl aldehyde (LAld) as a substrate was successful. The mass spectrum of the reaction product using ¹³C-labeled LAld as a substrate could be assigned as ¹³C-labeled 6,9-C17. Unlike the findings in other species, the decarbonylase derived from mites did not require a coenzyme.     

Three‐year surveillance (2016–2018) of chigger mites vector for tsutsugamushi disease in the Hwaseong‐Si area of Gyeonggi‐Do,Republic of Korea

Owing to climate change, the global resurgence of vector‐borne infectious diseases has emerged as a critical public health issue. Orientia tsutsugamushi is the etiological agent of tsutsugamushi disease (scrub typhus) a mite‐borne acute febrile disease occurring in the Asia‐Pacific region. We investigated the prevalence of tsutsugamushi disease transmitted by chigger mite vectors living on rodents. Using sticky‐type chigger traps for three months during 2016–2018, 1,057 chigger mites were collected (chigger mite index, 1.31) from four locations in the Hwaseong‐si area of Gyeonggi‐do, Republic of Korea. Five species distributed among three genera were identified. In addition, 94 rodents were captured (collection rate: 7.83%) using Sherman live traps over the course of three months (April, October, and November) during 2016–2017. Three rodent species were captured and identified and the striped field mouse (Apodemus agrarius) was the dominant rodent host species in the surveyed area. A total of 10,469 ectoparasitic chigger mites were recovered from the 94 rodents, from which 13 species distributed among four genera were identified. Of the 5,250 chigger mites examined, Leptotrombidium pallidum was most abundant (n = 2,558), followed by L. orientale, L. scutellare, L. zetum, Euschoengastia koreaensis, L. subintermedium, and Neotrombicula tamiyai. Of the examined chigger mites, no groups recovered from rodent hosts tested positive for O. tsutsugamushi. This study provides fundamental regional information on vector‐borne disease data collection in the Hwaseong‐si area, Gyeonggi‐do, and will further contribute to formulating disease control and prevention strategies.     

Reproduction and sexual dimorphism in two populations of the polymorphic spiny lizard Sceloporus minor from Hidalgo,México

Male‐biased sexual dimorphism is extensive in New World spiny lizards (Sceloporus: Phrynosomatidae) and is particularly prominent in the polymorphic minor lizard Sceloporus minor. However, the possible relationship between patterns of sexual dimorphism and gonadal development is little known for most species. In this study, we explored aspects of sexual dimorphism in noncolor morphological traits in S. minor and characterized the gonadal cycle in males and females from each of two sites (El Enzuelado and La Manzana) in Hidalgo, México, differing in key ecological aspects linked to life‐history trait expression in other lizards. Males were generally larger than females in each population and expressed larger forms of several other morphological traits, although not all comparisons attained statistical significance. Both sexes attained reproductive maturity at a larger size in El Enzuelado relative to La Manzana, and females from El Enzuelado had larger litters. Gonadal cycles differed substantially between the two populations and suggest that reproductive activity of males and females was synchronous at El Enzuelado and asynchronous at La Manzana, an unusual pattern. Geographic variation in sex‐specific responses to environmental variables may be at least partly responsible for the exceptional species diversity of spiny lizards in México.