Field response of non‐target beetles to Ips sexdentatus aggregation pheromone and pine volatiles

Although mass trapping cannot be a definitive control measure, it is one of the few ones available to contain the destruction of millions of cubic metres of conifer forests perpetrated every year worldwide by bark beetles. However, using bark beetle aggregation pheromones during both monitoring and control programs may negatively affect other saproxylic insects. The aim of this study was to describe the response of both Ips sexdentatus and its saproxylic beetle associates, especially predators, to traps baited with a commercial blend of I. sexdentatus aggregation pheromone. Furthermore, the usefulness of adding pine volatiles, such as (?)‐α‐pinene and ethanol, to the pheromone was discussed. The commercial blend proved to be attractive to I. sexdentatus adults, both when used alone and together with pine volatiles. Pheromone attractiveness, however, was lessened by the addition of the volatiles. The pheromone blend proved to be attractive to Thanasimus formicarius, as well as to other predator species. Overall, although during our study, traps baited only with (?)‐α‐pinene and ethanol attracted some predator specimens, I. sexdentatus pheromone traps were more attractive. Our study confirms that calendar differences in flight activity between the bark beetle and its predators are substantial; therefore, they should be taken into account when planning control measures. According to our data, the commercial blend of I. sexdentatus pheromone seems to be the most effective, among the baits used, in catching I. sexdentatus adults, while reducing the impact on T. formicarius.     

Interactions between the predators thanasimus formicarius (Col.: Cleridae) and rhizophagus depressus (Col: Rhizophagidae), and the bark beetle tomicus Piniperda (Col.: Scolytidae)

The occurrences of Thanasimus formicarius (L.) (Cleridae), Rhizophagus depressus (F.) (Rhizophagidae), and Epuraea marseuli Reitter (Nitidulidae) in cut Scots pines, Pinus sylvestris L., attacked by Tomicus piniperda (L.) (Col.: Scolytidae) were recorded in the field, and interactions between the species were studied in caged pine bolts attacked by T. piniperda. T. formicarius eggs and R. depressus adults were abundant in the T. piniperda attacked trees, whereas only a few individuals of E. marseuli were found. T. formicarius and R. depressus, but not E. marseuli, reproduced in the caged bolts. T. piniperda offspring production per unit area of bark was reduced by 41% when reared with R. depressus, by 81% when reared with T. formicarius, and by 89% when all three species were reared together, compared with T. piniperda alone. The interaction between T. formicarius and R. depressus was mutually antagonistic. When both species were present in the same bolt the total number of larvae was reduced by 49% for R. depressus and the number of large larvae (length > 10 mm) was reduced by 35% for T. formicarius compared with their respective production values when each species was present alone with the bark beetle. There was a positive relationship between T. piniperda egg gallery density and the production of R. depressus larvae per m². Larvae of both R. depressus and T. formicarius developed into new adults during the first summer.

---

Résumé Interactions entre les prédateursThanasimus formicarius (Col.: Cleridae) etRhizophagus depressus (Col.: Rhizophagidae) et le scolyteTomicus piniperda (Col.: Scolytidae) La présence deThanasimus formicarius (L.) (Cleridae),Rhizophagus depressus (F.) (Rhizophagidae), etEpuraea marseuli Reitter (Nitidulidae) a été étudiée sur le terrain dans des pins sylvestres (Pinus sylvestiris L) abattus, attaqués partomicus piniperda (L.) (Col.: Scolytidae) et les relations entre les espèces ont été étudiées sur des rondins de pin attaqués parT. piniperda et placés sous cage. Le nombre d’∄ufs deT. formicarius et d’adultes deR. depressus était important dans les arbres attaqués parT. piniperda, alors que seuls quelques individus deE. marseuli ont pu être trouvés.T. formicarius etR. depressus, mais pasE. marseuli, se sont reproduits dans les rondins sous cage. La production de descendants deT. piniperda par unité de surface d’écorce était réduite de 41% quand le scolyte était élevé avecR. depressus, de 81% en élevage avecT. formicarius et de 89% quand les trois espèces sont élevées ensemble, par comparaison avecT. piniperda seul. Les interactions entreT. formicarius etR. depressus étaient mutuellement antagonistes. Quand les deux espèces étaient présentes dans le même rondin, le nombre total de larves était réduit de 49% pourR. depressus et le nombre de grosses larves (longueur > 10 mm) était réduit de 35% pourT. formicarius comparé aux valeurs respectives quand chaque espèce était présente isolément avec le scolyte. Il y a une corrélation positive entre la densité de galeries avec des ∄ufs deT. piniperda et la production de larves deR. depressus par m². Les larves deR. depressus et deT. formicarius se sont transformés en adultes l’été suivant.

     

Ultrastructure of the mycangium of the southern pine beetle,Dendroctonus frontalis (Coleoptera: Curculionidae,Scolytinae): complex morphology for complex interactions

Yuceer, C, Hsu, C.‐Y., Erbilgin, N and Klepzig, K.D. 2011. Ultrastructure of the mycangium of the southern pine beetle, Dendroctonus frontalis (Coleoptera: Curculionidae, Scolytinae): complex morphology for complex interactions. —Acta Zoologica (Stockholm) 92 : 216–224. The southern pine beetle (SPB) (Dendroctonus frontalis Zimmermann) is the most economically important pest of southern pine forests. Beetles carry fungal cells within specialised cuticular structures, called mycangia. Little is known about the mycangia ultrastructure or function. We used cryo‐fracturing and scanning electron microscopy to examine the ultrastructural features of SPB mycangia and surrounding tissues. Mycangia, one on each side of anterior portion of the prothorax, are terminated on the dorsal side at a ‘mycangial bridge’. This sclerotised mycangial bridge does not appear to provide a passage between the two mycangia, suggesting that each mycangium functions independently. Mycangia are surrounded by abundant tracheoles connecting the structures to the outside via openings within the prothorax. Previously unknown pits overlying the mycangial gland cells were also observed in both the inner wall and anterior fold of prothorax. We hypothesise that these openings and pits may play roles in determining which fungi enter, and grow within, the mycangium.     

Field responses of the Asian larch bark beetle,Ips subelongatus,to potential aggregation pheromone components: disparity between two populations in northeastern China

Abstract Behavioral responses of the Asian larch bark beetle, Ips subelongatus Motsch. to three potential aggregation pheromone components, ipsenol (racemic or [?]‐enantiomer), ipsdienol (racemic or [+]‐enantiomer) and 3‐methyl‐3‐buten‐1‐ol, were tested using partial or full factorial experimental designs in two provinces (Inner Mongolia and Jilin) of northeastern China. Our field bioassays in Inner Mongolia (Larix principis‐rupprechtii Mayr. plantation) clearly showed that ipsenol, either racemic or 97%‐(?)‐enantiomer, was the only compound that significantly attracted both sexes of I. subelongatus, while all other compounds (singly or in combinations) were unattractive. There were no two‐ or three‐way synergistic interactions. However, in Jilin Province (L. gmelini[Rupr.] Rupr. Plantation), all the individual compounds tested were inactive, except a very weak activity by 97%‐(?)‐ipsenol in 2004 when the beetle population was very high. While a combination of ipsenol and ipsdienol (racemates or enantiomerically pure natural enantiomers) showed a significant attraction for both sexes of I. subelongatus, indicating a two‐way synergistic interaction between these two major components, addition of 3‐methyl‐3‐buten‐1‐ol to these active binary blend(s) did not have any effects on trap catches, suggesting that ipsenol and ipsdienol are the synergistic aggregation pheromone components of I. subelongatus in Jilin Province. It seems that 97%‐(?)‐ipsenol in Inner Mongolia or the binary blend of 97%‐(?)‐ipsenol and 97%‐(+)‐ipsdienol in Jilin Province are superior to their corresponding racemates, which might be due either to weak inhibitory effects of the antipode enantiomers or to reduced release rates of the active natural enantiomer(s) in the racemate(s). Our current bioassay results suggest that there is a strong geographical variation in aggregation pheromone response of I. subelongatus in northeastern China. Future research on the pheromone production and response of I. subelongatus from different regions in Northeast Asia will surely improve our understanding of the dynamic aggregation pheromone system of this economically important forest pest insect.     

An attack of Ips amitinus (Coleoptera: Curculionidae: Scolytinae) on arboretum in West Siberia: New host of invasive bark beetle among exotic conifers

Invasive populations of small spruce bark beetle Ips amitinus were first registered in 2019 in the southeast of Western Siberia. In natural stands of Siberian pine (Pinus sibirica Du Tour), several hundred hectares of outbreak foci of the alien bark beetle were identified. In 2020, a local focus of the bark beetle was found in the conifer collection in the arboretum “Kedr” of the Institute of Monitoring Climatic and Ecological Systems SB RAS, 30 km from Tomsk. The bark beetle caused the main damage to the collection of pines. I. amitinus colonized both host plants Scotch pine (Pinus sylvestris L.) and mountain pine (Pinus mugo Turra), which were previously known to it in the native range in Europe, and the local Siberian species Siberian pine (Pinus sibirica Du Tour), Siberian spruce (Picea obovata Ledeb.) and introduced Far Eastern Korean pine (Pinus koraiensis Sieb. et Zucc.). Demographic characteristics of I. amitinus studied on damaged trees indicate its high reproduction potential in Siberia. The bark beetle outbreak focus was suppressed; however, this plantation requires further annual monitoring of pest abundance and distribution, both to preserve the scientific dendroecological field station and to study the implementation of sential plant conception in relation to the invasion of I. amitinus.     

Field response of the northern spruce bark beetle Ips duplicatus (Sahlberg) (Coleoptera: Curculionidae,Scolytinae) to different combinations of synthetic pheromone with (−)‐α‐pinene and (+)‐limonene

相似文献   

Mitochondrial DNA haplotypes indicate two postglacial re‐colonization routes of the spruce bark beetle Ips typographus through northern Europe to Scandinavia

Species in northern Europe re‐colonized the region after the last glacial maximum via several routes, which could have lingering signatures in current intraspecific trait variation. The spruce bark beetle, Ips typographus, occurs across Europe, and biological differences have been found between southern and northern Scandinavian populations. However, the postglacial history of I. typographus in Scandinavia has not been previously studied at a fine geographical scale. Therefore, we collected specimens across northern Europe and analysed the genetic variation in a quite large mitochondrial fragment (698 bp). A high genetic diversity was found in some of the most northern populations, in the Baltic States, Gotland and central Europe. Detected genetic and phylogeographic structures suggest that I. typographus re‐colonized Scandinavia via two pathways, one from the northeast and one from the south. These findings are consistent with the re‐colonization history of its host plant, Picea abies. However, we observed low haplotype and nucleotide diversity in southern Scandinavian populations of I. typographus, indicating that (unlike P. abies) it did not disperse across the Baltic Sea in multiple events. Further, the divergence among Scandinavian populations was shallow, conflicting with a scenario where I. typographus expanded concurrently with its host plant from a ‘cryptic refugium’ in the northwest.     

Temperature-dependent parameters of stridulatory signals in the four-eyed fir bark beetle,Polygraphus proximus (Coleoptera: Curculionidae: Scolytinae)

Acoustic signals are an essential part of the multi-modal systems of conspecific communication among insects. The patterns of abiotic factors effects on their communication parameters are of great interest for prognostic purposes in current climatic instability and for practical application in order to manage their populations.The aim of this study was to reveal the dependence of the parameters of acoustic signals produced by bark beetle Polygraphus proximus, an aggressive alien stem pest on the environmental temperature. Male stridulatory signals were recorded in seven temperature settings (5–35 °C), and changes in their temporal parameters were evaluated under laboratory conditions.The obtained results allowed us to reveal the pattern of temperature dependence of signals produced by P. proximus. More than half of the insects were found to actively stridulate at 5 °C. Raising temperature caused an increment in chirp rate that continued to increase up to 30 °C. Further temperature increase led to suppression of signaling in most of the tested males. The obtained results showed a number of patterns of temperature effect on the parameters of acoustic signals which might be universal for representatives of different bark beetles genera with various stridulatory apparatus types.     

A host monoterpene influences Ips typographus (Coleoptera: Curculionidae,Scolytinae) responses to its aggregation pheromone

1 Host tree terpenes can influence attraction of conifer‐infesting bark beetles to their aggregation pheromones, and both synergistic and inhibitory effects have been reported. 2 We tested a gradient of ratios of (–)‐α‐pinene, the predominant monoterpene in Norway spruce, to the pheromone of Ips typographus, a major pest of Norway spruce. 3 Attraction of I. typographus increased as the release rate of (–)‐α‐pinene increased. The two highest (–)‐α‐pinene : pheromone ratios (526 : 1 and 2595 : 1) attracted twice as many I. typographus as pheromone alone, whereas low to intermediate ratios (56 : 1, 274 : 1) did not differ from pheromone alone. 4 Our results are in agreement with a proposed model, which suggests that bark beetles display unique response profiles to host terpenes depending on the physiological condition of the host trees that they typically colonize. Ips typographus, which is an aggressive species capable of colonizing and killing healthy trees, showed an increased attraction to monoterpene : pheromone ratios, and this may be high enough to inhibit attraction of less aggressive beetle species typically colonizing dead, dying or stressed trees. 5 Attraction of associates of I. typographus was also modified by (–)‐α‐pinene. Ips duplicatus, a competitor of I. typographus, showed increased attraction to the pheromone of I. typographus across all concentrations of (–)‐α‐pinene.     

Attacks on living spruce trees by the bark beetle Ips typographus (Col. Scolytidae) following a storm-felling: a comparison between stands with and without removal of wind-felled trees

Abstract 1 To maintain biodiversity in forests more wind‐felled trees must be left where they fall. However, there is concern among forest owners that this may result in higher tree mortality caused by the spruce bark beetle, Ips typographus (L.) (Col.: Scolytidae). 2 In the 5 years following a major storm disturbance the number of standing spruces killed by I. typographus was determined in a total of 53 stands. In five of the stands all wind‐thrown trees were left (unmanaged stands) and in 48 of the stands, which were situated at distances of 1.4–10.0 km from each focal unmanaged stand, the wind‐felled trees were removed directly after the storm (managed stands). In the winter preceding the fifth summer new storm‐fellings occurred in the study area. 3 In the 4‐year period between the first and second storm‐fellings, 50–322 standing trees were killed by I. typographus per unmanaged stand. There was a direct linear relationship between the number of storm‐felled spruces colonized by I. typographus and the number of trees subsequently killed in the unmanaged stands. 4 Tree mortality caused by I. typographus in the unmanaged stands was almost nil in the first year, peaked in the second or third year, and decreased markedly to a low level in the fourth and fifth years. 5 In the 4‐year period between the first and second storm‐fellings twice as many trees were killed per ha in the unmanaged stands than in the managed stands: the average difference being 6.2 killed trees per ha, equivalent to 19% of the number of spruce trees felled by the first storm in the unmanaged stands. 6 Much higher numbers of trees were killed per ha in the stand edges than in the interiors of both the unmanaged and the managed stands.     

Attraction of the southern pine beetle, Dendroctonus frontalis, to pheromone components of the western pine beetle, Dendroctonus brevicomis (Coleoptera: Curculionidae: Scolytinae), in an allopatric zone

Subtle differences in pheromone components of sympatric species should be attractive only to the producing species and unattractive or repellent to the nonproducing species, and thereby maintain reproductive isolation and reduce competition between species. Bark beetles Dendroctonus brevicomis and D. frontalis (Coleoptera: Curculionidae) are known to have common pheromone components, except for exo-brevicomin, which is produced by D. brevicomis. We predicted that D. frontalis would not respond to exo-brevicomin outside of the zone of sympatry with D. brevicomis. We conducted a field experiment to determine the effect of exo-brevicomin on attraction of D. frontalis and associated species in Mississippi. We determined whether D. frontalis pheromone production differed inside and outside the sympatric zone and compared the pheromone profiles with D. brevicomis within the sympatric zone. Trapping studies revealed that D. frontalis can perceive and respond positively to exo-brevicomin, an aggregation pheromone of a sympatric congener (D. brevicomis), at locations hundreds of kilometers outside the sympatric zone. Qualitative pheromone profiles showed that both species emit similar pheromone components: frontalin, endo-brevicomin, exo-brevicomin, trans-verbenol, verbenone, and myrtenol. Although not previously reported, D. frontalis males from Arizona produced exo-brevicomin. The predator Thanasimus dubius did not discriminate traps baited with exo-brevicomin and was most attracted to traps with frontalin. Hylastes beetles were significantly attracted to traps baited with exo-brevicomin in combination with other compounds. Our results raise new practical and evolutionary questions on the role of exo-brevicomin in the behavioral ecology of D. frontalis. The addition of exo-brevicomin to the current lure might increase the efficiency of trapping programs in the southeastern United States.     

Role of stressed mango host conditions in attraction of and colonization by the mango bark beetle Hypocryphalus mangiferae Stebbing (Coleoptera: Curculionidae: Scolytinae) and in the symptom development of quick decline of mango trees in Pakistan

The mango sudden death syndrome has become a serious threat to the mango industry and caused significant decline in mango production worldwide. The bark beetle Hypocryphalus mangiferae (Stebbing) (Coleoptera: Curculionidae: Scolytinae) has been suggested as a potential vector of the disease based primarily on field observations with little or no supporting empirical data. In this study, we investigated the role of infected mango trees in host attraction and colonization by H. mangiferae to determine if beetle attack and colonization contributes to the disease progression on mango trees. Initially, the role of various stress factors on beetle attraction and disease progression was assessed under lathe house conditions from 2008 to 2009. Results suggest that symptomatic or recently inoculated mango trees (without any obvious symptoms) are preferentially colonized by H. mangiferae. Although not significant, high numbers of beetles attacked stressed or wounded mango trees, compared to healthy or dead mango trees. Disease symptoms after beetle colonization, such as bark splitting, wilting and oozing, were further evaluated. These symptoms showed positive correlation with the degree of disease severity and host plant condition. Furthermore, two fungi, Ceratocystis fimbriata and Lasiodiplodia theobromae, were frequently isolated from the beetle and beetle-colonized trees. Based on these findings, they suggests that H. mangiferae can vector multiple fungi associated with mango sudden decline disease and play a significant role in outbreaks of this disease.     

Performance of the tree‐killing bark beetles Ips typographus and Pityogenes chalcographus in non‐indigenous lodgepole pine and their historical host Norway spruce

相似文献   

Temperature‐dependent development of the great European spruce bark beetle Dendroctonus micans (Kug.) (Coleoptera: Curculionidae: Scolytinae) and its predator Rhizophagus grandis Gyll. (Coleoptera: Monotomidae: Rhizophaginae)

相似文献   

Temperature‐dependent development of the double‐spined spruce bark beetle Ips duplicatus (Sahlberg, 1836) (Coleoptera; Curculionidae)

相似文献   

Prolonged development time of the bark beetle predator Thanasimus formicarius (Col.: Cleridae) in relation to its prey species Tomicus piniperda (L.) and Ips typographus (L.) (Col.: Scolytidae)

1 The generation time of the bark beetle predator Thanasimus formicarius (L.) (Col.: Cleridae) was found to be predominantly two years both in the field and in rearing experiments conducted with two of its main prey species, the pine shoot beetle Tomicus piniperda (L.) and the spruce bark beetle Ips typographus (L.) (Col.: Scolytidae). 2 Emergence of T. formicarius adults in the first summer was only observed in one of the two rearing experiments, and these individuals represented only 6% of that generation. 3 All individuals not emerging as adults in the first summer remained as larvae in their pupal chambers until the second summer. Pupae were found starting around mid-June, and adults (in pupal chambers) were found from late July through to the end of August. 4 Newly emerged adults had to feed in order to survive hibernation. 5 The existence of T. formicarius races, specialized on certain bark beetle species and with phenologies matching their hosts, could not be demonstrated. After hibernation there was no difference in feeding activity, timing of egg-laying or proportion of egg-laying females between the T. formicarius adults reared as larvae on T. piniperda (flight period in April) and those reared as larvae on I. typographus (main flight period generally starting in late May or early June) when exposed to a temperature and day-length typical of the early spring conditions prevailing during the flight period of T. piniperda. 6 T. formicarius was parasitized by Enclisis vindex (Tschek) (Hym.: Ichneumonidae) in the pupal chamber. 7 The importance of these findings for the population dynamics of bark beetles is discussed.     

Effect of varying monoterpene concentrations on the response of Ips pini (Coleoptera: Scolytidae) to its aggregation pheromone: implications for pest management and ecology of bark beetles

Abstract 1 Host plant terpenes can influence attraction of conifer bark beetles to their aggregation pheromones: both synergistic and inhibitory compounds have been reported. However, we know little about how varying concentrations of individual monoterpenes affect responses. 2 We tested a gradient of ratios of α‐pinene, the predominant monoterpene in host pines in the Great Lakes region of North America, to Ips pini's pheromone, racemic ipsdienol plus lanierone. 3 Ips pini demonstrated a parabolic response, in which low concentrations of α‐pinene had no effect on attraction to its pheromone, intermediate concentrations were synergistic and high concentrations were inhibitory. These results suggest optimal release rates for population monitoring and suppression programmes. 4 Inhibition of bark beetle attraction to pheromones may be an important component of conifer defences. At terpene to pheromone ratios emulating emissions from trees actively responding to a first attack, arrival of flying beetles was low. This may constitute an additional defensive role of terpenes, which are also toxic to bark beetles at high concentrations. 5 Reduced attraction to a low ratio of α‐pinene to pheromone, as occurs when colonization densities become high and the tree's resin is largely depleted, might reflect a mechanism for preventing excessive crowding. 6 Thanasimus dubius, the predominant predator of I. pini, was also attracted to ipsdienol plus lanierone, but its response differed from that of its prey. Attraction increased across all concentrations of α‐pinene. This indicates that separate lures are needed to sample both predators and bark beetles effectively. It also provides an opportunity for maximizing pest removal while reducing adverse effects on beneficial species. This disparity further illustrates the complexity confronting natural enemies that track chemical signals to locate herbivores.