Pathology,distribution, morphological and genetic identity of Deladenus proximus (Tylenchida: Neotylenchidae) a parasitic nematode of the woodwasp,Sirex nigricornis in the eastern United States

The woodwasp, Sirex nigricornis (Hymenoptera: Siricidae), is solitary and utilizes a symbiotic fungus to extract nourishment from pine trees to feed its larvae. The woodwasp has a brief adult life, but the larvae develop for 1–3 years in the tree xylem. Infections with the nematode Deladenus proximus have been documented in the native woodwasp, S. nigricornis in the eastern United States and Canada. These nematodes appear to sterilize female woodwasps; however, the extent of the pathology and other aspects of the biology of D. proximus remain unknown. In this study we examined the effects of D. proximus on S. nigricornis using fresh – not preserved – specimens. Between 2009 and 2012, a total of 1639 woodwasps were examined for internal nematodes from emerging sites in Illinois, Louisiana and South Carolina. From this total, only 112 individuals were infected with the nematode D. proximus, with varying prevalence across localities and years. Nematodes were found inside every egg of infected females, as well as the hemocoel and the mycangia. Morphometric analyses of mycetophagous reared adult nematodes suggest that a single species is present in localities from Arkansas, Illinois, Louisiana, New York and South Carolina. The screening of the mitochondrial cytochrome oxidase subunit 1 (cox1) of these organisms is consistent with this pattern in that all of these individuals belong to a single clade. Deladenus proximus appears to be an efficient sterilizer, yet its prevalence is relatively low. Experimental infections of the invasive Sirex noctilio are recommended to test the viability of using this nematode as a biological control agent.     

A comparison of control results for the alien invasive woodwasp,Sirex noctilio,in the southern hemisphere

1 Sirex noctilio has resulted in one of the most damaging biological invasions of pine forestry in the southern hemisphere. 2 An intensive, integrated control programme has been developed for this pest and is generally considered very successful. However, a critical comparison of S. noctilio infestations and control efforts throughout the southern hemisphere reveals that control has not been uniformly effective. Of particular concern is the apparently unexplained variability in establishment and success of biological control agents, including various parasitic wasps and the parasitic nematode Deladenus siricidicola. 3 An overlooked aspect in the establishment of the biological control interventions for S. noctilio is the potential influence of genetic bottlenecks on the ability of the agents to adapt to different environments and different populations of S. noctilio. 4 Despite established biological control agents, stress in forests caused by silvicultural practices or the environment will predispose trees to heavy infestation. Unfortunately, improved silvicultural practices are not always economically feasible and environmental changes are often unavoidable. 5 Sirex noctilio continues to pose a serious threat to pine forestry in many areas. Despite extensive earlier research into a single integrated control for S. noctilio, it is important to recognize that such a strategy will probably require significant local adaptation in new areas of infestation and over time.     

Sequence data reflect the introduction pathways of the Sirex woodwasp parasitoid,Ibalia leucospoides (Ibaliidae,Hymenoptera)

1. The parasitoid wasp Ibalia leucospoides is native to the northern hemisphere and has been introduced to the southern hemisphere as a biological control agent for the invasive woodwasp Sirex noctilio. Two subspecies of the parasitoid, Ibalia leucospoides leucospoides (Palearctic distribution) and Ibalia leucospoides ensiger (Nearctic distribution), were introduced and are reported to have hybridized.
2. Despite extensive records of the numbers and origins of the wasps imported into the southern hemisphere, nothing is known regarding their current population diversity. We investigated the genetic variation of I. leucospoides in its native and introduced ranges using mitochondrial (COI) and nuclear (ITS) markers.
3. Mitochondrial DNA diversity in the introduced range was limited, with only five haplotypes, although sequence divergence between these haplotypes was high. Similarly, the ITS rDNA sequences revealed multiple clades present in the introduced range.
4. These results reflect introductions from a wide geographical range but where genetic bottlenecks have possibly reduced the genetic diversity. The data further reflect the origin of the I. leucospoides populations in South America and South Africa from New Zealand or Australia. We found no evidence of hybridization between the two subspecies of the parasitoid in its introduced range, and no evidence that I. leucospoides ensiger has established outside its native range.

     

Effect of temperature on reproduction and parasitism of the egg parasitoid,Anastatus orientalis (Hymenoptera: Eupelmidae)

Anastatus orientalis is a solitary endoparasitoid of Lycorma delicatula (Hemiptera: Fulgoridae) eggs. We investigated the development, longevity, fecundity, and sex ratio of A. orientalis on different temperatures to establish the optimal temperature condition for laboratory mass rearing. There were significant differences in its development and longevity between 15 °C and the rest of temperature conditions (20, 25, and 30 °C), among which were no significant differences. The average number of eggs laid by A. orientalis was higher at 20 and 25 °C, but there was no statistically significant difference in its fecundity between the two temperatures. More females emerged at 15 and 20 °C than higher temperatures.Parasitisms of A. orientalis varied with host egg ages and densities. Even in 14 day old eggs of L. delicatula, parasitoids successfully emerged from 92.3% of the parasitized eggs. On the other hand, parasitism was lowest (13.8%) on just before hatching eggs. Parasitism was negatively dependent on host density.Oviposition behavior for A. orientalis primarily occurred at 1400–1600 h, not at 2400–0800 h. The majority of this parasitoid's emergence occurred at 0800–1000 h, largely before noon. These results may be useful for controlling the adequate time for supplying host eggs and release density of this parasitoid as well as for potentially predicting the accurate time for securing parasitoid adults in laboratory mass rearing of A. orientalis.     

松树蜂与其共生真菌的互利共生关系

松树蜂Sirex noctilio Fabricius是一种重要的国际林业检疫性害虫,主要危害针叶树,原产欧亚大陆和北非。近100多年来,先后入侵大洋洲(新西兰和澳大利亚)、南美洲(乌拉圭、阿根廷、巴西和智利)、北美洲(加拿大和美国),以及南非。2013年8月,在中国黑龙江省内首次发现松树蜂,目前发现其主要危害樟子松。松树蜂能与一种淀粉韧革菌属Amylostereum的真菌Amylostereum areolatum(Fr.)Boidin形成严格的互利共生关系,该虫除直接钻蛀树木外,还能通过产卵行为将自身毒素腺体分泌的毒素和体内共生真菌随同虫卵一起注入寄主树木体内,形成"虫-毒-菌"3个致害因子相互协作的特殊危害方式,加速树势的衰弱并造成寄主树木死亡。本文就国内外松树蜂与其共生菌互利共生关系的研究进行了综述,分别从结构与功能的层次上对其互利共生关系进行了梳理和总结,重点阐释了松树蜂与共生菌的营养共生关系,松树蜂携带传播共生菌的机制,共生菌的种群遗传学以及松树蜂毒素和共生菌在危害寄主树木时的协同关系等。以期为开展关于松树蜂的专项研究提供一些合理的建议,同时为积极有效地防控该害虫提供科学依据。     

Emergence of adult female Sirex nigricornis F. and Sirex noctilio F. (Hymenoptera: Siricidae) coincides with a decrease in daily minimum and maximum temperature

相似文献   

Assessing the influence of the entomopathogenic nematode Heterorhabditis baujardi LPP7 (Rhabiditina) on embryogenesis and hatching of the plant-parasitic nematode Meloidogyne mayaguensis (Tylenchina)

Two assays were conducted to assess the influence of infective juveniles (IJs) of Heterorhabditis baujardi LPP7 on the embryogenesis and hatching of Meloidogyne mayaguensis. In the first assay, eggs were incubated in water alone or in the presence of infective juveniles, and completion of embryogenesis was evaluated 14 days later. In the second assay, unhatched second-stage juveniles were incubated in distilled water alone or in the presence of infective juveniles. Cumulative hatching was compared at various time intervals. Embryogenesis was not affected, whereas second-stage juveniles hatching was delayed probably because of the eggs permeability to noxious metabolites released by Photorhabdus luminescens, which is the bacterial symbiont of H. baujardi.     

Efficiency and establishment of three introduced parasitoids of the mealybug Paracoccus marginatus (Hemiptera: Pseudococcidae)

Three introduced parasitoids Acerophagus papayae, Anagyrus loecki, and Pseudleptomastix mexicana of the mealybug Paracoccus marginatus have been released in Miami-Dade and Broward counties (Florida) in 2003. Efficiency and establishment of these previously introduced parasitoids to control P. marginatus were measured in 2005 and 2006, at three locations in Homestead (Miami-Dade). Mealybug populations were initially established on three branches (per plant) of 10 hibiscus plants inside closed-sleeve cages. The three treatments, closed, open, and no-cage environments were applied to the three established mealybug populations on each plant. The number of mealybugs and natural enemies was monitored in all treatments. After 72 h, the number of P. marginatus in the open-sleeve cage was higher than in the no-cage treatment but both were lower than the number in the closed-sleeve cage. Efficiency of parasitoids was evaluated by their percentage parasitism. Percentage parasitism (=recovery) was also used as an indicator for parasitoid establishment. Two of the three previously released parasitoids (A. papayae and A. loecki) were recovered in this study. Acerophagus papayae had a higher percentage parasitism than A. loecki in both the open-sleeve cage (31.0% vs 2.3%) and the no-cage treatments (21.4% vs 1.6%) and caused the most mortality of P. marginatus. There was no recovery of P. mexicana in either of the treatments. Although both A. papayae and A. loecki were established in tested areas, A. papayae was more efficient in controlling P. marginatus than A. loecki. The reasons for not recovering P. mexicana in release areas is yet unknown.     

Continuous rearing on Ephestia kuehniella reshaped quality of the parasitoid wasp Trichogramma brassicae (Hymenoptera: Trichogrammatidae)

Continuous mass rearing of Trichogramma brassicae (Bezdenko) at commercial mass-rearing insectaries may affect both quality and performance of natural enemies. In the present study, we studied the quality and performance of a colony of T. brassicae reared for over 45 generations (G) on Ephestia kuehniella Zeller using two-sex life table parameters and parasitism capacity. Our results revealed that although different generations showed no significant difference in terms of female longevity or total life span until G35, G5 and G10 had the highest values of fecundity, gross reproductive rate (GRR), net reproductive rate (R₀), intrinsic rate of natural increase (r), and finite rate of increase (λ). No significant difference in male adult longevity was found among different generations. The longest and shortest mean generation times (T) were found in G10 (13.65 ± 2.31 d) and G45 (13.25 ± 3.37 d), respectively. The finite rate of parasitism (ω) ranged from 0.355 ± 2.332 host/parasitoid/day in G5 to 0.242 ± 0.017 host/parasitoid/day in G45. However, ω did not show any significant difference until G20. These results indicate that T. brassicae wasps held under continuous laboratory rearing declined in quality after 20 generations, and therefore periodical rejuvenation of the colony by adding feral parasitoids is strongly recommended.     

Impacts of fluctuating temperature on the development and infectivity of entomopathogenic nematode Steinernema carpocapsae A10

Three different laboratory conditions were used to examine the impacts of fluctuating temperature on the development and infectivity of entomopathogenic nematode (EPN) Steinernema carpocaposae A10. Set I experiments focused on the impact of cold stress early in the development cycle. In these studies Galleria mellonella hosts were infected and incubated for 2 days at the control temperature of 23 degrees C and then subjected to lower temperatures of -10, 4, 10 or 14 degrees C, respectively, from days 3 to 36 post-infection (PI). Dissections of infected cadavers indicated arrested development at the adult stage at all lower temperatures tested. Set II experiments examined the impacts of cold stress early in the development followed by a return to 23 degrees C. Hosts were infected and incubated as in Set I and subjected to the same temperatures as above for 7 days, followed by incubation at 23 degrees C until 23 days PI. A limited number of EPN populations were able to complete development at 10 and 14 degrees C though emergent population numbers were significantly lower than those of control infections incubated continuously at 23 degrees C. In Set III experiments, infected hosts were subjected to cold stress later during development starting at day 4 post-infection followed by incubation at the control temperature. Population survival past first and second stage juveniles was reduced by at least 95% or more at the lower temperatures compared with controls. Emergent populations from the Set III cold-stressed hosts were not infectious. These studies may provide insights as to how EPN survive seasonal temperature fluctuations under natural environmental conditions.     

Effect of temperature on survival and immature development of Arma chinensis

Arma chinensis (Fallou) is a predaceous pentatomid with the potential to control a wide range of insect pests. In this study, the stage-specific temperature-dependent development and survival of A. chinensis was investigated under seven constant temperatures (range 18–35 °C) when fed with yellow mealworm (Tenebrio molitor L.). Developmental times (in days) for the immature stage, entire nymphal stage, and egg-to-adult development were inversely proportional to temperatures between 18 and 33 °C (30 °C for eggs and 1st instar nymphs). The lowest survival rate of A. chinensis was observed at 18 °C (6.7%), whereas it was the highest (80–93.3%) at temperatures ranging from 21 to 24 °C. The low temperature thresholds for the egg, entire nymph stage, and egg-to-adult development were 14.3, 12.28, and 12.8 °C, respectively, while the thermal constants for these stages were estimated to be 85.47, 334.9, and 423.8° days. Among the three non-linear models examined, the Taylor model showed the best fit for the egg data, the Briére1 model was the best fit for the 1st instar nymph stage, and the Lactin1 model was more approprate for all the other instar stages, the entire nymphal stage, and overall development. The upper temperature thresholds estimated using the Lactin1 model for eggs, overall nymphal stage, and egg-to-adult development were 38.57, 38.9, and 40.0 °C. The optimal temperature for the overall egg-to-adult period was estimated to be 33.5 °C. The results of this study can be used for the mass rearing of this natural pest enemy and development of phenology models of its seasonal progress.     

Sirex noctilio in North America: the effect of stem‐injection timing on the attractiveness and suitability of trap trees

• 1 Sirex noctilio Fabricius, an invasive woodwasp responsible for severe economic damage to pine industries in the southern hemisphere, is now established in the northeastern U.S.A. and portions of eastern Canada.
• 2 Parts of North America are considered to be high risk for S. noctilio invasion. Effective detection tools, including trap trees, are needed to monitor and survey S. noctilio populations.
• 3 The present study was conducted to determine the optimal time to chemically stress a tree when aiming to attract the most S. noctilio to the host substrate, as well as to determine which timing produced the most adult progeny. Both of these measures (host attraction and host suitability for development) support the main objectives of the study by offering improved methods for monitoring and management of S. noctilio.
• 4 Red pine (Pinus resinosa) and Scots pine (Pinus sylvestris) were treated with Dicamba at three time intervals. Multiple funnel lindgren traps were placed on these trees and, at the end of the flight season, the treatment trees were felled and brought into the laboratory. The number of S. noctilio caught in the traps (host attraction) and the number of S. noctilio emerged from the treated trees (host suitability) were determined.
• 5 Optimal timing of the chemical girdle was dependent on host species. Significantly more female S. noctilio were captured on trap trees prepared 1 month before flight (red pine and Scots pine) or prepared at flight (Scots pine) compared with other treatments. There were also significantly more females reared from Scots pine trap trees prepared at flight and red pine trap trees prepared 1 month before and/or at flight.
• 6 By the beginning of August, most (79%) of the S. noctilio for the flight season were caught in the traps at the trap trees. The sex ratio (males : females) was closer to 1 : 1 than previously reported in studies from other countries.
• 7 The results obtained in the present study demonstrate that timing is important when creating a trap tree with herbicide in North America, whether for the purpose of detection or as part of a biological control effort.

     

Effects of elevated temperature and carbon dioxide on the nutritional quality of leaves of oak (Quercus robur L.) as food for the Winter Moth (Operophtera brumata L.)

1. Pedunculate Oak trees were grown in ambient and elevated temperatures and CO₂. Leaves were fed to Winter Moth caterpillars reared either in constant conditions or with the trees (caged or on-tree).
2. Caterpillars in constant conditions ate the same mass and produced the same mass of faeces whether fed elevated or ambient temperature leaves. However, less was assimilated from elevated leaves, resulting in lighter pupae and fewer, lighter eggs.
3. Caterpillars in constant conditions ate more and produced more faeces when fed elevated CO₂ leaves than when fed ambient CO₂ leaves, but the mass assimilated and pupal mass were unchanged.
4. Caged caterpillars reared with the trees from which they were fed had constant pupal mass in all treatments, but pupated earlier at elevated temperature. Pupal mass was also unaffected when caterpillars fed on the trees.
5. Nitrogen was reduced in both elevated temperature and elevated CO₂ leaves. Increased fibre in the former prevented increased consumption and resulted in reduced pupal mass and fecundity. Reduced fibre in the latter allowed increased consumption, resulting in pupae of normal mass.
6. Despite the clear effect of nutrient quality, experiments rearing caterpillars and trees together suggest that anticipated climatic change will have no nutritional effect on Winter Moth development.     

Evaluation of certain entomopathogenic nematodes against the melon ladybird,Epilachna chrysomelina F. (Coleoptera: Coccinellidae)

Three native Egyptian nematode isolates; Heterorhabditis taysearae and Heterorhabditis sp. S1 (Heterorhabditidae) and Steinernema carpocapsae S2 (Steinernematidae) as well as H. bacteriophora Hp88 as an imported species, were used in the present work to evaluate their activities against larvae and adults of the melon ladybird, Epilachna chrysomelina. The target pest was found to be susceptible to all tested entomopathogenic nematodes under laboratory conditions of 30±5°C.

In the greenhouse, a single spray of nematode suspension (1000 infective juveniles per ml) of each of H. taysearae, H. bacteriophora Hp88 and Steinernema carpocapsae S2 on squash seedlings was enough to give a reasonable mortality of 4^th larval instar E. chrysomelina, reaching 65.2, 44.0 and 84.0%, respectively, one week after application. This gives evidence that the Egyptian nematode isolates could tolerate high temperature and could be recommended for application in the control programmes of E. chrysomelina larvae in cucurbit fields.     

Effect of insect cadaver desiccation and soil water potential during rehydration on entomopathogenic nematode (Rhabditida: Steinernematidae and Heterorhabditidae) production and virulence

We examined the influence of insect cadaver desiccation on the virulence and production of entomopathogenic nematodes (EPNs), common natural enemies of many soil-dwelling insects. EPNs are often used in biological control, and we investigated the feasibility of applying EPNs within desiccated insect cadavers. Desiccation studies were conducted using the factitious host, Galleria mellonella (Lepidoptera: Pyralidae, wax moth larvae) and three EPN species (Heterorhabditis bacteriophora ‘HB1’, Steinernema carpocapsae ‘All’, and Steinernema riobrave). Weights of individual insect cadavers were tracked daily during the desiccation process, and cohorts were placed into emergence traps when average mass losses reached 50%, 60%, and 70% levels. We tracked the proportion of insect cadavers producing infective juveniles (IJs), the number and virulence of IJs produced from desiccated insect cadavers, and the influence of soil water potentials on IJ production of desiccated insect cadavers. We observed apparent differences in the desiccation rate of the insect cadavers among the three species, as well as apparent differences among the three species in both the proportion of insect cadavers producing IJs and IJ production per insect cadaver. Exposure of desiccated insect cadavers to water potentials greater than −2.75 kPa stimulated IJ emergence. Among the nematode species examined, H. bacteriophora exhibited lower proportions of desiccated insect cadavers producing IJs than the other two species. Desiccation significantly reduced the number of IJs produced from insect cadavers. At the 60% mass loss level, however, desiccated insect cadavers from each of the three species successfully produced IJs when exposed to moist sand, suggesting that insect cadaver desiccation may be a useful approach for biological control of soil insect pests.     

Phoresy of the entomopathogenic nematode Heterorhabditis marelatus by a non-host organism, the isopod Porcellio scaber

Entomopathogenic nematodes are widespread in nature and commonly used in the biological control of insect pests. However, we understand little about how these organisms disperse. We show in a laboratory setting that the entomopathogenic nematode Heterorhabditis marelatus is phoretically dispersed by a non-host organism, the isopod Porcellio scaber. These species both inhabit tunnels excavated in the roots and lower stems of bush lupine (Lupinus arboreus) by the nematodes' primary prey, larvae of the ghost moth Hepialus californicus. Phoretic dispersal via P. scaber may play a role in the metapopulation dynamics of this nematode.     

Effect of dew temperature,post-inoculation condition,and pathogen dose on suppression of scentless chamomile by Colletotrichum truncatum

Scentless chamomile, a noxious weed in western Canada, has a high natural tolerance to many herbicides. Colletotrichum truncatum, a host specific fungal pathogen, is suppressive to scentless chamomile when applied inundatively. A broadcast application was used at 200 L ha^?1 to evaluate biocontrol potential of this pathogen under a range of dew temperatures (DT), post-inoculation conditions (PIC), and pathogen doses (PD). A DT between 20 and 25°C was more conducive to infection, resulting in higher levels of disease and weed suppression as compared to 15 and 30°C. Under similar post-inoculation temperature regimes, disease was only slightly more severe in growth chambers than in the greenhouse. There was a positive linear relationship between the PD and weed suppression. An inoculum concentration >1×10⁸ spores mL^?1 reduced plant fresh weight by approximately 50% when compared to untreated controls. These results indicate that biocontrol of scentless chamomile using C. truncatum in the semi-arid Canadian prairies will likely encounter frequent non-favourable field conditions.     

Effect of the trap crop Solanum sisymbriifolium and two biocontrol fungi on reproduction of the potato cyst nematode,Globodera pallida

The potato cyst nematode, Globodera pallida, is one of the most important pests of potato worldwide. Owing to regulatory considerations and potential environmental impact, control options for this nematode are becoming increasingly limited. Solanum sisymbriifolium and biological control agents offer viable alternative options for controlling G. pallida. Therefore, experiments were conducted to determine the effect of the nematode trap crop S. sisymbriifolium, alone or in combination with the biocontrol agents Trichoderma harzianum or Plectosphaerella cucumerina, on population decline of G. pallida. Experiments were conducted for three different ‘cropping systems’: potato (Solanum tuberosum), S. sisymbriifolium, or soil only (fallow), each followed by a potato crop. Soil was amended with P. cucumerina, T. harzianum or left unamended, and then infested with nematodes at a rate of five eggs g^?1 of soil. After 16 weeks in the greenhouse, plants were removed and the soil containing cysts was refrigerated at 4°C for 8 weeks, and then planted to potato. Cysts of G. pallida were counted after an additional 16‐week period. The P_f/P_i of G. pallida was significantly reduced by 99% in potato following S. sisymbriifolium compared to both the potato‐following‐fallow and the potato‐following‐potato treatments. Amendment of soil with T. harzianum significantly reduced P_f/P_i of G. pallida by 42–47% in the potato‐following‐potato but not in either the potato‐after‐fallow nor in the potato‐after‐S. sisymbriifolium cycles which supports evidence that the plant species may play a role in the biocontrol activity of this fungus. Addition of the fungus P. cucumerina resulted in a 64% decrease in P_f/P_i in the potato‐following‐fallow in one experiment, and an 88% decrease in P_f/P_i in potato‐following‐potato but the decrease in P_f/P_i was not consistent over all experiments. However, both biocontrol fungi resulted in lower numbers of progeny cysts after an initial 16‐week incubation with potato. To look at the effect of varied population density of the nematode on efficacy of S. sisymbriifolium to reduce G. pallida populations, potato, S. sisymbriifolium, or barley were planted into soil infested with G. pallida at rates of 5, 20 or 40 eggs g^?1 soil applied as cysts (20, 80 or 160 cysts pot^?1). After 16 weeks, numbers of cysts produced in each treatment were determined for each infestation rate. No new cysts were recovered from either S. sisymbriifolium or barley treatments, confirming that neither plant is a host for G. pallida. High numbers of cysts were recovered with potato. Soil from each treatment (containing original cysts and newly‐formed cysts when present) were then planted with potato. After an additional 16 weeks, few cysts were found in the potato‐after‐ S. sisymbriifolium treatments regardless of initial infestation rate. When potato followed barley, numbers of cysts were similar to those found after a single cycle of potato, indicating that the barley crop had no effect on the survival of initial inoculum. Overall, these results suggest that S. sisymbriifolium has potential to significantly reduce G. pallida populations, and also that the cropping system (i.e. the sequence of non‐host and host plants) may play a significant role in the efficacy of fungal biological control agents.     

Present status and future of boletoid fungi (Boletaceae) on the island of Cyprus: Cryptic and threatened diversity unravelled by ten-year study

Fungi historically placed in the iconic genera of Boletus, Leccinum and Xerocomus have been the subject of major taxonomic revisions in recent years. Yet, despite all advancements in systematics, boletoid fungi in insular ecosystems remain little explored and our knowledge of their diversity, distribution and abundance in Mediterranean ecoregions is far from complete. To shed light on this blind spot, the findings of a ten-year study from the island of Cyprus were analysed, integrating phylogenetic, ecological, morphological, phenological and chorological data. An unexpected diversity of Boletaceae fungi is unveiled, with twenty-five species phylogenetically confirmed to be present on the island, thirteen of them previously unreported. Sequencing of the ITS rDNA region, reveals crypticism within the Butyriboletus fechtneri, Caloboletus radicans, Rubroboletus lupinus and Rheubarbariboletus armeniacus species-complexes and infrageneric relationships are discussed. A strong link between boletoid fungi and Mediterranean oaks of the ilicoid group (Quercus alnifolia, Quercus coccifera subsp. calliprinos) is illustrated, with nineteen species (76%) overall found to be strictly or broadly associated with evergreen oaks. In stark contrast, the semi-deciduous Quercus infectoria subsp. veneris appears to be an unfavorable host for boletoid fungi, with just a single associated species so far. Phenological and chorological records indicate that most species on the island are rare, highly localized and fruit during very brief spells several years apart, mainly in response to increased annual, late summer or early autumn precipitation. The conservation status of these high-profile fungi is hence discussed, particularly in view of alarming climate changes, forecasted to have a dramatic impact on Mediterranean ecosystems in the years to come.