Studies on West Indian Scolytidae (coleoptera) 2. new distribution records and descriptions of a new genus and species

New distribution records for some Scolytidae occurring in the West Indies are presented. Xylebo‐rus solitariceps Schedl is transferred to Theoborus Hopkins. A new genus, Tryponophellos, and a new species, T. necopinus, are described from Cuba.     

Interactions of Hylastes species (Coleoptera: Scolytidae) with Leptographium species associated with loblolly pine decline

Hylastes spp. (Coleoptera: Scolytidae) were evaluated as potential vectors of Leptographium spp. fungi. Bark beetles were trapped from stands ofloblolly pine, Pinus taeda L., exhibiting a range of decline symptoms in central Alabama. Under controlled conditions, field-collected adult Hylastes salebrosus Eichoff (Coleoptera: Scolytidae) and Hylastes tenuis Eichoff (Coleoptera: Scolytidae), which had been surface-sterilized and inoculated with Leptographium terebrantis Barras & Perry and Leptographium serpens (Goid.) Wingfield, transmitted the fungi into 100% of wounded and unwounded loblolly root sections with which they were confined. None of the sterilized and uninoculated beetles transmitted any Leptographium spp. to roots. Significantly more H. salebrosus and H. tenuis brood emerged from roots infected with Leptographium species than from sterile roots, indicating an enhancement of Hylastes reproduction.     

Effects of habitat type and trap placement on captures of bark (Coleoptera: Scolytidae) and longhorned (Coleoptera: Cerambycidae) beetles in semiochemical-baited traps

Two studies were conducted to determine the effect of habitat selection and trap placement on catches of Scolytidae and Cerambycidae (Coleoptera) in northeastern U.S. forests. In a nonreplicated case study, four habitat types--closed canopy hardwood stand, closed canopy conifer stand, a low-intensity thinned Pinus strobus L. stand, and a high-intensity thinned P. strobus stand--were surveyed using alpha-pinene, ethanol, ipsenol, ipsdienol, and lanierone. Average trap catches, species richness, and the number of unique species captured were all highest in at least one of the thinned habitats. A second experiment that was replicated evaluated the placement of traps in relation to habitat patches. Semiochemical-baited traps (alpha-pinene and ethanol) were placed under a closed canopy forest, along an edge, and in a clearing and tested for effects on Scolytidae and Cerambycidae trap catches. Abundance and species richness were generally higher in the closed canopy and edge placements compared with traps in the open area. The highest number of unique species were captured in the edge and clearing.     

脐腹小蠹形态特征和生物学特性

脐腹小蠹Scolytus schevyrewi Seme.是榆树的一种重要蛀干害虫。本研究在宁夏盐池县通过室内观察和林间调查相结合,研究了脐腹小蠹的形态特征及其生活史、成虫寿命、习性、交尾行为等生物学特性。结果显示:脐腹小蠹虫在宁夏盐池县一年发生2代,以老熟幼虫或蛹越冬,老熟幼虫约占98.2%,蛹约占1.8%。越冬幼虫于5月上旬开始化蛹,5月中旬为化蛹盛期,5月下旬开始羽化,6月上旬为羽化盛期。第2代幼虫于6月底、7月初开始化蛹,7月下旬达羽化盛期,8月上旬羽化结束;脐腹小蠹雌成虫平均寿命为(27.14±3.74)d,雄成虫的平均寿命为(16.86±4.13)d,差异显著(P<0.05);此外,脐腹小蠹无滞育现象;脐腹小蠹的4种天敌,分别是榆小蠹长茧蜂Elachistocontrum sp.、虱形螨Pedieuloids ventricosus Newport、拟截斑郭公虫Thansimus sp.和蠼螋Labidura sp.。     

Effects of chronic gamma radiation on populations of Ips (Coleoptera: Scolytidae) in trap logs

Abstract. 1. Population dynamics of Ips calligraphus and I. grandicollis (Coleoptera: Scolytidae) were studied in a forest exposed to high doses of gamma radiation.
2. Populations were replicated at eleven dose rates by using 'trap logs'.
3. Adult beetles did not avoid high radiation intensities and attacked all sites equally.
4. Utilization of the cambium-inner bark area varied from c. 2% at a dose rate of 2520 R/20 h day to 90% at dose rates of 63 and 105 R/20 h day.
5. Developmental success of the new brood was directly dependent on the dose rate, and developing progeny were often killed by accumulated exposure.
6. Larger, slower developing species of subcortical beetles were eliminated at dose levels that allowed successful development of the two species of Ips bark beetles.     

Descriptive biogeography of Tomicus (Coleoptera: Scolytidae) species in Spain

Aim, location Tomicus (Coleoptera, Scolytidae) species are some of the principal pests of Eurasian forest and are represented by three coexisting species in Spain, Tomicus piniperda (Linnaeus, 1758), Tomicus destruens (Wollaston, 1865) and Tomicus minor (Harting, 1834). The distribution of two taxa are unknown as they have until recently been considered separate species. Therefore, we model the potential distribution centres and establish the potential distribution limits of Tomicus species in Iberia. We also assess the effectiveness of different models by comparing predicted results with observed data. These results will have application in forest pest management. Methods Molecular and morphological techniques were used to identify species from 254 specimens of 81 plots. For each plot, a Geographical Information System was used to extract a set of 14 environmental (one topographic, six climatic) and biotic variables (seven host tree distributions). General Additive Models and Ecological Niche Factor Analysis models are applied for modelling and predicting the potential distribution of the three especies of Tomicus. Results The results of both modelling methodologies are in agreement. Tomicus destruens is the predominant species in Spain, living in low and hot areas. Tomicus piniperda occurs in lower frequency and prefers wet and cold areas of north‐central Spain. We detected sympatric populations of T. destruens and T. piniperda in Northern coast of Spain, infesting mainly P. pinaster. Tomicus minor is the rarest species, and it occupies a fragmented distribution located in high and wet areas. The remarkable biotic variable is the distribution of P. sylvestris, incorporated into the models of T. destruens and T. piniperda. Main conclusions These results indicate that in wet areas of north‐central Spain where T. piniperda occurs (and possibly the high altitudes of the southern mountains), T. destruens has a climatic distribution limit. In the northern border of this area, both species overlap their distributions and some co‐occurrences were detected. Tomicus minor potentially occurs in high and wet fragmented areas.     

Ambrosia beetle (Coleoptera: Scolytidae) species, flight, and attack on living eastern cottonwood trees

In spring 2002, ambrosia beetles (Coleoptera: Scolytidae) infested an intensively managed 22-ha tree plantation on the upper coastal plain of South Carolina. Nearly 3,500 scolytids representing 28 species were captured in ethanol-baited traps from 18 June 2002 to 18 April 2004. More than 88% of total captures were exotic species. Five species [Dryoxylon onoharaensum (Murayama), Euwallacea validus (Eichhoff), Pseudopityophthorus minutissimus (Zimmermann), Xyleborus atratus Eichhoff, and Xyleborus impressus Eichhoff]) were collected in South Carolina for the first time. Of four tree species in the plantation, eastern cottonwood, Populus deltoides Bartram, was the only one attacked, with nearly 40% of the trees sustaining ambrosia beetle damage. Clone ST66 sustained more damage than clone S7C15. ST66 trees receiving fertilization were attacked more frequently than trees receiving irrigation, irrigation + fertilization, or controls, although the number of S7C15 trees attacked did not differ among treatments. The study location is near major shipping ports; our results demonstrate the necessity for intensive monitoring programs to determine the arrival, spread, ecology, and impact of exotic scolytids.     

Comparison of four trap types for ambrosia beetles (Coleoptera, Scolytidae) in Brazilian Eucalyptus stands

Eucalyptus spp. plantations represent >60% of the reforested area in Brazil. Although ambrosia beetle attacks on live trees were at first nonexistent, they have begun to appear with greater frequency. Monitoring for pest insects is a key factor in integrated pest management, and baited traps are one of the most widely used methods for insect population detection and survey. We compared the efficiency of the most widely used trap in Brazil to survey for ambrosia beetles and other Scolytidae, the ESALQ-84 type, with other traditionally employed traps: the multiple funnel (Lindgren trap); drainpipe; and slot (Theyson) traps, in a Eucalyptus grandis Hill ex Maiden stand in Brazil. The ESALQ-84 trap was the most efficient in trapping Hypothenemus eruditus Westwood and Hypothenemus obscurus (F.); the multiple funnel trap caught significantly more Cryptocarenus diadematus Eggers; whereas the slot trap caught more Premnobius cavipennis Eichhoff and Xyleborus affinis Eichhoff than the other traps. The drainpipe trap was the least effective trap overall. When corrected for number of beetles caught per trap surface area, catches were significantly higher on the ESALQ-84 trap for the majority of the species analyzed, probably because of a smaller trap surface area. The slot trap was recommended for it caught overall more beetles of the three most economically important scolytid species in eucalypt plantations in Brazil, P. cavipennis, X. affinis, and X. ferrugineus.     

The evolution of mating systems in bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae)

The extraordinary array of mating systems in the Scolytidae and Platypodidae has been largely overlooked by researchers interested in the evolution of sexual behaviour. This paper provides the first overview of reproductive behaviour in this important and widespread group, known to most biologists only by the reputations of tree-killing taxa. Referred to generally as ‘bark beetles’, these insects chew egg tunnels inside a variety of (usually dead) plant tissues, though most species are either phloeophagous (breeding in the inner bark of woody plants) or xylomycetophagous (all stages feeding on mutualistic fungi growing on sapwood or heartwood). In most species, permanent records of many aspects of reproductive behaviour are etched in the host; in many, engravings reveal female fecundity, eggs sired per male, hatching success, and offspring survivorship. Each gallery arm represents a good portion of a given female's lifetime reproduction, but in many species females commonly re-emerge to reproduce in one or two additional sites. In most species of bark beetles, each female initiates her own gallery, to be joined later by a male. These monogynous gallery systems are associated with mating systems defined by how long males stay with females: in a few species, males seldom if ever join females under the bark; in the vast majority of species, males stay for part or all of the oviposition period then leave to seek other mates; and a few groups exhibit permanent monogamy, in that both sexes die in their only gallery system. While these patterns emerge from an overview of the world scolytid fauna, the length of male residency has seldom been quantified, and the costs and benefits associated with male mating strategies have not been measured for any bark beetle. Male-initiated monogyny is uncommon in Scolytidae, though the rule in Platypodidae; all instances of which I am aware are summarized from a phylogenetic perspective. Inbreeding polygyny with highly biased sex ratios has arisen at least seven times in Scolytidae. These taxa are usually characterized by males being dwarfed, flightless, and uncommon. Sex determination is known for only a few examples, but both haplodiploidy and diplodiploidy have been reported. Multiple origins of harem polygyny (otherwise rare in invertebrates) add an exciting dimension to the comparative and experimental study of scolytid mating systems. In harem polygynous taxa, males initiate gallery construction. I summarize what little can be learned from the literature about the fine structure of harem polygynous mating systems in bark beetles, and the problem of measuring reproductive success. Data on the nature of harem polygyny in Pityophthorus lautus are presented, illustrating (a) the fluidity of harems; (b) that average eggs laid per gallery arm is relatively unaffected by harem size, but strongly influenced by resource quality; (c) that male egg-gain is strongly correlated with territory quality (a consequence of (b) above); and (d) the temporal patterning of immigration and emigration and its effects on gallery system sex ratios. The second half of this paper is a discussion of the evolution of bark and ambrosia beetle mating Mating systems, emphasizing sexual selection and the role of resources. Male, residence is interpreted as postcopulalory guarding—preventing sexual liaisons with wandering males. Operational sex ratio, encounter rate, synchrony of breeding, ejaculate competition, and spatiotemporal distribution of resources are discussed as evolutionary forces moulding scolytid and platypodid male postmating behaviour. The nature of male male competition is reviewed. The paucity of information on male behaviour in gallery systems is mentioned; whether or not males significantly aid females is not known. Three hypotheses are presented for why females re-emerge, a feature which strongly affects operational sex ratios. Finally, I summarize features of bark beetle existence predisposing them to the evolution of post-inseminative guarding. Male-initiated monogyny presents a puzzle. I propose that most uncontested examples can be explained by monogyny re-evolving from (male-initiated) harem polygyny, and I present an argument for the evolution of harem polygyny leading to the development of male gallery initiation. The evolution of harem polygyny in birds and mammals has attracted considerable attention. The Verner Willson Orians polygyny threshold model is discussed with respect to bark beetles in general and P. lautus in particular. Resource quality is a major factor in P. lautus harem dynamics: the cost to females of joining harems is apparently slight compared to benefits accrued from moving into sites with higher quality inner bark. Female-biased adult sex ratios have been suggested to lead to harem polygyny, and literature and original data pertinent to this hypothesis are examined. The geometric constraints model, based on the polygyny threshold concept but tailored to bark beetles, is proposed to account for the failure of most species to evolve harem polygyny, and testable predictions are derived that interrelate breeding systems, habitat quality, and progeny size. The evolution of Inbreeding is briefly covered, and two routes to inbreeding polygyny are suggested.     

Attack density and breeding success of bark beetles (Coleoptera, Scolytidae) at different distances from forest-clearcut edge

1 Attack density and breeding success of bark beetles (Coleoptera: Scolytidae) and the abundance of their predators were studied at forest-clearcut edges in southern Finland on Norway spruce, Picea abies, bolts placed at different distances from a forest-clearcut edge. 2 Attack densities of two species, Hylurgops palliatus and H. glabratus, increased markedly towards the forest interior. The breeding success of H. palliatus was increased with increasing distance from the stand edge. None of the recorded 10 bark beetle species was distinctly abundant near the edge, but Pityogenes chalcographus appeared to prefer this zone. 3 There were no significant differences in numbers of bark beetle predators between the forest interior and the edge. Forest-clearcut edge had a significant effect on the desiccation of sample bolts. 4 Thus, forest edge is likely to affect the colonization behaviour and breeding success of bark beetles via host material properties.     

Helicosporidium infection of the great European spruce bark beetle, Dendroctonus micans (Coleoptera: Scolytidae)

An infection of the great European spruce bark beetle Dendroctonus micans (from Turkey) by the parasitic green alga Helicosporidium is described. This is the first time that Helicosporidium has been found to infect a bark beetle (Scolytidae) and the first time that a naturally infected beetle has been reported for the Eurasian continent. The typical cysts of Helicosporidium contain three ovoid cells and one helical, filamentous cell. The morphological characteristics are revealed by light and electron microscopy. Distinct electron-dense inclusions with a peculiar ultrastructure may represent pyrenoids. Since D. micans is an important pest, the discovery of a natural pathogen may offer a chance for biological control.     

The first study on the bacterial flora of the european spruce bark beetle, Dendroctonus micans (Coleoptera: Scolytidae)

The European spruce bark beetle, Dendroctonus micans Kugelann (Coleoptera, Scolytidae), is one of the most serious pests of oriental spruce (Picea orientalis L.) in Turkey. In this study, we investigated bacterial flora of D. micans collected from different populations of the forests of Eastern Black Sea Region of Turkey from 2002 to 2004. Seven different bacteria were isolated from healthy, diseased and dead specimens based on the color of colony and morphology. According to morphological, physiological and biochemical properties, metobolic enyzme profile by BIOLOG microtiter plate system, and total cellular fatty acid profile by Microbial Identification System (MIS), isolates were identified as Micrococcus luteus, Bacillus thuringiensis subsp. morrisoni, Serratia grimesii, Enterobacter cloaceae, Enterobacter intermedius, Streptococcus sp. and Pseudomonas putida. This is the first study on the bacterial flora of D. micans.     

Tomicus piniperda (Coleoptera: Scolytidae) initial flight and shoot departure along a north-south gradient

The exotic pine shoot beetle, Tomicus piniperda (L.) (Coleoptera: Scolytidae), established in the north central and northeastern United States (U.S.) and adjacent regions in Canada, is regulated by a federal quarantine that restricts movement of pine material during specific times of the year based on the beetle's life history. Although climatic variation occurs across T. piniperda's range, a single set of dates is used for timing the movement of pine logs. We monitored T. piniperda spring flight, fall shoot departure, and air and internal tree temperatures at three sites along a 300-km north-south gradient in Michigan and Indiana. We also estimated dates for initial spring flight (12 degrees C threshold) and fall shoot departure (0 degrees C threshold) across an 850-km gradient using historical temperature records (1901 to 1999). Average daily temperatures in fall 1997 (8 October to 12 December) and spring 1998 (20 February to 21 April) were 1.8 to 2.4 degrees C colder, respectively, at the northern field site than at the southern field site. Fall shoot departure began at approximately the same time (day 289 to 290) at all three field sites, but complete shoot departure was extended by 3 wk at the southern site (day 336) compared with the northern site (day 317). T. piniperda adults were first captured in funnel traps on calendar day 86 at the northern site and on day 59 at the central and southern field sites. Peak flight occurred at approximately the same time (day 86) at all three sites. Within-shoot temperatures were very similar to air temperatures in the fall and aboveground inside-bark temperatures were similar to air temperatures in the spring. Average predicted dates based on historical temperature records varied by 31 d for initial shoot departure and 84 d for initial spring flight between northern Michigan and southern Indiana. Because considerable variation can occur in T. piniperda behavior across a broad geographic range, dates specified in the U.S. Federal quarantine should be adjusted according to local temperatures.     

Primary attraction and kairomonal host discrimination in three species of Dendroctonus (Coleoptera: Scolytidae)

Abstract 1 Synthetic blends of bole and foliage volatiles of four sympatric species of conifers were released from pheromone‐baited multiple‐funnel traps to determine if three species of tree‐killing bark beetles (Coleoptera: Scolytidae): (i) exhibited primary attraction to volatiles of their hosts and (ii) discriminated among volatiles of four sympatric species of host and nonhost conifers. 2 Bole and foliage volatiles from Douglas‐fir, Pseudotsuga menziesii (Mirb.) Franco, increased the attraction of coastal and interior Douglas‐fir beetles, Dendroctonus pseudotsugae Hopkins, to pheromone‐baited traps. Primary attraction to bole volatiles was observed in interior D. pseudotsugae. Beetles were significantly less attracted to the pheromone bait when it was combined with volatiles of lodgepole pine, Pinus contorta var. latifolia Engelm. or interior fir, Abies lasiocarpa × bifolia. 3 The monoterpene myrcene synergized attraction of mountain pine beetles, Dendroctonus ponderosae Hopkins, to their aggregation pheromones, but there was no evidence of primary attraction to host volatiles or discrimination among volatiles from the four conifers. 4 There was significant primary attraction of the spruce beetle, Dendroctonus rufipennis Kirby, to bole and foliage volatiles of interior spruce, Picea engelmannii × glauca, but beetles did not discriminate among volatiles of four sympatric conifers when they were combined with pheromone baits. 5 Our results indicate that host volatiles act as kairomones to aid pioneer Douglas‐fir beetles and spruce beetles in host location by primary attraction, and that their role as synergists to aggregation pheromones is significant. For the mountain pine beetle, we conclude that random landing and close range acceptance or rejection of potential hosts would occur in the absence of aggregation pheromones emanating from a tree under attack.     

Tree killing by Ips typographus (Coleoptera: Scolytidae) at stand edges with and without colonized felled spruce trees

Abstract 1 To maintain biodiversity in managed spruce forests in Sweden more wind‐felled trees must be retained. 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 To simulate wind‐felled trees, living spruce trees were cut at spruce stand edges bordering fresh clear‐cuttings. Treatments comprised edges with zero, one or five cut trees colonized by I. typographus. Edges with naturally wind‐felled trees colonized by I. typographus were also included in the analyses. 3 During the two following summers, the number of trees killed by I. typographus did not differ between edges with and without felled trees, or between edges with one or five felled trees. 4 Within edges with felled trees, there were more killed trees close to the felled trees than at other parts of the edges. Thus, felled trees provided focal points for attacks within edges. 5 It is concluded that small numbers of wind‐felled trees colonized by I. typographus may be left near spruce stand edges without increasing the risk of beetle‐induced tree mortality.     

Alternative Hosts for Bethylid Parasitoids of the Coffee Berry Borer, Hypothenemus hampei (Coleoptera: Scolytidae)

Three species of bethylid wasps, Prorops nasuta Waterston, Cephalonomia stephanoderis Betrem, and C. hyalinipennis Ashmead, attack the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae), by both predation and parasitism. C. hyalinipennis has only recently been reported to attack H. hampei. Its previously recorded hosts belong to the coleopteran families Curculionidae, Anobiidae, and Scolytidae. We evaluated five further coleopteran species, in the families Curculionidae, Bostrichidae, and Bruchidae, as alternative hosts. High proportions of all five species were both fed upon and oviposited on (normally by concurrent host feeding). Offspring developmental mortality varied greatly (12–95%) on different host species. Offspring production per host was about three times greater than on H. hampei when females were presented with the curculionids Caulophilus oryzae (Gyllenhal) and two species of Sitophilus. C. stephanoderis and P. nasuta are currently the main biological control agents of H. hampei: they have long been thought to be monophagous but C. stephanoderis has recently been reported to attack H. obscurus. We evaluated C. oryzae, as a potential host or prey for P. nasuta, and both C. oryzae and Sitophilus sp. for C. stephanoderis. Host feeding was very common in both parasitoid species. The majority of females also oviposited on C. oryzae (71% P. nasuta, 60% C. stephanoderis) and 20% of C. stephanoderis parasitized Sitophilus sp. Fifty-two percent of C. stephanoderis and 7% of P. nasuta offspring survived to adulthood when developing on C. oryzae. The lifetime fecundities of these parasitoids presented with these host species were, however, low (maximum 17 eggs, mean ≤ 8.25) and preoviposition periods were generally long (ca. 19 days). Adult female C. stephanoderis lived longer when presented C. oryzae rather than Sitophilus sp. Host feeding also increased longevity. We discuss these results in the context of mass rearing these bethylids for release as biological control agents.     

Behavior and Activity Pattern of Cephalonomia stephanoderis (Hymenoptera: Bethylidae) Attacking the Coffee Berry Borer,Hypothenemus hampei (Coleoptera: Scolytidae)

We describe behavioral sequences and daily activities of pre-ovipositing and ovipositing females of Cephalonomia stephanoderis (Hymenoptera: Bethylidae), an ectoparasitoid of the coffee berry borer, Hypothenemus hampei (Coleoptera: Scolytidae). Noticeable behavioral differences among preovipositing and ovipositing females include host examination, host stinging—probing, host feeding, and the oviposition per se. The female of C. stephanoderis feeds primarily on host eggs, but pupae are also exploited, mainly by pre-ovipositing females. After the onset of the oviposition period, C. stephanoderis examines the pupae repeatedly, stings them at frequent intervals, and spends more time feeding than during the pre-oviposition period. Host paralysis is linked both to host feeding and oviposition. It induces irreversible developmental arrest, which presumably allows preservation of the host until subsequent utilization, and contributes to successful offspring development, particularly by reducing host motility. Oviposition consists in a host selection process, a prolonged period of preparation of the potential host, and the egg-laying phase itself. Under our experimental conditions, pre-ovipositing and ovipositing females are active 17% and 36% of the day, respectively. Host handling time averages 6% and 23% in pre-ovipositing and ovipositing females, respectively. All coffee berry borer developmental stages are exploited by C. stephanoderis females, either for host feeding and/or oviposition activities. Such flexible behavior is advantageous given that host availability is limited inside the coffee berries.     

Interactions among bethylid parasitoid species attacking the coffee berry borer,Hypothenemus hampei (Coleoptera: Scolytidae)

The question of whether biological control is most likely achieved by deploying single or multiple species of biological control agents is much debated. While utilizing several natural enemies may enhance control, there is also the potential for disruptive inter-specific interactions. Such interactions may be studied in the laboratory by focusing on the details of the interactions themselves and attempting to infer population level consequences from their sum, or by focusing more directly on the overall effects on natural enemy populations: we term these approaches ‘reductionist’ and ‘holistic.’ Here we conduct a holistic laboratory study on interactions between three species of parasitoid wasps that are parasitoids of the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae): Cephalonomia stephanoderis Betrem, C. hyalinipennis Ashmead and Prorops nasuta Waterston (all Hymenoptera: Bethylidae). We find evidence for both intra- and inter-specific resource competition. Interactions between C. stephanoderis and P. nasuta, both indigenous to Africa, appear to be approximately symmetrical, while C. hyalinipennis, naturally found in the coffee plantations of Chiapas, Mexico, may exert a disruptive influence. C. hyalinipennis also has a low population growth rate. We now consider it to be a detrimental invader of the Mexican coffee agro-ecosystem that should not be encouraged by augmentative release or introduced into other regions. Overall, the most successful species, in terms of both emergence and female production, was P. nasuta. We compare these results with those from prior reductionist and holistic studies, and with observations on patterns of establishment of these bethylid species in the field. Given that it is increasingly clear that disruptive inter-specific interactions are generally common when multiple species are deployed in biological control, screening of potential agents should consider such interactions alongside the more ‘traditional’ focus on host specificity.     

红脂大小蠹后肠挥发性物质的鉴定、触角电位和室内趋向实验

对外来松树害虫红脂大小蠹Dendroctonus valens LeConte的信息化学物质进行了研究。通过GC-MS测定,鉴定出红脂大小蠹后肠挥发性物质中除了含有松树挥发性物质α-蒎烯、β-蒎烯、3-蒈烯、月桂烯和柠檬烯外,还含有马鞭草烯醇和马鞭草烯酮;利用触角电位技术,对马鞭草烯醇、马鞭草烯酮以及在林间引诱效果最好的3-(+)-蒈烯进行了触角电生理测试;利用Y-型双向选择嗅觉仪对这些物质进行了室内趋向实验。实验结果表明: 1 μg的马鞭草烯醇、马鞭草烯酮和3-(+）-蒈烯引起雌雄触角的电位反应分别达416 μV/470 μV、597 μV/630 μV和926 μV/1 099 μV。浓度为1 μL/mL的马鞭草烯酮引起红脂大小蠹的正趋向反应,而在100 μL/mL浓度下引起红脂大小蠹的负趋向反应;在1 μL/mL的浓度下,3-(+ )-蒈烯引起了红脂大小蠹正趋向反应,而马鞭草烯醇则对红脂大小蠹具有驱避作用,说明这些物质在红脂大小蠹搜寻寄主和调节虫口密度方面起着重要作用。     

Neoparasitylenchus amvlocercus sp. n. (Tylenchida: Nematodea) from Conophthorus monophyllae (Scolytidae: Coleoptera) in California with a synopsis of the nematode genera found in bark beetles

Neoparasitylenchus amvlocercus sp. n. (Tylenchida: Nematodea) is described as a parasite of the singleleaf pinyon cone beetle, Conophthorus monophyllae (Scolytidae: Coleoptera) in California. In a sample of 21 beetles randomly selected from cones of Pinus monophylla, 62% were parasitized by N. amvlocercus. Heavily infected beetles showed a reduction in fat body, ovaries, and longevity. They were poorly coordinated, flew less, and showed a weaker flight than that of nonparasitized beetles. A summary of the effects of allantonematid nematodes on bark beetles is included and a synopsis of the nematodes occurring inside bark beetles is given, including a key to the genera of Allantonematidae parasitizing scolytids.