红脂大小蠹Dendroctonus valens(Coleoptera,Scolytidae)和大唼蜡甲 Rhizophagus grandis(Coleoptera,Rhizophagidae)的耐寒性

红脂大小蠹 Dendroctonus valens LeConte (Red turpentine beetle,RTB)是近年来在中国爆发的入侵生物,在我国主要以老熟幼虫在油松伐桩和立木的根部越冬.室内测定昆虫的过冷却点(SCP)和短时间致死低温(LLT)是评价昆虫耐寒能力的重要方法.实验结果显示,红脂大小蠹越冬幼虫的平均过冷却点为一11.98±2.55℃,是一种耐冰冻的昆虫.红脂大小蠹的过冷却点在不同地理分布区的种群问有明显差异,老熟幼虫的过冷却点明显低于低龄幼虫,在越冬前和越冬后的幼虫问没有明显差异.红脂大小蠹幼虫在冬季至少町以忍受-23.5℃的大气温度安全越冬.从2001年开始引入我国的云杉大小蠹的捕食者大唼蜡甲(Rhizophagus grandis cyll.)幼虫的过冷却点为-18.05±2.76℃,低于红脂大小蠹所有虫态的过冷却点,说明比红脂大小蠹有更强的耐寒能力.     

Cost-effectiveness analysis of options within an Integrated Crop Management regime against great spruce bark beetle, Dendroctonus micans, Kug. (Coleoptera: Scolytidae)

1 Great spruce bark beetle Dendroctonus micans (Kug.) (Coleoptera: Scolytidae) has been subject to an Integrated Crop Management (ICM) regime in Great Britain since its first discovery in 1982. The elements of the ICM approach are sanitation felling of the initial infestations, restriction on movement of potentially infested conifers to prevent spread to uninfested parts of the country and biological control through rearing and release of the specific predatory beetle Rhizophagus grandis Gyll. (Coleoptera: Rhizophagidae). Such a programme carries costs that have to be evaluated against the benefits to the ICM strategy. 2 This paper presents a cost-effectiveness analysis of three options – (i) continue with the current policy of restriction on movement of infested timber and use of the imported predator R. grandis, (ii) do nothing (i.e. drop all attempts to reduce the spread of D. micans), or, (iii) introduce a new east–west Dendroctonus Micans Control Area (DMCA) to define the management area. Assumptions on rates of mortality and natural spread were based on research into D. micans in Britain’s spruce forests. 3 Appraisal indicated that the current policy was the most cost-effective, even when subject to sensitivity analysis to test the limits of the assumptions included in the models. It is concluded that the current policy should remain in force.     

An electroantennogram apparatus for testing the activity of semiochemicals on the olive beetle, Phloeotribus scarabaeoides (Coleoptera: Scolytidae): first recordings of the response to ethylene

Abstract. An electroantennogram (EAG) apparatus for testing the activity of pheromones of the olive beetle, Phloeotribus scarabaeoides , is described. This inexpensive device is suitable for whole antennal recording from scolytids. The modification of the amplifier and sample injection system, described previously, eliminate parasitic noise and improve the recording of the EAG signal.
Results from previous studies revealed significant beetle attraction to a source releasing ethylene. Serial solutions of 2-chloro-ethyl phosphonic acid were tested, and 10% acetic acid served as a standard.
A significant variation in amplitude of depolarization was found among the different concentrations of 2-chloro-ethyl phosphonic acid tested. Maximum depolarization was elicited at a concentration of 0.1% in both males and females. In general, no statistical differences in responses were found between males and females, but females showed a significantly lower threshold of response.     

Isolation and virulence of entomopathogenic fungi against the great spruce bark beetle,Dendroctonus micans (Kugelann) (Coleoptera: Scolytidae)

Twelve fungal strains including Lecanicillium muscarium (Petch.) Zare and Gams, Isaria farinosa (Holmsk.) Fr., Fusarium sp., Beauveria bassiana Sensu Lato and Beauveria sp. were isolated from larvae and adults of D. micans. In addition, virulence of these isolates against this pest was determined. Conidia suspensions of 1×10⁶ conidia mL^–1 were applied to larvae and adults. The highest mortality and mycosis for larvae were obtained from isolate ARSEF 9271 (Beauveria bassiana) with 90% mortality and mycosis within 10 days. ARSEF 9271 also produced 93% mortality and mycosis in adults. On the other hand, the highest mortality and mycosis for adults were obtained with isolate ARSEF 9272 (Beauveria sp.), with 100% mortality and 80% mycosis within 10 days. These results indicate that isolates ARSEF 9271 and ARSEF 9272 seem to be the most promising potential fungal biocontrol agents against D. micans.     

Flight muscle changes in male pine engraver beetles during reproduction: the effects of body size, mating status and breeding failure

Abstract. In a pattern that is typical for bark beetles, the lateralis medius flight muscle of male pine engravers, Ips pini Say (Coleoptera: Scolytidae), was found to decrease four-fold in volume (from mean ± SE = 1.36 ± 0.06 × 10^?2 mm³ to 0.34 ± 0.06 × 10^?2 mm³) within five days of the initiation of breeding galleries, and then to regenerate gradually to functional capacity during subsequent weeks. Although there was considerable variation in the timing and extent of flight muscle regeneration in males, this variation was not a consequence of differences between small (length < 4.0 mm) and large (length ≥ 4.0 mm) males. Two subsequent experiments revealed that male pine engravers can control the timing of flight muscle regeneration. In the first experiment, the flight muscles of males that were denied mates degenerated within 5 days of gallery initiation, but then showed complete regeneration 5 days later. In the second experiment, mated males that were removed from their breeding galleries (to simulate breeding failure) also showed extensive muscle degeneration 5 days after gallery initiation, but then regenerated their flight muscles to functional capacity by the tenth day. The ability of males to regenerate their flight muscles in response to conditions at the gallery is probably adaptive because it allows them to fly in search of new breeding opportunities when they are unable to attract mates or when breeding attempts fail.     

Orientation of flying male Anobium punctatum (Coleoptera: Anobiidae) to sex pheromone: separating effects of visual stimuli and physical barriers to wind

Abstract. Flying male woodworm, Anobium punctatum , are able to locate a source of female pheromone offered as a point source but land more quickly if the same odour source is presented on a model 'tree' (cylinder). We tested the response to a two-dimensional black 'tree' marked as a silhouette on the upwind screen of the wind tunnel, with or without a hidden upwind barrier to the wind. The beetles responded equally to pheromone presented on a visual silhouette with wind barrier and to the hidden upwind wind-barrier alone, suggesting that the wind-barrier itself has a significant effect on insect orientation and landing: visual stimuli do not add to the landing response if the barrier is present. However, without the barrier upwind, landing was faster when the visual stimulus was present than without. This is the third forest-living species to be shown to respond in this way, which suggests this phenomenon may be more widespread. The possibility that this phenomenon is present in other, non-forest, phytophagous insects, their predators and parasitoids is discussed.     

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.     

Influence of insecticide, wax and biofungicide treatments, applied to Pinus sylvestris and Picea abies, on the olfactory orientation of the large pine weevil, Hylobius abietis L. (Coleoptera: Curculionidae)

1 A four-arm olfactometer was used to test the effect of permethrin ‘Gori 920^®’ and the wax treatment ‘CereNat^® E30’ on the response of mature adult Hylobius abietis to olfactory stimuli from seedlings of Pinus sylvestris and Picea abies. 2 Also investigated in the olfactometer was the effect of Rotstop^®, a biofungicide for the control of Fomes root and butt rot, Heterobasidion annosum, on the responses of mature adult female H. abietis to stump material of both P. sylvestris and P. abies. 3 Hylobius abietis was significantly more attracted to untreated P. sylvestris seedlings compared to those treated with CereNat^® E30 or permethrin Gori 920^®. No differences in response to P. abies seedlings were found. 4 With Rotstop^®, no changes in the attractiveness of P. sylvestris stump material were found, but that of P. abies was significantly increased compared to untreated material.     

Lethal and sub-lethal selectivity of fenbutatin oxide and sulfur to the predator <Emphasis Type="Italic">Iphiseiodes zuluagai</Emphasis> (Acari: Phytoseiidae) and its prey, <Emphasis Type="Italic">Oligonychus ilicis</Emphasis> (Acari: Tetranychidae), in Brazilian coffee plantations

Lethal concentration (LC) has been widely used to estimate pesticide toxicity. However, it does not consider the sub-lethal effects. Therefore we included the instantaneous rate of increase in association with LC to estimate population-level effects of the acaricides fenbutatin oxide and sulfur on the predator Iphiseiodes zuluagai and its prey, the phytophagous southern red mite, Oligonychus ilicis. The predator was 32.84x and 17.20x more tolerant to fenbutatin oxide and sulfur, respectively, than its prey, based on LC₅₀ estimates obtained from acute concentration–mortality bioassays. The instantaneous rate of population growth in both mite species decreased with increasing acaricide concentration. Both acaricides provided effective control of O. ilicis at their recommended concentrations, but sulfur drastically compromised the predator populations quickly leading them to extinction due to the low reproductive potential of this species compared with its prey.