Behavior and survival ofReticulitermes hesperus banks (Isoptera: Rhinotermitidae) on selected sawdusts and wood extracts

Survival ofReticulitermes hesperus workers was assessed inPseudotsuga menziesii, Lysiloma seemanii, andTabebuia ochracea sawdusts; and on heartwood solvent extracts ofP. menziesii, L. seemanii, T. ochracea, Pinus ponderosa, Tabebuia guayacan, and aCentrolobium species. Survival inP. menziesii sawdust was 100% at 5 days and 81–87% at 15 days. Survival inL. seemanii andT. ochracea sawdusts was significantly less over both 5 and 15 days than in the starvation control, indicating toxicity. Survival on filter papers treated with solvent extracts ofT. ochracea andP. ponderosa was significantly less than that on control papers, but onlyP. ponderosa differed significantly from the starvation control. In behavioral assays with groups and with individualR. hesperus workers, extracts ofP. menziesii andP. ponderosa were preferred. In the individual behavioral assays, extracts ofT. guayacan andT. ochracea were repellent. Results of toxicity assays were not predictable from preference assays.     

Antennnal olfactory and behavioral response of southern pine beetle,Dendroctonus frontalis,to analogs of its aggregation pheromone frontalin

Antennal olfactory (electroantennogram) and laboratory and field behavioral tests were carried out on the response ofDendroctonus frontalis to its aggregation pheromone frontalin and analogs. The analogs were compounds modified by altering the position and methyl groups and/or by their deletion. Any modification to the frontalin structure significantly reduced both the antennal olfactory and behavioral response byD. frontalis. Beetle response, although significantly reduced, was elicited at the receptor level and in a laboratory bioassay by all analogs. However, only one analog (endo-5,7-dimethyl-Frontalin) elicited significant response from field populations of the beetle.Texas Agricultural Experiment Station paper TA-22507. The work was funded in part by McIntire-Stennis project 1525 and by an operating grant from the Alberta Forest Service through the Forest Development Research Trust Fund. The findings, opinions, and recommendations expressed are those of the authors and not necessarily those of the U.S. Department of Agriculture. All programs and information of the Texas Agricultural Experiment Station are available without regard to race, ethnic origin, religion, sex, or age.     

Arrestment of male twospotted spider mite caused by female sex pheromone

A glass slide bioassay was used to evaluate male twospotted spider mite,Tetranychus urticae Koch, arrestment caused by quiescent deutonymph extract. Males that were guarding quiescent deutonymphs prior to being tested were arrested by a 3-mm-diameter circle of quiescent deutonymph extract; nonguarding males and adult females were not arrested. Extracts of allT. urticae instars tested caused male arrestment, but mean arrestment duration was longest with quiescent deutonymph extract. Arrestment by volatile perception of pheromone and upwind orientation to point sources of extract were not observed. The mono- and sesquiterpene alcohols previously identified as components of the pheromone did not arrest males. HPLC separation of extract resulted in four active fractions; a subtractive bioassay showed that three were essential to elicit maximum male response.     

A system of defined (Sensu stricto) media for daphnid (Cladocera) culture

MS is a set of defined media. It is comprised of inorganics, plus crystalline vitamin B₁₂ and, usually, a glycylglycine buffer, which are dissolved in distilled-deionized water. Algal and animal media differ only in that algal media contain more phosphate, nitrate and silicate. MS supports the culture of a variety of daphnids. In particular long term (50 + generations), healthy (300 + progeny per mother in 15 + regularly-spaced broods), cultures of Daphnia pulex (de Geer) and D. magna (Straus) have been maintained. Undefined organics (fish chow, yeast, liver extracts, complex vitamin or protein mixtures) and the uncertain array of inorganic contaminants which they carry are avoided by controlling two trophic levels. Because it can be precisely reproduced in any reasonably equipped laboratory, MS holds promise as a basis for genuinely repeatable daphnid chronic bioassay yielding reproducible results.     

Computer tracking as a behavioral GC detector: Nematode responses to vapor of host roots

A computer tracking system previously developed for studying the behavioral responses of nematodes to volatile stimuli was modified so that the effluent of a gas chromatograph passed over the nematodes while their behavior was analyzed. Since the behavior of several hundred nematodes can be analyzed simultaneously, this technique has the potential to provide a sensitive assay for behaviorally active fractions from the GC. This potential was tested with infective juveniles of the root-knot nematodeMeloidogyne incognita and vapor from the roots of host tomato plants. Direct injection of 1 ml of vapor led to reproducible responses at times corresponding to nitrogen plus oxygen elution and to carbon dioxide elution. Experiments with pure gases demonstrated responses to oxygen and to carbon dioxide. Attempts were made to find less volatile and less active components by pulling large volumes of vapor through a trap of Tenax GC and subsequently eluting them onto the GC. This approach did not lead to the detection of other activities. We conclude that, other than carbon dioxide, there are no volatile stimuli released from host roots in effective quantities.     

Dodecanoic Acid Is the Oviposition Pheromone ofLutzomyia longipalpis

The sandfly,Lutzomyia longipalpis (Lutz and Neiva), produces an oviposition pheromone in the accessory glands that is secreted onto the eggs during oviposition. This compound attracts and/or stimulates gravid females for egg-laying. The compound was identified as dodecanoic acid, using gas chromatography–mass spectrometry, gas chromatography, and chemical derivatizations. The synthetic analog induced the same behavioral response in gravid sandflies as the whole egg extract when present in biologically relevant quantities. When single sensillum recordings were taken from the ascoid on the antennae of female sandflies, the response to egg extract and dodecanoic acid was similar. There was a dose dependent response to dodecanoic acid and preferential sensitivity compared to other fatty acids. There was a strong additive interaction upon the behavior ofL. longipalpis when dodecanoic acid was tested in a bioassay with the known oviposition attractant apneumones from rabbit feces, hexanal, and 2-methyl-2-butanol. The results suggested that sandflies acquired hexadecanoic acid (palmitic acid) from the blood meal and over a period of four days this was converted to dodecanoic acid. The role of these token semiochemicals in sandfly oviposition is discussed with respect to additive interactions and the significance of their origin from larval food resources.     

In-vitro bioassay of electrophoretically deposited hydroxyapatite–zirconia nanocomposite coating on Ti–6Al–7Nb implant

Hydroxyapatite–zirconia (HA–ZrO₂) nanocomposite coatings were prepared on Ti–6Al–7Nb implant by electrophoretic deposition at constant voltage of 50?V. The influence of zirconia content on the phase transition, morphological evolution, wettability and in vitro cyto-compatibility, together with the bioactivity of the nanostructured coatings was examined. From the X-ray diffractometer patterns, a tangible increase and decrease in the peak intensity and width of the characteristic peaks were observed after subsequent sintering at 1000°C for 1?h under a constant flow of argon gas. The sintered HA and HA–ZrO₂ composite coatings showed higher hydrophilicity than the bare substrate. From the in vitro bioassays, surface treatment of Ti67 implant by HA–ZrO₂ nanocomposite coating increased the cell response as well as the apatite formability, in simulated body fluid within 5 days of incubation.     

烯唑醇对水稻重要病原菌的毒力测定及复配研究

烯唑醇对稻纹枯病菌、稻瘟病菌和稻曲病菌具有很强的抑制效果,EC50分别为0.033、0.085和0.147μg/ml。烯唑醇与多菌灵以0.5:10、1.0:10、1.5:10、2.0:10和2.5:10五种比例复配,除1.5:10复配剂对稻瘟病菌的抑制有一定的增效作用外,其他复配剂对稻瘟病菌和纹枯病菌的抑制大都表现为相加作用,而对稻曲病菌的抑制则多为拮抗作用。因此,就增效而言,两者复配对上述三种水稻病害的防治意义不大。     

Pheromones in white pine cone beetle,Conophthorus coniperda (schwarz) (Coleoptera: Scolytidae)

Female white pine cone beetles,Conophthorus coniperda, attacking second-year cones of eastern white pine,Pinus strobus L., produced a sex-specific pheromone that attracted conspecific males in laboratory bioassays and to field traps. Beetle response was enhanced by host monoterpenes. The female-produced compound was identified in volatiles collected on Porapak Q and in hindgut extracts as (+)-trans-pityol, (2R,5S)-(+)-2-(1-hydroxy-1-methylethyl)-5-methyltetrahydrofuran. Males and females produced and released the (E)-(-)-spiroacetal, (5S,7S)-(-)-7-methyl-1,6-dioxaspiro[4.5]decane, which was not an attractant for either sex, but acted as a repellent for males. Porapak Q-trapped volatiles from both sexes contained (+)-trans-pinocarveol and (-)-myrtenol. In addition, hindgut extracts of females containedtrans-verbenol, while males had pinocarvone and verbenone. Work in Georgia and Canada confirmed that the same isomers of pityol and spiroacetal are present in two distinct and widely separated populations ofC. coniperda.     

紫外消毒数值模拟及生物验证

为建立紫外消毒系统优化方法,基于光强分布、流场分布、当量剂量求解,开展紫外消毒的数值模拟,针对腔体式紫外消毒反应器,在80%～95%透光率和240～600 L/h流量条件下对模型进行生物验证.结果表明：该模型能够较准确地预测消毒效果,当量剂量模拟结果与实验结果在不同条件下相差3%～12%.有效剂量随处理流量的增加而降低...