cis-Jasmone treatment induces resistance in wheat plants against the grain aphid,Sitobion avenae (Fabricius) (Homoptera: Aphididae)

cis-Jasmone is a plant volatile known to have roles as an insect semiochemical and in inducing plant defence. It was evaluated in laboratory and field trials for control of cereal aphids. In an olfactometer bioassay cis-jasmone was repellent to alatae of the grain aphid, Sitobion avenae (Fabricius) (Homoptera: Aphididae). Moreover, wheat, Triticum aestivum (L), seedlings sprayed with formulated cis-jasmone 24 h previously were less susceptible to attack by S. avenae than control plants. In field simulator studies, significantly fewer alate S. avenae settled on cis-jasmone-treated plants over a 24-h period. In addition, the intrinsic rate of population increase, r(m), of S. avenae apterae was reduced on cis-jasmone treated seedlings. In a series of small-plot experiments conducted over four years, cis-jasmone applications reduced cereal aphid populations infesting wheat in the field.     

Semiochemical strategies for sea louse control: host location cues

The development of behavioural bioassays and electrophysiological recording techniques has enabled the role of semiochemicals to be investigated for the first time in Lepeophtheirus salmonis (Kr?yer). Adult male sea lice L salmonis were activated by, and attracted to, salmon-conditioned water (SCW) and SCW extract. Non-host fish odours, turbot-conditioned water (TCW) and turbot-conditioned water extract (TCW extract), elicited activation but no attraction in the lice. Solid-phase extraction techniques were developed to extract low molecular weight components of fish odours, and biological activity was shown to be confined to these. Electrophysiological activity from aesthetascs in the first antennae was found and neural responses to odours were recorded from the antennal nerves. Preliminary experiments on individual chemicals (isophorone, 1-octen-3-ol) linked to salmon revealed behavioural activation and electrophysiological responses in adult male L salmonis. Isophorone was shown to be significantly attractive to sea lice when placed in a slow-release system in a perfused tank of seawater in a choice situation. Proof of concept has been established for successfully extracting odour cues from seawater, analysing their biological activity and applying these to slow-release technologies for field trapping of lice. Future work involving linked GC-MS techniques using behaviour, electrophysiological responses, and organolepsis will establish further host location cues specific to Atlantic salmon.     

Improved filter system for an equine artificial vagina

A polyester filter to separate the gel from the gel-free portion of the ejaculum is part of many equine artificial vaginas. The filter itself retains many spermatozoa. Therefore, filters fabricated from nylon, micromesh cloth with pore sizes of 30 or 37 m were evaluated together with a conventional polyester filter. Five ejaculates were collected from each of six stallions using each filter. Both nylon filters were effective in retaining gel. More spermatozoa were retained in the polyester filter than in the 30- or 37-m nylon filters (2.5, 0.5 and 0.6 × 10⁹ sperm; P less than 0.05). Because of the absorption of fluid and retention of spermatozoa by the polyester filter, with samples devoid of gel the polyester filter retained a number of spermatozoa about equal to the number recovered in the semen. Use of a nylon filter allowed recovery of more spermatozoa in the semen for ejaculates without gel and caused no greater loss of spermatozoa from samples with gel. We recommend that a 37 μm nylon filter be used rather than a polyester filter.     

Interaction of bluetongue virus with preimplantation embryos from mice and cattle

Preimplantation embryos from mice and cattle were exposed to bluetongue virus in vitro to determine whether the virus would replicate in these early embryos and, if so, what pathologic consequences would ensue. A high proportion of zona pellucida-free, 2-cell embryos and morulae from mice, and morulae from cattle became infected. The infection was rapidly cytopathic in embryos from both species. Indirect immunofluorescence was used to demonstrate accumulation of virus antigen in the blastomeres of these embryos. The zona pellucida of both murine and bovine embryos provided effective protection from virus present in culture fluid.     

Evaluation of aqueous tear production in dogs following general anesthesia

Pre- and postanesthetic Schirmer tear test (STT) values were measured in 46 dogs. All subjects had normal preanesthetic STT values (18.3 +/- 2.8 mm per min in the left eye [OS] and 18.3 +/- 3.0 mm per min in the right eye [OD]). Significant differences were found between pre- and postanesthetic STT values. Significant decreases in tear production were evident for up to 24 hours following the anesthetic event. Subject age did not significantly influence the results. Duration of anesthesia significantly affected the rate of return to preanesthetic STT values, with anesthetic events greater than two hours in duration having a prolonged effect as compared to anesthetic events less than two hours in duration. Anticholinergic administration prior to or during anesthesia further lowered postanesthetic STT values.     

Effect of topical 1% atropine sulfate on intraocular pressure in normal horses

OBJECTIVE: To determine the effect of topical 1% ophthalmic atropine sulfate on intraocular pressure (IOP) in ocular normotensive horses. Animals Studied Eleven clinically healthy horses. Procedures IOP was measured bilaterally twice daily, at 8 AM and 4 PM, for 5 days. No medication was applied for the first 2 days of the study. Thereafter, one eye of each horse was treated with 0.1 mL of topical 1% atropine sulfate ointment twice daily (7 AM and 7 PM) for 3 days. The contralateral eye served as a control. In eight of the horses, an additional IOP reading was taken 3 days following cessation of the atropine treatment. RESULTS: There was no significant difference in the IOP of control vs. treatment eyes in the pretreatment period, days 1 and 2 (P = 0.97 and 0.55, respectively). During the treatment period, treated eyes of 10 of the horses had significantly lower IOP than control eyes (P = 0.03). The mean IOP reduction in treated eyes, relative to untreated eyes, was 11.2%. One horse had a significant rise in IOP in the treated eye compared to the remaining study animals. The IOP of control eyes did not vary significantly over the observation period (P = 0.27). There was no significant variation in IOP between the 8 AM and 4 PM measurement (P = 0.9). CONCLUSIONS: Topical 1% atropine sulfate causes a small, but significant decline in IOP in most ocular normotensive horses. Because topical atropine may elevate IOP in some horses, it should be used with caution in the treatment of glaucoma in this species.     

屏边杉木林基地县速生丰产育林技术探讨

屏边是我省杉木生产基地之一，其速生丰产技术的研究，对我省用材林的生产发展有着重要意义。本文根据林分密度效应规律，经过统计分析，优化计算，编制该县人工杉木密度管理图，立地指数图表，并对林分适宜密度变化规律及抚育间伐技术等营林措施进行了讨论，精度符合要求，可用于生产。     

Non-target effects of the ‘push–pull’ habitat management strategy: Parasitoid activity and soil fauna abundance

We assessed the non-target effects of a habitat management system (‘push–pull’) on maize stemborer specialist natural enemy activity and soil Collembola. Two study sites in western Kenya were sampled. There were two treatments at each site, maize monocrop and ‘push–pull’. The latter comprised an intercrop of maize and Desmodium, Desmodium uncinatum Jacq., with Napier grass, Pennisetum purpureum (Schumach), as a trap crop planted around the edge of the plot (spaced 1 m from main crop). Trichogramma spp. were recovered from stemborer eggs while Cotesia sesamiae and Cotesia flavipes were recovered from stemborer larvae, and Dentichasmias busseolae from pupae. Mean number of eggs parasitized was significantly higher in the maize monocrop than in the ‘push–pull’ plots however proportions parasitized did not differ between the two systems. The number of larvae and pupae parasitized and dead from causes other than parasitism similarly did not differ between cropping systems. Proportions of larvae and pupae parasitized were significantly higher in the ‘push–pull’ than in the monocrop plots, indicating that the activity of larval and pupal parasitoids was enhanced. C. sesamiae female wasps were attracted to the volatiles from Desmodium flowers but not those from the leaves in a four-arm olfactometer bioassay. A total of 1530 individual Collembola in seven families were recovered from the plots. The ‘push-pull’ strategy did not have any significant effect on Collembola abundance and dominance. The factors underlying these observations and their implications are discussed.     

Low-temperature synthesis of zintl compounds with a single-source molecular precursor

Thermolysis of the heterobimetallic phosphinidene complex [Sb(PCy)3]2- Li6.6HNMe2 (Cy = C6H11) at 303 to 313 kelvin gives Zintl compounds containing (Sb7)3- anions. The complex thus constitutes a stable molecular single-source precursor to Zintl compounds and provides a potential low-temperature route to photoactive alkali metal antimonates. The new chemical reaction involved, which is driven thermodynamically by the formation of P-P bonds, has implications in the low-temperature synthesis of other technologically important materials (such as gallium arsenide).