Butterfly milkweed extract as a feeding deterrent of the wireworm, Melanotus communis

Crude extracts of butterfly milkweed, Asclepias tuberosa L., were tested for deterrent properties against the corn wireworm, Melanotus communis Gyll (Coleoptera:Elateridae). When offered milkweed-treated and control baits, wireworms fed almost exclusively on untreated food. In no-choice tests, there was a significantly lower frequency of damage to treated baits than control baits. Extended exposure of wireworms to the extract did not affect their survival, feeding vigor, or preference in subsequent feeding tests. Seed corn treated with crude extract exhibited slight phytotoxicity in the form of delayed germination and depressed growth rates.

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Résumé Les propriétés dissuadantes des extraits bruts d'Asclepias tuberosa L. ont été testées contre Melanotus communis Gyll. Quand on a présenté des appâts traités avec A. tuberosa et des appâts témoins, les taupins ont consommé presque exclusivement l'aliment non traité. Dans des expériences sans choix, les appâts traités étaient significativement moins attaqués que les appâts témoins. Une exposition prolongée des taupins à l'extrait n'avait pas modifié leur survie, leur appétit ou leur préférence dans des expériences alimentaires ultérieures. Des graines de maïs traitées avec des extraits bruts ont présenté une légère phytotoxicité sous la forme d'une germination retardée et d'un taux de croissance ralenti.

     

Screening of crude plant extracts as feeding deterrents of the wireworm, Melanotus communis

Extracts from 78 plant species (24 families) were screened for antifeedant activity against the corn wireworm, Melanotus communis Gyll. (Coleoptera: Elateridae). Five extracts from four families significantly reduced wireworm feeding damage in a series of choice feeding tests. Two extracts, Asclepias tuberosa and Hedera helix, exhibited exceptional levels of feeding deterrency. An x-ray technique indicated that wireworms burrowed indiscriminately between soil containing either of these extracts and surrounding untreated soil, but were found more frequently in the untreated areas.

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Résumé L'aptitude à empêcher la prise de nourriture de Melanotus communis Gyll. a été recherchée dans les extraits de 78 plantes appartenant à 24 familles. Cinq extraits de 4 familles ont réduit significativement les dégâts alimentaires lorsqu'il y avait choix alimentaire. Deux extraits — Asclepias tuberosa et Hedera helix — présentaient des niveaux exception-nellement élevés de dissuasion de l'alimentation. Une technique aux rayons X a montré que les taupins fouillaient indistinctement le sol contenant de ces extraits ou le sol avoisinant non traité, mais on les recontrait plus fréquemment dans le sol non traité.

     

TrackBeam, a simple tool for estimating potential exposure to the solar beam underneath tree canopies

A simple tool, TrackBeam, for rapid in situ estimates of potential exposure to the solar beam of objects underneath tree canopies is presented, tested and demonstrated to be useful in insect conservation studies. The tool can be used whenever accurate data on sun exposure is of use e.g., in ecological studies of saproxylic insects. TrackBeam draws upon the principles behind the analysis of hemispherical photographs but its use is much less dependent on the weather at the time of sampling. It may be used for detecting canopy openings in directions corresponding to the solar path. Based on this, periods of time with potential beam exposure and/or the proportion of sky that is not obscured by canopy for objects such as dead wood may be estimated. The results of using TrackBeam compares well between operators and with the corresponding results of analysed hemispherical photographs. Results are presented which show that TrackBeam was successfully used to characterise the habitat light requirements of the saproxylic beetle Melanotus castanipes (Coleoptera: Elateridae).     

筛胸梳爪叩甲幼虫寄主调查及其土壤空间分布

对安吉竹博园内筛胸梳爪叩甲Melanotus cribricolls(Faldermann)的寄主危害进行调查,主要调查竹种隶属于刚竹属(Phyllostachys)、矢竹属(Pseudosasa)、大明竹属(Pleioblastus)、唐竹属(Sinobambusa)、短穗竹属(Brachystachyum)、少穗竹属(Oligostachyum)和箣竹属(Bambusa),共7个属,包括47个竹种,其中41种寄主都不同程度地受到筛胸梳爪叩甲幼虫期的危害,新发现受害寄主30余种。据筛胸梳爪叩甲幼虫在5个竹种林区间的空间分布表明:筛胸梳爪叩甲较大体型的幼虫在竹林土壤中主要为聚集分布。调查过程发现,除筛胸梳爪叩甲幼虫对竹种的危害以外,竹笋夜蛾Apamea spp.也是导致退笋的主要虫害之一,二者一并成为目前竹博园内竹笋退笋的主要害虫。此外,园内竹种也受到浙江栉蝠蛾Bipectilus zhejiangensi、叶甲、白蚁和腐生蝇的侵害。鉴于筛胸梳爪叩甲幼虫危害的竹种范围比以往报道的有扩大的趋势,在竹种移植、土壤改良及敏感品种的选育应考虑到这些方面。     

Estimation of dispersal distance by mark-recapture experiments using traps: correction of bias caused by the artificial removal by traps

Although in mark-recapture experiments traps are useful to estimate the dispersal distance of organisms, they cause a dilemma that may be called a kind of Heisenberg effect: a large number of traps should be placed to yield a precise estimate of mean dispersal distance, while these traps shorten the mean dispersal distance itself by intercepting organisms that should have dispersed for further distances. We propose a procedure to solve this dilemma by placing traps uniformly in a lattice pattern, and by assuming a random movement and a constant rate of settlement for organisms. We applied this procedure to estimate the dispersal distance of the sugarcane wireworm Melanotus okinawensis Ohira (Coleoptera: Elateridae). The estimated mean dispersal distance was 143.8 m. Through the use of a conventional method of estimation, the mean dispersal distance was estimated to be 118.1 m. Thus, it was shown that the conventional estimate of dispersal distance was 18% smaller than the corrected estimate in our experiment.     

饥饿胁迫对褐纹金针虫生理特征的影响

【目的】褐纹金针虫Melanotus caudex发生为害日趋严重。本研究分析饥饿环境条件下褐纹金针虫的生理特征变化,以期揭示其饥饿胁迫下的生理和生态适应对策。【方法】以2-3龄幼虫为试验的起始对象,以喂食小麦(中旱101)苗的褐纹金针虫为对照,在土壤和蛭石两种饲养环境条件下测定不同饥饿时期金针虫的存活率、活动性、蜕皮次数、体重、含水量及呼吸率的变化。【结果】饥饿胁迫下褐纹金针虫存活率、蜕皮次数与喂食(对照)组之间无显著差异,在饥饿120 d的情况下仍有90%以上的存活率,蜕皮次数10次左右,试虫在触碰时全部具有活动性。土壤和蛭石环境饥饿胁迫下褐纹金针虫的鲜重、干重分别呈下降趋势,与喂食组相比存在显著差异。处理120 d时,土壤和蛭石环境饥饿褐纹金针虫的含水量分别达到72.52%和72.22%,相应对照组的含水量分别为49.01%和51.37%,饥饿组含水量较喂食对照组显著升高。随饥饿处理时间的延长褐纹金针虫呼吸率表现为显著下降趋势,土壤和蛭石环境饥饿胁迫下褐纹金针虫的CO2释放率分别下降了62.11%和60.46%。【结论】褐纹金针虫具有较强的耐饥饿能力,在饥饿胁迫下可通过降低呼吸代谢的生理对策维持其生长发育(正常蜕皮)。     

Production of 2-(2-phenylethyl) Chromones in Cell Suspension Cultures of <Emphasis Type="Italic">Aquilaria sinensis</Emphasis>

2-(2-Phenylethyl) chromones are the major constituents responsible for the quality of agarwood, which is one of the most valuable non-timber products used as incenses, perfumes, traditional medicines and other products. In this study, cell suspension culture of Aquilaria sinensis (Lour) Gilg was used to monitor the eliciting effects of crude fungal extracts on cell growth and chromones production. Crude extracts of Melanotus flavolivens (B. etc) Sing. prepared with different solvents were used to elicit the production of 2-(2-phenylethyl) chromones in cell suspension cultures of A. sinensis. Four 2-(2-phenylethyl) chromones,␣6,7-dimethoxy-2-(2-phenylethyl) chromone (1), 6,7-dimethoxy-2-[2-(4′-methoxyphenyl)ethyl] chromone (2), 6-methoxy-2-[2-(4′-methoxyphenyl)ethyl] chromone (3) and 6-methoxy-2-(2-phenylethyl) chromone␣(4),␣were detected by LC–MS in the cell suspension culture of A. sinensis elicited with crude extracts of M. flavolivens. Three hundred and seventy eight, 196 and 31 μg g⁻¹ DW of 2-(2-phenylethyl) chromones were obtained in the cell cultures induced by water extracts, 50 and 95% ethanol extracts of M. flavolivens, respectively. The results show that water-soluble materials in the crude extracts are the main components inducing the production of 2-(2-phenylethyl) chromones in the cell cultures.