Using Insect Electroantennogram Sensors on Autonomous Robots for Olfactory Searches

Robots designed to track chemical leaks in hazardous industrial facilities¹ or explosive traces in landmine fields² face the same problem as insects foraging for food or searching for mates³: the olfactory search is constrained by the physics of turbulent transport⁴. The concentration landscape of wind borne odors is discontinuous and consists of sporadically located patches. A pre-requisite to olfactory search is that intermittent odor patches are detected. Because of its high speed and sensitivity^5-6, the olfactory organ of insects provides a unique opportunity for detection. Insect antennae have been used in the past to detect not only sex pheromones⁷ but also chemicals that are relevant to humans, e.g., volatile compounds emanating from cancer cells⁸ or toxic and illicit substances^9-11. We describe here a protocol for using insect antennae on autonomous robots and present a proof of concept for tracking odor plumes to their source. The global response of olfactory neurons is recorded in situ in the form of electroantennograms (EAGs). Our experimental design, based on a whole insect preparation, allows stable recordings within a working day. In comparison, EAGs on excised antennae have a lifetime of 2 hr. A custom hardware/software interface was developed between the EAG electrodes and a robot. The measurement system resolves individual odor patches up to 10 Hz, which exceeds the time scale of artificial chemical sensors¹². The efficiency of EAG sensors for olfactory searches is further demonstrated in driving the robot toward a source of pheromone. By using identical olfactory stimuli and sensors as in real animals, our robotic platform provides a direct means for testing biological hypotheses about olfactory coding and search strategies¹³. It may also prove beneficial for detecting other odorants of interests by combining EAGs from different insect species in a bioelectronic nose configuration¹⁴ or using nanostructured gas sensors that mimic insect antennae¹⁵.     

Development of highly nutritive culture media

Summary A highly nutritive culture medium (MGM-464) was developed for insect cell primary culture. The new medium consists of 6 inorganic salts, 4 organic acids, 21 amino acids, 3 sugars, 10 vitamins, and 8 other chemicals, including natural substances. The complete medium was generated by adding 20 ml fetal bovine serum to 100 ml MGM-464. The detail of the composition of the medium is given in a table, and the protocol to prepare the medium is described in the text. Among the 15 kinds of cultures made with MGM-464, embryonic cells from a walking stick and ovarian cells from the common white were subcultured more than 70 times, and embryonic cells of a chrysomelid beetle were subcultured more than 15 times. Other cultures could not be subcultured. However, embryonic cells from the commercial silkworm and a cockroach, ovarial cells from the commercial silkworm and a sphingid moth, nervous cells from the commercial silkworm and two sphingid moths, and cells from the dorsal vessel plus surrounding tissue of the commercial silkworm survived for several mo. The cells from the honeybee embryos, aphid embryos, and planthopper embryos were rather short-lived, and deteriorated after about 1 mo.     

Biodiversity of galling insects: historical, community and habitat effects in four neotropical savannas

Five hypotheses were tested to explain the pattern of galling insect species richness in four neotropical savanna physiognomies, 'canga ', 'campo sujo', 'cerrado' s. st., and 'cerradão', that occur in Minas Gerais, southeastern Brazil. We found 125 species of galling insects on 80 host plant species. The increase of plant species richness explained 35% of the variation in galling insect richness, corroborating the plant species richness hypothesis. Most of the galling species occurred on trees, followed by shrubs, and herbs. However, the difference in mean number of galls was only statistically significant between herbs and trees, corroborating partially the plant structural complexity hypothesis. A significant relationship was observed between galling species richness and density of herbs, and shrubs, corroborating partially the resource concentration hypothesis. Galling insect richness showed a negative correlation with magnesium, potassium, and zinc on soil, corroborating the soil fertility hypothesis. The content of magnesium, potassium, iron and CTC (T) explained 72% of the variation in galling insect richness. Plant family size positively influenced galling insect richness, corroborating the plant family size hypothesis. Overall, the results corroborate the hypothesis that predicts that habitat stress is the main factor generating the patterns of galling insect richness in Brazilian savannas.     

Influence of host log age and refuge from natural enemies on colonization and survival of Phoracantha semipunctata

The pine cone weevil, Pissodes validirostris Gyll. (Coleoptera: Curculionidae), attacks seed cones of most Eurasian pine species, except these of Swiss stone pine (Pinus cembra L.). Behavioural responses of adult weevils to cone volatile emissions of Swiss stone pine and to those of a common host, mountain pine (Pinus uncinata Ram.), were compared in an olfactometer. Weevils were significantly attracted by the volatile blend emitted by mountain pine, but Swiss stone pine volatiles elicited an inverse response, with most weevils moving in the opposite direction to the odour source. However, the majority of second instar weevil larvae that were extracted from mountain pine cones and transferred into Swiss stone pine cones were capable of developing to the adult stage. This suggests that Swiss stone pine cones do not contain strong feeding deterrents that could prevent larval development. The possible factors involved in the absence of colonization of Swiss stone pine cones by cone weevils are discussed.     

昆虫RNAi通路及其核心元件的研究综述

RNAi作为分子生物学的一种重要技术,在昆虫基因功能和功能基因组研究中得到广泛应用,同时,有关昆虫RNAi的机制也受到了大家的关注。近年来的研究结果表明,昆虫RNAi的通路与其他动物相同,根据引起基因沉默的RNA分子的类型,可以分为siRNA、miRNA和piRNA 3种不同的通路。昆虫RNAi通路中的核心元件包括了:(1)行使切割作用的RNaseⅢ家族成员Drosha和Dicer;(2)用来降解目的 mRNA的Argonaute蛋白;(3)dsRNA结合蛋白Pasha、R2D2和Loquacious。了解昆虫RNAi的通路及其核心元件,有助于我们更好地理解昆虫RNAi的分子机制和改进实现RNAi的方法,对促进昆虫RNAi技术的研究及其在害虫防控中的应用具有指导意义。     

The gut microbiota of the pine weevil is similar across Europe and resembles that of other conifer‐feeding beetles

The pine weevil (Hylobius abietis, Coleoptera: Curculionidae) is an important pest of conifer seedlings in Europe. Despite its economic importance, little is known about the composition of its gut microbial community and the role it plays in mediating the weevil's ability to utilize conifers as a food source. Here, we characterized the gut bacterial communities of different populations of H. abietis across Europe and compared them to those of other beetles that occupy similar ecological niches. We demonstrate that the microbial community of H. abietis is similar at higher taxonomic levels (family and genus) across locations in Europe, with Wolbachia as the dominant microbe, followed by Enterobacteria and Firmicutes. Despite this similarity, we observed consistent differences between countries and locations, but not sexes. Our meta‐analysis demonstrates that the gut bacterial community of the pine weevil is very similar to that of bark beetles that also exploit conifers as a food source. The Enterobacteriaceae symbionts of both host taxa are especially closely related phylogenetically. Conversely, the microbiota of H. abietis is distinct from that of closely related weevils feeding on nonconifer food sources, suggesting that the microbial community of the pine weevil is determined by the environment and may be relevant to host ecology. Furthermore, several H. abietis‐associated members of the Enterobacteriaceae family are known to contain genes involved in terpenoid degradation. As such, we hypothesize that the gut microbial community is important for the utilization of conifer seedlings as a food source, either through the detoxification of plant secondary metabolites or through the supplementation of essential nutrients.     

In silico and bio assay of juvenile hormone analogs as an insect growth regulator against Galleria mellonella (wax moth) – Part I

Juvenile hormone (JH) analogs are nowadays in use to control harmful pests. In order to develop new bioactive molecules as potential pesticides, we have incorporated different active structural features like sulfonamide, aromatic rings, amide group, and amino acid moiety to the base structure. We have screened a series of designed novel JH analogs against JH receptor protein (jhbpGm-2RCK) of Galleria mellonella in comparison to commercial insect growth regulators (IGRs) – Pyriproxyfen (T₁) and Fenoxycarb (T₂). All analogs exhibit the binding energy profile comparable to commercial IGRs. Based upon these results, a series of sulfonamide-based JHAs (T₃–T₈) as IGRs have been synthesized and characterized. Further, the efficacy of synthesized analogs (T₃–T₈) and commercial IGRs (Pyriproxyfen and Fenoxycarb) has been assessed against fourth instars larvae of G. mellonella under the laboratory conditions. LC₅₀ values of all the analogs (T₁–T₈) against the fourth instars larvae were 9.99, 10.12, 24.76, 30.73, 38.45, 34.15, 34.14, 19.48 ppm and the LC₉₀ 153.27, 131.69, 112.15, 191.46, 427.02, 167.13, 217.10, 172.00 ppm, respectively. Among these analogs, N-(1-isopropyl-2-oxo-3-aza-3-N-ethyl-pentanyl)-p-toluene sulfonamide (T₈) and N-(1-isopropyl-2-oxo-3-aza-3-N-ethyl-pentanyl) benzene sulfonamide (T₇) exhibited the good pest larval mortality at different exposure periods (in hours) and different concentrations (in ppm) in comparison to in use IGRs- T₁ and T₂. Bio assay results are supported by docking at higher concentration. The present investigation clearly exhibits that analog T₈ could serve as a potential IGR in comparison to in use IGRs (T₁ and T₂). The results are promising and provide new array of synthetic chemicals that may be utilized as IGRs.     

Relative contribution of ruminal buffering systems to pH regulation in feedlot cattle fed either low- or high-forage diets

The relative contribution of ruminal short-chain fatty acid (SCFA) absorption and salivary buffering to pH regulation could potentially change under different dietary conditions. Therefore, the objective of this study was to investigate the effects of altering the ruminal supply of rapidly fermentable carbohydrate (CHO) on absorptive function and salivation in beef cattle. Eight heifers (mean BW±SD=410±14 kg) were randomly allocated to two treatments in a crossover design with 37-day periods. Dietary treatments were barley silage at 30% low forage (LF) or 70% high forage (HF) of dietary dry matter (DM), with the remainder of the diet consisting of barley grain (65% or 25% on a DM basis) and a constant level (5%) of supplement. The LF and HF diets contained 45.3% and 30.9% starch, and 4.1% and 14.0% physically effective fiber (DM basis), respectively. Ruminal pH was continuously measured from day 17 to day 23, whereas ruminal fluid was collected on day 23 to determine SCFA concentration. Ruminal liquid passage rate was determined on day 23 using Cr-ethylenediaminetetraacetic acid. Eating or resting salivation was measured by collecting masticate (days 28 and 29) or saliva samples (days 30 and 31) at the cardia, respectively. On days 30 and 31, the temporarily isolated and washed reticulo-rumen technique was used to measure total, and Cl⁻-competitive (an indirect measure of protein-mediated transport) absorption of acetate, propionate and butyrate. As a result of the higher dietary starch content and DM intake, the ruminal supply of rapidly fermentable CHO, total ruminal SCFA concentration (118 v. 95 mM; P<0.001) and osmolality (330 v. 306 mOsm/kg; P=0.018) were greater in cattle fed LF compared with HF. In addition, feeding LF resulted in a longer duration (2.50 v. 0.09 h/day; P=0.02) and a larger area (0.44 v. 0.01 (pH×h)/day; P=0.050) that pH was below 5.5. There was no diet effect on total and Cl⁻-competitive absorption (mmol/h and %/h) of acetate, propionate, butyrate and total SCFA (acetate+propionate+butyrate), but eating salivation was less (131 v. 152 ml/min; P=0.02), and resting salivation tended to be less (87 v. 104 ml/min; P=0.10) in cattle fed an LF diet. In summary, lower ruminal pH in cattle with greater rapidly fermentable CHO intake was attributed to an increase in SCFA production and decrease in salivation, which were not compensated for by an increase in epithelial permeability.     

花颜色和花气味的量化研究方法

花颜色和花气味是花部构成的重要内容。在已开展的传粉生态学研究中对二者的报道主要是描述性的,而其量化研究可以为揭示传粉机制提供有力的实验证据。本文主要介绍了花颜色的测量和标定方法,包括比色卡、分光色差仪和便携式光谱仪等;花气味的采集方法,包括动态顶空套袋-吸附采集法、吸附-溶剂洗脱法和固相微萃取法等;花气味的检测和分析方法,包括气相色谱-质谱联用仪分析和电子鼻型超速气相色谱仪分析等;以及昆虫行为学实验方法,包括气相色谱-昆虫触角电位联用技术、Y型嗅觉仪和飞行箱实验等。科研人员可以根据实验材料的特点和实验目的选择适合的量化研究方法。     

香溪河水生昆虫功能性状及功能多样性空间格局

近年来,生物多样性研究已从群落物种多样性拓展至功能多样性层面,使用功能性状表征功能组成及功能多样性是当前底栖动物生态学研究的热点之一。物种功能性状对环境变化敏感,对群落和种群沿环境梯度的演替具有许多潜在的指示作用。为了解香溪河水系水生昆虫功能性状空间分布格局及环境因子对功能多样性的影响,于2005年12月及2006年1月、2月对该水系的香溪河、九冲河、高岚河、古夫河4条河流的水生昆虫进行了调查,并对理化指标进行了测定;参考相关文献资料,本研究选择化性、漂移性、游泳能力、吸附能力、形状、个体大小、流态偏好、温度偏好、生活型、营养习性等10个功能性状纳入分析。研究结果发现,香溪河水系共鉴定水生昆虫127种,四节蜉(Baetis sp.)、高翔蜉(Epeorus sp.)、短尾石蝇(Nemoura sp.)为区域优势分类单元,相对丰度分别为38.6%、9.1%、6.7%;4条河流间优势物种组成差异较大。10个功能性状中相对丰度最高的等级性状分别为1世代/a(Volt2)、高漂移率(Drft3)、无游泳能力(Swim1)、无吸附能力(Atch1)、流线型(Shpe1)、小型个体(Size1)、沉积/侵蚀流态兼好型(Rheo2)、广温型(Ther2)、附着型(Habi4)、收集者(Trop1);单因素方差分析及独立样本T检验表明,化性、附着能力、大小、流速偏好、温度偏好、漂移性、生活型、营养习性等性状级别间差异显著,而游泳能力、形状性状等级间无显著差异。对10个功能性状的33个等级性状在4条河流间相对丰度的差异性进行研究,结果发现,Volt1、Drft2、Swim2、Atch1、Atch2、Size3、Rheo1、Ther3、Habi2、Habi3、Trop3、Trop5等12个等级性状相对丰度在4条河流间差异显著。功能性状多样性、树状图功能多样性用来描述4条河流功能多样性,结果表明,功能性状多样性指数均值在古夫河、高岚河、九冲河、香溪河分别为2.8、3.2、6.9和5.4;树状图功能多样性指数均值在分别为4.8、5.7、11.1、8.8。功能冗余度均值在4条河流分别为2.9、3.4、4.6、3.9。运用逐步回归分析功能多样性、功能冗余度与环境参数的关系,结果表明,功能性状多样性指数受总氮、水深影响显著;树状图功能多样性指数受总氮、水深、流速影响显著;功能冗余度指数受硝态氮、溶解氧、二氧化硅影响显著。