Reverse chemical ecology approach for the identification of an oviposition attractant for Culex quinquefasciatus.

Pheromones and other semiochemicals play a crucial role in today's integrated pest and vector management strategies. These semiochemicals are typically discovered by bioassay-guided approaches. Here, we applied a reverse chemical ecology approach; that is, we used olfactory proteins to lead us to putative semiochemicals. Specifically, we used 7 of the top 10 odorant receptors (ORs) most expressed in the antennae of the southern house mosquito, Culex quinquefasciatus, and which are yet to be deorphanized. We expressed these receptors in the Xenopus oocyte recording system and challenged them with a panel of 230 odorants, including physiologically and behaviorally active compounds. Six of the ORs were silent either because they are not functional or a key odorant was missing. CquiOR36, which showed the highest transcript levels of all OR genes in female antennae, was also silent to all odorants in the tested panel, but yielded robust responses when it was accidentally challenged with an old sample of nonanal in ethanol. After confirming that fresh samples were inactive and through a careful investigation of all possible "contaminants" in the old nonanal samples, we identified the active ligand as acetaldehyde. That acetaldehyde is activating CquiOR36 was further confirmed by electroantennogram recordings from antennae of fruit flies engineered to carry CquiOR36. Antennae of female mosquitoes also responded to acetaldehyde. Cage oviposition and dual-choice assays demonstrated that acetaldehyde is an oviposition attractant in a wide range of concentrations and thus of potential practical applications

Kairomonal effect of walking traces from Euschistus heros (Heteroptera: Pentatomidae) on two strains of Telenomus podisi (Hymenoptera: Scelionidae)

The semiochemical cues used by geographically isolated strains of the parasitoid, Telenomus podisi (Ashmed), to find eggs of the stink bug Euschistus heros were investigated

Verification of Argentine ant defensive compounds and their behavioral effects on heterospecific competitors and conspecific nestmates.

The invasive Argentine ant (Linepithema humile) has become established worldwide in regions with Mediterranean or subtropical climates. The species typically disrupts the balance of natural ecosystems by competitively displacing some native ant species via strong exploitation and interference competition. Here we report that Argentine ants utilize glandular secretions for inter and intra-specific communications during aggressive interactions with a heterospecific competitor, California harvester ant (Pogonomyrmex californicus). Chemical analyses indicated that Argentine ants deploy glandular secretions containing two major volatile iridoids, dolichodial and iridomyrmecin, on the competitor's cuticular surface during aggressive interactions. Bioassays indicated that the glandular secretions function as a defensive allomone, causing high levels of irritation in the heterospecific. Furthermore, the same glandular secretions elicited alarm and attraction of conspecific nestmates, potentially enabling more rapid/coordinated defense by the Argentine ants. Two major volatile constituents of the glandular secretion, dolichodial and iridomyrmecin, were sufficient to elicit these responses in conspecifics (as a mixture or individual compounds). The current study suggests that invasive Argentine ants' superior exploitation and interference competition may rely on the species' effective semiochemical parsimony

Pheromone of the banana-spotting bug, Amblypelta lutescens lutescens Distant (Heteroptera: Coreidae): identification, synthesis, and field bioassay

The banana-spotting bug, Amblypelta lutescens lutescens Distant (Heteroptera: Coreidae), is one of the principal pests of tree fruits and nuts across northern and eastern Australia. Apart from visual damage assessment, there are currently no reliable methods for monitoring bug activity to aid management decisions. An attractant pheromone for this species that could be used as a trap lure could potentially fill this void. Earlier, two male-specific compounds were identified in airborne extracts from A. lutescens lutescens, (E,E)-α-farnesene and (R,E)-nerolidol; an unknown compound with a molecular weight 220 was also detected. We now report the identification of this hitherto unknown compound as (R,E,E)-α-farnesene-10,11-oxide. Synthesis of this epoxide was conducted using a regioselective asymmetric dihydroxylation of a sulfolene. A blend mimicking the natural proportions of (E,E)-α-farnesene, (R,E)-nerolidol, and (R,E,E)-α-farnesene-10,11- oxide attracted male and female A. lutescens lutescens as well as nymphs in the field, verifying that the aggregation pheromone comprises or is contained within this group of compounds. Copyrigh

An Observational Study on Perfusion Index to Predict and Correlate Incidences of Hypotension Following Spinal Anaesthesia Using Pulse Oximeter

Perfusion Index (PI) is the ratio of the pulsatile blood flow to the non-pulsatile or static blood in the peripheral tissues. It is a new parameter tried for predicting hypotension during spinal anaesthesia.  Our aim was to observe Perfusion Index as an early predictor of hypotension under spinal anaesthesia in patients undergoing elective surgeries. In this observational study, 30 patients between the age group of 18-50years and belonged to ASA I and II category were taken. Spinal anaesthesia was performed with 3-4 ml of injection Bupivacaine 0.5% (hyperbaric) at L3–L4 interspace. Following spinal anaesthesia heart rate, blood pressure, and PI were recorded for 30 minutes. Hypotension was defined as fall in the MAP of 20% from the baseline and was treated with fluids, parasympatholytic ± vasopressors. Analysis was performed using software IBM SPSS statistics for windows, Data was presented as mean ± standard deviation. A P value < 0.05 was considered statistically significant. Regression analysis with Spearman's rank correlation coefficient was done to assess the correlation between baseline PI and hypotension. Receiver operating characteristic (ROC) curve was plotted for PI and occurrence of hypotension.&nbsp

Reverse chemical ecology approach for the identification of an oviposition attractant for Culex quinquefasciatus.

Pheromones and other semiochemicals play a crucial role in today's integrated pest and vector management strategies. These semiochemicals are typically discovered by bioassay-guided approaches. Here, we applied a reverse chemical ecology approach; that is, we used olfactory proteins to lead us to putative semiochemicals. Specifically, we used 7 of the top 10 odorant receptors (ORs) most expressed in the antennae of the southern house mosquito, Culex quinquefasciatus, and which are yet to be deorphanized. We expressed these receptors in the Xenopus oocyte recording system and challenged them with a panel of 230 odorants, including physiologically and behaviorally active compounds. Six of the ORs were silent either because they are not functional or a key odorant was missing. CquiOR36, which showed the highest transcript levels of all OR genes in female antennae, was also silent to all odorants in the tested panel, but yielded robust responses when it was accidentally challenged with an old sample of nonanal in ethanol. After confirming that fresh samples were inactive and through a careful investigation of all possible "contaminants" in the old nonanal samples, we identified the active ligand as acetaldehyde. That acetaldehyde is activating CquiOR36 was further confirmed by electroantennogram recordings from antennae of fruit flies engineered to carry CquiOR36. Antennae of female mosquitoes also responded to acetaldehyde. Cage oviposition and dual-choice assays demonstrated that acetaldehyde is an oviposition attractant in a wide range of concentrations and thus of potential practical applications

Serendipitous, cross familial discovery of the first long-range chemical attractants for antlions (Neuroptera: Myrmeleontidae): (1R,2S,5R,8R)-Iridodial and Z,E-nepetalactol

Synthetic (1R,2S,5R,8R)-iridodial, the key pheromone component of many green lacewings in the genus Chrysopa, strongly attracted adult males and females of the North American antlion, Dendroleon speciosus Banks. In addition, one of the common sex pheromone components of many aphids to which Chrysopa spp. are weakly attracted, Z,E-nepetalactol, was also weakly attractive to D. speciosus adults. Iridodial and Z,E-nepetalactol also elicited strong and weak electroantennogram detector (EAD) responses, respectively, in D. speciosus adults. Previously reported semiochemicals from European and Israeli antlion species did not elicit EAD or behavioral responses from D. speciosus adults. The earlier studied antlions release volatile chemicals from male-specific metathoracic glands associated with structures on the hind wings (Eltringham’s organs) that are thought to enhance evaporation of the secretion. Although D. speciosus males have Eltringham’s organs similar to those of other antlion species, we discovered that D. speciosus males have a pair of white tubular glands that extend posteriorly into the abdomen, opening in the resting pits of the Eltringham’s organs. Further gas chromatograph (GC)-EAD analysis of another commercially available antlion species, Myrmeleon crudelis Walker, showed that this species did not respond to the lacewing or aphid related volatile compounds, but strongly responded to the reported antlion semiochemicals, namely, nerol, 10-homonerol and nerol oxide. The male-specific abdominal glands of D. speciosus are presumably pheromone glands; hopefully, positive verification of this supposition will help clarify the semiochemical relationships between antlions, lacewings and aphids