Graeme R. Jones

A Mosaic of Chemical Coevolution in a Large Blue Butterfly

Mechanisms of recognition are essential to the evolution of mutualistic and parasitic interactions between species. One such example is the larval mimicry that Maculinea butterfly caterpillars use to parasitize Myrmica ant colonies. We found that the greater the match between the surface chemistry of Maculinea alcon and two of its host Myrmica species, the more easily ant colonies were exploited. The geographic patterns of surface chemistry indicate an ongoing coevolutionary arms race between the butterflies and Myrmica rubra, which has significant genetic differentiation between populations, but not between the butterflies and a second, sympatric host, Myrmica ruginodis, which has panmictic populations. Alternative hosts may therefore provide an evolutionary refuge for a parasite during periods of counteradaptation by their preferred hosts.

Pretender punishment induced by chemical signalling in a queenless ant

Animal societies are stages for both conflict and cooperation. Reproduction is often monopolized by one or a few individuals who behave aggressively to prevent subordinates from reproducing (for example, naked mole-rats, wasps and ants). Here we report an unusual mechanism by which the dominant individual maintains reproductive control. In the queenless ant Dinoponera quadriceps, only the alpha female reproduces. If the alpha is challenged by another female she chemically marks the pretender who is then punished by low-ranking females. This cooperation between alpha and low-rankers allows the alpha to inflict punishment indirectly, thereby maintaining her reproductive primacy without having to fight.

Evaluation of a Molecular-imprinted Polymer for use in the Solid Phase Extraction of Propranolol From Biological Fluids

The use of a polymer, prepared in the presence of racemic propranolol in order to form a ‘molecular imprint’, for the highly selective extraction of the drug from a variety of aqueous media, including biological samples, is described. It is shown that the conditions chosen for elution of the adsorbed propranolol are extremely important to ensure selectivity. Thus eluents based on methanol–water 1% TEA proved to provide greater selectivity than those based on methanol–water 1% TFA.

The Evolution of Invasiveness in Garden Ants

It is unclear why some species become successful invaders whilst others fail, and whether invasive success depends on pre-adaptations already present in the native range or on characters evolving de-novo after introduction. Ants are among the worst invasive pests, with Lasius neglectus and its rapid spread through Europe and Asia as the most recent example of a pest ant that may become a global problem. Here, we present the first integrated study on behavior, morphology, population genetics, chemical recognition and parasite load of L. neglectus and its non-invasive sister species L. turcicus. We find that L. neglectus expresses the same supercolonial syndrome as other invasive ants, a social system that is characterized by mating without dispersal and large networks of cooperating nests rather than smaller mutually hostile colonies. We conclude that the invasive success of L. neglectus relies on a combination of parasite-release following introduction and pre-adaptations in mating system, body-size, queen number and recognition efficiency that evolved long before introduction. Our results challenge the notion that supercolonial organization is an inevitable consequence of low genetic variation for chemical recognition cues in small invasive founder populations. We infer that low variation and limited volatility in cuticular hydrocarbon profiles already existed in the native range in combination with low dispersal and a highly viscous population structure. Human transport to relatively disturbed urban areas thus became the decisive factor to induce parasite release, a well established general promoter of invasiveness in non-social animals and plants, but understudied in invasive social insects.

Chemistry of a Mating Plug in Bumblebees

In the bumblebee B. terrestris males transfer a mating plug into the queens sexual tract shortly after sperm transfer. The plug is a sticky, opaque secretion of the male accessory gland. In order to clarify the meaning of the mating plug, we collected the plug substance directly from the males accessory gland and identified the chemical substances present with gas chromatography. The main compounds found in the mating plug were four fatty acids (palmitic, linoleic, oleic, and stearic acids) and a cyclic peptide (cycloprolylproline). Mixing the four fatty acids resulted in a similar sticky, opaque mass as found in natural plugs, indicating that cycloprolylproline is not necessary for the physical attributes of the plug. The function of the fatty acids may therefore be to build up a physical barrier, optimizing sperm placement before the spermathecal duct or preventing sperm backflow. Cycloprolylproline, on the other hand, may influence female mating behavior so as to reduce her receptivity. In fact, peptides are known to reduce female receptivity in other insects. This would explain why queens of B. terrestris are only singly mated, although multiple mating is beneficial during the colony cycle with respect to parasitism and fitness.

Optimisation of procedures for the extraction of structural analogues of propranolol with molecular imprinted polymers for sample preparation

A propranolol-derived molecular imprinted polymer (MIP) was prepared using methacrylic acid as monomer and ethylene glycol dimethacrylate as cross-linker. The extraction properties of five compounds structurally related to propranolol were assessed on the MIP and on a blank polymer made under the same conditions but in the absence of an imprint molecule. Using application from aqueous solution with methanol-water-triethylamine (TEA)-based solvents for elution (i.e. reversed-phase conditions) the MIP showed only marginal selectivity for the compounds on the MIP compared to the blank. Despite the limited selectivity there did appear to be a relationship between structure of the compound (relative to propranolol) and the extent of selective retention. Application of the compounds in toluene with elution using toluene-TEA or toluene-trifluoroacetic acid resulted in the MIP showing dramatically enhanced retention and selectivity of the compounds on the MIP compared to the blank. The enhanced selectivity for extraction on to the MIP relative to the blank, for all compounds using normal-phase solvents seem to be a class effect as there was no apparent relationship between compound structure and retention.

Glucose sensor with improved haemocompatibilty.

A new biocompatible copolymer has been synthesised and used in an electrochemical enzyme-based glucose sensor. The copolymer incorporates three segments including a monomer with an electrically neutral phosphorylcholine head group that is able to reject protein adsorption and two segments that increase the affinity to polyurethane substrate. Peel and solution circulation tests showed that this material has high attachment to polyurethane. With the new copolymer as the outermost layer and the polyurethane as the diffusion-limiting membrane, the sensor showed extended linearity up to 50 mM glucose and stable output in bovine serum for 70 h. During in vivo tests, the sensor exhibited a steady current signal and a rapid transient response when the glucose concentration was raised. These results imply that the haemocompatibility of the glucose sensor coated with the new copolymer has been improved, which is crucial for a sensor used for clinical real-time monitoring. The material may also be suitable for application to other implantable devices.

Methodology for assessing the properties of molecular imprinted polymers for solid phase extraction

Four molecular imprinted polymers (MIPs) were prepared using propranolol as template molecule. The retention and recovery of propranolol and eleven structurally related compounds were assessed on all four MIPs and a blank polymer in solid phase extraction (SPE) experiments using methanol–water–triethylamine (TEA) (1%) elution solvents. Cumulative elution curves were produced and these were compared between blank and imprinted polymer for each compound. Only one polymer demonstrated significantly different retention properties compared to the blank indicating that only this polymer was sufficiently selective to be considered for SPE. In the case of the selective MIP, two classes of compounds were observed, with one group demonstrating selective retention whilst the second group showed similar retention on both MIP and blank. The compounds showing selective retention on the MIP were closely structurally related to the template propranolol, differing in having methoxy substituents on the naphthyl or a modified alkyl side chain whilst those that were equally well retained on the blank and MIP all contained amide groups close to the secondary amino group on the side chain. The use of eleven structurally related compounds in this way enabled the key structural features important to specific binding to the molecular imprints to be explored. They also provide a means to rapidly evaluate the polymers in order to select those suitable for SPE from aqueous solutions.

Cuticular Hydrocarbon Pheromones for Social Behavior and Their Coding in the Ant Antenna

The sophisticated organization of eusocial insect societies is largely based on the regulation of complex behaviors by hydrocarbon pheromones present on the cuticle. We used electrophysiology to investigate the detection of cuticular hydrocarbons (CHCs) by female-specific olfactory sensilla basiconica on the antenna of Camponotus floridanus ants through the utilization of one of the largest family of odorant receptors characterized so far in insects. These sensilla, each of which contains multiple olfactory receptor neurons, are differentially sensitive to CHCs and allow them to be classified into three broad groups that collectively detect every hydrocarbon tested, including queen and worker-enriched CHCs. This broad-spectrum sensitivity is conserved in a related species, Camponotus laevigatus, allowing these ants to detect CHCs from both nestmates and non-nestmates. Behavioral assays demonstrate that these ants are excellent at discriminating CHCs detected by the antenna, including enantiomers of a candidate queen pheromone that regulates the reproductive division of labor.

Fertility signaling—the proximate mechanism of worker policing in a clonal ant

In eusocial insects, the ability to regulate reproduction relies on cues that signal the presence of fertile individuals. We investigated the variation of cuticular hydrocarbons (CHCs) with reproductive status in Platythyrea punctata, an ant, in which all workers are capable of producing daughters from unfertilized eggs (thelytoky). Who reproduces is determined through dominance and worker policing. New reproductives, which developed their ovaries after separation from an old reproductive for a short period of time, were attacked by nonreproductives upon reintroduction into their colony. In contrast, aggression against new reproductives with fully developed ovaries, which had been separated over a longer period, was initiated by fights between old and new reproductives. CHC profiles varied with ovarian development. New reproductives were only attacked when they expressed a CHC profile similar to old reproductives, but not when it was similar to that of nonreproductives. CHCs appear to signal the fertility of individuals and induce policing behavior towards surplus reproductive workers.