Direct evidence of the use of multiple drugs in Bronze Age Menorca (Western Mediterranean) from human hair analysis.

Human hair dated to Late Prehistory is exceedingly rare in the Western Mediterranean. Archaeological excavations in the Bronze Age burial and cult cave of Es Càrritx, in Menorca (Balearic Islands) provided some human hair strands involved in a singular funerary rite. This finding offered the opportunity to explore the possible use of drug plants by Late Bronze Age people. Here we show the results of the chemical analyses of a sample of such hair using Ultra-High-Performance Liquid Chromatography-High Resolution Mass Spectrometry (UHPLC-HRMS). The alkaloids ephedrine, atropine and scopolamine were detected, and their concentrations estimated. These results confirm the use of different alkaloid-bearing plants by local communities of this Western Mediterranean island by the beginning of the first millennium cal BCE.

Chemical Responses of Nicotiana tabacum (Solanaceae) Induced by Vibrational Signals of a Generalist Herbivore.

Plants are able to sense their environment and respond appropriately to different stimuli. Vibrational signals (VS) are one of the most widespread yet understudied ways of communication between organisms. Recent research into the perception of VS by plants showed that they are ecologically meaningful signals involved in different interactions of plants with biotic and abiotic agents. We studied changes in the concentration of alkaloids in tobacco plants induced by VS produced by Phthorimaea operculella (Lepidoptera: Gelechiidae), a generalist caterpillar that naturally feeds on the plant. We measured the concentration of nicotine, nornicotine, anabasine and anatabine in four treatments applied to 11-weeks old tobacco plant: a) Co = undamaged plants, b) Eq = Playback equipment attached to the plant without VS, c) Ca = Plants attacked by P. operculella herbivory and d) Pl = playback of VS of P. operculella feeding on tobacco. We found that nicotine, the most abundant alkaloid, increased more than 2.6 times in the Ca and Pl treatments as compared with the Co and Eq treatments, which were similar between them. Nornicotine, anabasine and anatabine were mutually correlated and showed similar concentration patterns, being higher in the Eq treatment. Results are discussed in terms of the adaptive significance of plant responses to ecologically important VS stimuli.

Pollen Types Used by the Native Stingless Bee, Tetragonisca angustula (Latreille), in an Amazon-Chiquitano Transitional Forest of Bolivia.

Samples of corbicular and stored pollen gathered by Tetragonisca angustula (Latreille, 1811) in an Amazon-Chiquitano transitional forest during the dry season were analyzed. The pollen spectrum was established as well as the dynamics of the relationship between the stingless bee and the surrounding flora. Pollen samples obtained from three rational hives were subjected to acetolysis and 55 pollen types were identified, the most frequent being from Anadenanthera (Fabaceae), Chenopodiaceae, and Dydimopanax (Araliaceae). Significant differences in pollen families used between hives along the months of collection were found in stored pollen and non-significant differences in corbicular pollen. Mean values of alpha diversity (H') showed T. angustula as a generalist while beta diversity qualitatively showed that pollen composition was similar between two hives both of which differed from the third hive. Pollen types in corbicular and stored pollen were in general related with richness of flowering plants in the foraging area; the pollen offer was less diverse than the pollen collected, and a trend to prefer the collection of pollen from the most abundant flowering species could be discerned. T. angustula showed polylectic feeding habits and a capacity to adapt to food availability.

Host location by ichneumonid parasitoids is associated with nest dimensions of the host bee species.

Parasitoid fitness depends on the ability of females to locate a host. In some species of Ichneumonoidea, female parasitoids detect potential hosts through vibratory cues emanating from them or through vibrational sounding produced by antennal tapping on the substrate. In this study, we (1) describe host location behaviors in Grotea gayi Spinola (Hymenoptera: Ichneumonidae) and Labena sp. on nests of Manuelia postica Spinola (Hymenoptera: Apidae), (2) compare nest dimensions between parasitized and unparasitized nests, (3) correlate the length of M. postica nests with the number of immature individuals developing, and (4) establish the relative proportion of parasitized nests along the breeding period of M. postica. Based on our results, we propose that these parasitoids use vibrational sounding as a host location mechanism and that they are able to assess host nest dimensions and choose those which may provide them with a higher fitness. Finally, we discuss an ancestral host-parasitoid relationship between Manuelia and ichneumonid species.

Male wing fanning by the aphid parasitoid Aphidius ervi (Hymenoptera: Braconidae) produces a courtship song.

We, herein, report evidence that wing fanning by the aphid parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae) constitutes a courtship song. Complete removal of the forewings or only the distal half of them reduced male copulation success in comparison to intact males. Males that achieved copulation within the observation period produced wing fanning at a higher rate than males that did not copulate. Playback of wing fanning sound altered the behaviour of virgin females, increasing the time they devoted to grooming, as compared with subjects that were exposed to silence or white noise. Our findings contribute to the understanding of the acoustic dimension of the sensory modalities employed by this aphid parasitoid in sexual signalling.

Olfactory conditioning in mate searching by the parasitoid Aphidius ervi (Hymenoptera: Braconidae).

Despite the fact that insect learning capacity has been broadly demonstrated, the role that this process plays during mate searching has been scarcely explored. We studied whether the sexual behaviour of a male parasitic wasp can be conditioned to the odours from two alternative host plant complexes (HPCs) present during its first copulation. The experimental subjects were newly emerged males of the aphid parasitoid, Aphidius ervi, and two alternative HPCs (alfalfa or wheat). In the training protocol, copulation experience corresponded to an unconditioning stimulus and HPC odours to the conditioning stimuli. The initial (just after eclosion) and trained responses were assessed in a glass Y-olfactometer. The results showed that neither alfalfa HPC nor wheat HPC stimuli elicited sexual-related behaviours in initial male responses. Conversely, both HPCs triggered strong attraction and wing fanning courtship behaviour in trained responses when the male was exposed to a female plus HPC during training. In males trained with females plus a given HPC but tested with the alternative HPC in the olfactometer, trained response showed a similar trend to the non-associative treatments. Hence, through learning, the olfactory stimulus context present during copulation could become a predictive cue for further mate searching. These results are discussed in terms of parasitic wasp ecology and host fidelity.

Contrasting performances of generalist and specialist Myzus persicae (Hemiptera: Aphididae) reveal differential prevalence of maternal effects after host transfer.

Transgenerational maternal effects on performance (rm) after host transfer were evaluated in the generalist aphid Myzus persicae s.s., and in its subspecies specialized on tobacco, M. persicae nicotianae Blackman. We tested whether the performance of these taxa, when reared separately on optimal and suboptimal hosts (as sources of different maternal background) and then transferred to optimal hosts, experienced variations along four successive generations. Additionally, to compare the tolerance of both taxa to stress following host transfers, developmental instability (fluctuating asymmetry and body abnormalities) along the four generations was assessed. Taxon, rearing host, and generation affected the performance after host transfer. In the generalist, there was a significant improvement of rm along generations when transferred from suboptimal to optimal host and a significant decrease when transferred from optimal to optimal host; in the specialist, no increase or decrease occurred in any host transfer treatment. Transfer from suboptimal to optimal hosts caused higher losses of remaining replicates along generations than transfers from optimal to optimal hosts, and the specialist showed higher losses than the generalist. The only significant effect detected in comparisons involving fluctuating asymmetry values was that of taxon on length of siphunculi. Frequency of body abnormalities was not affected by treatments. Collectively, these results show a transgenerational weakening of maternal effects in the generalist but not in the specialist aphid, and suggest that rearing the latter in a suboptimal host causes not easily reversible changes that further give rise to constraints in performance.

Genetic structure and clonal diversity of an introduced pest in Chile, the cereal aphid Sitobion avenae.

In Chile, the aphid Sitobion avenae is of recent introduction, lives on cultivated and wild Poaceae, and is thought to reproduce by permanent parthenogenesis. In order to study the genetic variability and population structure of this species, five microsatellite loci were typed from individual aphids collected from different cultivated and wild host plants, from different geographical zones, and years. Chilean populations showed a high degree of heterozygosity and a low genetic variability across regions and years, with four predominant genotypes representing nearly 90% of the sample. This pattern of low clonal diversity and high heterozygosity was interpreted as the result of recent founder events from a few asexually reproducing genotypes. Most geographical and temporal variation observed in the genetic composition resulted from fluctuations of a few predominant clones. In addition, comparisons of the genotypes found in Chile with those described in earlier surveys of S. avenae populations in Western Europe led us to identify 'superclones' with large geographical distribution and high ecological success, and to make a preliminary exploration of the putative origin(s) of S. avenae individuals introduced to Chile.

Host selection by the generalist aphid Myzus persicae (Hemiptera: Aphididae) and its subspecies specialized on tobacco, after being reared on the same host.

Decision-making during host selection by phytophagous insects has proved to be related to host range, with specialists taking faster decisions than generalists; however, this pattern fails to materialize in some host selection studies performed with aphids. Differences found in testing designs point to rearing effects on aphid host selection. To test whether specialization patterns derive from the nature of the aphid or as a consequence of rearing environment, host selection behaviours were compared between the generalist Myzus persicae (Sulzer) s.s. and its subspecies specialized on tobacco when reared on a common host and offered the choice of an alternative host and a non-host plant. Pre-alighting (host finding and attraction towards host volatiles) and post-alighting (leaf surface exploration and probing) behaviours did not differ between the generalist and the tobacco-specialist, except in the allocation of time to probing behaviour; furthermore, all specialists chose the host on which they performed best. Thus, although the specialist was not faster than the generalist, it showed a higher level of commitment to its preferred host plant.

Diet breadth and its relationship with genetic diversity and differentiation: the case of southern beech aphids (Hemiptera: Aphididae).

Herbivorous insect species with narrow diet breadth are expected to be more prone to genetic differentiation than insect species with a wider diet breadth. However, a generalist can behave as a local specialist if a single host-plant species is locally available, while a specialist can eventually behave as a generalist if its preferred host is not available. These problems can be addressed by comparing closely related species differing in diet breadth with overlapping distributions of insect and host populations. In this work, diet breadth, genetic diversity and population differentiation of congeneric aphid species from southern beech forests in Chile were compared. While at the species level no major differences in genetic diversity were found, a general trend towards higher genetic diversity as diet breadth increased was apparent. The aphid species with wider diet breadth, Neuquenaphis edwardsi (Laing), showed the highest genetic diversity, while the specialist Neuquenaphis staryi Quednau & Remaudière showed the lowest. These differences were less distinct when the comparisons were made in the same locality and over the same host. Comparison of allopatric populations indicates that genetic differentiation was higher for the specialists, Neuquenaphis similis Hille Ris Lambers and N. staryi, than for the generalist N. edwardsi. Over the same host at different locations, genetic differentiation among populations of N. edwardsi was higher than among populations of N. similis. The results support the assumption that specialists should show more pronounced genetic structuring than generalists, although the geographical distribution of host plants may be playing an important role.

Genetic diversity and insecticide resistance of Myzus persicae (Hemiptera: Aphididae) populations from tobacco in Chile: evidence for the existence of a single predominant clone.

The tobacco-feeding race of Myzus persicae (Sulzer), formerly known as M. nicotianae Blackman, was introduced into Chile during the last decade. In order to evaluate the genetic diversity and insecticide resistance status of Chilean tobacco aphid populations, a field survey was conducted in 35 tobacco fields covering a 300 km latitudinal survey. The populations sampled were characterized using microsatellite markers and morphometric multivariate analysis. Insecticide resistance levels were assessed through a microplate esterase assay and the mutation status of the kdr gene. All samples collected corresponded to the same anholocyclic aphid genotype, and showed morphological variation within the range expected for the tobacco-feeding race of M. persicae. Esterase activity showed the level and variability expected for an R1 clone lacking mutations in the sodium channels (susceptible kdr), thus corresponding to a type slightly resistant to organophosphate and carbamate, and susceptible to pyrethroid insecticides.

Effects of DIMBOA on detoxification enzymes of the aphid Rhopalosiphum padi (Homoptera: aphididae).

The presence of glutathione transferases and esterase activity was investigated in Rhopalosiphum padi and the effects of the cereal hydroxamic acid, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) on these detoxification enzymes was studied. Activity of glutathione S-transferases and general esterases was determined for adult aphids feeding on a natural diet lacking DIMBOA and on an artificial DIMBOA-containing diet for 48 hours. In vivo, DIMBOA in the diet inhibited the activities of esterases by 50-75% at all concentrations tested (0.5-4 mM). The activity of glutathione transferase was inhibited to a lesser extent (30%) at the higher concentrations of DIMBOA. In vitro, DIMBOA generally inhibited the activity of esterases with an IC(50) of 33 micro M, and had a slight inhibitory effect on glutathione S-transferases. These effects of DIMBOA could make the aphids vulnerable to electrophilic agents and insecticides which may be metabolized via esterases and GSTs. In cereals, therefore, DIMBOA may act by interfering with esterase- or GST-mediated detoxification of xenobiotics by aphids.

Temporal variation of RAPD-PCR phenotype composition of the grain aphid Sitobion avenae (Hemiptera: Aphididae) on wheat: the role of hydroxamic acids.

Hydroxamic acids (Hx) contained in wheat are active mutagens which play an important role in the defence of the plant against aphids. Random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) dominant markers were used to assess genetic variability in the aphid Sitobion avenae (Fabricius) in relation to hydroxamic acid levels in their host-plants. Colonies of aphids belonging to a single RAPD-PCR profile were grown on different host-plants differing in their Hx content under greenhouse conditions. The RAPD-PCR phenotypic pattern showed the appearance of two new RAPD-PCR variants after four to five generations of exposure to wheat cv. Chagual (high Hx levels), one after exposure to wheat cv. Huayún (low Hx levels), and none after exposure to oat (lacking Hx). Differential appearance of new RAPD-PCR aphid phenotypes also occurred on field-grown wheat. While the overall phenotypic 'richness' diminished during the season, the number of RAPD-PCR phenotypes decreased on cv. Huayún and increased on cv. Chagual. The preferential appearance in the field and in the greenhouse of new RAPD-PCR phenotypes of S. avenae on cv. Chagual is discussed on the basis of mutagenesis induced by hydroxamic acids and by the products of their transformation within the aphid. Aphid abundance is interpreted in terms of antixenosis and antibiosis by hydroxamic acids. The appearance on cv. Chagual of phenotypes first detected on cv. Huayún was accounted for by intercrop migrations.

Chemical composition of precloacal secretions of Liolaemus lizards.

Interspecific chemical variation of precloacal pore secretions of Liolaemus lizards was characterized in 20 species, and intraspecific chemical variation was characterized using nine individuals of L. bellii. The latitude (Chile, 18 degrees to 33 degrees South latitude) and altitude (100 to 4350 m.a.s.l.) of the capture sites were recorded, as well as the number of precloacal pores of each lizard. Secretions were analyzed by GC-MS. A total of 49 compounds were found distributed among the 20 species of Liolaemus. Different chemical patterns occurred at intra- and interspecific levels. Compounds belonged to three main families: n-alkanes, long chain carboxylic acids, and steroids. Cholesterol and five carboxylic acids (tetradecanoic, hexadecanoic, hexadecenoic, octadecanoic, and Z-9-octadecenoic) appeared in all species. The number of precloacal pores correlated positively with altitude and negatively with latitude, suggesting that lizards produce more secretions under harsh environments.

Behavioural thermoregulation in Acyrthosiphon pisum (Homoptera: Aphididae): the effect of parasitism by Aphidius ervi (Hymenoptera: Braconidae).

The effects of parasitisation by Aphidius ervi on the thermoregulatory behaviour of the pea aphid Acyrtosiphon pisum were studied in alfalfa fields and in an experimental thermal gradient. In the field, mummies were found exclusively on the adaxial surface of the upper leaves, and aphids in the mid canopy. The adaxial surface of the upper leaves was ca. 2 degrees C hotter that the mid-canopy. In the thermal gradient, the thermal effect (selected minus exposure temperature) was higher in magnitude in non-parasitised than in parasitised aphids; the thermal effects of both types of aphids were linearly and negatively correlated with exposure temperature (i.e. aphids showed negative thermal sensitivity). The thermal sensitivity of parasitised aphids was lower than that of non-parasitised aphids. The results are discussed in relation to hypotheses on factors governing the host-parasite relationship.

Feeding by the aphid Sipha flava produces a reddish spot on leaves of Sorghum halepense: an induced defense?

Feeding by the aphid Sipha flava produces a reddish spot on mature leaves of Sorghum halepense. The present work is aimed at determining whether this plant response entails induced resistance against the aphid. Old and young leaves showed the same response to aphid feeding (reddish coloration). Water-stressed plants displayed a similar reddish coloration to aphid-infested plants. This was verified by evaluation of absorbance peaks of the respective leaf extracts. Aphid fecundity was reduced on previously infested (and hence reddish colored) leaves. However, aphid fecundity was not affected on water stressed plants. Furthermore, aphid survival was not different on artificial diets containing increasing concentrations of the reddish pigment. It is concluded that the reddish spot is correlated with, but is not itself responsible for, the observed induced resistance of S. halepense against S. flava.

Isolation, characterization, and biological activity of naphthoquinones from Calceolaria andina L.

Two compounds recognized as responsible for the insecticidal activity of extracts of Calceolaria andina L. (Scrophulariaceae) have been isolated and characterized as 2-(1, 1-dimethylprop-2-enyl)-3-hydroxy-1,4-naphthoquinone and the corresponding acetate, 2-acetoxy-3-(1,1-dimethylprop-2-enyl)-1, 4-naphthoquinone. Their activities against 29 pest species and 9 beneficial species of arthropod from a total of 11 orders have been determined. Activities against homopteran and acarine species are of the same order as those of established pesticides, and, significantly, no cross-resistance is observed for strains resistant to established classes of insecticide. Mammalian toxicities are low.

Presence of a hydroxamic acid glucoside in wheat phloem sap, and its consequences for performance ofRhopalosiphum padi (L.) (Homoptera: Aphididae).

Phloem sap of wheat seedlings differing in whole leaf hydroxamic acid (Hx) concentrations was collected by cutting stylets of feeding aphids. DIMBOA-glucoside was the only Hx-related product found. Concentration of DIMBOA-glucoside in phloem sap showed a tendency to be negatively correlated with aphid performance.

Hydroxamic acid glucosides in honeydew of aphids feeding on wheat.

DIMBOA glucoside (2-O-/gb-D-glucopyranosyl-4-hydroxy-7-meth-oxy-1,4-benzoxazin-3-one), the main hydroxamic acid (Hx) in intact wheat plants, was detected in the honey dew ofRhopalosiphum padi feeding on seedlings of six wheat cultivars that differed in their concentration of Hx, suggesting that the chemical circulates in the phloem. Neither the aglucone (DIMBOA) nor its main breakdown product were found in any of the honeydew samples. Honey dew production by aphids caged on seedlings of the wheat cultivars and DIMBOA glucoside concentrations in the honeydew followed biphasic curves when plotted against Hx concentration, suggesting passive ingestion of the chemical from the phloem at low Hx concentrations and limited ingestion due to feeding deterrency by Hx in mesophyll cells at high Hx concentrations. The presence of plant toxins such as Hx glucosides in the phloem sap, the main ingesta of aphids, and in the mesophyll cells, has major implications for plant defense, through a feeding deterrent effect during stylet penetration, and deterrency (antixenosis) along with antibiosis during feeding.

Effect of DIMBOA, an aphid resistance factor in wheat, on the aphid predatorEriopis connexa Germar (Coleoptera: Coccinellidae).

DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one), a secondary metabolite found in cereal extracts, confers resistance in wheat to aphids. Its effect on beneficial organisms was tested on larvae of the aphid predatorEriopis connexa Germar. Larvae were fed until pupation on artificial diets to which different concentrations of DIMBOA (2-200µg/g diet) were added, as well as on aphids that had been feeding on wheat seedlings with different DIMBOA levels (140-440 µg/g fresh tissue). In diets, the effect of DIMBOA was greatest on survival of third-instar larvae and on the duration of the second and fourth instars. When aphids were provided as food, those that had fed on a wheat cultivar with an intermediate DIMBOA level led to a significantly longer larval duration in the predator than did those that fed on either low or high DIMBOA cultivars. Shortest predator development times were obtained with aphid prey that had fed on high DIMBOA seedlings. Higher DIMBOA levels in the plant appear to reduce aphid feeding rates (and rates of DIMBOA ingestion), decreasing aphid survival and minimizing the effect of the toxin on the predator.