Ecological convergence in phytochemistry and flower-insect visitor interactions along an Andean elevation gradient.

The diversity of specialized molecules produced by plants radiating along ecological gradients is thought to arise from plants' adaptations to local conditions. Therefore, closely related species growing in similar habitats should phylogenetically converge, or diverge, in response to similar climates, or similar interacting animal communities. We here asked whether closely related species in the genus Haplopappus (Asteraceae) growing within the same elevation bands in the Andes, converged to produce similar floral odors. To do so, we combine untargeted analysis of floral volatile organic compounds with insect olfactory bioassay in congeneric Haplopappus (Asteraceae) species growing within the same elevation bands along the Andean elevational gradient. We then asked whether the outcome of biotic interactions (i.e., pollination vs. seed predation) would also converge across species within the same elevation. We found that flower odors grouped according to their elevational band and that the main floral visitor preferred floral heads from low-elevation band species. Furthermore, the cost-benefit ratio of predated versus fertilized seeds was consistent within elevation bands, but increased with elevation, from 6:1 at low to 8:1 at high elevations. In the light of our findings, we propose that climate and insect community changes along elevation molded a common floral odor blend, best adapted for the local conditions. Moreover, we suggest that at low elevation where floral resources are abundant, the per capita cost of attracting seed predators is diluted, while at high elevation, sparse plants incur a higher herbivory cost per capita. Together, our results suggest that phytochemical convergence may be an important factor driving plant-insect interactions and their ecological outcomes along ecological gradients.

La gran diversidad de moléculas especializadas producidas por plantas a lo largo de gradientes ecológicos se atribuye a la adaptación de plantas a sus condiciones locales. Por tanto, especies de plantas estrechamente relacionadas que crecen en hábitats similares deberían de converger en la producción de fitoquímicos similares, en respuesta a climas similares o comunidades de animales con las que interactúan. En este estudio exploramos esta hipótesis caracterizando la metabolómica no dirigida de compuestos orgánicos volátiles florales y conduciendo bioensayos olfativos de insectos en especies cogenéticas del género Haplopappus (Asteraceae) que crecen dentro de las mismas bandas altitudinales a lo largo de un gradiente altitudinal andino. Conjuntamente investigamos si el resultado de las interacciones bióticas (ej. polinización versus depredación) también convergen entre especies que crecen dentro de la misma banda altitudinal. Encontramos que los olores de las flores se agrupan de acuerdo con su banda altitudinal, y que el visitante floral más común prefiere los capítulos florales de las especies de bandas de baja elevación. Además, la relación entre el costo (depredación) y beneficio (polinización) es consistente dentro de las bandas de elevación pero incrementa con elevación, de 6:1 en elevaciones bajas a 8:1 en elevaciones altas. Por lo tanto, proponemos que los cambios climáticos y la comunidad de insectos a lo largo de la elevación resultaron en una mezcla común de olores de flores, mejor adaptada a las condiciones locales. Asimismo, sugerimos que a baja altura donde los recursos florales son abundantes, el costo per cápita de atraer a los depredadores de semillas se diluye, mientras que en sitios altos, las plantas escasas incurren en un costo per cápita de herbivoría más alto. Nuestros resultados sugieren que la convergencia fitoquímica puede ser un factor importante que impulsa las interacciones planta­insecto y sus resultados ecológicos a lo largo de gradientes ecológicos.

Erratum: Are eavesdroppers multimodal? Sensory exploitation of floral signals by a non-native cockroach Blatta orientalis.

[This corrects the article DOI: 10.1093/czoolo/57.2.162.].

Insect Epigenetic Mechanisms Facing Anthropogenic-Derived Contamination, an Overview.

Currently, the human species has been recognized as the primary species responsible for Earth's biodiversity decline. Contamination by different chemical compounds, such as pesticides, is among the main causes of population decreases and species extinction. Insects are key for ecosystem maintenance; unfortunately, their populations are being drastically affected by human-derived disturbances. Pesticides, applied in agricultural and urban environments, are capable of polluting soil and water sources, reaching non-target organisms (native and introduced). Pesticides alter insect's development, physiology, and inheritance. Recently, a link between pesticide effects on insects and their epigenetic molecular mechanisms (EMMs) has been demonstrated. EMMs are capable of regulating gene expression without modifying genetic sequences, resulting in the expression of different stress responses as well as compensatory mechanisms. In this work, we review the main anthropogenic contaminants capable of affecting insect biology and of triggering EMMs. EMMs are involved in the development of several diseases in native insects affected by pesticides (e.g., anomalous teratogenic reactions). Additionally, EMMs also may allow for the survival of some species (mainly pests) under contamination-derived habitats; this may lead to biodiversity decline and further biotic homogenization. We illustrate these patterns by reviewing the effect of neonicotinoid insecticides, insect EMMs, and their ecological consequences.

A cross-sectional study of hard ticks (acari: ixodidae) on horse farms to assess the risk factors associated with tick-borne diseases.

Zoonotic diseases are significant public health issues. There is an urgent need to focus our efforts on the development of strategies that prevent and control potential arthropod vector-borne pathogens. Hard ticks transmit a variety of viral, bacterial and protozoan pathogens to their vertebrate hosts. This is becoming of more concern, as anthropogenic alterations of the environment may unleash the spread of tick-borne diseases throughout the world. Developing countries that are highly dependent on the livestock economy are a hot spot for tick-borne infectious diseases. In this work, through a cross-sectional approach that included a bibliographic survey, field collection and epidemiological questionnaire, we identified five tick species that were found to parasitize equines and transmit tick-borne pathogens. Our data revealed a gap in fundamental knowledge of ticks and tick-borne infectious diseases among equine breeders and owners. This article highlights the relevant risk factors that were found and the urgent actions that are needed to prevent the wide spread of hard ticks and their associated zoonotic diseases.

Hyalomma anatolicum resistance against ivermectin and fipronil is associated with indiscriminate use of acaricides in southwestern Balochistan, Pakistan.

Ivermectin and fipronil have been used regularly to control the hard tick Hyalomma anatolicum (Acari: Ixodidae) in domestic ruminants for more than a half-decade in Balochistan, Pakistan. Inappropriate and indiscriminate use of these acaricides has resulted in the development of resistances in tick species. In this work, acaricides (ivermectin and fipronil) resistance was evaluated in H. anatolicum through in vitro and in vivo bioassays in a horse farm of Quetta, Balochistan province, Pakistan. A participatory epidemiological survey was conducted to assess potential risk factors associated with the development of acaricide resistance in H. anatolicum. The results of the epidemiological survey revealed that the horse keepers did not follow the manufacturer's instructions for the use of acaricides and applied indiscriminate doses of acaricides. The results of in vitro bioassays (adult immersion test and larval immersion test) showed that fipronil and ivermectin have protective efficacy against H. anatolicum. The results of in vivo bioassay (adult-tick mortality assay) revealed that fipronil had a higher efficacy (78.16%) than ivermectin (49.94%). More than 80% of tick mortality was not achieved in any bioassays, even for the highest acaricide concentration (100 ppm), which suggests the development of acaricide resistance against fipronil and ivermectin. This study highlights the urgency to implement a country-wide awareness about resistance monitoring and effective tick control. Graphical abstract.

Native bees of high Andes of Central Chile (Hymenoptera: Apoidea): biodiversity, phenology and the description of a new species of Xeromelissa Cockerell (Hymenoptera: Colletidae: Xeromelissinae).

High-altitude ecosystems are found in mountain chains and plateaus worldwide. These areas tend to be underrepresented in insect biodiversity assessments because of the challenges related to systematic survey at these elevations, such as extreme climatic and geographic conditions. Nonetheless, high-altitude ecosystems are of paramount importance because they have been seen to be species pumps for other geographic areas, such as adjacent locations, functioning as buffers for population declines. Moreover, these ecosystems and their biodiversity have been proposed to be fast-responding indicators of the impacts caused by global climate change. Bees have been highlighted among the insect groups that have been affected by these problems. This work used bees as a proxy to demonstrate and reinforce the importance of systematic surveys of high-altitude ecosystems. Here, field collections were undertaken and an updated review was conducted for the native bee biodiversity of the high-altitude ecosystem found at the Andes system of central Chile, including the phenological trends of these insects during the flowering season. Of the 58 species that have been described for this location, we were able to confirm the occurrence of 46 of these species as a result of our sampling. In addition, thanks to these recent collections, a new species of Xeromelissa Cockerell is described in the present work. These findings highlight the need for further high-altitude insect surveys of this biome, which include both temporal and spatial complexity in their design, to allow for accurate assessment of bee species diversity and compositional changes in these mountain regions.

Nicosulfuron sorption kinetics and sorption/desorption on volcanic ash-derived soils: Proposal of sorption and transport mechanisms.

Nicosulfuron sorption/desorption kinetics were studied through batch sorption studies in ten volcanic ash-derived Andisol and Ultisol soils with acidic pH and variable surface charge. Two different kinetic models were used to fit the experimental data: i) Models to establish kinetic parameters (Pseudo-First and Pseudo-Second-Order), and ii) Models to describe solute transport mechanisms of organic compounds on sorbents (Intraparticle Diffusion, Dimensionless Intraparticle, Boyd, and Two-Site Nonequilibrium). Sorption kinetic data best fit the pseudo-second-order model. Application of these models to describe solute transport suggests that underlying mechanisms are complex in all soils due to: i) surface sorption, with mass transfers controlling sorption kinetics across the boundary layer; and ii) pore diffusion (i.e. intraparticle diffusion into macropores and micropores). The Freundlich model explained equilibrium sorption data in all cases (R2 > 0.9979) with Kf values higher than those reported for different class of soils (6.85-16.08 µg1-1/n mL1/n  g-1). The hysteresis was significant in all studied soils. The lower sorption rate on Ultisols must be considered in regards to Nicosulfuron leaching potential.

Bees may drive the reproduction of four sympatric cacti in a vanishing coastal mediterranean-type ecosystem.

BACKGROUND: Sympatric congeneric plants might share pollinators, or each species might avoid competition by evolving specialized traits that generate partitions in pollinator assemblages. In both cases, pollen limitation (a decrease in the quality and quantity of compatible reproductive pollen) can occur, driving the plant mating system to autogamy as a mechanism of reproductive assurance. We assessed the relationships between pollinator assemblages and mating systems in a group of sympatric congeneric plants. We attempted to answer the following questions: (i) How similar are pollinator assemblages among sympatric cactus species? (ii) Which mating systems do sympatric cactus species use? METHODS: We studied sympatric Eriosyce taxa that inhabit a threatened coastal strip in a mediterranean-type ecosystem in central Chile. We performed field observations on four taxa and characterized pollinators during the years 2016 and 2017. We estimated differences in the pollinator assemblages using the Bray-Curtis index. To elucidate the mating systems, we conducted hand-pollination experiments using three treatments: manual cross-pollination, automatic self-pollination, and control (unmanipulated individuals). We tested differences in seed production for statistical significance using Kruskal-Wallis analysis. RESULTS: Eriosyce subgibbosa showed a distinctive pollinator assemblage among the sympatric species that we studied (similarity ranged from 0% to 8%); it was visited by small bees and was the only species that was visited by the giant hummingbird Patagona gigas. Pollinator assemblages were similar between E. chilensis (year 2016 = 4 species; 2017 = 8) and E. chilensis var. albidiflora (2016 = 7; 2017 = 4); however, those of E. curvispina var. mutabilis (2016 = 7; 2017 = 6) were less similar to those of the aforementioned species. E. curvispina var. mutabilis showed the highest interannual variation in its pollinator assemblage (18% similarity). Reproduction in E. subgibbosa largely depends on pollinators, although it showed some degree of autogamy. Autonomous pollination was unfeasible in E. chilensis, which depended on flower visitors for its reproductive success. Both E. chilensis var. albidiflora and E. curvispina var. mutabilis showed some degree of autogamy. DISCUSSION: We observed differences in pollinator assemblages between E. subgibbosa and the remaining Eriosyce taxa, which depend on hymenopterans for pollen transfer. Pollinator assemblages showed considerable interannual variation, especially those of E. subgibbosa (ornithophilous syndrome) and E. curvispina var. mutabilis (melitophilous syndrome). Autogamous reproduction in these taxa may act as a reproductive assurance mechanism when pollinator availability is unpredictable. Our study contributes to improving our understanding of the reproductive systems of ecological interactions between threatened species in a Chilean mediterranean-type ecosystem.

Electrochemical method to study the environmental behavior of Glyphosate on volcanic soils: Proposal of adsorption-desorption and transport mechanisms.

Glyphosate is used extensively worldwide, but current evidence suggests detrimental effects on the environment, pollinators, and human health. Glyphosate adsorption kinetics and adsorption/desorption were studied through batch sorption experiments in ten typical volcanic ash-derived soils from Andisol and Ultisol orders. Two kinetic models were used to fit the experimental data: i. Models that allowed establishment of principally kinetic parameters and modeling of the adsorption process, and ii. Models described solute transport mechanisms commonly used for remediation purposes. Adsorption kinetic data were best fitted by the pseudo-second-order kinetic model and Two-Site Nonequilibrium model. These models suggest that mechanisms are complex due to rapid surface adsorption in ultisols with mass transfer controlling adsorption kinetics across the boundary layer, as indicated by the highhand lowt1/2values. High intraparticle diffusion into macropores and micropores was observed for Andisols. The Freundlich model accurately represented adsorption equilibrium data in all cases (R2 > 0.9580) with comparatively higher adsorption capacity on Andisols. Kf values (2.50-52.28 µg1-1/n mL1/n g-1) and hysteresis were significant in all studied soils. Taken together, these data suggest that Glyphosate may be adsorbed more on Andisol soils in comparison to Ultisols.

Differences in larval emergence chronotypes for sympatric Rhagoletis brncici Frías and Rhagoletis conversa (Bréthes) (Diptera, Tephritidae)

ABSTRACT In central Chile, Rhagoletis brncici and R. conversa, can be found in sympatry, associated with the fruit of their native host plants: Solanum tomatillo and S. nigrum (Solanaceae), respectively. Third-stage larvae must emerge from its host in search of pupation sites, and during this period larvae must find an appropriate pupation microhabitat while avoiding predation and adverse abiotic factors. In this study, we explored whether these sympatric species differ in terms of the timing of their larval exit from the host fruit in search of pupation sites. Field-collected fruits from host plants were checked daily for larval emergence, within 24 h, under laboratory conditions, in order to determine the time of the event. We found that these species differed significantly in their diel larval emergence. For R. brncici, most larvae left the host fruit between late evening and past midnight, meanwhile larvae from R. conversa concentrated their peak of emergence near midnight and early morning. We discuss these findings in terms of the ecological and evolutionary implications of the temporal separation of larval emergence regarding the use of pupation sites, abiotic stress and risk of predation for these sympatric species.

Along urbanization sprawl, exotic plants distort native bee (Hymenoptera: Apoidea) assemblages in high elevation Andes ecosystem.

Native bees contribute a considerable portion of pollination services for endemic as well as introduced plant species. Their decline has been attributed to several human-derived influences including global warming as well as the reduction, alteration, and loss of bees' habitat. With human expansion comes along the introduction of exotic plant species with negative impacts over native ecosystems. Anthropic effects may even have a deeper impact on communities adapted to extreme environments, such as high elevation habitats, where abiotic stressors alone are a natural limitation to biodiversity. Among these effects, the introduction of exotic plants and urbanization may have a greater influence on native communities. In this work, we explored such problems, studying the relationship between the landscape and its effect over richness and abundance of native bees from the subandean belt in the Andes mountain chain. Furthermore, we investigated the effects of exotic plant abundance on this high-altitude bee assemblage. Despite the landscape not showing an effect over bee richness and abundance, exotic plants did have a significant influence over the native bee assemblage. The abundance of exotic plants was associated with a relative increase in the proportion of small and medium bee species. Moreover, Halictidae was the only family that appeared to be favored by an increase in the abundance of exotic plant species. We discuss these results and the urgent need for further research of high-altitude environments due to their vulnerability and high endemicity.

Stress in the Educational System as a Potential Source of Epigenetic Influences on Children's Development and Behavior.

Despite current advances on the relevance of environmental cues and epigenetic mechanisms in biological processes, including behavior, little attention has been paid to the potential link between epigenetic influences and educational sciences. For instance, could the learning environment and stress determine epigenetic marking, affecting students' behavior development? Could this have consequences on educational outcomes? So far, it has been shown that environmental stress influences neurological processes and behavior both in humans and rats. Through epigenetic mechanisms, offspring from stressed individuals develop altered behavior without any exposure to traumatizing experiences. Methylated DNA and noncoding RNAs regulate neurological processes such as synaptic plasticity and brain cortex development in children. The malfunctioning of these processes is associated with several neurological disorders, and these findings open up new avenues for the design of enriched environments for education and therapy. In this article, we discuss current cases of stress and behavioral disorders found in youngsters, and highlight the importance of considering epigenetic processes affecting the development of cognitive abilities and learning within the educational environment and for the development of teaching methodologies.

Pest Cockroaches May Overcome Environmental Restriction Due to Anthropization.

Our species have altered their surroundings since its early dispersion on Earth. Unfortunately, thanks to human-modified habitats, several pest organisms such as domiciliary insects have expanded their distributions. Moreover, pest-related microorganisms may also be aided by anthropization. Pest cockroaches are globally distributed and capable of carrying several diseases. We explored if urbanization may buffer environmental conditions allowing pest insects to expand their distribution. Specifically, we suggest that human settlements may generate suitable microhabitats for synanthropic cockroaches, helping them to survive and establish with disregard to overall climatic restrictions. To test this idea we studied the distribution of pest cockroaches spanning the length of Chilean territory. Chile, along its 4270 km length north to south extent, is a country offering a formidable sampling of Earth's climatic diversity accompanied by dense urbanizations. We studied entomological collections and spatially analyzed pest cockroach distribution found in Chile and discovered that synanthropic cockroach populations are consistently concentrated near most urban developed zones of the country and not limited by overall temperature. Furthermore, health-concern pest cockroach species were widely distributed in Chilean territory, found even in its most southern urban centers as well as Easter Island. Therefore, these disease vectors could exist even in isolated and extreme climatic zones as long as urbanization provides the adequate microhabitat. We discuss the need for further research in order to assess if these distributions can be extrapolated to the pathogenic strains these pest insects may be carrying as reported in other regions of the planet.

Lioptilodes friasi (Lepidoptera: Pterophoridae) Niche Breadth in the Chilean Mediterranean Matorral Biome: Trophic and Altitudinal Dimensions.

Understanding the factors driving the diet breadth of phytophagous insects remains one of the main questions in ecological research. In this study we explored the diet breadth and plant-insect associations in the plume moth Lioptilodes friasi Vargas & Parra (Lepidoptera: Pterophoridae). This phytophagous insect was originally described in association with a single host species, Haplopappus foliosus (Asteraceae), a native shrub of the Chilean Mediterranean matorral. In order to address the breadth of host plant choice, we surveyed other Haplopappus species growing along the elevation gradient of central Chile from sea level to 2600 m. We were able to obtain L. friasi adults from five additional Haplopappus species: Haplopappus chrysantemifolius and Haplopappus decurrens from the coastal zone, Haplopappus multifolius and Haplopappus schumanii from the mid-elevation zone, and Haplopappus scrobiculatus at high elevation. Our results demonstrate that the genus-specialized endophagous herbivore L. friasi has a wider distribution and climatic tolerance than previously described. Its biogeographical range extends from the lowland coastal habitats up to the Andean subnival level. We propose that shared flower phenotypic traits such as morphology and chemical composition may have allowed the colonization of closely related Haplopappus species in central Chile, the expansion of which is limited by the harsh high elevation conditions.

A new genus and species of Lasiopteridi (Diptera, Cecidomyiidae) on Haplopappus foliosus (Asteraceae) from Chile

ABSTRACT A new genus and species of gall midge, Haplopappusmyia gregaria, is described and illustrated (larva, pupa, male, and female). This species induces apical galls on Haplopappus foliosus (Asteraceae), an endemic shrub from central Chile. The specimens were collected at La Ligua Municipality, Petorca Province, Valparaiso region, Chile, during spring of 2011-2014. This area corresponds to one of the fifth Mediterranean Matorral biome, considered among Earth's biodiversity hotspots. The new genus is characterized by presenting lateral margin of antennal scape with a mesal reentrance; four-segmented palpus, one-toothed tarsal claws, R5 straight, reaching C anterior to wing apex; male seventh and eighth tergites lacking sclerotization mesally, beyond proximal margin; presence of trichoid sensilla on the abdominal terga and sterna of both sexes, protrusible ovipositor with elongate fused cerci, and larva with 4 pairs of setose terminal papillae.

Distribution, habitat use and plant associations of Moluchia brevipennis (Saussure, 1864) (Blattodea: Ectobiidae): an endemic cockroach from Chilean Mediterranean Matorral biome

ABSTRACT Wild cockroaches are often described as abundant and diverse insects from wet tropical zones; however, they can also be found in arid and semiarid areas. It is proposed that in these drier environments cockroach survival may dependent on its tight association with native plant species. In this work, using bait trapping and active collection methods, we surveyed cockroach species along central Chile coastal scrubland; the southern limit of the semiarid Mediterranean Matorral biome in the Neotropical Region (32° S). Based on morphological and DNA barcoding methods we found that our collected cockroaches belonged to native species Moluchia brevipennis (Saussure, 1864) (Blattodea: Ectobiidae). Furthermore, thanks to field sampling, we noticed for the first time that M. brevipennis predominantly can be found in patches of native vegetation from Matorral biome, for instance, associated to endemic plant species from Puya (Bromeliaceae) genus, where we recorded these wild cockroaches feeding on flowers at dusk. Under the light of these findings, we discuss the relevance of the association between M. brevipennis and native plants for its survival in this semiarid habitat, its potential ecological function and the ongoing hazards for native insect species resulting from nearby urban sprawl in coastal central Chile.

The Importance of ncRNAs as Epigenetic Mechanisms in Phenotypic Variation and Organic Evolution.

Neo-Darwinian explanations of organic evolution have settled on mutation as the principal factor in producing evolutionary novelty. Mechanistic characterizations have been also biased by the classic dogma of molecular biology, where only proteins regulate gene expression. This together with the rearrangement of genetic information, in terms of genes and chromosomes, was considered the cornerstone of evolution at the level of natural populations. This predominant view excluded both alternative explanations and phenomenologies that did not fit its paradigm. With the discovery of non-coding RNAs (ncRNAs) and their role in the control of genetic expression, new mechanisms arose providing heuristic power to complementary explanations to evolutionary processes overwhelmed by mainstream genocentric views. Viruses, epimutation, paramutation, splicing, and RNA editing have been revealed as paramount functions in genetic variations, phenotypic plasticity, and diversity. This article discusses how current epigenetic advances on ncRNAs have changed the vision of the mechanisms that generate variation, how organism-environment interaction can no longer be underestimated as a driver of organic evolution, and how it is now part of the transgenerational inheritance and evolution of species.

Spatiotemporal variation in the reproductive ecology of two parapatric subspecies of Oenothera cespitosa (Onagraceae).

UNLABELLED: • PREMISE OF THE STUDY: Flowering plants that rely on pollinators for most of their reproduction may experience unpredictable and inconsistent availability of effective pollinators throughout their reproductive lifetime. We investigated the reproductive ecology of two subspecies of the tufted evening primrose, Oenothera cespitosa, which occupy geographically and edaphically distinct habitats in western North America: O. cespitosa subsp. navajoensis inhabits sandstone soils on open sites or rocky slopes in the Colorado Plateau and O. cespitosa subsp. cespitosa grows in clay soils on talus slopes and exposed rocky ridges in the western Great Plains and northern Rocky Mountains of the United States. • METHODS: Pollen augmentation and selfing experiments, floral visitor observations, and single-visit effectiveness experiments were conducted over 4 years to examine the breeding system and spatiotemporal variation in pollinator behavior, assemblage, and abundance at different populations for each subspecies. • KEY RESULTS: Both subspecies of O. cespitosa were self-incompatible and pollen-limited, suggesting that the relative abundance, effectiveness, and movement patterns of different insects as pollinators influenced the quality and quantity of seed production in these plants. Medium-sized vespertine hawkmoths (Hyles lineata, Sphinx vashti) were effective pollinators when present, as were large matinal bees (Anthophora affabilis, A. dammersi, Xylocopa tabaniformis androleuca), whereas small oligolectic Lasioglossum bees primarily functioned as pollen thieves in the evening and morning. • CONCLUSIONS: These findings highlight the importance of variability of pollinator composition and abundance in the evolution of plant breeding systems and reproductive success at varying spatial and temporal scales.

The effect of larval and early adult experience on behavioural plasticity of the aphid parasitoid Aphidius ervi (Hymenoptera, Braconidae, Aphidiinae).

The relevance of the integration of preimaginal and eclosion experiences on the subsequent habitat preferences and mate finding by the adult has been rarely tested in holometabolous insects. In this work, the effect of larval and early adult experiences on the behavioural responses of adult males of the aphid parasitoid, Aphidius ervi, towards volatiles from the host-plant complex (HPC) and from conspecific females were evaluated. Two experience factors were considered: host diet (normal diet=ND; artificial diet=AD), and eclosion, i.e. extraction or non-extraction of the parasitoid larva from the parasitised aphid (extracted=EX; non-extracted=NE). Thus, four treatments were set up: ND/NE, ND/EX, AD/NE and AD/EX. Glass Y-tube olfactometers were used to investigate the responses of adult A. ervi males to the odour sources used. Males from the ND/NE treatment showed a shorter latency to the first choice of olfactometer arms, displayed a marked preference towards the HPC olfactometer arm, and spent more time in the HPC arm than males from the other treatments. Only the interaction of host diet and eclosion experiences proved to be relevant in explaining the differences in latency to first choice, time spent in olfactometers arms, and behaviours displayed in the olfactometer arms. These results show the importance of the integration of larval and eclosion experiences in the development of stereotyped responses of the adults. This process may involve memory retention from the preimaginal and emergence period, but further research is needed to disentangle the contribution of each stage. The response to conspecific females was much less affected by the treatments in relation to first arm choice and times in olfactometer arms, suggesting a pheromone-mediated behaviour, even though a prompter and more intense wing fanning courtship behaviour was registered in the ND/NE males compared to males from the AD/NE treatment. These results show that sexual behaviours are less affected by early experiences than behaviours related with finding a HPC for foraging or oviposition. Taken together, our results demonstrate for first time that larval and eclosion experiences affect in a differential way the early responses of the adult towards environment-derived cues and mate related cues.

Pre-pupation behaviour of the aphid parasitoid Aphidius ervi (Haliday) and its consequences for pre-imaginal learning.

Olfactory learning may occur at different stages of insect ontogeny. In parasitoid wasps, it has been mostly shown at adult emergence, whilst it remains controversial at pre-imaginal stages. We followed larval growth of the parasitoid wasp, Aphidius ervi Haliday, inside the host aphid, Acyrthosiphom pisum Harris, and characterised in detail the behaviour of third instar larvae. We found that just before cocoon spinning begins, the third instar larva bites a hole through the ventral side of the mummified aphid exoskeleton. We then evaluated whether this period of exposure to the external environment represented a sensitive stage for olfactory learning. In our first experiment, the third instar larvae were allowed to spin their cocoon on the host plant (Vicia faba L.) surface or on a plastic plate covering the portion of the host plant exposed to the ventral opening. Recently emerged adults of the first group showed a preference for plant volatiles in a glass Y-olfactometer, whereas no preference was found in adults of the second group. In a second experiment, during the period in which the aphid carcass remains open or is being sealed by cocoon spinning, third instar larvae were exposed for 24 h to either vanilla odours or water vapours as control. In this experiment, half of the parasitoid larvae were later excised from the mummy to avoid further exposure to vanilla. Adult parasitoids exposed to vanilla during the larval ventral opening of the mummy showed a significant preference for vanilla odours in the olfactometer, regardless of excision from the mummy. The larval behaviour described and the results of the manipulations performed are discussed as evidences for the acquisition of olfactory memory during the larval stage and its persistence through metamorphosis.