Phenotypic plasticity of a winter-diapause mechanism copes with the effects of summer global warming in an ectothermic predator.

To adapt to changes in temperature, animals tend to invest more energy in thermal tolerance to enhance survival, which can have simultaneous costs on plastic traits. Would a decrease in genetic variability, due to global warming, affect the ability of populations with existing metabolic regulatory mechanisms to cope with extreme temperatures? To address this question, we conducted a series of experiments based on the A1B scenario of global warming, assessing within-population genetic variance in (a) morphological traits, (b) metabolic rate allometries, and (c) survival of a winter-diapausing predator ectotherm. Our study focused on the lacewing species Chrysoperla pallida, using both exogamic and endogamic artificial genetic lines. We discovered that both lines use their winter-diapausing phenotype to adapt to summer extreme temperatures caused by extreme heating conditions, but the exogamic line is prone to express phenotypic plasticity in metabolic scaling, with a trade-off between body size and mandible size, i.e. larger individuals tended to develop smaller mandibles to better survive. These findings highlight the significance of substantial phenotypic plasticity and pre-existing metabolic regulatory mechanisms in enabling ectotherms to cope with potential extreme heating occurring in global warming.

Vegetation Cover Management and Landscape Plant Species Composition Influence the Chrysopidae Community in the Olive Agroecosystem.

Habitat manipulation through the promotion of semi-natural habitats such as cover and patch vegetation is a possible means of offsetting the negative impacts of the agricultural practices. A baseline situation is crucial before any successful habitat manipulation is attempted. We studied the effects that current vegetation cover management practices have on plant composition and the potential attraction that the plant families from the semi-natural habitats could have on the Chrysopidae community, a key pest control agent, in five olive farms in Granada (Spain). Vegetation cover was assessed using a point quadrat methodology in eight transects per farm. In addition, the patch vegetation was characterized with 60 transects using a line intercept methodology. The woody patch vegetation and olive tree canopies were vacuumed using a field aspirator to collect adult Chrysopidae. In the cover vegetation we observed great variability in both the richness and diversity of plant communities caused by the vegetation cover management techniques and the transect position (in the middle of the rows or beneath the tree canopy). The plant families with the greatest plant cover were the Asteraceae and Fabaceae, where Asteraceae was favoured by tillage and Fabaceae by grazing, while in the patch vegetation, the predominant families were the Rosaceae and Fagaceae. Our results indicate that the genus Chrysoperla was mostly correlated with the Plantaginaceae, Brassicaceae and Asteraceae plant families in the cover vegetation, and with the Caryophyllaceae and Rosaceae families in the patch vegetation. The genera Apertochrysa and Pseudomallada were associated with the families Malvaceae and Poaceae in the cover vegetation, and with the families Cupressaceae, Poaceae and Pinaceae in the patch vegetation. Our study shows to the farmers the possibilities of vegetation cover management to select plant families for the cover vegetation.

The suitability of native flowers as pollen sources for Chrysoperla lucasina (Neuroptera: Chrysopidae).

Green lacewings (Neuroptera: Chrysopidae) are key biological control agents found in a broad range of crops. Given the importance of enhancing their presence and conservation, in this study, we aim to identify and to determine the relative importance of the pollen consumed by Chrysoperla lucasina (Lacroix, 1936) from 29 pollen types offered by 51 native plant species sown in an experimental farm in Villarrubia in the south of Spain. For the purposes of this study, C. lucasina specimens were captured in the late spring of 2016 and 2017. The pollen types and other components in the alimentary canal of C. lucasina were microscopically identified using the transparency method, which is a novel technique applied to green lacewings captured in the field. The results show that (i) C. lucasina feeds on over half of the pollen types offered by the sown plant species, with no differences in behaviour by sex or year; (ii) Capsella bursa-pastoris was the most frequently identified pollen type in the alimentary canal; (iii) the majority of pollen types identified correspond to sown native plant species and not to surrounding plant species; and that (iv) most of the adults studied also consumed honeydew. Our feeding study has important implications for the selection of plant mixtures for ground cover restoration and flower vegetation strips in Mediterranean agroecosystems, which complements our previous findings on how C. lucasina use native plant species as host and reproduction sites. The plant species Capsella bursa-pastoris and Biscutella auriculata, which are best suited to provide pollen, host and reproduction sites for C. lucasina in late spring, should consequently be included in the proposed plant mixtures for Mediterranean agroecosystems.

Abundance and Population Decline Factors of Chrysopid Juveniles in Olive Groves and Adjacent Trees.

Numerous species of the family Chrysopidae, commonly found in agroecosystems, whose larvae predate on several pests of economic importance, are regarded as biological control agents. Their abundance and diversity are influenced by vegetation cover, although little is known about the effects of semi-natural habitats on their populations. The objective of this study is to gain a better understanding of the relationship between the trees in semi-natural habitats adjacent to olive groves, juvenile stages of the family Chrysopidae and factors influencing their population decline, which is crucial for an effective habitat management program aimed at conserving these important predators. Using cardboard band traps (eight per tree), the juvenile stages were collected from 25 almond, oak, olive and pine trees over a one-year sampling period. The population decline was caused by parasitoids (26.5%), predators (5.1%) and unknown factors (13.2%). In addition, chrysopids established in olive trees showed the lowest rate of parasitism. We identified ten chrysopid species that emerged from the juveniles collected from almond, oak, olive and pine trees, with a predominance of Pseudomallada prasinus. The chrysopid-parasitoid complex was composed of five species; Baryscapus impeditus (Eulophidae), which was the most abundant, was preferentially associated with Chrysopa pallens, Chrysoperla lucasina and Chrysoperla mediterranea.

Late Summer Oviposition of Green Lacewings (Neuroptera: Chrysopidae) on Olive Groves and Adjacent Trees.

In this study, we assess how chrysopids (generalist predators widely used as biological control agents) use olive, almond, oak, and pine trees for oviposition. We sampled clutches of chrysopids from tree canopies in August 2016 and 2017. Additionally, we checked the stage (alive, predated, emerged, or parasitized) and the site (upper side, edge, or underside of leaves) and mode (single and cluster clutches) for oviposition in every clutch. The clutches collected alive in August 2016 were raised in the laboratory and identified to species level. No differences in clutch abundance were observed amongst tree species, years and locations, suggesting that chrysopids are geographically well spread and that all of the tree species are equally suitable to support clutches of active chrysopids in this period. Additionally, chrysopids preferred to lay their clutches on the edge and upper side of the leaves and the single clutches were the most frequent. We collected clutches of 9 chrysopid species (Neuroptera: Chrysopidae) belonging to four genera, from which Pseudomallada prasinus (Burmeister, 1839), Cunctochrysa baetica (Hölzel, 1972), and Chrysoperla mutata (McLachlan, 1898) were the most abundant. The almond trees shelter the highest chrysopid species richness. We found C. mutata as the only Chrysoperla Steinmann, 1964 species laying on the olive trees and Chrysoperla lucasina (Lacroix, 1912) and Chrysoperla pallida Henry et al., 2002 on the almond trees. Although every tree species is able to shelter a similar abundance of eggs of chrysopids, conserving different trees ensures the existence of a diverse assemblage of chrysopids that might respond to periodical perturbations and moves to olive groves in the case of a pest outbreak.

Anthropogenic impacts in protected areas: assessing the efficiency of conservation efforts using Mediterranean ant communities.

In countries with high levels of urbanization, protected areas are often subject to human disturbance. In addition to dealing with fragmentation, land managers also have to confront the loss of characteristic ecosystems due to biotic homogenization, which is the increasing similarity of species assemblages among geographically separate regions. Using ants as a model system, we explored whether anthropogenic factors negatively affect biodiversity of protected areas of a regional network. We first analysed the effect of fragmentation and human activity on ant biodiversity within protected areas. Secondly, we tested whether homogenization could occur among protected areas. We sampled 79 plots in the most common habitats of 32 protected areas in southern Spain and calculated ant community richness and diversity indices, endemic richness, and Bray-Curtis similarity indices (between pairs of plots). We related these indices with patch fragmentation and human disturbance variables, taking into account environmental, spatial and landscape covariates. We used ANOSIM to test for differences between similarity indices, specifically among levels of anthropogenic disturbance. Species richness was positively correlated with the distance from the border of the protected areas and the number of endemic species was negatively correlated with the degree of fragmentation. Ant communities were similar within each protected area but differed across regions. Human disturbance was not correlated with community similarity among sampling points. Our approach suggests how the ability of European protected areas to sustain biodiversity is limited because they remain susceptible to anthropogenic impacts. Although ant communities maintained their biological distinctiveness, we reveal how fragmentation within protected areas is important for community richness and endemism maintenance.

Armed rollers: does nestling's vomit function as a defence against predators?

Chemical defences against predators are widespread in the animal kingdom although have been seldom reported in birds. Here, we investigate the possibility that the orange liquid that nestlings of an insectivorous bird, the Eurasian roller (Coracias garrulus), expel when scared at their nests acts as a chemical defence against predators. We studied the diet of nestling rollers and vomit origin, its chemical composition and deterrent effect on a mammal generalist predator. We also hypothesized that nestling rollers, as their main prey (i.e. grasshoppers) do from plants, could sequester chemicals from their prey for their use. Grasshoppers, that also regurgitate when facing to a threat, store the harmful substances used by plants to defend themselves against herbivores. We found that nestling rollers only vomit after being grasped and moved. The production of vomit depended on food consumption and the vomit contained two deterrent chemicals (hydroxycinnamic and hydroxybenzoic acids) stored by grasshoppers and used by plants to diminish herbivory, suggesting that they originate from the rollers' prey. Finally, we showed for the first time that the oral secretion of a vertebrate had a deterrent effect on a model predator because vomit of nestling rollers made meat distasteful to dogs. These results support the idea that the vomit of nestling rollers is a chemical defence against predators.

Olive trees protected from the olive bark beetle, Phloeotribus scarabaeoides (Bernard 1788) (Coleoptera, Curculionidae, Scolytinae) with a pyrethroid insecticide: Effect on the insect community of the olive grove.

Field studies were performed in two successive years, 2005 and 2006, in different olive groves of the province of Granada (South-eastern Spain) by spraying olive trees (Olea europaea) with a pyrethroid insecticide, deltamethrin, for the control of the olive bark beetle Phloeotribus scarabaeoides (Bernard 1788) (Coleoptera, Curculionidae, Scolytinae). Three olive groves received each year three treatments in June consisting of water (control) and two insecticide doses, which were halved the second year. From June to September six olives trees per site were inspected every 15d for feeding galleries in olive branches; the arthropods, collected in traps placed below the olive trees (three traps per site), were identified and counted. Results show that feeding galleries were significantly reduced, what proves that the pyrethroid insecticide efficiently protected the olive trees from the olive bark beetle with a single application and even at the lower dose employed in 2006. Some repellent effect may occur as deduced from the number of P. scarabaeoides individuals captured. Other individuals from the insect community were also affected to a great extent by insecticide application, though no statistical differences were found among the treatments due to the high variability in insect captures. Among the parasitoids, Scelionidae, Encyrtidae, Eurytomidae and Pteromalidae were captured in great numbers. Mirids were the predators whose numbers drastically increased in traps placed under the treated trees, while spiders and ants were less affected. A knock-down effect was noticed for some insect groups, for instance mirids and Euphyllura olivina. Approximately 80% of their captures corresponded to the first date of sampling after insecticide application.

Dufour's gland secretion as a repellent used during usurpation by the slave-maker ant Rossomyrmex minuchae.

In slave-making ants, the invasion of the host colony by newly mated queens is a critical stage. We studied the strategy used by Rossomyrmex minuchae queens to invade their host Proformica longiseta. Field observations revealed that queens enter the host nest unchallenged by the host workers in the vicinity of the nest entrance. Pre-usurpation queens were found to possess a highly inflated Dufour's gland, which considerably reduces in size after successful usurpation. Chemical analysis of these queen glands revealed tetradecanal to be the major product in pre-usurpation Rossomyrmex queens, but to be almost absent in queens that have been adopted by P. longiseta. We consequently hypothesized that tetradecanal is a repellent that is used by queens to prevent host worker aggression. We tested its repellent effect by attempting to deter starved, highly motivated workers from a droplet of honey. Tetradecanal indeed proved to be highly repellent both to host worker P. longiseta and non-host worker Formica selysi. It was even more powerful than limonene, a reported general ant repellent. These results are consistent with the hypothesis that R. minuchae queens use Dufour's gland secretion as a weapon during nest usurpation. The general use of tetradecanal as a defensive compound, and its seemingly non-specific repellent effect on ants, indicate that it may act as a general ant repellent. Its adoption by R. minuchae queens thus provides them with an efficient defensive and offensive chemical weapon during their long and risky search for new host nests.

Mating behaviour in a slave-making ant, Rossomyrmex minuchae (Hymenoptera, Formicidae).

The mating behaviour of the ant Rossomyrmex minuchae, a rare, protected slave-making species in Spain, seems to be significantly affected by its particular life history and patchy habitat. The mating behaviour of the entire genus Rossomyrmex is virtually unknown. We present here the results of a 3-year study of mating behaviour in R. minuchae.Behavioural observations and limited nest excavations revealed that R. minuchae does not produce sexuals every year, the number of sexuals is low, and the sex ratio tends to be female biased. Females typically exhibit two distinct activity periods. The first, the mating period, takes place in early afternoon: the ants "call" near the natal nest, mate and then return to their nest. The second, the dispersal period takes place in late afternoon: the mated females exit their nest and fly in search of a new, non-parasitized Proformica longiseta host nest. Males are highly active during the mating period, but will remain inactive in the dispersal period even if experimentally presented with virgin females. It appears that females are monogamous, while males are polygamous. When males are late arriving at the female calling site, the females will frequently congregate presumably calling in chorus. The low reproductive efficiency exhibited by R. minuchae, coupled with the postulated low genetic variation in the population, as sisters may mate with the same male, could result in a low survival rate and risk of eventual extinction. The observed decrease in nest density we observed during the 2004 season may be indicative of such a process.