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Citizen science is a valuable tool for early detection, distribution, and spread of invasive alien species (IAS). Nevertheless, citizen science initiatives have several potential biases and may be complemented with long-term structured monitoring schemes. We analyzed the spatial-temporal dynamics of the invasion of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) in Chile, based upon two citizen sciences databases (WEB and INAT) and one structured monitoring (SAG). We collected 8638 H. axyridis occurrences between 2009 and 2020. WEB had a higher number of records than SAG and INAT, and in all databases, the number of records has increased over time. The three databases showed that the invasion started in central Chile and then spread toward the north and south. The WEB and SAG recorded occurrences in the extreme north and south, whereas INAT concentrated all the occurrences in a more limited area, included in WEB and SAG. Both citizen science initiatives concentrated their records in areas of high human populations whereas SAG records had a more even distribution across regions. At 2020, WEB accounted for 55%, SAG 54%, and INAT 8% of the total area accumulated with H. axyridis, with only 16% of area shared among databases. WEB and INAT obtained most of their records in urban and industrial land cover types, while SAG records were more evenly represented in different land cover types. Our results confirm that combined methods, including citizen science initiatives, national surveillance system, and localized samplings, complement each other in providing knowledge to understand the patterns, processes, and consequences of this invasion.

The invasion of Harmonia axyridis has had negative consequences on coccinellid assemblages, with a decline in abundance and diversity, but the coexistence of invasive and resident species may depend on the strength of intra- and interspecific exploitative competitive interactions. These antagonistic interactions have been scarcely studied in coccinellids. Through a laboratory study we assessed aphid consumption, weight gain and reproduction when the invasive Harmonia axyridis, the alien Hippodamia variegata and the native Eriopis chilensis were alone, in conspecific and heterospecific groups, at low and high aphid densities. Under intraspecific competition, coccinellids were more voracious than when they were alone, particularly H. axyridis and H. variegata at high aphid density; H. axyridis and H. variegata gained more weight than E. chilensis, and H. axyridis barely reproduced at low aphid densities, even when alone, while in the other two species reproduction was not affected by the presence of conspecifics. Under interspecific competition, weight gain and reproduction results suggest that H. axyridis was responsible for most aphid consumption; H. variegata gained less weight and barely reproduced in heterospecific groups, but its reproduction was not affected. Eriopis chilensis weight gain and reproduction was low but not affected by the presence of the other species. The lack of negative effects of intraspecific competition on H. axyridis and its better performance in heterospecific groups suggests that this species is the stronger competitor, negatively affecting H. variegata, but not E. chilensis. Thus, exploitative interspecific competition is an important mechanism explaining the dominance of H. axyridis and the decline of some species following its invasion. Therefore, this interaction deserves more attention than what has been paid up to now.

We tested two questions: (i) whether the climatic conditions of the Azorean Islands in Portugal may have restricted the invasion of Harmonia axyridis across this archipelago and (ii) determine what population of this species could have a higher probability of invading the islands. We used MaxEnt to project the climate requirements of different H. axyridis populations from three regions of the world, and the potential global niche of the species in the Azorean islands. Then we assessed the suitability of the islands for each of the three H. axyridis populations and global potential niche through histograms analysis, Principal Component Analysis (PCA) of climate variables, and a variable-by-variable assessment of the suitability response curves compared with the climatic conditions of the Azores. Climatic conditions of the Azores are less suitable for the U.S. and native Asian populations of H. axyridis, and more suitable for European populations and the global potential niche. The PCA showed that the climatic conditions of the islands differed from the climatic requirements of H. axyridis. This difference is mainly explained by precipitation of the wettest month, isothermality, and the minimum temperature of the coldest month. We concluded that the climatic conditions of the Azores could have influenced the establishment and spread of H. axyridis on these islands from Europe. Our results showed that abiotic resistance represented by the climate of the potentially colonizable zones could hinder the establishment of invasive insects, but it could vary depending of the origin of the colonizing population. A.A.G thanks FONDECYT 1140662 and A.O.S thanks the grants of Direção Regional da Ciência e Tecnologia within the project M1.1.a/009/Funcionamento-C- /2016 (GBA) and Fundação para a Ciência e Tecnologia within the -UID/BIA/00329/2013 project. E.B.A’s modeling work with the CIELO model was developed within the framework of the project PROAAcXXIs (PO Açores 01-0145-FEDER-000037). info:eu-repo/semantics/publishedVersion

6th International Entomophagous Insects Conference, Perugia, 9-13 September 2019. Since the late 19th century, exotic ladybirds (Coleoptera: Coccinellidae) have been used extensively for suppressing herbivorous insects of economic importance. In recent decades, the introduction of non-native biological control (BC) agents has been greatly limited due to the awareness of the potential non-target effects of introductions. Nonetheless, recent episodes of biological invasions of economically important pests have raised the need to carefully consider whether the expected benefits of pest control go beyond the possible environmental risks of introduction. To better understand the factors that contributed to successful BC programs, here we review the literature behind classical and augmentative BC using exotic ladybirds. Additionally, by means of case studies, we discuss the BC efficacy of selected exotic species, e.g., Coccinella septempunctata L., Harmonia axyridis (Pallas), and Hippodamia variegata (Goeze), and their position within the communities of predators in the introduced areas of USA, Canada, and Chile. In Europe, much of the research on exotic ladybirds has been conducted on the undesired impact of H. axyridis. Therefore, we summarize the risk assessment data for this species and review the field research investigating the ecological impact on European aphidophagous predators. According to the BIOCAT database of classical BC programs, 212 ladybird species belonging to 68 genera have been released in about 130 years of BC activity, with 14.6% of introductions having resulted in partial, substantial, or complete control of the target pest. However, because post-release evaluation of establishment and BC success has not always been conducted, this rate could underestimate the successful cases. Among other factors, ladybird establishment and pest suppression mostly depend on (1) intrinsic factors, i.e., high voracity, synchronized predator-prey life cycle, and high dispersal ability, and (2) extrinsic factors, i.e., adaptability to the new environment and landscape composition. This review contributes to improved understanding of ladybirds as exotic BC agents. info:eu-repo/semantics/publishedVersion

Fil: Zamorano, Jorge. Universidad de Chile. Programa de Doctorado en Ciencias Silvoagropecuarias y Veterinarias. Facultad de Ciencias Veterinarias y Pecuarias. Santiago, Chile. Fil: Bartomeus, Ignasi. Estación Biológica de Doñana. Sevilla, España. Fil: Grez, Audrey A. Universidad de Chile. Facultad de Ciencias Veterinarias y Pecuarias. Santiago, Chile. Fil: Garibaldi, Lucas A. Universidad Nacional de Río Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina. Fil: Garibaldi, Lucas A. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina. Pendiente a incorporación en un volumen de la revista Conventional intensification of agriculture has reduced the availability of resources for pollinators, reducing their diversity and affecting plant pollination, both in natural habitats and croplands. Field margin floral enhancements such as flower strips or restored field margins could counteract these negative effects. The approaches to assess the success of these management measures generally evaluate separately the pollinator response at the edge and within the crop, as proxies for pollinator conservation and pollination services, respectively. We performed a meta‐analysis to understand the influence of field margin floral enhancements on the abundance and richness of pollinators at the edge and within the field, and on crop yield. We estimated 137 effect sizes from 40 studies, all from the northern hemisphere. Overall, the field margin floral enhancements increased the abundance and richness of pollinators at the field edge but had no consistent effect in the interior of the crop fields. Few studies evaluated crop yield, and in these studies no effects were observed. These results suggest that field margin floral enhancements can constitute a positive conservation action for pollinators but not necessarily associated with pollination ecosystem service.

The replacement of native forests by Pinus radiata plantations modifies habitat availability and quality for wildlife, constituting a threat to species survival. However, the presence of understory in mature pine plantations minimizes the negative impacts of native forest replacement, rendering a secondary habitat for wildlife. Whether forest-dwelling species recolonize clear-felled areas pending on the spontaneous development of accompanying vegetation growing after harvesting is yet to be assessed. In this context, we analyze the abundance, movement and habitat selection of the endemic ground beetle Ceroglossus chilensis (Coleoptera: Carabidae) in an anthropic forest landscape consisting of native forest remnants, adult pine plantations (> 20 years) with a well-developed understory, and young (1–2 years) pine plantations with varying degrees of accompanying vegetation development. Particularly, we analyze the likelihood that C. chilensis would recolonize young pine plantations depending on the presence (> 70% cover) or the absence (

1. Harmonia axyridis has invaded many regions of the world, with negative effects on local biodiversity, and thus it is of global concern for biological conservation. Recently it has invaded central Chile, one of the world’s biodiversity hotspots, where the abundance and richness of ladybird species, particularly native species in agroecosystems, have declined following its arrival. \ud 2. Harmonia axyridis is particularly abundant in spring in the valleys of central Chile, but there is a dramatic decline in its abundance during the hot summer months. \ud 3. This study reports the occurrence of this invasive alien species in the summer at high altitudes (3578 m asl) in the Andes, which is the highest record worldwide. Individuals were observed on native cushion plants, in a unique environment rich in endemic species. Harmonia axyridis were active, reproducing and co-occurring with three other species of coccinellids. \ud 4. The dispersal of H. axyridis and other coccinellids from the valleys to high altitudes could represent a mechanism to escape the adverse high temperatures during the summer, returning to the valleys in autumn. Our study highlights the need to study the impacts of invasive alien species across a range of habitats, including not only agricultural landscapes, but also extreme ecosystems.

Mediterranean ecosystems have been recognized as a priority for biodiversity conservation due to their high levels of species richness and endemism. In South America, these environments are restricted to central Chile and represent a biodiversity hotspot. The study of saproxylic beetles in this area is an unexplored topic, despite the ecological role they play in these ecosystems and their potential usefulness for monitoring the degree of forest conservation. We investigated the diversity distribution of trophic guilds of saproxylic beetles in Chilean Mediterranean forests, to identify the main environmental variables that influence their distribution. We also analyzed seasonal dynamics as a key factor influencing insect communities and the effect of human disturbance on their diversity and composition. We identified characteristic species of perturbation degree as bioindicators for habitat monitoring. A total of 40 window traps were used to survey three Mediterranean forest types in the Río Clarillo National Reserve and the adjacent non-protected areas. We found that the diversity, abundance and composition of saproxylic beetles varied significantly spatiotemporally among the studied forest types and among perturbation degrees, showing different patterns depending on the trophic guild. Results indicated that conservation decisions should include the preservation of a larger range of different vegetation types and the nearby zones that have suffered low levels of disturbance or fragmentation and where actions promoting the presence of old native trees would have a significant conservation value. Financial support was given by the research Project FONDECYT 3140322 (Fondo Nacional de Ciencia y Tecnología) of the Chilean Government.

Records of extreme altitudes where several coccinellid species from SouthAmerica inhabit the Andes of Argentina, Bolivia, Chile, Colombia, Ecuador,and Peru are provided. After an intensive review of several entomologicalcollections and literature, records for 35 species with at least one locationover 3500-m elevation were obtained, including the genera Cycloneda(ten species), Eriopis (15 species and one subspecies), Harmonia (one species),Hippodamia (two species), Mimoscymnus (two species), Psyllobora(one species), and Stenadalia (four species). In total, 184 location recordsare listed, of which 119 were frombetween 3000 and 4000m, 57 between4000 and 4900 m and eight above 4900 m, with the highest altituderecord at 5250 m for Eriopis minima Hofmann. All records above4000 m were obtained in the Puna biogeographic province within theParamo Puneña biogeographic subregion. These records are the highestaltitudes observed for the American continent and by far surpass othersknown for coccinellids worldwide. Several species of coccinellids living insympatry at these high altitudes were verified, and in some cases, in situ development was inferred by the presence of immature stages. Thesefindings are important to foresee the future effects of global warming thatwill affect especially the biological communities of extreme altitudes.

Tree plantations may play a role in the conservation of global forest biodiversity. At the landscape scale, plantations with a complex understory may provide surrogate habitats for forest-dwelling organisms. This was tested using a manipulative experiment in which the abundance, movement and survivorship of Ceroglossus chilensis (an endemic and flightless ground beetle) was examined in plantation forest stands where the density of the understory vegetation was manipulated. Between 2009 and 2012, we collected C. chilensis by pitfall trapping in nineteen plots with naturally high, naturally low and experimentally removed understory cover. Beetle movement was evaluated by direct observation, and survival was quantified as the proportion of days that individuals survived in closed and open containers half-buried in the soil. C. chilensis exhibited higher abundance in plots with naturally high than with low or experimentally removed understory cover. Beetles traveled shorter distances and preferred to stay in stands with developed understory. C. chilensis had significantly higher mortality by predators in plantations with scarce understory cover. Therefore, forest plantations with a dense understory can become surrogate habitats for C. chilensis, and may contribute to the conservation of its populations.

The current trend toward simplification of agricultural landscapes, as well as the associated loss of perennial cover types, can decrease landscape heterogeneity and also natural enemy abundance and diversity, favouring exotic species. We evaluated the effects of agricultural landscape composition and heterogeneity at two different spatial scales (radii of 250 and 1000 m), on the diversity and abundance of native and exotic coccinellids, associated with alfalfa fields located in two regions of Central Chile. Data were analyzed using partial least square regressions, considering the whole coccinellid assemblage and the three most abundant species. In both regions, coccinellid diversity and the abundance and proportion of native coccinellids in alfalfa responded differentially from total abundance and the abundance of exotic coccinellids. The diversity and abundance of coccinellids in alfalfa increased with the compositional and configurational heterogeneity of the landscape. The abundance of both native and exotic coccinellids in alfalfa fields decreased as the area covered by cultivated lands, such as annual crops and orchards, increased. Nevertheless, the responses of native and exotic coccinellids were not consistent among regions, which may be explained by responses of the dominant species in each region. The results of the present study suggest that variables related to a higher intensification of agricultural landscapes (lower compositional and configurational heterogeneity, as well as more annual crops) reduce coccinellid diversity and abundance in alfalfa fields. To maintain a higher abundance and diversity of these natural enemies in alfalfa, more heterogeneous landscapes with less annual crops should be promoted.

Predators are important natural enemies, often responsible for preventing pest population outbreaks of in many crops. Complementarity in resource use involves spatial or temporal segregation of predators, which can result in better biological control when several species of natural enemies share a prey. In this study, we investigated the seasonal, spatial and diel segregation of Acyrthosiphon pisum predators and its predation in alfalfa fields, by setting out cards with sentinel aphids, and making observations every 3 h for a 24 h period. A temporal and spatial segregation of predators was observed. Coccinellids were the most abundant predators, representing 51% of the total observations, followed by syrphid larvae. Coccinellids were also responsible for high levels of predation throughout the year, although the species responsible varied from spring to summer and autumn. On the other hand, syrphids were only found in spring and summer, while spiders only in autumn. Predator species also differed on their preferred sites for predation, with Heteropterans and syrphids found on the foliage, the spider Neomaso articeps only on the ground, and coccinellid and Anyphaenidae species on both sites. The two main predator groups also showed distinct diel patterns, with coccinellids observed only during day and syrphids only during night. This predatory activity corresponded with aphid predation, observing more predation in spring, on the foliage and during the day time. The proportion of predators observed preying on cards in the different seasons did not corresponded tightly with their field abundance, particularly in the case of coccinellids, which maintained high levels of predation in spite of great variations in its field abundance. Our results support the hypothesis of a spatio-temporal segregation of the predators associated with A. pisum in alfalfa, which might be beneficial for the outcome of biological control of this pest.

Human-assisted introductions, including those in the context of biological control, are considered to be one of the most important factors of global environmental change. However, the mechanisms underlying environmental changes, such as a decrease in the relative abundance of native species, are poorly understood. Since the introduction of the ladybird beetle, Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae), in Chile in the 1970s for biological control of aphids, a reduction in the relative abundance of the native ladybird beetle Eriopis connexa (Germar) has been noticed. To explore the role of cannibalism, intraguild predation (IGP) or competition as possible mechanisms that might increase dominance of H. variegata over E. connexa, several laboratory experiments were carried out. The native and the exotic species were very similar in their voracity and biotic interactions. Although H. variegata was able to maintain constant reproductive performance, E. connexa reproduction decreased at lower densities of aphids, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae). The impacts of cannibalism, IGP, and competition exerted by these species were very symmetrical in both larvae and adults. We conclude that these biotic factors may not fully explain the increase in relative abundance of H. variegata. The higher sensitivity of E. connexa to prey patch size, along with other factors such as chemical-mediated negative interspecific interactions may be operating in alfalfa fields, changing the composition of associated coccinellid assemblages.

Among the aphidophaga guild present in alfalfa [Medicago sativa L. (Fabaceae)], coccinellids forage on aphids most of the time on the foliage and carabids on the ground. The result of their combined effect can be synergistic, additive, or antagonistic, but this may depend on the prey density and interacting predatory species. In this study, we first determined, under laboratory conditions, the relative tendencies of Therioaphis trifolii (Monell), Acyrthosiphon pisum (Harris), and Aphis craccivora Koch (all Hemiptera: Aphididae) to drop in the presence and absence of two predators: Eriopis connexa (Germ) and Hippodamia variegata (Goeze) (both Coleoptera: Coccinellidae). These experiments showed that T. trifolii and A. pisum dropped more frequently than A. craccivora, and dropping was more frequent in the presence of H. variegata. We also determined the functional responses to aphid densities of five beetle species (Coleoptera: Carabidae) commonly found in alfalfa fields in Chile. All carabid species consumed aphids, with Trirammatus aerea (Dejean) being one of the most voracious. Then, we tested the hypothesis that the interactions between both coccinellid species and T. aerea would be antagonistic at low prey densities, because of competition or intraguild predation, and synergistic as prey density increases. For this, we recorded aphid consumption when predators were alone, or in combinations of a foliar and a ground predator, for five prey densities. For all predators and combinations, aphid consumption increased continuously with aphid density, and more prey were eaten when a foliar- and a ground-foraging predator were combined than when either predator was present. But, contrary to our expectations, we found that the interaction of these foliar- and ground-foraging predators was additive for all prey densities. Our results suggest that coexistence of these species would not interfere with aphid biological control in alfalfa.

Based on their effect on prey populations, predators can interact synergistically, additively, or antagonistically. Predator attraction by semiochemicals in response to herbivory is well documented; however, the possibility of semiochemicals mediating synergistic interactions has not been explored. Eriopis connexa (Germar) and Hippodamia variegata (Goeze) (both Coleoptera: Coccinellidae) interact synergistically with carabid species in Central Chile, a phenomenon in which semiochemicals may be involved. Moreover, olfactory behaviour in these coccinellids is unknown. Olfactometries contrasting non-infested vs. infested plants with Acyrthosiphon pisum Harris (Hemiptera: Aphididae) were performed to study olfactory prey-searching in E. connexa, H. variegata, and Trirammatus striatula (Fabricius) (Coleoptera: Carabidae). To evaluate whether semiochemicals can mediate synergistic predatory interactions, four experiments were established: olfactometries contrasting (1) infested plants with and without a predator, (2) uninfested plants with and without a predator; (3) predator vs. air, and (4) plants with previous physical activity of a predator vs. clean plants (nine combinations of predator species, according to whether they corresponded to the stimulus or focal individual). Hippodamia variegata and T. striatula were attracted to infested plants when contrasted with non-infested plants. Infested plants with a conspecific and H. variegata elicited attraction in E. connexa, whereas T. striatula preferred infested plants with E. connexa or H. variegata. Treatments with only predators (with or without the plant) did not elicit responses, except in E. connexa which was repelled by conspecifics and H. variegata, perhaps indicating an antagonistic interaction between them; plants with previous physical activity of predators did not elicit responses. These results corroborated the importance of semiochemicals produced by herbivory in the prey-searching behaviour of aphidophagous predators. In addition, presence of predators on the foliage may favour emission of aphid alarm pheromones, which could attract E. connexa and T. striatula. Volatiles can intervene in synergistic interactions between carabids and coccinellids; this should be replicable in other systems where predator-facilitation between aphidophagous predators is observed.

In agro-ecosystems, habitat loss and fragmentation may alter the assemblage of aphidophagous insects, such as foliar- foraging (coccinellids) and ground-foraging predators (carabids), potentially affecting intraguild interactions. We evaluated how habitat loss (0, 55 and 84%), fragmentation (1, 4 and 16 fragments) and their combination affected the abundance and species rich- ness of coccinellids and carabids, and aphid abundance, both in the short-term (summer: December to February) and over a longer time span (autumn: March to May), when different demographic mechanisms may participate. We created four types of 30 × 30 m patches (landscapes) in which alfalfa was grown: Control (1F - 0%, 30 × 30 m patch of alfalfa with no fragmentation or habitat loss), 4F - 55% (4 alfalfa fragments, with 55% total habitat loss), 4F - 84% (4 alfalfa fragments, with 84% total habitat loss), and 16F - 84% (16 alfalfa fragments, with 84% total habitat loss). Each landscape type was replicated five times. Insects were sampled by sweep-netting and pitfall traps, from December (summer) to May (autumn). Total abundance and species richness of carabids, in the short-term, was highest in the 16F - 84% landscapes. Total abundance of adult coccinellids was similar among landscapes, but at the species level Hyperaspis sphaeridioides, in the short-term, and Adalia bipunctata, in the long-term, had their highest densities in fragments within landscapes with high habitat loss (84%), independently of habitat fragmentation. Species richness in the long-term was higher in the landscapes with 84% habitat loss. Among aphids, in the long term Aphis craccivora was less abundant in land- scapes with high habitat loss and fragmentation (16-84%), while Therioaphis trifolii showed the opposite trend. These results sug- gest that habitat loss and fragmentation may increase the density and diversity of aphidophagous insects, while their effects on aphids are more variable.

Carabids and coccinellids are the most abundant aphid predators in alfalfa. Depending on the amount of prey consumed, the impact of their combined effect can be additive, antagonistic, or synergistic. Laboratory trials demonstrated that a higher proportion of Aphis craccivora Koch dropped from the alfalfa plants in the presence of coccinellids, and that the interaction between these predators was additive or synergistic, but never antagonistic, suggesting that they might be good partners in controlling aphids.

1. Habitat loss and fragmentation are the main causes of changes in the distribution and abundance of organisms, and are usually considered to negatively affect the abundance and species richness of organisms in a landscape. Nevertheless, habitat loss and fragmentation have often been confused, and the reported negative effects may only be the result of habitat loss alone, with habitat fragmentation having nil or even positive effects on abundance and species richness. 2. Manipulated alfalfa micro-landscapes and coccinellids (Coleoptera: Coccinellidae) are used to test the effects habitat loss (0% or 84%), fragmentation (4 or 16 fragments), and isolation (2 or 6 m between fragments) on the density, species richness, and distribution of native and exotic species of coccinellids. 3. Generally, when considering only the individuals in the remaining fragments, habitat loss had variable effects while habitat fragmentation had a positive effect on the density of two species of coccinellids and on species richness, but did not affect two other species. Isolation usually had no effect. When individuals in the whole landscape were considered, negative effects of habitat loss became apparent for most species, but the positive effects of fragmentation remained only for one species. 4. Native and exotic species of coccinellids did not segregate in the different landscapes, and strong positive associations were found most often in landscapes with higher fragmentation and isolation. 5. The opposing effects of habitat loss and fragmentation may result in a nil global effect; therefore it is important to separate their effects when studying populations in fragmented landscapes.

1 Plant patch shape may affect the abundance of herbivorous insects. Patches of the same size but longer or irregular have a higher perimeter/area relationship (P/A) than square or regular ones, which may determine the immigration, emigration and abundance of individuals in the patch. 2 Only specialist species should be affected by plant patch shape. Those species that are more abundant in smaller patches should be more abundant in patches with higher P/A, whereas those that are more abundant in larger patches should be more abundant in patches with lower P/A. 3 We studied the density of eggs, larvae and pupae of Pieris brassicae, Plutella xylostella and Trichoplusia ni in square (low P/A) and I-shaped (high P/A) patches of 144 plants of Brassica oleracea. We also estimated their immigration to these patches, and the final plant weight. 4 Plant patch shape affected the abundance, but not the distribution, of the two specialist species. Whereas P. brassicae was denser in I-shaped patches, P. xylostella was more abundant in square patches. The generalist T. ni was not affected by patch shape. Immigration of P. brassicae was higher in I-shaped patches, but immigration of P. xylostella and T. ni was not affected by patch shape. Plants were heavier in the centre of square patches. 5 Our results suggest that plant patch shape affects the density of herbivorous insects and should be considered independently from other plant patch variables when studying the population dynamics of these organisms.

We assessed the effect of plant patch shape and surrounding vegetation on the density, emigration, and immigration of predatory coccinellids, and on the density of their aphid prey Brevicoryne brassicae (L.). Between spring 1997 and fall 1999, we set up square and I-shaped patches of Brassica oleracea Plenck surrounded by Medicago sativa L. or Allium porrum L. Medicago sativa is frequently used by coccinellids, whereas A. porrum is not. We used a factorial (2 × 2) randomized block design, and evaluated the density of coccinellids and aphids every 10 d. We also evaluated emigration and immigration of adult coccinellids through mark-recapture experiments. We quantified the population increase of aphids, and the final live mass of plants. All insects were more abundant in patches surrounded by A. porrum than in those surrounded by M. sativa, and coccinellids were occasionally more dense in square patches than in I-shaped ones. Coccinellids emigrated less from square patches, either surrounded by A. porrum or M. sativa, and immigrated more to patches surrounded by A. porrum. Aphids showed a higher population increase, and plants of B. oleracea ended up being heavier in patches surrounded by A. porrum, particularly in I-shaped patches. Surrounding vegetation and plant patch shape seem to have a direct effect on the density of coccinellids by modifying their immigration and emigration patterns, but also seem to have an indirect effect by changing plant growth and its effect on herbivore recruitment.

We asked if the structural heterogeneity of a laboratory arena differentially affected the abandonment of the plot, residence time, locomotory rate, pause duration and turning rate of adult Eriopis connexa and Hippodamia variegata (Coleoptera: Coccinellidae). We simulated an increase in heterogeneity by distributing vertically-oriented toothpicks in a circular arena: one control (without toothpicks), one uniform plot (toothpicks every 1 cm) and one random plot (randomly distributed toothpicks). No food was provided inside the arena. Coccinellids were released individually in the centre of each plot and their movement was videotaped. Fewer H. variegata adults left the plots as these become more heterogeneous. E. connexa did not discriminate between plots in their residence time, but H. variegata remained longer in the uniform and longest in the random plots. H. variegata only stayed longer than E. connexa in the random plots. This resulted because adults of H. variegata were stationary for longer periods, moved more slowly and less linearly and explored a higher number of toothpicks than adults of E. connexa in more heterogeneous environments. Thus, the physical structure of the environment differentially affects the movement patterns of insects. Eriopis connexa seems to be less sensitive to structural heterogeneity than H. variegata.

Habitat fragmentation may affect the dispersal behaviour of individuals across the landscape. If there is a high boundary contrast between the remaining fragments and the matrix, individuals should tend to stay inside the fragments, but the configuration of the landscape, i.e. the level of fragmentation and isolation distance between fragments, may modulate this. To test these ideas, we made several mark-recapture experiments with the ladybird Eriopis connexa (Germ.) in manipulated alfalfa model landscapes (30 × 30 m). Specifically we evaluated (i) ladybird movement and permanence in alfalfa and bare ground areas, (ii) how they move across fragment/matrix boundaries, (iii) how their movement between fragments within a landscape is affected by fragmentation level and isolation distance, and (iv) how their permanence in the landscape is affected by fragmentation level and isolation distance. The frag- mented alfalfa landscapes had a constant level of habitat loss (84%), but varied in the level of habitat fragmentation (4 or 16 frag- ments), and isolation distance between fragments (2 or 6 m). We also sampled aphid abundance in the different landscapes through time. We found that ladybirds stay longer and displace less in alfalfa than on bare ground, and that they move less from the alfalfa fragments to the neighbouring bare ground matrix than vice versa. At the landscape level, ladybirds had a higher inter-fragment movement when fragments were closer, they tended to remain in less fragmented landscapes, regardless of their isolation distance. Aphid abundance increased in time, but it was similar in all landscapes. Ladybird movement within fragments, in the matrix and in the boundary between both habitats explains why ladybirds concentrate within alfalfa fragments. However, their dispersal move- ments at the landscape level do not reflect the higher abundance sometimes found for several species of ladybirds in more frag- mented landscapes. At this larger scale, other mechanisms may have a stronger influence in determining the abundance of ladybirds.