Regional Variation in Parasite Species Richness and Abundance in the Introduced Range of the Invasive Lionfish,Pterois volitans

Parasites can play an important role in biological invasions. While introduced species often lose parasites from their native range, they can also accumulate novel parasites in their new range. The accumulation of parasites by introduced species likely varies spatially, and more parasites may shift to new hosts where parasite diversity is high. Considering that parasitism and disease are generally more prevalent at lower latitudes, the accumulation of parasites by introduced hosts may be greater in tropical regions. The Indo-Pacific lionfish (Pterois volitans) has become widely distributed across the Western Atlantic. In this study, we compared parasitism across thirteen locations in four regions, spanning seventeen degrees of latitude in the lionfish''s introduced range to examine potential spatial variation in parasitism. In addition, as an initial step to explore how indirect effects of parasitism might influence interactions between lionfish and ecologically similar native hosts, we also compared parasitism in lionfish and two co-occurring native fish species, the graysby grouper, Cephalopholis cruentata, and the lizardfish, Synodus intermedius, in the southernmost region, Panama. Our results show that accumulation of native parasites on lionfish varies across broad spatial scales, and that colonization by ectoparasites was highest in Panama, relative to the other study sites. Endoparasite richness and abundance, on the other hand, were highest in Belize where lionfish were infected by twice as many endoparasite species as lionfish in other regions. The prevalence of all but two parasite species infecting lionfish was below 25%, and we did not detect an association between parasite abundance and host condition, suggesting a limited direct effect of parasites on lionfish, even where parasitism was highest. Further, parasite species richness and abundance were significantly higher in both native fishes compared to lionfish, and parasite abundance was negatively associated with the condition index of the native grouper but not that of the lionfish or lizardfish. While two co-occurring native fishes were more heavily parasitized compared to lionfish in Panama any indirect benefits of differential parasitism requires further investigation. Future parasitological surveys of lionfish across the eastern coast of North America and the Lesser Antilles would further resolve geographic patterns of parasitism in invasive lionfish.     

Low Susceptibility of Invasive Red Lionfish (Pterois volitans) to a Generalist Ectoparasite in Both Its Introduced and Native Ranges

Escape from parasites in their native range is one of many mechanisms that can contribute to the success of an invasive species. Gnathiid isopods are blood-feeding ectoparasites that infest a wide range of fish hosts, mostly in coral reef habitats. They are ecologically similar to terrestrial ticks, with the ability to transmit blood-borne parasites and cause damage or even death to heavily infected hosts. Therefore, being highly resistant or highly susceptible to gnathiids can have significant fitness consequences for reef-associated fishes. Indo-Pacific red lionfish (Pterois volitans) have invaded coastal habitats of the western tropical and subtropical Atlantic and Caribbean regions. We assessed the susceptibility of red lionfish to parasitic gnathiid isopods in both their native Pacific and introduced Atlantic ranges via experimental field studies during which lionfish and other, ecologically-similar reef fishes were caged and exposed to gnathiid infestation on shallow coral reefs. Lionfish in both ranges had very few gnathiids when compared with other species, suggesting that lionfish are not highly susceptible to infestation by generalist ectoparasitic gnathiids. While this pattern implies that release from gnathiid infestation is unlikely to contribute to the success of lionfish as invaders, it does suggest that in environments with high gnathiid densities, lionfish may have an advantage over species that are more susceptible to gnathiids. Also, because lionfish are not completely resistant to gnathiids, our results suggest that lionfish could possibly have transported blood parasites between their native Pacific and invaded Atlantic ranges.     

An incipient invasion of brown anole lizards (<Emphasis Type="Italic">Anolis sagrei</Emphasis>) into their own native range in the Cayman Islands: a case of cryptic back-introduction

Human-mediated dispersal has reshaped distribution patterns and biogeographic relationships for many taxa. Long-distance and over-water dispersal were historically rare events for most species, but now human activities can move organisms quickly over long distances to new places. A potential consequence of human-mediated dispersal is the eventual reintroduction of individuals from an invasive population back into their native range; a dimension of biological invasion termed “cryptic back-introduction.” We investigated whether this phenomenon was occurring in the Cayman Islands where brown anole lizards (Anolis sagrei) with red dewlaps (i.e., throat fans), either native to Little Cayman or invasive on Grand Cayman, have been found on Cayman Brac where the native A. sagrei have yellow dewlaps. Our analysis of microsatellite data shows strong population-genetic structure among the three Cayman Islands, but also evidence for non-equilibrium. We found some instances of intermediate multilocus genotypes (possibly 3–9% of individuals), particularly between Grand Cayman and Cayman Brac. Furthermore, analysis of dewlap reflectance data classified six males sampled on Cayman Brac as having red dewlaps similar to lizards from Grand Cayman and Little Cayman. Lastly, one individual from Cayman Brac had an intermediate microsatellite genotype, a red dewlap, and a mtDNA haplotype from Grand Cayman. This mismatch among genetic and phenotypic data strongly suggests that invasive A. sagrei from Grand Cayman are interbreeding with native A. sagrei on Cayman Brac. To our knowledge, this is the first evidence of cryptic back-introduction. Although we demonstrate this phenomenon is occurring in the Cayman Islands, assessing its frequency there and prevalence in other systems may prove difficult due to the need for genetic data in most instances. Cryptic back-introductions may eventually provide some insight into how lineages are changed by the invasion process and may be an underappreciated way in which invasive species impact native biodiversity.     

Higher parasite richness, abundance and impact in native versus introduced cichlid fishes

Empirical studies suggest that most exotic species have fewer parasite species in their introduced range relative to their native range. However, it is less clear how, ecologically, the loss of parasite species translates into a measurable advantage for invaders relative to native species in the new community. We compared parasitism at three levels (species richness, abundance and impact) for a pair of native and introduced cichlid fishes which compete for resources in the Panama Canal watershed. The introduced Nile tilapia, Oreochromis niloticus, was infected by a single parasite species from its native range, but shared eight native parasite species with the native Vieja maculicauda. Despite acquiring new parasites in its introduced range, O. niloticus had both lower parasite species richness and lower parasite abundance compared with its native competitor. There was also a significant negative association between parasite load (abundance per individual fish) and host condition for the native fish, but no such association for the invader. The effects of parasites on the native fish varied across sites and types of parasites, suggesting that release from parasites may benefit the invader, but that the magnitude of release may depend upon interactions between the host, parasites and the environment.     

Differential effects of native vs. invasive predators on a common Caribbean reef fish

Predators may have consumptive (lethal) and non-consumptive (sub-lethal) effects on prey. Non-consumptive effects include altered behavior and reduced growth and fecundity. Native prey may not recognize non-native predators as a threat, and therefore may suffer pronounced effects. Additionally, non-native predators may elicit different behavioral responses from prey compared to native predators. Theory predicts that consumptive effects should be greater for non-native predators (due to prey naiveté), and non-consumptive effects should be greater for native predators (due to predator recognition). To test these hypotheses, I monitored bicolor damselfish (Stegastes partitus) in the presence of invasive predatory Pacific lionfish (Pterois spp.), a native predator (graysby, Cephalopholis cruentata), and an egg predator (bluehead wrasse, Thalassoma bifasciatum). Body size and location of lionfish and graysby were monitored on reefs in the Bahamas. Bicolor fecundity was measured as the number and size of egg-masses that individual fish laid. Bicolor fecundity was negatively correlated with lionfish density but not graysby or bluehead density. Neither predator had a detectable effect on bicolor body size, but lionfish density was negatively correlated with the size of mature adult damselfish. I observed behavioral responses of bicolors to the two piscivores, to bluehead wrasse, and to two herbivorous fishes (Acanthurus coeruleus, Scarus spp.) as non-aggressive controls. Bicolors changed behavior (feeding and aggression) in the presence of all native fishes, but not in the presence of lionfish. Thus, differential effects exist between native and non-native predators, and invasive lionfish pose a non-consumptive threat to bicolor damselfish via reduced growth and fecundity.     

Effects of invasive Pacific red lionfish Pterois volitans versus a native predator on Bahamian coral-reef fish communities

The recent irruption of Pacific red lionfish (Pterois volitans) on Caribbean and Atlantic coral reefs could prove to be one of the most damaging marine invasions to date. Invasive lionfish are reaching densities much higher than those reported from their native range, and they have a strong negative effect on the recruitment and abundance of a broad diversity of native coral-reef fishes. Otherwise, little is known about how lionfish affect native coral-reef communities, especially compared to ecologically similar native predators. A controlled field experiment conducted on small patch-reefs in the Bahamas over an 8-week-period demonstrated that (1) lionfish caused a reduction in the abundance of small native coral-reef fishes that was 2.5?±?0.5 times (mean?±?SEM) greater than that caused by a similarly sized native piscivore, the coney grouper Cephalopholis fulva (93.7 vs. 36.3?% reduction); (2) lionfish caused a reduction in the species richness of small coral-reef fishes (loss of 4.6?±?1.6 species), whereas the native piscivore did not have a significant effect on prey richness; (3) the greatest effects on the reef-fish community, in terms of both abundance and richness, occurred when both native and invasive predators were present; and (4) lionfish grew significantly faster (>6 times) than the native predator under the same field conditions. These results suggest that invasive lionfish have stronger ecological effects than similarly sized native piscivores, and may pose a substantial threat to native coral-reef fish communities.     

Living with the enemy: parasites and pathogens of the ladybird <Emphasis Type="Italic">Harmonia axyridis</Emphasis>

Harmonia axyridis is an invasive alien predator in many countries across the world. The rapid establishment and spread of this species is of concern because of the threat it poses to biodiversity as a generalist predator. Understanding the mechanisms that contribute to the success of this species as an invader is not only intriguing but also critical to our understanding of the processes governing such invasions. The enemy release hypothesis (ERH) could explain the rapid population growth of many invasive alien species. However, empirical evidence in support of the ERH is lacking. An alternative hypothesis that could explain rapid population growth is evolution of increased competitive ability (EICA). Here we provide an overview of the parasites and pathogens of coccinellids with a particular focus on H. axyridis as a host. We examine the differential susceptibility of host species and highlight the resilience of H. axyridis in comparison to other coccinellids. We recognise the paucity and limitations of available information and suggest that studies, within a life-table framework, comparing life history traits of H. axyridis in both the native and introduced ranges are necessary. We predict that H. axyridis could benefit from both enemy release and EICA within the introduced range but require further empirical evidence.     

Indo-Pacific lionfish are larger and more abundant on invaded reefs: a comparison of Kenyan and Bahamian lionfish populations

The invasion by Indo-Pacific lionfish (Pterois volitans and P. miles) of the western Atlantic, Caribbean and Gulf of Mexico is emerging as a major threat to coral reef communities across the region. Comparing native and introduced populations of invasive species can reveal shifts in ecology and behaviour that can accompany successful invasions. Using standardized field surveys replicated at multiple sites in Kenya and the Bahamas, we present the first direct comparisons of lionfish density, body size, biomass and behaviour between native and invaded coral reefs. We found that lionfish occur at higher densities with larger body sizes and total biomass on invaded Bahamian coral reefs than the ecologically equivalent species (P. miles) does on native Kenyan reefs. However, the combined average density of the five lionfish species (Pterois miles, P. antennata, P. radiata, Dendrochirus brachypterus and D. zebra) on Kenyan reefs was similar to the density of invasive lionfish in the Bahamas. Understanding the ecological processes that drive these differences can help inform the management and control of invasive lionfish.     

Lionfish in the eastern Pacific: a cellular automaton approach to assessing invasion risk

The lionfish invasion in the Atlantic and Caribbean has proceeded with vigor since their introduction in the 1980s or early 1990s. Lionfish affect recruitment of juvenile fish to reefs due to predation and are found in densities far surpassing that of their native Indo-Pacific. There is concern that the lionfish may become introduced and proliferate (through aquarium releases, transport on floating debris, or passage through the Panama Canal in ship ballast water) in the eastern tropical and north Pacific. This study presents the first known prediction of the potential for establishment of lionfish in the eastern Pacific Ocean. Through computational modeling, we compare and contrast the dynamics of random hypothetical introductions of lionfish into the eastern Pacific and Atlantic Oceans in order to highlight the different potentials for invasion in both basins. Connectivity between discrete regions (precincts) in both the Atlantic and eastern Pacific are examined and settlement densities are calculated to indicate possible locations of establishment of breeding lionfish populations. Our results suggest that lionfish, which are successful invaders in the Atlantic, may not be as successful in the eastern Pacific due to weak mesoscale connectivity which reduces the rapid spread of lionfish larvae.     

Forecasting lionfish sources and sinks in the Atlantic: are Gulf of Mexico reef fisheries at risk?

Invasive lionfish (Pterois volitans/miles complex) now permeate the entire tropical western Atlantic, Caribbean Sea, and Gulf of Mexico, but lionfish abundance has been measured only in select locations in the field. Despite its rapid range expansion, a comprehensive meta-population analysis of lionfish ‘sources’ and ‘sinks’ and consequentially the invader’s potential abundance and impacts on economically important, sympatric reef fishes have not been assessed. These data are urgently needed to spatially direct control efforts and to plan for and perhaps mitigate lionfish-caused damage. Here, we use a biophysical computer model to: (1) forecast larval lionfish sources and sinks that are also delineated as low to high lionfish ‘density zones’ throughout their invaded range, and (2) assess the potential vulnerability of five grouper and snapper species—Epinephelus morio, Mycteroperca microlepis, Epinephelus flavolimbatus, Lutjanus campechanus, and Rhomboplites aurorubens—to lionfish within these density zones in the Gulf of Mexico. Our results suggest that the west Florida shelf and nearshore waters of Texas, USA, and Guyana, South America, function both as lionfish sources and sinks and should be a high priority for targeted lionfish control. Furthermore, of the five groupers and snappers studied, the high fishery value E. morio (red grouper) is the Gulf of Mexico species most at risk from lionfish. Lacking a comprehensive lionfish control policy, these risk exposure data inform managers where removals should be focused and demonstrate the risk to five sympatric native groupers and snappers in the Gulf of Mexico that may be susceptible to dense lionfish aggregations, should control efforts fail.     

Reconstructing the lionfish invasion: insights into Greater Caribbean biogeography

Aim Lionfish (Pterois volitans and P. miles) are popular ornamental fishes native to the Indo‐Pacific that were introduced into Florida waters and are rapidly spreading and establishing throughout the Western Atlantic (WA). Although unfortunate, this invasion provides an excellent system in which to test hypotheses on conservation biology and marine biogeography. The goals of this study are: (1) to document the geographical extent of P. volitans and P. miles; (2) to determine whether the progression of the lionfish invasion is the result of expansion following the initial introduction event or the consequence of multiple introductions at various WA locations; and (3) to analyse the chronology of the invasion in conjunction with the genetic data in order to provide real‐time assessments of hypotheses of marine biogeography. Location The Greater Caribbean, including the US east coast, Bermuda, the Bahamas and the Caribbean Sea. Methods Mitochondrial control region sequences were obtained from lionfish individuals collected from Bermuda and three Caribbean locations and analysed in conjunction with previously published data from five native and two non‐native locations (US east coast and the Bahamas; a total of six WA locations). Genetic variation within and among groups was quantified, and population structure inferred via spatial analyses of molecular variance, pairwise Φ_ST, exact tests, Mantel tests and haplotype networks. Results Mitochondrial DNA screening of WA lionfish shows that while P. miles is restricted to the northernmost locations (Bermuda and the US east coast), P. volitans is ubiquitous and much more abundant. Invasive populations of P. miles and P. volitans have significantly lower levels of genetic diversity relative to their native counterparts, confirming that their introduction resulted in a strong founder effect. Despite the relative genetic homogeneity across the six WA locations, population structure analyses of P. volitans indicate significant differentiation between the northern (US east coast, the Bahamas and Bermuda) and the Caribbean populations. Main conclusions Our findings suggest that the ubiquity of WA lionfish is the result of dispersal from a single source of introduction in Florida and not of multiple independent introductions across the range. In addition, the progression of the lionfish invasion (as documented from sightings), integrated with the genetic evidence, provides support for five of six major scenarios of connectivity and phylogeographical breaks previously inferred for Caribbean organisms.     

Potential impact of the Asian shore crab <Emphasis Type="Italic">Hemigrapsus sanguineus</Emphasis> on native northeast Pacific crabs

Asian shore crabs (Hemigrapsus sanguineus De Haan) are a dominant invasive species in the northwest Atlantic, where recent evidence suggests that they have been introduced multiple times from their native range of Japan and Korea. Despite favorable environmental conditions and a high level of shipping traffic across the Pacific, this crab has not become established in the northeast Pacific. This may be due to interactions with the native shore crab assemblage, which previous studies have found to outcompete juvenile H. sanguineus for shelter. The present study used a combination of feeding and behavioral experiments to quantify the feeding behavior of native crabs (Pachygrapsus crassipes, Hemigrapsus nudus, Hemigrapsus oregonensis) with and without the presence of H. sanguineus. H. sanguineus ate more than the native crabs combined at both 7 and 13 °C. Crabs in the mixed treatment which included all four species ate less than expected, indicating that at least one species reduced its feeding rate. However, time-lapse photography revealed similar amounts of time feeding in both treatments for all 4 species, suggesting that there were changes in feeding intensity when all crabs were together. The high feeding rates but lack of a competitive advantage for H. sanguineus make it an unlikely but potentially impactful invader in the northeast Pacific.     

Hot or not? Comparative behavioral thermoregulation,critical temperature regimes,and thermal tolerances of the invasive lionfish <Emphasis Type="Italic">Pterois</Emphasis> sp. versus native western North Atlantic reef fishes

Temperature influences the geographic range, physiology, and behavior of many ectothermic species, including the invasive lionfish Pterois sp. Thermal parameters were experimentally determined for wild-caught lionfish at different acclimation temperatures (13, 20, 25 and 32 °C). Preferences and avoidance were evaluated using a videographic shuttlebox system, while critical thermal methodology evaluated tolerance. The lionfish thermal niche was compared experimentally to two co-occurring reef fishes (graysby Cephalopholis cruentata and schoolmaster Lutjanus apodus) also acclimated to 25 °C. The physiologically optimal temperature for lionfish is likely 28.7 ± 1 °C. Lionfish behavioral thermoregulation was generally linked to acclimation history; tolerance and avoidance increased significantly at higher acclimation temperatures, but final preference did not. The tolerance polygon of lionfish shows a strong correlation between thermal limits and acclimation temperature, with the highest CT_max at 39.5 °C and the lowest CT_min at 9.5 °C. The tolerance range of invasive lionfish (24.61 °C) is narrower than those of native graysby (25.25 °C) and schoolmaster (26.87 °C), mostly because of lower thermal maxima in the former. Results show that lionfish display “acquired” thermal tolerance at higher and lower acclimation temperatures, but are no more eurythermal than other tropical fishes. Collectively, these results suggest that while lionfish range expansion in the western Atlantic is likely over the next century from rising winter sea temperatures due to climate change, the magnitude of poleward radiation of this invasive species is limited and will likely be equivalent to native tropical and subtropical fishes with similar thermal minima.     

Prevalence and evolutionary relationships of haematozoan parasites in native versus introduced populations of common myna Acridotheres tristis

The success of introduced species is frequently explained by their escape from natural enemies in the introduced region. We tested the enemy release hypothesis with respect to two well studied blood parasite genera (Plasmodium and Haemoproteus) in native and six introduced populations of the common myna Acridotheres tristis. Not all comparisons of introduced populations to the native population were consistent with expectations of the enemy release hypothesis. Native populations show greater overall parasite prevalence than introduced populations, but the lower prevalence in introduced populations is driven by low prevalence in two populations on oceanic islands (Fiji and Hawaii). When these are excluded, prevalence does not differ significantly. We found a similar number of parasite lineages in native populations compared to all introduced populations. Although there is some evidence that common mynas may have carried parasite lineages from native to introduced locations, and also that introduced populations may have become infected with novel parasite lineages, it may be difficult to differentiate between parasites that are native and introduced, because malarial parasite lineages often do not show regional or host specificity.     

High parasite infection level in non‐native invasive species: it is just a matter of time

The enemy release hypothesis is often used to explain the success of non‐native species invasions. Growing evidence indicates that parasite or pathogen species richness increases over time in invasive non‐native species; however, this increase should not directly translate into release from enemy pressure as infection intensity of parasites (number of parasites per host) has a more profound impact on host fitness. The changes in intensity of parasitic infections in invasive non‐native species have not yet been thoroughly analysed in newly colonized areas. The goal of this study was to determine whether gastrointestinal parasite (nematode and trematode) infection intensity has increased with time since the populations of American mink Neovison vison were established and how host demographic parameters affect infection intensity. We tested the enemy release hypothesis by substituting space for time, evaluating parasite abundance in American mink at six sites along a chronosequence of mink invasion history. Nematode and trematode abundance increased with time since mink introduction, from a few parasites on average per mink after 16 yr, to 200–250 parasites per mink after 34 yr. The rate of increase in parasite abundance varied among demographic groups of mink (sex and age). Both nematodes and trematodes were more abundant in males than in females, and in subadults than in adults. Higher nematode abundance negatively affected body condition of mink. Our results provide evidence that non‐native species are released from enemy pressure only in the first phase of invasion, and that infection is modulated by host demographics and season. These results contribute to the evaluation of the long‐term patterns of parasite accumulation in invasive non‐native species after their colonization of new territories.     

Invasive lionfish drive Atlantic coral reef fish declines

Indo-Pacific lionfish (Pterois volitans and P. miles) have spread swiftly across the Western Atlantic, producing a marine predator invasion of unparalleled speed and magnitude. There is growing concern that lionfish will affect the structure and function of invaded marine ecosystems, however detrimental impacts on natural communities have yet to be measured. Here we document the response of native fish communities to predation by lionfish populations on nine coral reefs off New Providence Island, Bahamas. We assessed lionfish diet through stomach contents analysis, and quantified changes in fish biomass through visual surveys of lionfish and native fishes at the sites over time. Lionfish abundance increased rapidly between 2004 and 2010, by which time lionfish comprised nearly 40% of the total predator biomass in the system. The increase in lionfish abundance coincided with a 65% decline in the biomass of the lionfish's 42 Atlantic prey fishes in just two years. Without prompt action to control increasing lionfish populations, similar effects across the region may have long-term negative implications for the structure of Atlantic marine communities, as well as the societies and economies that depend on them.     

Aggregation patterns of helminth populations in the introduced fish, Liza haematocheilus (Teleostei: Mugilidae): disentangling host–parasite relationships

A number of hypotheses exist to explain aggregated distributions, but they have seldom been used to investigate differences in parasite spatial distribution between native and introduced hosts. We applied two aggregation models, the negative binomial distribution and Taylor’s power law, to study the aggregation patterns of helminth populations from Liza haematocheilus across its native (Sea of Japan) and introduced (Sea of Azov) distribution ranges. In accordance with the enemy release hypothesis, we predicted that parasite populations in the introduced host range would be less aggregated than in the native host area, because aggregation is tightly constrained by abundance. Contrary to our expectation, aggregation of parasite populations was higher in the introduced host range. However, the analyses suggested that the effect of host introduction on parasite aggregation depends on whether parasite species, or higher level taxonomic groups, were acquired in or carried into the new area. The revealed similarity in the aggregation parameters of co-introduced monogeneans can be attributed to the repeatability and identity of the host–parasite systems. In contrast, the degree of aggregation differed markedly between regions for higher level taxa, which are represented by the native parasites in the Sea of Japan versus the acquired species in the Sea of Azov. We propose that the host species plays a crucial role in regulating infra-population sizes of acquired parasites due to the high rate of host-induced mortality. A large part of the introduced host population may remain uninfected due to their resistance to native naïve parasites. The core concept of our study is that the comparative analysis of aggregation patterns of parasites in communities and populations, and macroecological relationships, can provide a useful tool to reveal cryptic relationships in host–parasite systems of invasive hosts and their parasites.     

Predicting impacts of lionfish (<Emphasis Type="Italic">Pterois volitans</Emphasis>) invasion in a coastal ecosystem of southern Brazil

The opportunistic feeder Pterois volitans is a voracious invader, causing large impacts in marine food-webs. We have used a Ecopath-with-Ecosim model to hypothesize an invasion by lionfish and to predict the likely impact of this potential generalist mesopredator in a subtropical food-web model. With thirty-three functional groups, the initial Ecopath model was balanced with a low biomass of lionfish (0.07 t/km²). In Ecosim, three scenarios of different vulnerability settings for the linkages between the introduced fish and its prey were tested, representing the default setting, a top-down control, and an extreme top-down control. The scenarios were tested using different assumptions on the ability of the invasive fish to change the proportions of prey consumed according to prey availability. Our model predicted that the hypothesized lionfish invasion would have a strong impact on this subtropical marine food web: (1) by reducing prey populations and, consequently, food for native predators, and; (2) by predating on key species, causing direct impacts and possibly cascading trophic effects. Reef fish were the most affected, including some groups ecologically and economically important, like lutjanids and groupers. However, some adaptations in the fishing strategy of fishermen are expected which may affect other fish groups. Stakeholders should be warned of the potential ecological and socio-economic impacts that may arise from a lionfish invasion and various strategies and policy options should be immediately developed and applied (1) to prevent the arrival and establishment of the lionfish, and; (2) to make the ecosystem more resilient to this and other possible exotic species.     

Predators and parasitoids of the harlequin ladybird, <Emphasis Type="Italic">Harmonia axyridis</Emphasis>, in its native range and invaded areas

The harlequin ladybird Harmonia axyridis (Coleoptera: Coccinellidae) has rapidly spread in several continents over the past 30 years and is considered an invasive alien species. The success of H. axyridis as an invader is often attributed to weak control by natural enemies. In this paper, we provide an overview of current knowledge on predators and parasitoids of H. axyridis. The common feature of predators and parasitoids is that they directly kill exploited organisms. Currently available data show that H. axyridis, displaying a variety of chemical, mechanical, and microbiological anti-predator defenses, is usually avoided by predators. However, some birds and invertebrates can eat this ladybird without harmful consequences. The primary defenses of H. axyridis against parasitoids include immune response and physiological and nutritional unsuitability for parasitoid development. These defenses are probably relatively efficient against most ladybird parasitoids, but not against flies of the genus Phalacrotophora. The latter are idiobiont parasitoids and hence can evade the host’s immune response. Indeed, rates of parasitism of H. axyridis by Phalacrotophora in the Palaearctic region (both in the native range in Asia and in Europe) are relatively high. While strong evidence for enemy release on the invasive populations of H. axyridis is lacking, several cases of parasitoid acquisition have been recorded in Europe, North America, and South America. We conclude that enemy release cannot be excluded as a possible mechanism contributing to the spread and increase of H. axyridis in the early stages of invasion, but adaptation of parasitoids may lead to novel associations which might offset previous effects of enemy release. However, further work is required to elucidate the population-level effects of such interactions.