Arthropod Invasions Research Articles

Impacts of continental invasion of Raoiella indica in the Americas

The invasion of the Red Palm Mite (RPM), Raoiella indica, in the western hemisphere, is probably the most extensive, fastest, and better-documented plant pest arthropod invasion in recent decades. RPM was initially detected in the Lesser Caribbean Antilles, and it rapidly spread hooping through the islands and reaching continental areas in North, Central and South America.

Accelerated invasion through the evolution of dispersal behaviour

AbstractAimThe continuous spread of invasive species is attributed to demographic processes and high dispersal rates. Both can change and evolve during range expansion, eventually accelerating spread dynamics. Here, we document such an accelerated spread for one of the most invasive spiders in Europe, the dwarf spider Mermessus trilobatus, and test whether dispersal, reproduction or competitive ability is at the source of this pattern.LocationEurope.Time period1981–2021.Major taxon studiedMermessus trilobatus (Arachnida: Araneae: Linyphiidae).MethodsFirst, we collected records from 21 countries across Europe to document the speed of progression of the invasion front over the last 40 years. Second, we collected live individuals from populations in the longest and more recently invaded areas and compared the dispersal propensity of offspring raised under standardized conditions. Third, we compared the reproduction and competitive ability of females derived from the populations of long‐invaded areas against areas with more recent establishment.ResultsThe progression of the invaded range increased from about 150 km in the 1980s to some 400 km between 2010 and 2020. Dispersal‐related behaviour was nearly twice as frequent in offspring from invasion front populations compared to the core area. By contrast, we found no differences in reproduction or competitive ability among the studied populations. Further, neither joint inheritance nor trade‐offs of dispersal, reproduction or competitive ability were identified.Main conclusionAs high dispersal is recessively inherited in M. trilobatus, our results suggest that the accelerated invasion is due to the accumulation of dispersive but not more reproductive or competitive genotypes in newly colonized areas. Given the high climatic amplitude of the species in North America, we expect it to spread over the remaining parts of Europe and large parts of Asia in the coming decades. Accelerated range expansion through the evolution of dispersal behaviour could play a role in numerous arthropod invasions worldwide.

Arthropod Invasions Versus Soybean Production in Brazil: A Review.

Soybean production in Brazil has been markedly affected by invasions of non-native arthropod species that feed on the crop, severely impacting biodiversity, food security, health, and economic development. Data on soybean production losses and increase in insecticide usage over the last two decades have not been explored in association with past invasion events, and the dynamics underlying the recent blitz of invasive species into Brazil remain largely unclear. We provide a review of arthropod invasions in the Brazilian soybean agroecosystem since 1990, indicating that the introductions of Bemisia tabaci (Gennadius) MEAM1 (Hemiptera: Aleyrodidae), Tetranychus urticae (Koch) (Acari: Tetranychidae), and Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) are likely correlated with periods of increase in insecticide usage for soybean production. Using these three cases as examples, we review factors that could lead to increased likelihood of future invasions by particular pests, outlining four possible criteria to evaluate potential invasiveness of non-native arthropods: likelihood of entry, likelihood of establishment, biological features of the species, and availability of control measures. Spodoptera litura (F.) (Lepidoptera: Noctuidae) and Aphis glycines (Matsumura) (Hemiptera: Sternorrhynca) are examples of highly damaging soybean pests, related to one or more of these factors, that could be introduced into Brazil over the next years and which could lead to problematic scenarios. Melanagromyza sojae (Zehnter) (Diptera: Agromyzidae) also meets these criteria and has successfully invaded and colonized Brazilian soybean fields in recent years. Our review identifies current issues within soybean pest management in Brazil and highlights the need to adopt management measures to offset future costs and minimize lost revenue.

Distributions of Invasive Arthropods across Heterogeneous Urban Landscapes in Southern California: Aridity as a Key Component of Ecological Resistance.

Urban systems often support large numbers of non-native species, but due to the heterogeneity of urban landscapes, species are not evenly distributed. Understanding the drivers of ecological resistance in urban landscapes may help to identify habitats that are most resistant to invasion, and inform efforts to model and conserve native biodiversity. We used pitfall traps to survey non-native ground-dwelling arthropods in three adjacent, low-elevation habitat types in southern California: California sage scrub, non-native grassland, and suburban development. We found that non-native species were fewer and less widely distributed in the sage scrub and grassland habitats. Due to the proximity of our sites, differences in propagule pressure is an unlikely explanation. Instead, we suggest that the absence of water subsidies in the sage scrub and grassland habitats increases those habitats’ resistance to arthropod invasions. Comparisons to studies conducted at fragments closer to the coast provide further support for the relationship between aridity and invasibility in southern California. Our findings highlight that inland fragments are important for conserving native arthropod diversity, that models of non-native species distributions in arid and semi-arid urban systems should include aridity measures, and that reducing resource subsidies across the region is critical to mitigating spread of non-natives.

Exotic biological control agents: A solution or contribution to arthropod invasions?

Biological control is a valuable and effective strategy for controlling arthropod pests and has been used extensively against invasive arthropods. As one approach for control of invasives, exotic natural enemies from the native range of a pest are introduced to areas where control is needed. Classical biological control began to be used in the late 1800s and its use increased until, beginning in 1983, scientists began raising significant concerns and questions about nontarget and indirect effects that can be caused by these introductions. In recent years, similar issues have been raised about augmentative use of exotic natural enemies. Subsequently, international guidelines, national regulations and scientific methods being used for exotic natural enemies in biological control have changed to require appropriate specificity testing, risk assessment and regulatory oversight before exotic natural enemies can be released. National and international standards aimed at minimizing risk have increased awareness and promoted more careful consideration of the costs and benefits associated with biological control. The barriers to the implementation of classical and augmentative biological control with exotic natural enemies now are sometimes difficult and, as a consequence, the numbers of classical biological control programs and releases have decreased significantly. Based in part on this new, more careful approach, classical biological control programs more recently undertaken are increasingly aimed at controlling especially damaging invasive arthropod pests that otherwise cannot be controlled. We examine evidence for these revised procedures and regulations aimed at increasing success and minimizing risk. We also discuss limitations linked to the apparent paucity of post-introduction monitoring and inherent unpredictability of indirect effects.

Quarantine arthropod invasions in Europe: the role of climate, hosts and propagule pressure

AbstractAimTo quantify the relative importance of propagule pressure, climate‐matching and host availability for the invasion of agricultural pest arthropods in Europe and to forecast newly emerging pest species and European areas with the highest risk of arthropod invasion under current climate and a future climate scenario (A1F1).LocationEurope.MethodsWe quantified propagule pressure, climate‐matching and host availability by aggregating large global databases for trade, European arthropod interceptions, Koeppen–Geiger world climate classification (including the A1F1 climate change scenario until 2100) and host plant distributions for 118 quarantine arthropod species.ResultsAs expected, all the three factors, propagule pressure, climate suitability and host availability, significantly explained quarantine arthropod invasions in Europe, but the propagule pressure only had a positive effect on invasion success when considered together with climate suitability and host availability. Climate change according to the A1F1 scenario generally increased the climate suitability of north‐eastern European countries and reduced the climate suitability of central European countries for pest arthropod invasions.Main conclusionsTo our knowledge, this is the first demonstration that propagule pressure interacts with other factors to drive invasions and is not alone sufficient to explain arthropod establishment patterns. European countries with more suitable climate and large agricultural areas of suitable host plants for pest arthropods should thus be more vigilant about introduction pathways. Moreover, efforts to reduce the propagule pressure, such as preventing pests from entering pathways and strengthening border controls, will become more important in north‐eastern Europe in the future as the climate becomes more favourable to arthropod invasions.

Arthropod invasion disrupts Cycas micronesica seedling recruitment

We recently described characteristics of reproductive effort for the cycad Cycas micronesica on the island of Guam. The data were serendipitously recorded just prior to the devastating invasion of the armored scale Aulacaspis yasumatsui. This invasion decimated the cycad population and after six years of infestation no recruitment is occurring among the survivors. We describe various underlying mechanisms that may explain how this homopteran insect has eliminated host recruitment among categories including plant-pollinator mutualism disruptions, direct damage to reproductive structures, population level responses to declining plant health, and failures of seedlings to establish. Our pre-invasion data on reproductive effort will serve as the benchmark for quantifying how this alien pest is endangering the endemic cycad.

Neonicotinoid Insecticide Imidacloprid Causes Outbreaks of Spider Mites on Elm Trees in Urban Landscapes

BackgroundAttempts to eradicate alien arthropods often require pesticide applications. An effort to remove an alien beetle from Central Park in New York City, USA, resulted in widespread treatments of trees with the neonicotinoid insecticide imidacloprid. Imidacloprid's systemic activity and mode of entry via roots or trunk injections reduce risk of environmental contamination and limit exposure of non-target organisms to pesticide residues. However, unexpected outbreaks of a formerly innocuous herbivore, Tetranychus schoenei (Acari: Tetranychidae), followed imidacloprid applications to elms in Central Park. This undesirable outcome necessitated an assessment of imidacloprid's impact on communities of arthropods, its effects on predators, and enhancement of the performance of T. schoenei.Methodology/Principal FindingsBy sampling arthropods in elm canopies over three years in two locations, we document changes in the structure of communities following applications of imidacloprid. Differences in community structure were mostly attributable to increases in the abundance of T. schoenei on elms treated with imidacloprid. In laboratory experiments, predators of T. schoenei were poisoned through ingestion of prey exposed to imidacloprid. Imidacloprid's proclivity to elevate fecundity of T. schoenei also contributed to their elevated densities on treated elms.Conclusions/SignificanceThis is the first study to report the effects of pesticide applications on the arthropod communities in urban landscapes and demonstrate that imidacloprid increases spider mite fecundity through a plant-mediated mechanism. Laboratory experiments provide evidence that imidacloprid debilitates insect predators of spider mites suggesting that relaxation of top-down regulation combined with enhanced reproduction promoted a non-target herbivore to pest status. With global commerce accelerating the incidence of arthropod invasions, prophylactic applications of pesticides play a major role in eradication attempts. Widespread use of neonicotinoid insecticides, however, can disrupt ecosystems tipping the ecological balance in favor of herbivores and creating pest outbreaks.

DAISIE and arthropod invasions in Europe

A milestone in the knowledge of alien species in Europe has been achieved by the DAISIE (Delivering Alien Invasive Species Inventories for Europe) project. Th rough the Sixth Framework Programme of the European Union, DAISIE has delivered a major portal for information on biological invasions that is publicly available at http://www. europe-aliens.org. Th e rationale was to develop a pan-European inventory of invasive alien species by integrating existing databases, to describe patterns and evaluate trends in biological invasions in Europe, identify priority species and assess their ecological, economic and health risks and impacts. Although an on-going process, the foundation, scope, and technological architecture of DAISIE was established through a consortium of leading researchers of biological invasions in Europe from 19 institutions across 15 countries and delivered through the cooperation of experts in ecology and taxonomy from throughout Europe that in total amounted to 182 contributors. Th e inventory, accounts, and distribution maps today provide the fi rst qualifi ed reference system on invasive alien species for the European region. Th e information presents an outstanding resource to synthesise current knowledge and trends in biological invasions in Europe. Th e data will help identify the scale and spatial pattern of invasive alien species in Europe, understand the environmental, social, economic and other factors involved in invasions, and can be used as a framework for considering indicators for early warning. A key component of DAISIE is Th e European Alien Species Database, an inventory of all alien species in Europe, and resulted from compiling and peer-reviewing national and regional lists of alien fungi, bryophytes, vascular plants, invertebrates, fi sh, amphibians, reptiles, birds and mammals. Data were collated for all 27 European Union member states (and separately for their signifi cant island regions), other European states (Andorra, Iceland, Liechtenstein, Moldova, Monaco, Norway, the European BioRisk 4(1): 1–3 (2010)

Micro-managing arthropod invasions: eradication and control of invasive arthropods with microbes

Non-indigenous arthropods are increasingly being introduced into new areas worldwide and occasionally they cause considerable ecological and economic harm. Many invasive arthropods particularly pose problems to areas of human habitation and native ecosystems. In these cases, the use of environmentally benign materials, such as host-specific entomopathogens, can be more desirable than broader spectrum control tactics that tend to cause greater non-target effects. The majority of successful eradication programs using arthropod pathogens have targeted invasive Lepidoptera with Bacillus thuringiensis kurstaki (Btk), such as eradication efforts against the gypsy moth, Lymantria dispar (L.), in North America and New Zealand. Both Btk and Lymantria dispar nucleopolyhedrovirus have been successfully used in efforts to limit the spread of L. dispar in the United States. For invasive arthropod species that are well established, suppression programs have successfully used arthropod-pathogenic viruses, bacteria, fungi and nematodes for either short- or long-term management. We will summarize the use of pathogens and nematodes in invasive arthropod management programs within a general context, and compare the use of microbes in gypsy moth management with diverse microbes being developed for use against other invasive arthropods.

Decomposition Patterns in Terrestrial and Intertidal Habitats on Oahu Island and Coconut Island, Hawaii

Decomposition studies were conducted at two sites on the Island of Oahu, Hawaii, to compare patterns of decomposition and arthropod invasion in intertidal and adjacent terrestrial habitats. The animal model used was the domestic pig. One site was on Coconut Island in Kaneohe Bay on the northeast side of Oahu, and the second was conducted in an anchialine pool located at Barber's Point Naval Air Station on the southwest shore of Oahu. At both sites, the terrestrial animal decomposed in a manner similar to what has been observed in previous studies in terrestrial habitats on the island of Oahu. Rate of biomass depletion was slower in both intertidal studies, and decomposition was primarily due to tide and wave activity and bacterial decomposition. No permanent colonization of carcasses by insects was seen for the intertidal carcass at Coconut Island. At the anchialine pool at Barber's Point Naval Air Station, Diptera larvae were responsible for biomass removal until the carcass was reduced below the water line and, from that point on, bacterial action was the means of decomposition. Marine and terrestrial scavengers were present at both sites although their impact on decomposition was negligible. Five stages of decomposition were recognized for the intertidal sites: fresh, buoyant/floating, deterioration/disintegration, buoyant remains, and scattered skeletal.

Arthropod Invasion of Land During Late Silurian and Devonian Times

Fossil floras and faunas of a Lower Devonian black shale from Alken, Germany, include aquatic, amphibious, and terrestrial forms. The presence of these forms suggests conditions in favor of an invasion of the land. Various arthropod adaptations to terrestrial life are present, including the development of a preoral cavity.

EVOLUTION IN THE NOTOSTRACA

The Notostraca are phyllopod Crustacea in which the carapace is shield-shaped and covers the anterior part of the body; together with other phyllopods, they are considered to be relatively unevolved Crustacea-there is a high, but irregular, number of appendages (forty to sixty pairs are usual) and the segmentation of the body is anameristic. It is characteristic of phyllopods that they occur in temporary rain pools, generally in arid or steppe country where such pools are common, and are unable to maintain themselves in the face of competition from higher Crustacea or Insecta (Ard6, 1947). The survival of such primitive and vulnerable animals poses an interesting problem-the key to which may lie in their main adaptation to a temporary habitat, the drought-resistant egg. The possession of such an egg, from which hatching normally occurs only after desiccation, is an obvious prerequisite for the exploitation of a temporary freshwater habitat by a group of animals which do not have the capacities of aerial migration which the Insects possess. These drought-resistant eggs of phyllopods are the only possible means of dispersal for the group, for the pools in which the animals occur are isolated from one another, and are only rarely part of a stream system along which dispersal of adults would be possible. The eggs are small, light in weight because of their dry alveolar shells, and are sticky when laid in at least one genus (Triops, Notostraca); further, the eggs of some Anostraca are known to retain viability after passing through the guts of Amphibia (Mathias, 1937). These facts suggest several possible means of dispersal-in or upon larger animals, attached to dry pieces of wind-blown vegetation, or airborne singly in wind currents (a desert dust-devil will whirl particles much denser than the eggs of phyllopods high into the air). That 'these passive means of dispersal are effective is quite clearly shown by the ubiquitous occurrence of phyllopods in suitable pools wherever these occur. Notostraca occur on such isolated oceanic islands as the Hawaiian group, and in the few suitable pools that the rainy English climate permits. The phyllopods show another characteristic of passively distributed invertebrates-that of very widely spread, sometimes almost cosmopolitan species; in a recent study of the Notostraca for a systematic revision I found that Triops longicaudatus, which Linder (1952) showed was the only species of the genus in the Americas, extends from the West Indies through Central America and right across the Pacific to Japan by way of the Galapagoes, Oahu and New Caledonia. In all this area there is virtually no morphological change (Longhurst, 1955). These facts of dispersal and geographical distribution seem to me to explain the survival of the phyllopods. The initial arthropod invasion of temporary pools may well have been performed by the primitive fresh-water Crustacean fauna and has radiated into the forms of phyllopods we see today-the carnivorous Notostraca, the pelagic Anostraca, and the burrowing, detritus-feeding Conchostraca. This early fauna would have spread and occupied at least a high proportion of the suitable pools, and such a cosmopolitan occupation would have effectively prevented any geographically iso-