Brood parasitism by mites (Uropodidae) in an invasive population of the pest-ant Pheidole megacephala

We report that in Okinawa Island (southern Japan) the pupae of the invasive ant Pheidole megacephala were parasitized by an undescribed Uropodidae mite species. Our observations suggest that by sucking the hemolymph of the ant pupae during its own development, mites induce some conspicuous morphological changes and the death of parasitized P. megacephala pupae. Of the 75 collected nests, 69 (92%) were infested by the mite species. The prevalence of parasitism varied strongly among the worker and sexual castes, with the soldier and male pupae being the most attacked, followed by the minor and queen pupae. Our data represent the first case of such high parasitism in an invasive ant population. Received 2 August 2005; revised 29 September 2005; accepted 7 November 2005.     

Survey for natural enemies of the invasive alien chrysomelid, Diabrotica virgifera virgifera, in Central Europe

The western corn rootworm, Diabrotica virgifera virgifera LeConte(Coleoptera: Chrysomelidae), is the mostdestructive pest of maize (Zea mays L.)in North America, and began to successfullyinvade Central Europe in the early 1990's. Thispaper reports a three-year field surveyconducted in Hungary, Yugoslavia, and Croatia,which are currently the focal points ofinvasion, with the aim to determine theoccurrence of indigenous natural enemies ofD. v. virgifera in Europe. A total of9,900 eggs, 550 larvae, 70 pupae and 33,000adults were examined for the occurrence ofparasitoids, nematodes, and fungal pathogens. It can be concluded from the survey resultsthat effective indigenous natural enemies arenot attacking any of the life stages of D.v. virgifera in Europe. The exception is theoccurrence of the fungi Beauveriabassiana (Bals.) Vuill. (Mitosporic fungi;formerly Deuteromyces) and Metarhiziumanisopliae (Metsch.) Sorok (Mitosporic fungi)attacking adults of D. v. virgifera at anextremely low level (< 1%). However no otherentomopathogenic fungal pathogens,entomopathogenic nematodes, or parasitoids werefound on eggs, larvae, pupae or adults. Whileseveral natural enemies in North and CentralAmerica are known to attack D. v.virgifera, it is apparent that indigenousnatural enemies in Europe have not adapted tothe high population density of the alieninvasive species D. v. virgifera. Classical biological control may provide anopportunity to reconstruct the natural enemycomplex of an invading alien pest, and itsapplication to manage D. v. virgiferapopulations in Europe should be considered.     

New records of the carabidicolous laboulbeniales (Ascomycetes) of Japan

Six carabidicolous species of Laboulbeniales are reported as new for the Japanese mycoflora. They areDixomyces stomonaxi, Laboulbenia picardii, L. tenera, L. slackensis, L. aristata andL. kwangjuensis. Two forms ofD. stomonaxi are distinguished, one form of which resemblesD. nigromarginatus. A remarkable ornamentation consisting of a coillike pattern occurs on the receptacle ofL. picardii. InL. tenera andL. slackensis, the outer appendage has somewhat constricted, blackened septa near the base.Laboulbenia aristata andL. kwangjuensis have spirally arranged outer wall cells. Antheridia were observed inL. tenera, L. slackensis, L. aristata andL. kwangjuensis.     

New geographical distribution and host records of rust fungi from northern Thailand

Ten species of rust fungi (Crossopsora 2, Maravalia 1, Pileolaria 1, Puccinia 1, Ravenelia 1, Sphaerophragmium 1, Uredo 2, and Uromyces 1) are newly recorded together with six new host plants in Thailand.Contribution no. 194, Laboratory of Plant Parasitic Mycology, Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan     

Invasion of alien macroalgae in different Mediterranean habitats

The study evaluated different macroalgal invasions in the main Mediterranean coastal habitats on hard bottom. Biodiversity, species composition and structure of macroalgal assemblages were compared among non-invaded areas and areas invaded by the Chlorophyta Caulerpa racemosa var. cylindracea and by the turf-forming Rhodophyta Womersleyella setacea in three different habitats: shallow rocky bottom, deep rocky bottom and dead matte of the seagrass Posidonia oceanica. Results showed that alien macroalgae constituted a relevant component of benthic assemblages in invaded areas of the Mediterranean Sea. Assemblages invaded by Womersleyella setacea and Caulerpa racemosa showed lower values of diversity and large differences in the structure and species composition related to non-nvaded assemblages. The species that mostly suffered from invasion were erect species reproducing sexually; moreover, the dominance of W. setacea led to low abundance of native filamentous algae, while C. racemosa colonization seemed particularly threatening for encrusting algae. All the studied habitats appeared highly invasible by alien macroalgae, even if W. setacea appeared more invasive in deeper habitats, while colonization of C. racemosa seemed more serious in shallower habitats; the dead matte of P. oceanica represented a suitable substrate for the spread of both species. Differences among assemblages in different habitats were reduced in invaded areas.     

Shifts in aquatic macroinvertebrate biodiversity associated with the presence and size of an alien crayfish

To investigate the effects of Procambarus clarkii on macroinvertebrate diversity, we conducted a mesocosm experiment simulating small pools in rice field pads after the rice season. We hypothesized that crayfish predation would negatively impact macroinvertebrate diversity, and the magnitude of this impact should vary with the size of P. clarkii. We conducted a short-term mesocosm experiment to determine macroinvertebrate diversity in the presence of three size classes and in the absence of crayfish, as well as the diet composition of crayfish from the three size classes. At the end of the experiments, the diet of crayfish was composed of the most available taxa (Culicidae, Chironomus, Tanytarsini and Orthocladinae). These results also show evidence that, in confined areas, crayfish are important predators of major rice pests such as rice Chironominae larvae. Macroinvertebrate diversity was negatively affected by crayfish presence, but the effect was inversely proportional to crayfish size. The highest diversity index was obtained in the absence of P. clarkii, and juvenile crayfish significantly reduced macroinvertebrate diversity. Thus, the impact of P. clarkii on aquatic macroinvertebrates is size dependent and may be relevant in small pools formed in rice field pads from early autumn to late winter. Overall, our findings suggest that the negative effects of P. clarkii on macroinvertebrate diversity may be particularly strong in local natural assemblages confined to puddles of water or small ponds in wetland areas.     

New records of minute litter-decomposing basidiomycetes from Japan.Actiniceps thwaitesii (Pterulaceae) new to Japan andAnastrophella podocarpicola sp. nov. (Tricholomataceae)

Actiniceps thwaitesii (Pterulaceae) new to Japan andAnastrophella podocarpicola sp. nov. (Tricholomataceae) are described and illustrated. The former is characterized by forming stipitate-capitate basidiomata under 1 mm tall with encrusted cystidia and acanthophyses. The latter, occurring on a decaying leaf ofPodocarpus macrophyllus, differs from other taxa ofAnastrophella in having undifferentiated hymenial cystidia and smaller basidiospores and basidia. Their cultural features are also presented.     

Piscivorous fishes diet dominated by the Asian cyprinid invader,topmouth gudgeon (<Emphasis Type=Italic>Pseudorasbora parva</Emphasis>)

Predation on the non-native cyprinid, Pseudorasbora parva, was reported during an annual study in a small connecting canal about 40 km south of Brno, Czech Republic. Two cyprinid fish species (Pseudorasbora parva, Rutilus rutilus) were identified in the diet of 23 piscivores belonging to three native fishes (Perca fluviatilis, Sander lucioperca, Esox lucius). The relative abundance of prey fishes changed seasonally and was dominated by the topmouth gudgeon in spring. Thereafter roach incidence continuously increased. In contrast, topmouth gudgeon was found to be a more sized-available prey and was the most dominant prey species in the diet of all piscivorous fishes during the whole season. Strong piscivory towards this alien might be beneficial for its eradication or control to support ecological integrity in natural and modified seminatural habitats.     

New species and new records of Callionymus from the Pacific Ocean (Teleostei: Callionymidae)

Recently obtained material of Callionymus from the Pacific Ocean includes: Callionymus marquesensis sp. n. (Marquesas Islands), characterized within the C. variegatus-group of the subgenus Calliurichthys by its preopercular spine formula of with an upcurved main tip and a bony keel between the points on the dorsal margin, and a spotted dorsal fin without filaments which is higher than the 1st D₂ ray in both sexes; C. pleurostictus Fricke, 1982, record from New Britain and Solomon Islands, with a discussion of competition with C. delicatulus; C.simplicicornis Valenciennes, 1837, record from Society Islands and Marquesas Islands, with a discussion of competition with C. marquesensis; C. obscurus sp. n. (Ambon, Indonesia) which is characterized within the subgenus Spini-capitichthys by its preopercular spine formula with an upcurved main tip and very small ventral serrae, its weakly armed head, and its 7 anal fin rays.     

Complex interactions between native and invasive fish: the simultaneous effects of multiple negative interactions

We suggest that the ultimate outcome of interactions between native species and invasive species (extinction or coexistence) depends on the number of simultaneous negative interactions (competition and predation), which depends on relative body sizes of the species. Multiple simultaneous interactions may constrain the ability of native species to trade fitness components (i.e., reduced growth for reduced risk of predation) causing a spiral to extinction. We found evidence for five types of interactions between the adults and juveniles of introduced western mosquitofish (Gambusia affinis) and the juveniles of native least chub (Iotichthys phlegethontis). We added ten large (23–28 mm) and seven small (9–13 mm) young-of-the-year (YOY) least chub to replicate enclosures with zero, low, and high densities of mosquitofish in a desert spring ecosystem. Treatments with mosquitofish reduced the average survival of least chub by one-third. No small YOY least chub survived in enclosures with high mosquitofish densities. We also performed two laboratory experiments to determine mortality to predation, aggressiveness, and habitat selection of least chub in the presence of mosquitofish. Mean mortality of least chub due to predation by large mosquitofish was 69.7% over a 3-h trial. Least chub were less aggressive, selected protected habitats (Potamogeton spp.), and were more stationary in the presence of mosquitofish where the dominance hierarchy was large mosquitofish>>large least chubsmall mosquitofish>>small least chub. Least chub juveniles appear to be figuratively caught in a vice. Rapid growth to a size refuge could reduce the risk of predation, but the simultaneous effects of competition decreased least chub growth and prolonged the period when juveniles were vulnerable to mosquitofish predation.     

The role of cuticular hydrocarbons as chemical cues for nestmate recognition in the invasive Argentine ant (<Emphasis Type="Italic">Linepithema humile</Emphasis>)

Argentine ants (Linepithema humile) in their native South American range, like most other ant species, form spatially restricted colonies that display high levels of aggression toward other such colonies. In their introduced range, Argentine ants are unicolonial and form massive supercolonies composed of numerous nests among which territorial boundaries are absent. Here we examine the role of cuticular hydrocarbons (CHCs) in nestmate recognition of this highly damaging invasive ant using three supercolonies from its introduced range. We conducted behavioral assays to test the response of Argentine ants to workers treated with colonymate or non-colonymate CHCs. Additionally, we quantified the amount of hydrocarbons transferred to individual ants and performed gas chromatography-mass spectrometry (GC/MS) to qualitatively characterize our manipulation of CHC profiles. The GC/MS data revealed marked differences in the hydrocarbon profiles across supercolonies and indicated that our treatment effectively masked the original chemical profile of the treated ants with the profile belonging to the foreign individuals. We found that individual workers treated with foreign CHCs were aggressively rejected by their colonymates and this behavior appears to be concentration-dependent: larger quantities of foreign CHCs triggered higher levels of aggression. Moreover, this response was not simply due to an increase in the amount of CHCs applied to the cuticle since treatment with high concentrations of nestmate CHCs did not trigger aggression.The results of this study bolster the findings of previous studies on social insects that have implicated CHCs as nestmate recognition cues and provide insight into the mechanisms of nestmate recognition in the invasive Argentine ant. Received 6 February 2007; revised 31 May and 27 July 2007; accepted 16 August 2007.     

New records of the carabidicolous Laboulbeniales (Ascomycetes) of Japan (II)

Six carabidicolous species of Laboulbeniales are reported as new for the Japanese mycoflora. They areLaboulbenia finitima, L. separata, L. borneensis, L. manubriolata, Dimeromyces caribaeus, andDixomyces ornatus. In Japan, the former three species are parasitic onMochtherus luctuosus and the latter three species onPerigona nigriceps. Laboulbenia finitima occurs on the left legs (tarsi and tibiae);L. separata on the left elytral margin:L. borneensis on the pronotum;L. manubriolata on the pronotum and elytra;Dimeromyces caribaeus on the right inferior posterior surface of the prothorax (pronotal hypomeron); andDixomyces ornatus on the outer margin of the right elytron. Comments and photographs are given for each fungus.     

New records of Conidae (Mollusca: Gastropoda) from the New Zealand region

Abstract

Conus howelli Iredale is recorded from New Zealand. C. howelli and C. raoulensis Powell are considered to be very closely related, and Kermasprella Powell is thus probably a svnonvm of Endemoconus Iredale. C. teramachii (Kuroda) and C. smirna Bartsch ' Rehder are recorded from off northern New Zealand, and the known range of C. kermadecensis Iredale is extended southward.     

Genomic organization and evolution of the 5S ribosomal DNA in Tilapiini fishes

Summary 5S rDNA sequences present an intense dynamism and have proved to be valuable as genetic markers to distinguish closed related species and also in the understanding of the evolutionary dynamic of repetitive sequences in the genomes. In order to identify patterns of 5S rDNA organization and their evolution in the genome of fish species, such genomic segment was investigated in the tilapias Oreochromis niloticus and Tilapia rendalli, and in the hybrid O. urolepis hornorum × O. mossambicus. A dual 5S rDNA system was identified in the three analyzed tilapia samples. Although each 5S rDNA class was conserved among the three samples, a distinct 5S rDNA genome organization pattern could be evidenced for each sample. The presence of a dual 5S rDNA system seems to be a general trait among non-related teleost fish orders, suggesting that evolutionary events of duplication have occurred before the divergence of the main groups of teleost fishes.     

Unadapted behaviour of native,dominant ant species during the colonization of an aggressive,invasive ant

Among the factors driving the invasive success of non-indigenous species, the “escape opportunity” or “enemy release” hypothesis argues that an invader’s success may result partly from less resistance from the new competitors found in its introduced range. In this study, we examined competitive interactions between the little fire ant Wasmannia auropunctata (Roger) and ant species of the genus Pheidole in places where both are native (French Guiana) and in places where only species of Pheidole are native (New Caledonia). The experimental introduction of W. auropunctata at food resources monopolized by the Pheidole species induced the recruitment of major workers only for the Guianian Pheidole species, which were very effective at killing Wasmannia competitors. In contrast, an overall decrease in the number of Pheidole workers and no recruitment of major workers were observed for the New Caledonian species, although the latter were the only ones able to kill the Wasmannia workers. These results emphasize the inappropriate response of native dominant New Caledonian species to W. auropunctata and, thus, the importance of enemy recognition and specification in the organization of ant communities. This factor could explain how invasive animal species, particularly ants, may be able to successfully invade species-rich communities.     

Predicting invasion dynamics of four alien Pinus species in a highly fragmented semi-arid shrubland in South Africa

This study explored the determinants of spread of four alien Pinus species and the ability of models to predict invasion dynamics in a complex fragmented landscape. The role of environmental factors, natural and anthropogenic disturbance in relation to invasion history was assessed for different stages in the invasion process using a Geographic Information System. Pines escaped from plantations over the past 30 years and spread into the natural semi-arid shrubland (renosterveld). The pattern of spread was compared with a simulated random distribution using two different techniques, a standard logistic regression, and a new recursive modelling approach (Formal Inference-based Recursive Modelling; FIRM). FIRM analysis improved the accuracy of predictions and revealed interactive effects of variables hidden by the logistic regression analysis. More than 80% of isolated pine individuals were found in 20% of the habitat classified as suitable by the models. Soil pH was the most important predictor for the distribution of isolated trees, whereas the establishment of dense pine stands was largely determined by fire history. Differences in invasive behaviour could be explained by species attributes such as limited dispersal for P. canariensis, and better drought-tolerance for P. halepensis. Sixty-five percent of the current pine distribution was accurately predicted by the spatial distribution of the first trees to have invaded. Such models could be used to predict potential spread of invasive plants and gain a better understanding of the main factors driving the invasion process. However, the spread of invasive species in fragmented landscapes, strongly modified by human activities, is very complicated, and the spread remains difficult to predict in the long term. The dynamics of invasion are discussed in relation to changes in land use and disturbance regime.     

Life-history styles of fishes in South African estuaries

Synopsis Fish utilizing South African estuaries may be divided into two major groups according to the location of their spawning sites. The marine group comprises large species which spawn at sea, enter estuaries mainly as juveniles, and return to the sea prior to attaining sexual maturity. The estuarine group is dominated by small species which have the ability to complete their life cycle within the estuarine environment. They tend to produce relatively few, demersal eggs, or exhibit parental care, which facilitates the retention of eggs and young within the estuary, whereas the marine group release large numbers of small pelagic eggs during spawning and exhibit no parental care. This is contrary to the theory that estuaries (unpredictable environments) should favour altricial life-history styles and the marine inshore zone (a more predictable environment) should favour precocial styles. However, if the total ichthyofauna of South African estuaries is considered, then altricial species predominate. The fact that both altricial and precocial traits are well represented within the overall estuarine fish community suggests that the various taxa have adapted their life-history styles, in different ways, to ensure the utilization of abundant food resources available within these fluctuating systems. A detailed comparison of the life-history styles of the estuarine teleostGilchristella aestuaria and the marine fishMugil cephalus is used to illustrate the contrasting manner in which these two species have succeeded in exploiting South African estuaries.