Local host ant specificity of Phengaris (Maculinea) teleius butterfly,an obligatory social parasite of Myrmica ants

1. Phengaris butterflies are obligatory social parasites of Myrmica ants. Early research suggested that there is a different Myrmica host species for each of the five European Phengaris social parasites, but more recent studies have shown that this was an oversimplification. 2. The pattern of host ant specificity within a Phengaris teleius metapopulation from southern Poland is reported. A combination of studying the frequency distribution of Phengaris occurrence and morphometrics on adult butterflies were used to test whether use of different host species is reflected in larval development. 3. Phengaris teleius larvae were found to survive in colonies of four Myrmica species: M. scabrinodis, M. rubra, M. ruginodis, and M. rugulosa. Myrmica scabrinodis was the most abundant species under the host plant but the percentage of infested nests was similar to other host ant species at two sites and lower in comparison to nests of M. rubra and M. ruginodis at the other two sites. Morphometric measurements of adult butterflies reared by wild colonies of M. scabrinodis and M. ruginodis showed that wing size and number of wing spots were slightly greater for adults eclosing from nests of M. ruginodis. 4. Our results suggest that P. teleius in the populations studied is less specialised than previously suggested. The results are consistent with the hypothesis that P. teleius is expected to be the least specific of the European Phengaris species, as it has the largest and best defended fourth‐instar caterpillars and, as a predatory species, it spends less time in the central larval chambers of the host colonies. The fact that individuals reared by M. ruginodis had wider hind wings may suggest that P. teleius had better access to resources in M. ruginodis than in M. scabrinodis colonies.     

Larvae of Maculinea rebeli, a large-blue butterfly, and their Myrmica host ants: wild adoption and behaviour in ant-nests

The behavioural interactions between caterpillars of Maculinea rebeli Hir. and their Myrmica ant hosts were studied, both in the wild at the time of adoption, and inside captive nests of six Myrmica species.
In the wild, freshly moulted, final instar caterpillars left their food-plants at a time of day that coincided with the peak foraging activity of Myrmica (18:00-20:00 h). Once on the ground, caterpillars made no attempt to search for Myrmica but settled and waited for foraging ants to find them, which took up to 1.5 h. There was no adoption ritual: foragers of any Myrmica species picked up the caterpillars within 1–4 sec of discovery, and carried them directly to their nests.
Caterpillars grew from < 2 mg to 110 mg in laboratory ant-nests. About 60 mg was gained in autumn but 40% of this was lost during the winter, while the temperature was < 14 °C. Although caterpillars survived best with their normal host, Myrmica schencki , they could also survive in the nests of other Myrmica species. The presence of queen ants had no effect upon survival. The behaviour of the caterpillars was described and illustrated: this included the production of secretions that were drunk by the ants, begging for food and direct feeding by ants. The preferred solid food was ant eggs.
The results are discussed in terms of the social biology of Myrmica ants. It is hypothesized that Maculinea rebeli caterpillars mimic the touch pheromones of ant worker-larvae. This would explain the inability of ants to recognize caterpillars before touching them, their immediate adoption by any Myrmica species after discovery, host specificity inside wild ant-nests, the absence of queen-effect and the intimate attention of host workers.     

Chemical mimicry and host specificity in the butterfly Maculinea rebeli,a social parasite of Myrmica ant colonies

Although it has always been assumed that chemical mimicry and camouflage play a major role in the penetration of ant societies by social parasites, this paper provides the first direct evidence for such a mechanism between the larvae of the parasitic butterfly Maculinea rebeli and its ant host Myrmica schencki. In the wild, freshly moulted fourth-instar caterpillars, which have no previous contact with ants, appear to be recognized as ant larvae by foraging Myrmica workers, which return them to their nest brood chambers. Three hypotheses concerning the mechanism controlling this behaviour were tested: (i) the caterpillars produce surface chemicals that allow them to be treated as ant larvae; (ii) mimetic compounds would include hydrocarbons similar to those employed by Myrmica to recognize conspecifics and brood; and (iii) the caterpillars'' secretions would more closely mimic the profile of their main host in the wild, M. schencki, than that of other species of Myrmica. Results of behavioural bioassays and chemical analyses confirmed all three hypotheses, and explained the high degree of host specificity found in this type of highly specialized myrmecophile. Furthermore, although caterpillars biosynthesized many of the recognition pheromones of their host species (chemical mimicry), they later acquired additional hydrocarbons within the ant nest (chemical camouflage), making them near-perfect mimics of their individual host colony''s odour.     

Habitat requirements and niche selection of Maculinea nausithous and M. teleius (Lepidoptera: Lycaenidae) within a large sympatric metapopulation

Identifying the factors determining the distribution and abundance of species is a fundamental question in population ecology. Based on habitat characteristics, we sought to identify factors affecting the abundance of two vulnerable large blue butterflies, Maculinea teleius and Maculinea nausithous. Both species often occur in sympatry and thus seem to have very similar requirements with regard to their wetland habitats. Even though, M. nausithous is usually far more widespread and abundant than M. teleius in Central Europe. For understanding this difference despite a similar ecology, more data is needed on the niche selection of both species. We have recorded Maculinea numbers, vegetation structure, food-plant abundance and ant community for 120 patches within a large sympatric metapopulation of both species in the Westerwald area (Germany). Unexpectedly (based on previous data), both species were equally common in the study area, reaching high densities of up to 61 (M. teleius) and 58 (M. nausithous) individuals per 50 m2. In 116 out of 120 patches both species occurred sympatrically. The preferred habitat was extensively managed grassland, being mown or grazed twice a year. The abundance of both Maculinea species was positively related to vegetation height, food-plant and Myrmica rubra abundance. There was no association between M. teleius and its putative main host-ant Myrmica scabrinodis, indicating that M. rubra may serve as an important host in the Westerwald area. The positive effect of food-plant abundance was more pronounced for M. teleius, coinciding with a higher food-plant abundance at sites dominated by M. teleius compared to those dominated by M. nausithous. Thus, M. teleius seems to be slightly more demanding than M. nausithous in terms of food-plant availability.     

Distribution,host specificity,and the potential for cryptic speciation in hoverfly Microdon myrmicae (Diptera: Syrphidae), a social parasite of Myrmica ants

1. In 2002 Microdon myrmicae, a social parasite of Myrmica ants, was taxonomically separated from Microdon mutabilis. The original study in the U.K. found Microdon myrmicae to be specific to one ant species, Myrmica scabrinodis, yet it became apparent that the range of Microdon myrmicae includes at least the western Palaearctic. 2. Current knowledge of the European distributions of both Microdon myrmicae and Microdon mutabilis in Europe is reviewed. Also, in detailed studies of two Polish populations, Microdon myrmicae was found to survive equally well with two Myrmica ant species. We examine, however, the possibility that this reflects the presence of two separate Microdon species, each connected to one species of Myrmica. 3. Forty populations of Microdon myrmicae and 37 populations of Microdon mutabilis are currently known in Europe. All the populations in central and southern Europe that were visited after the separation of the two species were identified as Microdon myrmicae, while Microdon mutabilis’ recognised range is now restricted to the British Isles and Scandinavia. Myrmica scabrinodis was found to host Microdon myrmicae in 26 out of 31 populations investigated. Four other Myrmica species were identified to the host Microdon myrmicae: Myrmica gallienii (eight populations), Myrmica rubra (four), Myrmica vandeli (one), and Myrmica sabuleti (one). Microdon myrmicae occurs in waterlogged grassland habitats, mainly of the ‘Molinietum’ type, resulting in a patchy distribution relative to its host ants. 4. In two populations Myrmica scabrinodis and Myrmica gallienii are both abundant and rear Microdon myrmicae in equal proportions. Microdon myrmicae pupae from Myrmica gallienii nests were heavier and the anterior respiratory organs were of significantly different shape. In contrast, the comparisons of Microdon myrmicae pupae among all other populations showed no significant differences, suggesting only one species throughout the European range.     

Heritability,covariation and natural selection on 24 traits of common evening primrose (Oenothera biennis) from a field experiment

This study explored genetic variation and co‐variation in multiple functional plant traits. Our goal was to characterize selection, heritabilities and genetic correlations among different types of traits to gain insight into the evolutionary ecology of plant populations and their interactions with insect herbivores. In a field experiment, we detected significant heritable variation for each of 24 traits of Oenothera biennis and extensive genetic covariance among traits. Traits with diverse functions formed several distinct groups that exhibited positive genetic covariation with each other. Genetic variation in life‐history traits and secondary chemistry together explained a large proportion of variation in herbivory (r² = 0.73). At the same time, selection acted on lifetime biomass, life‐history traits and two secondary compounds of O. biennis, explaining over 95% of the variation in relative fitness among genotypes. The combination of genetic covariances and directional selection acting on multiple traits suggests that adaptive evolution of particular traits is constrained, and that correlated evolution of groups of traits will occur, which is expected to drive the evolution of increased herbivore susceptibility. As a whole, our study indicates that an examination of genetic variation and covariation among many different types of traits can provide greater insight into the evolutionary ecology of plant populations and plant–herbivore interactions.     

Phagocytosis of the protozoan parasite, Marteilia sydneyi, by Sydney rock oyster (Saccostrea glomerata) hemocytes

QX disease is a fatal disease in Sydney rock oysters caused by the protozoan parasite Marteilia sydneyi. The current study investigates the phagocytosis of M. sydneyi by Sydney rock oyster hemocytes. It also compares the in vitro phagocytic activities of hemocytes from oysters bred for QX disease resistance (QXR) with those of wild-type oysters. After ingestion of M. sydneyi, hemocyte granules fused with phagosome membranes and the pH of phagosomes decreased. Significantly (p = <0.05) more phagosomes in QXR hemocytes showed obvious changes in pH within 40 min of phagocytosis, when compared with wild-type hemocytes. Phenoloxidase deposition was also evident in phagosomes after in vitro phagocytosis. Most importantly, ingested and melanised M. sydneyi were detected in vivo among hemocytes from infected oysters. Overall, the data suggest that Sydney rock oyster hemocytes can recognise and phagocytose M. sydneyi, and that resistance against QX disease may be associated with enhanced phagolysosomal activity in QXR oysters.     

A gamomermis pachysoma (Linstow, 1905) N. Comb. (Mermithidae: nematoda), a parasite of social Wasps (I)

Summary Gordius vespae vulgaris Baird, 1853, is suppressed as a synonym ofMermis pachysoma Linstow, 1905.M. pachysoma is transferred to the collective groupAgamomermis Stiles, 1903. Examination of the head of the species revealed 16 papillae in six groups and small vase-shaped amphids.

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Zusammenfassung In dieser Arbeit istGordius vespae vulgaris Baird, 1853 als ein Synonym vonMermis pachysoma Linstow, 1905, beschrieben.M. pachysoma Linstow ist in die kollektive GattungAgamomermis Stiles, 1903 gestellt. Sechzehn Papillen in sechs Gruppen und kleinen vasenförmigen Amphiden waren auf dem Kopf des Artes gefunden.

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Sommaire Gordius vespæ vulgaris Baird, 1853, est un synonyme deMermis pachysoma Linstow, 1905.M. pachysoma est transféré au genre collectifAgamomermis Stiles, 1903. On rencontre sur la tête de cet animal 16 papilles réparties en 6 groupes et de patites amphides en forme de vase.

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Contribution No. 3814, Entomology Division, Science Service, Department of Agriculture, Ottawa, Canada.     

Electronic spectra of the chromium chalcocarbonyl complexes,Cr(CO)5(CX) and (η6-C6H6)Cr(CO)2(CX) (X= O,S,Se)

The room-temperature electronic spectra of the chromium chalcocarbonyl complexes, Cr(CO)₅(CX) and (η⁶-C₆H₆)Cr(CO)₂(CX) (X = O, S, Se), have been recorded in solution, and in some cases, in the gas phase. Assignments for the thiocarbonyl and selenocarbonyl spectra are proposed on the basis of the literature assignments for the parent all-CO derivatives. Overall, the data support the order of increasing electron withdrawing capacity of the chalcocarbonyl ligands as CO < CS < CSe.     

Spectral properties and bio-activity of copper(II) clofibriates, part III: crystal structure of Cu(clofibriate)2(2-pyridylmethanol)2, Cu(clofibriate)2(4-pyridylmethanol)2(H2O) dihydrate, and Cu2(clofibriate)4(N,N-diethylnicotinamide)2

New copper(II) clofibriates (clof, {2-(4-chlorophenoxy)-2-methylpropionic or 2-(4-chlorophenoxy)isobutyric acid}) of composition Cu(clof)₂L₂ (where L=2-pyridylmethanol (2-pymeth) (1), N-methylnicotinamide (Menia) (4), N,N-diethylnicotinamide (Et₂nia) (5), isonicotinamide (isonia) (7) or methyl-3-pyridylcarbamate (mpc) (8)), [Cu(clof)₂(4-pymeth)₂(H₂O)] · 2H₂O (4-pymeth=4-pyridylmethanol) (2 · 2H₂O) and Cu(clof)₂L (where L=4-pymeth (3) or Et₂nia (6)) have been prepared and spectroscopically characterized. All the Cu(clof)₂L₂ compounds seem to possess distorted octahedral copper(II) stereochemistry with differing tetragonal distortions. An X-ray analysis of 1 was carried out and it featured a tetragonal-bipyramidal geometry around the copper(II) atom. X-ray analysis of 2 · 2H₂O featured a square-pyramidal geometry around copper(II) atom. Both the Cu(clof)₂L compounds seem to consist of a binuclear unit of tetracarboxylate type bridging. An X-ray analysis of 6 revealed typical binuclear paddle-wheel type structure, consisting of two copper(II) atoms in square-pyramidal geometry bridged by four carboxylate anions in the xy-plane. All complexes under study were characterized by EPR and electronic spectroscopy. The antimicrobial effects have been tested on various strains of bacteria, yeasts and filamentous fungi.     

Ammonia excretion in the seawater blue crab (Callinectes sapidus) occurs by diffusion, and not Na+/NH4+ exchange

Summary A series of experiments was conducted to investigate whether ammonia is excreted across the seawater-acclimated blue crab's gills as ionized NH ₄ ⁺ or as the free base, NH₃. The net excretion rate of ammonia was not changed by transfer of the crabs to reduced (150 mM) Na⁺ solutions, by transfer to Na⁺- and K⁺-free artificial sea water, or by the sodium transport inhibitor amiloride. Ammonia excretion, therefore, does not appear to be linked to Na⁺ uptake in these animals, and appears to take place by passive diffusion. Since ammonia could diffuse either as NH ₄ ⁺ or NH₃, we examined two other kinds of evidence. The trans-epithelial potential was measured in sea water and the various artificial media. In spite of a 10 mV more negative potential in Na⁺-, K⁺-free medium, the ammonia excretion was not reduced. Also, in alkalinized seawater in which the partial pressure gradient of NH₃ was reduced, but the concentration gradient of NH ₄ ⁺ increased, ammonia excretion was reduced by about 70%. These results are consistent with the conclusion that ammonia excretion takes place by diffusion of the free base, NH₃.Abbreviations SW sea water - ASW artificial sea water - t.e.p. transepithelial potential The University of Texas Marine Science Institute Contribution No. 461Supported by NSF Grant PCM77-24358     

Morpho-physiological variability and differentiation of reproductive roles among foundresses of the primitively eusocial wasp, Belonogaster petiolata (Degeer) (Hymenoptera, Vespidae)

Summary: Pre-nesting foundresses of Belonogaster petiolata (Degeer) displayed a continuous variation in body size and ovarian development, wherein the majority (96%) of females possessed well-developed or developing ovaries. The latter indicates that most foundresses, including those that ultimately become subordinates in multiple-foundress colonies, have the potential to lay eggs when they first initiate or join nests. Relatively small differences in ovarian development between associated females at the start of the nesting season became pronounced over the course of the pre-emergence and early pre-matrifilial period concurrently with the differentiation of their roles as queens or subordinates. In pre-matrifilial colonies, ovarian development of queens was significantly greater than that of subordinates. Dominance rank and ovarian development among subordinates in pre-matrifilial colonies were not correlated, probably due to advanced ovarian regression in these females. The majority (96.5%) of foundresses from three successive nesting seasons were inseminated and would therefore have been capable of laying female-producing (i.e. worker- and queen-destined) eggs. Although queens of B. petiolata were not significantly larger than subordinates, they were the largest females in 41% of colonies. Similarly, #-foundresses were larger on average than %-foundresses. This indicates that body size may contribute to social and reproductive dominance, but is probably of secondary importance compared with hormonal and nutritional factors. These and previously published findings from B. petiolata suggest that the fitness benefits of associating with other foundresses during colony foundation may be largely mutualistic, and favoured by individual selection in addition to kin selection.