Life-history consequences of bidirectional selection for male morph in a male-dimorphic bulb mite.

Intralocus sexual conflict (IASC) arises when males and females have different trait optima. Some males pursue different alternative reproductive tactics (ARTs) with different trait optima, resulting in different strengths of IASC. Consequently, for instance daughter fitness is differentially affected by her sire's morph. We tested if-and which-other life-history traits correlatively change in bidirectional, artificial selection experiments for ARTs. We used the male-dimorphic bulb mite Rhizoglyphus robini, the males of which are high-fitness 'fighters' or low-fitness 'scramblers'. Twice in each of the five generations of selection, we assessed clutch composition (number of mites of the various life stages present) and size (total number of offspring). Furthermore, we tracked offspring from egg to adulthood in the first and final generation to detect differences between selection lines in the size and duration of stages, and in maturation time. We found that selection for male morph increased the frequency of that morph. Furthermore, compared to fighter lines, scrambler lines produced more females, which laid larger eggs (in the final generations), and maintained a higher egg-laying rate for longer. Otherwise, our results showed no consistent differences between the selection lines in clutch size and composition, life stage size or duration, or maturation time. Though we found few correlated life-history trait changes in response to selection on male morph, the differences in egg laying rate and egg size suggest that IASC between fighters is costlier to females than IASC with scramblers. We hypothesize that these differences in reproductive traits allow fighter-offspring to perform better in small, declining populations but scrambler-offspring to perform better in large, growing populations.

[Study on community of acaroid mites breeding in home storages in Linquan Area, Anhui Province].

OBJECTIVE: To investigate the species and diversity of acaroid mites community in home storages in Linquan area, Anhui Province. METHODS: The samples of 48 kinds of storages from the residents in Linquan County were collected, and the mites in them were separated in a microscope directly. RESULTS: Totally 19 species of acaroid mites belonging to 14 genera of 6 families were obtained from the 48 kinds of samples. The diversity analysis showed that the number of species, the species richness index and species diversity index of mites in the habitats were in the order of the other storages > drysaltery > grains. CONCLUSIONS: The quantities of breeding acaroid mites in storages in Linquan area are much larger, meanwhile the species are also very rich, thus in order to reduce the harm of acaroid mites, we should take active measures to control their breeding.

Morph-specific artificial selection reveals a constraint on the evolution of polyphenisms.

Theory predicts that the evolution of polyphenic variation is facilitated where morphs are genetically uncoupled and free to evolve towards their phenotypic optima. However, the assumption that developmentally plastic morphs can evolve independently has not been tested directly. Using morph-specific artificial selection, we investigated correlated evolution between the sexes and male morphs of the bulb mite Rhizoglyphus echinopus Large 'fighter' males have a thick and sharply terminating pair of legs used to kill rival males, while small 'scrambler' males have unmodified legs, and search for unguarded females, avoiding fights. We selected on the relative leg width of only the fighter male morph, tracked the evolutionary responses in fighters and the correlated evolutionary responses in scramblers and females that were untouched by direct selection. Fighters diverged in relative leg thickness after six generations; assaying scramblers and females at the ninth generation we observed correlated responses in relative leg width in both. Our results represent strong evidence for the evolution of intraspecific phenotypic diversity despite correlated evolution between morphs and sexes, challenging the idea that male morphs are genetically uncoupled and free to independently respond to selection. We therefore question the perceived necessity for genetic independence in traits with extreme phenotypic plasticity.

Investigating species boundaries using DNA and morphology in the mite Tyrophagus curvipenis (Acari: Acaridae), an emerging invasive pest, with a molecular phylogeny of the genus Tyrophagus.

Mites of the genus Tyrophagus (Acari: Acaridae) are among the most widespread and common mites, inhabiting diverse natural and anthropogenic habitats. Some species are pests of agricultural products and stored food and/or live in house dust, causing allergies to humans. We sequenced 1.2 kb of the mitochondrial COI gene for 38 individuals belonging to seven species of Tyrophagus, including T. curvipenis, T. putrescentiae, T. fanetzhangorum, T. longior, T. perniciosus, and T. cf. similis. Molecular phylogenetic analyses (1) recovered two major clades corresponding to the presence or absence of eyespots, and (2) separated all included morphological species. Tyrophagus curvipenis and T. putrescentiae had the lowest between-species genetic distances (range, mean ± SD): 14.20-16.30, 15.17 ± 0.40 (K2P). The highest within-species variation was found in T. putrescentiae 0.00-4.33, 1.78 ± 1.44 (K2P). In this species, we recovered two distinct groups; however, no geographical or ecological dissimilarities were observed between them. Based on our analyses, we document important morphological differences between T. curvipenis and T. putrescentiae. For the first time, we record the occurrence of T. curvipenis in the New World and suggest that it may be an emerging pest as it is currently spreading in agricultural produce.

A new species of Thyreophagus (Acari: Acaridae) from Brazil, with notes on species associated with stored food and human habitats and a key to species of this genus.

A new species Thyreophagus cracentiseta n. sp. is described morphologically based on adult females, adult homeomorphic and heteromorphic males collected from chicken feed in Brazil. The Thyreophagus species associated with stored food and human habitats are reviewed, and a key to separate species of this genus is provided.

[Morphological observation on hypopus of Caloglyphus berlesei by optical microscope].

OBJECTIVE: To understand the structure characteristics of hypopus of Caloglyphus berlesei. METHODS: The hypopus of C. berlesei was collected from the feed of Chinese Polyphaga, and was made into the conventional glass specimens. The structure characteristics of hypopus of C. berlesei were observed by an optical microscope. RESULTS: The hypopus of C. berlesei had 4 pairs of legs, and the foot claws and tarsus were well-developed. The structural features were shown, such as the setae of tibia and setae of genu. Genital plates were obviously ossified. CONCLUSION: The research on hypopus of Caloglyphus berlesei provides the reference for its further scientific classification and research on the life cycle.

[Thyreophagus entomophagus breeding in beer yeast powder].

OBJECTIVE: To separate and identify Thyreophagus entomophagus from beer yeast powder and observe its morphological characteristics. METHODS: The beer yeast powder was collected from the scum after fermentation of the beer material, the mites in it were separated and made into slide specimens, and then they were identified and observed for the morphological characteristics under an optical microscope. RESULTS: The mites separated from the beer yeast powder were identified as female Thyreophagus entomophagus. Under the optical microscope, the bodies of the mites were long and narrow, which showed an oval shape, the gnathosoma was wide, the epidermis was colorless but lustrous, the external vertical seta, internal scapular seta, inner humerals, anterior lateral seta, and dorsal body setae were all absent, the bristles on the back of the body were relatively long, and all the feet were thick and strong. CONCLUSIONS: Thyreophagus entomophagus can breed in the beer yeast powder, and therefore, the powder should be stored properly to avoid the contamination caused by the mites.

[Tyrophagus palmarum and its hypopus found in feed of Tenebrio molitor].

OBJECTIVE: To observe the Tyrophagus palmarum and its hypopus in feed of Tenebrio molitor. METHODS: Feed samples were collected from T. molitor farms, and T. palmarum and its hypopus were separated from the samples by the vibration sieve method and floating method. The glass specimens were prepared and T. palmarum and its hypopus were observed under an optical microscope. RESULTS: Under the light microscope, the skin of T. palmarum was smooth and bright, the color of legs and chelicerae was relatively dark, the length of dorsal seta d2 was 3-4 times longer than d1 and la; The ω1 in tarsus of leg Ⅰ, Ⅱ was short rod, and its top was not tapered; the sucker plate in tarsus of leg Ⅳ located in the middle of the section. The hypopus was oblate, and there were two pairs of legs in front which extended to body. The rear end of hypopus became pointless and round, wrapping around a transparent and ossification skin. CONCLUSIONS: Light microscopy shows the morphological characteristics of T. palmarum and its dormant body, providing the basis for identifying the hypopus.

The Crotonia fauna of New Zealand revisited (Acari: Oribatida): taxonomy, phylogeny, ecological distribution and biogeography.

New Zealand contains 13 of the 69 species of Crotonia described globally and is the only place where all three genera of the Crotoniinae-Crotonia, Austronothrus and Holonothrus-have been recorded. Due to the pioneering work of Hammer (1966) and Luxton (1982) it also has the highest number of distribution records of Crotonia spp. anywhere. In the present study I build upon previous work to re-examine the Crotonia fauna of New Zealand in the light of recent taxonomic and biogeographical research. A new species is described, C. ramsayi sp. nov., a member of the Unguifera species group, and supplementary descriptions are provided for C. brachyrostrum (Hammer 1966), C. caudalis (Hammer, 1966), C. cophinaria (Michael, 1908), and C. unguifera (Michael 1908), as well as a key to species. Crotonia spp. from New Zealand occur predominantly in localities with relatively low mean annual temperature and high water balance, reflecting a requirement for cool, moist conditions. In New Zealand Crotonia spp. occur in an extremely wide variety of vegetation communities compared with other regions in its range (Australia, Africa and South America), and this is indicative that water balance requirements are met, regardless of vegetation type. Some elements of the New Zealand Crotonia fauna, notably the Cophinaria species group, are common to Australia, Africa and South America, indicating a shared evolutionary history pre-dating the separation of Africa from Gondwana 110 mya. The high proportion of species that occur west of the Alpine Fault is consistent with a relictual distribution of Gondwanan elements on the Australian Plate. However, it is unclear whether uplift of the Southern Alps formed a barrier to dispersal. A high representation of the morphologically closely-related Obtecta, Flagellata and Unguifera groups, shared only with South America (and, for Unguifera, with Oceania) represents a dramatically different faunal composition compared with other former Gondwanan landmasses and is consistent with submergence of most of New Zealand during the Oligocene (ca. 25 mya). All of these characteristics indicate a distinctive evolutionary pathway for the Crotonia fauna since New Zealand separated from the rest of Gondwana 80 mya.

Morphologic features of Sancassania berlesei (Acari: Astigmata: Acaridae), a common mite of stored products in China.

OBJECTIVE: Sancassania berlesei (S. berlesei) is the leading threatening mite in breeding industry of Eupolyphaga sinensis and public health. METHODS: Living specimens of S. berlesei were obtained from the surface of Eupolyphaga sinensis and purified with double-distilled water. The egg, larva, nymph, hypopus, adult male and female of S. berlesei were screened and picked out under microscope. RESULTS: Morphological variations of S. berlesei, including its legs, setae, external genitalia and accessories, are clearly identified under SEM. The larva has three pairs of legs, with no leaf-like setae, yet its coxal rod is well-developed. By nymph stage, four pairs of legs and the fourth dorsal seta arise, whereas the genital area looks still under-developed. At hypopus, the claws and tarsules appear well-built, and leaf-like setae, setae of tibia and setae of genu are seen. The sucker plate totally contains nine suckers and four shell-like dimplings in which there are symmetric distributions with 1 pair of central suckers, 2 pairs of side suckers and 1 pair of anterior suckers, respectively. One pear-like posterior sucker is located at the back of sucker plate. All suckers are smooth except for anterior sucker with radial stripe. The genital sense organ of adults exhibits itself with cordiform external aspect and typical ossification texture; whereas the male is dissimilar with the female regarding seta number on the genital sense organ. CONCLUSION: Description of the morphological structure in great detail for S. berlesei tends to supply the important information for the taxonomy and further study.

Objetivo: sancassania berlesei (S. berlesei) es el lider en la industria de cría amenaza mite eupolyphaga sinensis y la salud pública.Métodos: los especimenes vivos de S. berlesei fueron obtenidos a partir de la superficie de eupolyphaga sinensis y purificado con agua bidestilada.El huevo, larva, ninfa, hypopus, macho adulto y la hembra de S. berlesei fueron evaluados y elegidos bajo microscopio.Resultados: las variaciones morfológicas de S. berlesei, incluidas sus piernas, setas, genitales externos y accesorios, están claramente identificadas en la SEM.La larva tiene tres pares de patas, sin hojas como setas, pero su coxal Rod es desarrollada.Por la etapa de ninfa, cuatro pares de patas y el cuarto dorsal seta surgen, mientras que la zona genital se ve aún en desarrollo.En hypopus, las garras y tarsules aparecen bien construido, y la hoja como setas, setas de tibia y setas de Genu son vistos.La ventosa plato totalmente contiene nueve retoños y cuatro Shell como dimplings en que hay distribuciones simétricas con 1 par de mamones, 2 pares de lado anterior de ventosas y 1 par de tontos, respectivamente.Una pera como posterior ventosa está ubicado en la espalda de Sucker plato.Todos los tontos son suaves excepto anterior Sucker con franja radial.El órgano de sentido genital adultos exhibe con cordiforme aspecto externo y osificación típica textura; mientras que el macho es diferente con la hembra respecto a seta numero en el sentido de órganos genitales.Conclusión: descripción de la estructura morfologica en gran detalle para S. berlesei tiende a suministrar la información importante para la taxonomía y más estudio.

[Morphology observation of Histiostoma feroniarum hypopus].

OBJECTIVE: To observe the external morphology of Histiostoma feroniarum hypopus under light microscope. METHODS: The samples were collected in a mushroom cultivation base, and the Histiostoma feroniarum hypopus was isolated and purified. The slide samples were prepared and observed under an optical microscope. RESULTS: The back body of the Histiostoma feroniarum hypopus was flat with tiny bristles, the epidermis was of significant ossification, the ventral had four pairs of slender feet stretched, the sucker plate was prosperous in the end of the body, and the sucker plate had eight suckers. The gnathosoma was thin, long and highly specialized. CONCLUSION: The light microscopy shows the morphological characteristics of Histiostomaferoniarum hypopus, providing the basis for identifying the hypopus.

Fitness trade-offs and the maintenance of alternative male morphs in the bulb mite (Rhizoglyphus robini).

Alternative reproductive phenotypes (ARPs) occur across a wide range of taxa. Most ARPs are conditionally expressed in response to a cue, for example body size, that reliably correlates with the status of the environment: individuals below the (body size) threshold then develop into one morph, and individuals above the threshold develop into the alternative morph. The environmental threshold model provides a theoretical framework to understand the evolution and maintenance of such ARPs, yet no study has examined the underlying fitness functions that are necessary to realize this. Here, we empirically examined fitness functions for the two male morphs of the bulb mite (Rhizoglyphus robini). Fitness functions were derived in relation to male size for solitary males and in relation to female size under competition. In both cases, the fitness functions of the two morphs intersected, and the resulting fitness trade-offs may play a role in the maintenance of this male dimorphism. We furthermore found that competition was strongest between males of the same morph, suggesting that fitness trade-off in relation to male size may persist under competition. Our results are a first step towards unravelling fitness functions of ARPs that are environmentally cued threshold traits, which is essential for understanding their maintenance and in explaining the response to selection against alternative morphs.

A new feather mite species of the genus Picalgoides Cerný, 1974 (Astigmata: Psoroptoididae) from a passerine host in Costa Rica.

A new feather mite species, Picalgoides giganteus n. sp. (Psoroptoididae: Pandalurinae), is described from the tawny-throated leaftosser Sclerurus mexicanus Sclater (Passeriformes: Furnariidae) in Costa Rica. Among the 10 species of Picalgoides Cerný, 1974, including the new one, this is the third recorded from a passerine host; the remaining seven nominal species are associated with hosts of the order Piciformes. Brief data on the host-parasite associations of Picalgoides spp. are provided. Megninia megalixus Trouessart, 1885 from the short-tailed green magpie Cissa thalassina (Temminck) is transferred to Picalgoides as P. megalixus (Trouessart, 1885) n. comb.

Habitat complexity drives experimental evolution of a conditionally expressed secondary sexual trait.

The conditional expression of alternative phenotypes underlies the production of almost all life history decisions and many dichotomous traits, including male alternative reproductive morphs and behavioral tactics. Changes in tactic fitness should lead to evolutionary shifts in developmental switch points that underlie tactic expression. We used experimental evolution to directly test this hypothesis by rearing ten generations of the male-dimorphic mite Rhizoglyphus echinopus in either simple or three-dimensionally complex habitats that differed in their effects on morph fitness. In R. echinopus, fighter males develop weapons used for killing rivals, whereas scrambler males do not. Populations evolving in complex 3D habitats, where fighters had reduced fitness, produced fewer fighters because the switch point for fighter development evolved to a larger critical body size. Both the reduced mobility of fighter males and the altered spatial distribution of potential mates and rivals in the complex habitat were implicated in the evolutionary divergence of switch point between the habitats. Our results demonstrate how abiotic factors like habitat complexity can have a profound effect on evolution through sexual selection.

Context-dependent intergenerational effects: the interaction between past and present environments and its effect on population dynamics.

Intergenerational effects arise when parents' actions influence the reproduction and survival of their offspring and possibly later descendants. Models suggest that intergenerational effects have important implications for both population dynamical patterns and the evolution of life-history traits. However, these will depend on the nature and duration of intergenerational effects. Here we show that manipulating parental food environments of soil mites produced intergenerational effects that were still detectable in the life histories of descendents three generations later. Intergenerational effects varied in different environments and from one generation to the next. In low-food environments, variation in egg size altered a trade-off between age and size at maturity and had little effect on the size of eggs produced in subsequent generations. Consequently, intergenerational effects decreased over time. In contrast, in high-food environments, variation in egg size predominantly influenced a trade-off between fecundity and adult survival and generated increasing variation in egg size. As a result, the persistence and significance of intergenerational effects varied between high- and low-food environments. Context-dependent intergenerational effects can therefore have complex but important effects on population dynamics.

Ácaros em produtos armazenados comercializados em supermercados e feiras livres da cidade do Recife / Mites in stored foods commercialized in supermarkets and markets in Recife

Este trabalho teve como objetivo avaliar a acarofauna em grãos de feijão, milho e ração em supermercados e feiras livres da cidade do Recife, PE. Em cada estabelecimento foi coletada uma amostra de 500 g de cada grão e ração, em intervalos bimensais, no período de agosto/2002 a junho/2003. Cada amostra foi dividida em duas sub-amostras de 250 g. Uma delas foi submetida à extração de ácaros logo após a coleta e a outra foi incubada a 26°C e umidade relativa de 78 por cento por 30 dias. Ao final desse período a segunda sub-amostra foi processada da mesma forma que a primeira. Os ácaros foram montados em lâminas para microscopia em meio de Hoyer e identificados pelo menos até o nível de gênero. Foram coletados 11.956 ácaros pertencentes às famílias Acaridae, Ebertiidae, Glycyphagidae, Cheyletidae, Stigmaeidae, Pyemotidae, Tarsonemidae, Tydeidae, Cunaxidae, Ameroseiidae, Ascidae e Phytoseiidae. Dentre os ácaros primários, a espécie Suidasia medanensis Oudemans foi a predominante no levantamento (3.035 indivíduos), seguida de Caloglyphus hughesi (Samsinak) (436 indivíduos). Metapronematus sp. foi predominante (3.417 indivíduos), dentre os ácaros secundários, seguido de Tarsonemus granarius Lindquist (3.003). O número de ácaros coletados nas amostras incubadas foi sempre superior em relação às amostras não incubadas, assim como nas amostras de feira livre em relação às de supermercado.

The mite fauna was assessed in bean, maize and pet food in supermarkets and markets in Recife, PE, Brazil. A 500 g sample of each grain and food was collected in each establishment at two weekly intervals, from August 2002 to June 2003. The sample was divided into two 250 g sub-samples. One of them was submitted to spider mite evaluation shortly after collection and the other was incubated at 26°C and 78 percent humidity for 30 days. At the end of this period the second sub-sample was processed in the same way as the first. The spider mites were mounted on slides for microscopy in Hoyer medium and identified at least at genus level. Eleven thousand nine hundred and fifty-six spider mites were collected belonging to the Acaridae, Ebertiidae, Glycyphagidae, Cheyletidae, Stigmaeidae, Pyemotidae, Tarsonemidae, Tydeidae, Cunaxidae, Ameroseiidae, Ascidae e Phytoseiidae families. Among the primary spider mites the Suidasia medanensis Oudemans species was predominant in the survey (3,035 individuals) followed by Caloglyphus hughesi (Samsinak) (436 individuals). Metapronematus sp. was predominant (3,417 individuals) among the secondary spider mites followed by Tarsonemus granarius Lindquist (3,003). The number of mites collected in the incubated samples was always greater compared to the non-incubated samples in both the market and supermarket samples.

Testing the status-dependent ESS model: population variation in fighter expression in the mite Sancassania berlesei.

The conditional evolutionarily stable strategy (ESS) with status-dependent tactics is the most commonly invoked ESS for alternative reproductive tactics within the sexes. Support for this model has recently been criticized as apparent rather than real. We address key predictions of the status-dependent ESS in three populations of the male dimorphic mite Sancassania berlesei. In S. berlesei'fighter' males are characterized by a thickened pair of legs used for killing rivals; 'scramblers' are benign. Most males in each population could be manipulated to become fighters by decreasing density, fulfilling the prediction that males make a 'decision'. There was evidence of genetic covariance between sire status and offspring morph, but also a strong effect of sire morph on offspring morph ratio. This was consistent with considerable genetic variation for the status-dependent switch point as a breeding experiment found no support for single-locus inheritance. We also found evidence that switch points evolve independently of distributions of status. This study supports the current status-dependent ESS model.

Heritability of male morph in the bulb mite, Rhizoglyphus robini (Astigmata, Acaridae).

In several species of Acaridae (Astigmata), heteromorphic males, possessing a sharply terminated third pair of legs which they use to mortally stab other males, coexist with scrambler males with unmodified legs. Previous research showed that in the bulb mite, Rhizoglyphus robini (Claparède), the male morph is heritable. In this study I used a different population and carried out selection in both downward and upward direction in order to change the proportion of morphs. Starting from the proportion of about 0.2 homeomorphs in the population, I obtained a significant response to 8-10 generations of selection in two repetitions. The response was asymmetrical (stronger in upward direction). Realised heritabilities were in the range of 0.3 (downward) and 0.8 (upward).

Structure of the salivary glands of the unfed male tick Amblyomma cajennense (Fabricius) (Acarina: Ixodidae)

Acini in the salivary glands of unfed male Amblyomma cajennense of different ages, were studied. The salivary glands consist of one agranular and three granular acini types. The agranular acini are directly attached to the medial and anterior portion of the main salivary duct, and to some branches of the secondary ducts. A large, clear, central cell occupies the centre and this cell is in contact with the acinar lumen. There is no valve to the lumen. Granular acini consist of approximately six to fourteen cells (type II acini) or eight to thirteen (type III acini). The type II acini have three types of granular cells ("a", "b" and "c") and a valve: the type III acini have three types of granular cells ("d", "e" and "f" and a valve