Common endosymbionts affect host fitness and sex allocation via egg size provisioning.

It is hard to overemphasize the importance of endosymbionts in arthropod biology, ecology and evolution. Some endosymbionts can complement host metabolic function or provide defence against pathogens; others, such as ubiquitous Wolbachia and Cardinium, have evolved strategies to manipulate host reproduction. A common reproductive manipulation strategy is cytoplasmic incompatibility (CI) between differently infected individuals which can result in female mortality or male development of fertilized eggs in haplodiploid hosts. Recently, an additional role of endosymbionts has been recognized in the modification of sex allocation in sexually reproducing haplodiploids. This was theoretically expected due to the maternal inheritance of endosymbionts and natural selection for them to increase infected female production, yet the underlying mechanism remained unknown. Here, we tested whether and how Cardinium and Wolbachia causing different CI types interact to increase female production in a haplodiploid thrips species where sex allocation depends on both maternal condition and egg size provisioning. We found that Cardinium augmented female production by increasing maternal fitness and egg size, thereby boosting fertilization rate and offspring fitness. Wolbachia, in contrast, reduced the beneficial effects of Cardinium. Our results demonstrate different invasion strategies and antagonistic effects of endosymbiotic bacteria on host fitness and evolution of sex allocation.

Endosymbionts moderate constrained sex allocation in a haplodiploid thrips species in a temperature-sensitive way.

Maternally inherited bacterial endosymbionts that affect host fitness are common in nature. Some endosymbionts colonise host populations by reproductive manipulations (such as cytoplasmic incompatibility; CI) that increase the reproductive fitness of infected over uninfected females. Theory predicts that CI-inducing endosymbionts in haplodiploid hosts may also influence sex allocation, including in compatible crosses, however, empirical evidence for this is scarce. We examined the role of two common CI-inducing endosymbionts, Cardinium and Wolbachia, in the sex allocation of Pezothrips kellyanus, a haplodiploid thrips species with a split sex ratio. In this species, irrespective of infection status, some mated females are constrained to produce extremely male-biased broods, whereas other females produce extremely female-biased broods. We analysed brood sex ratio of females mated with males of the same infection status at two temperatures. We found that at 20 °C the frequency of constrained sex allocation in coinfected pairs was reduced by 27% when compared to uninfected pairs. However, at 25 °C the constrained sex allocation frequency increased and became similar between coinfected and uninfected pairs, resulting in more male-biased population sex ratios at the higher temperature. This temperature-dependent pattern occurred without changes in endosymbiont densities and compatibility. Our findings indicate that endosymbionts affect sex ratios of haplodiploid hosts beyond the commonly recognised reproductive manipulations by causing female-biased sex allocation in a temperature-dependent fashion. This may contribute to a higher transmission efficiency of CI-inducing endosymbionts and is consistent with previous models that predict that CI by itself is less efficient in driving endosymbiont invasions in haplodiploid hosts.

Dorsipes caspius n. sp. (Acari: Podapolipidae), a subelytral parasite of Pterostichus caspius (Menetries) (Coleoptera: Carabidae) with notes on host range of the genus and the distribution of the platysmae group.

The ectoparasitic mite Dorsipes caspius n. sp. (Heterostigmata: Podapolipidae) belonging to the platysmae species group collected from the beneath elytra of Pterostichus (Lyrothorax) caspius (Menetries) (Coleoptera: Carabidae) in northern Iran, is described. This is the first record of species of the platysmae group from the Middle East. Keys to adult and larval female stages of world species of the platysmae group are provided. The host range of all species of the genus and the distribution of all representatives of the group are discussed.

Urban greening with shrubs can supercharge invertebrate abundance and diversity.

In urban areas, diverse and complex habitats for biodiversity are often lacking. This lack of diversity not only compromises essential ecological processes, such as pollination and nutrient cycling, but also diminishes the resilience of urban ecosystems to pests and diseases. To enhance urban biodiversity, a possible solution is to integrate shrubs alongside trees, thereby increasing the overall amount of vegetation, structural complexity and the associated resource diversity. Here, using a common garden experiment involving a variety of trees and shrubs planted alone and in combination, we evaluate how canopy-associated invertebrate assemblages are influenced by vegetation type. In particular, we test whether the presence of shrubs, alone or with trees, results in increased abundance and taxonomic richness of invertebrates, compared to trees on their own. We found that the overall abundance of invertebrates, and that of specific functional groups (e.g., herbivores, pollinators, detritivores), was higher on shrubs, compared to trees, and when trees and shrubs were planted in combination (relative to trees on their own). Our results suggest that planting shrub and tree species with wide and dense crowns can increase the associated abundance and taxonomic and functional group richness of invertebrate communities. Overall, our findings indicate that urban planning would benefit from incorporating shrubs alongside urban trees to maximise invertebrate abundance, diversity and function in urban landscapes.

Two New Phoretic Species of Heterostigmatic Mites (Acari: Prostigmata: Neopygmephoridae and Scutacaridae) on Australian Hydrophilid Beetles (Coleoptera: Hydrophilidae).

Many heterostigmatic mites (Acari: Prostigmata: Heterostigmata) display a wide range of symbiotic interactions, from phoresy to parasitism, with a variety of insects. Australia is expected to harbour a rich diversity of heterostigmatic mites; however, its phoretic fauna and its host associations remain mainly unexplored. We conducted a short exploration of Australian insect-associated phoretic mites in summer 2020 and found two new phoretic heterostigmatic species on a semiaquatic hydrophilid beetle species, Coelostoma fabricii (Montrouzier, 1860) (Coleoptera: Hydrophilidae). Here, we describe these two new species, Allopygmephorus coelostomus sp. nov. (Neopygmephoridae) and Archidispus hydrophilus sp. nov. (Scutacaridae), which both belong to the superfamily Pygmephoroidea. Both species are distinct from their congeners, with a plesiomorphic character, bearing a median genital sclerite (mgs). Our study reports both genera for the first time from Australia.

Sheltered life beneath elytra: three new species of Eutarsopolipus (Acari, Heterostigmatina, Podapolipidae) parasitizing Australian ground beetles.

In this study, we conducted a summer sampling of carabid beetles in eastern Australia to identify their associated parasitic mites. Here, we describe three new species of the genus Eutarsopolipus from under the elytra (forewings) of three native carabid species (Coleoptera: Carabidae): Eutarsopolipus paryavae n. sp. (pterostichi group) from Geoscaptus laevissimus Chaudoir; Eutarsopolipus pulcher n. sp. (leytei group) from Gnathaphanus pulcher (Dejean); and Eutarsopolipus chlaenii n. sp. (myzus group) from Chlaenius flaviguttatus Macleay. We further provide an identification key of the world species of pterostichi and leytei species groups as well as closely related species of the myzus group possessing similar characters including short cheliceral stylets. The significant diversity of Eutarsopolipus recovered here suggests that the current knowledge about Australian podapolipid mites (specially Eutarsopolipus) is still in its infancy and deserves further study.

TITLE: Vivre à l'abri sous les élytres : trois nouvelles espèces d'Eutarsopolipus (Acari, Heterostigmatina, Podapolipidae) parasitant des carabes australiens. ABSTRACT: Dans cette étude, nous avons effectué un échantillonnage estival de carabes dans l'est de l'Australie pour identifier leurs acariens parasites associés. Nous décrivons trois nouvelles espèces du genre Eutarsopolipus sous les élytres (ailes antérieures) de trois espèces de carabes indigènes (Coleoptera : Carabidae) : Eutarsopolipus paryavae n. sp. (groupe pterostichi) de Geoscaptus laevissimus Chaudoir, Eutarsopolipus pulcher n. sp. (groupe leytei) de Gnathaphanus pulcher (Dejean) et Eutarsopolipus chlaenii n. sp. (groupe myzus) de Chlaenius flaviguttatus Macleay. Nous fournissons en outre une clé d'identification des espèces mondiales des groupes d'espèces pterostichi et leytei ainsi que des espèces étroitement apparentées du groupe myzus possédant des caractères similaires, y compris des stylets chélicéraux courts. La diversité importante des Eutarsopolipus collectés ici suggère que les connaissances actuelles sur les acariens podapolipidés australiens (en particulier Eutarsopolipus) en sont encore à leurs balbutiements et méritent une étude plus approfondie.

Constrained sex allocation after mating in a haplodiploid thrips species depends on maternal condition.

In females of haplodiploid animals, female production requires fertilization, whereas male production does not. Therefore, haplodiploid species can display extraordinary sex ratios. Constrained sex allocation occurs when a female cannot produce daughters. This can be due to virginity but may also occur after mating due to insemination failure, selfish genetic elements or physiological constraints. Here, we investigated the mechanism underlying constrained sex allocation in Pezothrips kellyanus. In this species some mated females produce highly female-biased broods, yet, for unknown reasons, others produce extremely male-biased broods. Using crossing experiments controlled for maternally inherited endosymbionts we confirmed that constrained females were successfully inseminated. Furthermore, male-biased offspring production was not paternally inherited, ruling out paternal sex ratio elements previously identified as sex ratio distorters in some parasitoid wasps. Next, we excluded mating time and paternal fitness effects (male size) on sex allocation. However, we found that constrained sex allocation only occurred in small females producing smaller eggs than large females producing larger eggs and female-biased broods. Consequently, the bimodal sex allocation pattern correlates with maternal condition, and may have arisen (adaptively or non-adaptively) in association with an egg size-mediated fertilization mechanism recently detected in some haplodiploids, with egg size positively affecting fertilization success.

First Description of Male and Larval Female of Parasitic Mite Eutarsopolipus abdominis (Acari: Podapolipidae) with Redescription of the Adult Female.

Male and larval female of the parasitic mite Eutarsopolipus abdominis Regenfuss, 1968 (Acari: Prostigmata: Podapolipidae) belonging to the myzus species group are described and illustrated for the first time on the basis of the materials recovered from under elytra of Agonum sp. (Coleoptera: Carabidae) from Mazandaran Province, northern Iran. A redescription of the adult female is also provided. It is the first record of this species from Asia and fourth representative of parasitic mites of the myzus species group found from Iran. Furthermore, this finding revealed the first record of the association between tribe Platynini (Coleoptera: Carabidae: Harpalinae) and mites of myzus species group, and one of the highest levels of polyxeny among mites of the genus Eutarsopolipus.

Pseudopygmephorellus mazandaranicus sp. nov. (Acari: Heterostigmata: Pygmephoridae), phoretic on scarabaeid dung beetles (Coleoptera: Scarabaeidae) from Iran.

The mite species Pseudopygmephorellus mazandaranicus Katlav and Hajiqanbar sp. nov. (Acari: Prostigmata: Pygmephoridae) is described and illustrated from northern Iran. This new species was discovered phoretic on three different scarabaeid dung beetles: Onthophagus sp., Aphodius depressus (Kugelann, 1792), Aphodius varians Duftschmid, 1805. This finding presents the first record of the genus Pseudopygmephorellus Khaustov, 2008 from Asia. The host range/habitat and world-wide distribution of species of the genus Pseudopygmephorellus is reviewed and a key to world species of the genus is provided.