Phoretic mite infestations associated with Rhynchophorus palmarum (Coleoptera: Curculionidae) in southern California

Francesc Gómez-marco, Hans Klompen, Mark Hoddle. Systematic & Applied Acarology. VOL. 26, NO. 10 (2021). DOI: https://doi.org/10.11158/saa.26.10.6

Abstract

The South American palm weevil, Rhynchophorus palmarum (Coleoptera: Curculionidae), established in San Diego County, California, USA sometime around 2014. Attached to the motile adults of this destructive palm pest, we identified three species of uropodine mites (Parasitiformes: Uropodina), Centrouropoda n. sp., Dinychus n. sp. and Fuscuropoda marginata. Two of these species, Centrouropoda n. sp. and Dinychus n. sp. are recorded for the first time in the USA and were likely introduced by R. palmarum. Several species of mites, primarily of Uropodina, have previously been recorded as phoretic on Rhynchophorus spp. In this study, we examined 3,035 adult R. palmarum trapped over a 2.5-year period, July 2016 to December 2018, and documented the presence of and species composition of phoretic mites and their relationship with weevil morphometrics (i.e., pronotum length and width). The presence and species composition of mites on weevil body parts changed over the survey period. No mites were found under weevil elytra in 2016 and mite prevalence under elytra increased over 2017–2018 due to an increased abundance of Centrouropoda n. sp per individual beetle. Mite occurrence levels were significantly correlated with reduced pronotum widths of male weevils only. The significance of this finding on male weevil fitness is unknown. Potential implications of phoretic mites on aspects of the invasion biology of R. palmarum are discussed.

Evidence that copepod biomass during the larval period regulates recruitment of Lake Erie walleye

Cassandra J. Maya, Richard R.Budnik, Stuart A. Ludsin, Daniel R. O'Donnell, James M. Hood, Edward F. Roseman, Elizabeth A. Marschall. Journal of Great Lakes Research. 2021. https://doi.org/10.1016/j.jglr.2021.09.009

Abstract

Walleye (Sander vitreus) is an economically and culturally important species in Lake Erie that has experienced large interannual variability in recruitment. We examined the importance of prey biomass during the larval period to walleye recruitment while also considering the importance of temperature. Using nine years of field data over a 22-year period (1994–2016) for larval walleye and zooplankton, we found that strong recruitment events occurred in years when the biomass (dry µg L-1) of copepods (e.g., calanoids, cyclopoids) was greater during the spring larval period. Conversely, the biomass of cladocerans and mean spring water temperatures were poor predictors of walleye recruitment. Our results highlight the need to consider zooplankton availability during the larval period when seeking to understand the recruitment dynamics of freshwater fish populations such as Lake Erie walleye.

Hairs distinguish castes and sexes: identifying the early ontogenetic building blocks of a fungus-farming superorganism (Hymenoptera: Formicidae)

Rachelle M.M. Adams, Rasmus S. Larsen, Nicoletta Stylianidi, Dave Cheung, Bitao Qiu, Stephanie K. Murray, Guojie Zhang & Jacobus J. Boomsma. Myrmecol. News 31: 201-216. 2021. doi: 10.25849/myrmecol.news_031:201

Abstract

Ants are among the best-known insects, but the morphology and development of their larvae are rarely studied in a systematic manner. Precise information on larval development is needed not only to understand ontogenetic development of caste phenotypes but also ultimately to allow a better understanding of the integrated development of entire ant colonies – superorganisms that have an inseminated founding queen as germ-line, cohorts of unmated workers as soma, and the iteroparously produced gyne and male reproductives as gamete analogues. Here, we present a survey of larval morphology of the fungus-growing ant Acromyrmex echinatior (Forel, 1899), documenting the four instars of large and small workers and the five instars of gyne and male larvae. We used a combination of quantitative traits (body length, body curvature, hair patterning, head to body length ratio) and binary traits (presence / absence of anchor-tipped hairs, gut full / empty, head moving or not), and we document variation across the instars and sexes for 251 individuals with z-stacked images. Based on the statistical resolution of single and combined traits, we provide a key for the 3rd to 5th instar larvae, where sex and developmental stage can be unambiguously identified, and offer notes on the second instar, where identifications are statistically possible but with lower accuracy. This key is also available as an electronic resource <https://megalomyrmex.osu.edu/apps/acro-larva-key/>. We discuss the challenges involved in this type of research and highlight opportunities for addressing new research questions that become accessible when sex-specific and caste-specific larval instars can be distinguished. 

Comparative and predictive phylogeography in the South American diagonal of open formations: Unravelling the biological and environmental influences on multitaxon demography

Isabel A S Bonatelli, Marcelo Gehara, Bryan C Carstens, Guarino R Colli, Evandro M Moraes. Mol Ecol. 2021 Oct 6. https://doi.org/10.1111/mec.16210. 

Abstract

Phylogeography investigates historical drivers of the geographical distribution of intraspecific lineages. Particular attention has been given to ecological, climatic and geological processes in the diversification of the Neotropical biota. Several species sampled across the South American diagonal of open formations (DOF), comprising the Caatinga, Cerrado and Chaco biomes, experienced range shifts coincident with Quaternary climatic changes. However, comparative studies across different spatial, temporal and biological scales on DOF species are still meagre. Here, we combine phylogeographical model selection and machine learning predictive frameworks to investigate the influence of Pleistocene climatic changes on several plant and animal species from the DOF. We assembled mitochondrial/chloroplastic DNA sequences in public repositories and inferred the demographic responses of 44 species, comprising 70 intraspecific lineages of plants, lizards, frogs, spiders and insects. We then built a random forest model using biotic and abiotic information to identify the best predictors of demographic responses in the Pleistocene. Finally, we assessed the temporal synchrony of species demographic responses with hierarchical approximate Bayesian computation. Biotic variables related to population connectivity, gene flow and habitat preferences largely predicted how species responded to Pleistocene climatic changes, and demographic changes were synchronous primarily during the Middle Pleistocene. Although 22 (~31%) lineages underwent demographic expansion, presumably associated with the spread of aridity during the glacial Pleistocene periods, our findings suggest that nine lineages (~13%) exhibited the opposite response due to taxon-specific attributes.

10-year trends reveal declining quality of seeded pollinator habitat on reclaimed mines regardless of seed mix diversity

Andrew H Lybbert, Sarah J Cusser, Keng-Lou James Hung, Karen Goodell. Ecol Appl. 2021 Oct 6;e02467. doi: 10.1002/eap.2467. PMID: 34614245 DOI: 10.1002/eap.2467

Abstract

Plant-pollinator interactions represent a crucial ecosystem function threatened by anthropogenic landscape alterations. Disturbances that reduce plant diversity are associated with floral resource and pollinator declines. Establishing wildflower plantings is a major conservation strategy targeting pollinators, the success of which depends on long-term persistence of seeded floral communities. However, most pollinator-oriented seeding projects are monitored for a few years, making it difficult to evaluate the longevity of such interventions. Selecting plant species to provide pollinators diverse arrays of floral resources throughout their activity season is often limited by budgetary constraints and other conservation priorities. To evaluate the long-term persistence of prairie vegetation seeded to support pollinators, we sowed wildflower seed mixes into plots on a degraded reclaimed strip-mine landscape in central Ohio, USA. We examined how pollinator habitat quality, measured as floral abundance and diversity, changed over 10 years (2009-2019) in the absence of management, over the course of the blooming season within each year, and across three seed mixes containing different numbers and combinations of flowering plant species. Seeded species floral abundance declined by more than 75% over the study, with the largest decline occurring between the fifth and seventh summers. Native and non-native adventive flowering plants quickly colonized the plots and represented > 50% of floral community abundances on average. Floral richness remained relatively constant throughout the study, with a small peak one year after plot establishment. Plots seeded with high-diversity mixes averaged 2-3 more species per plot compared to a low-diversity mix, despite having been seeded with twice as many plant species. Within years, the abundance and diversity of seeded species were lowest early in the blooming season and increased monotonically from June to August. Adventive species exhibited the opposite trend, such that complementary abundance patterns of seeded and adventive species blooms resulted in a relatively constant floral abundance across the growing season. Seeded plant communities followed classic successional patterns in which annual species quickly established and flowered but were replaced by perennial species after the first few summers. Long-term data on establishment and persistence of flower species can guide species selection for future-oriented pollinator habitat restorations.