Life history traits and interactions of Stylops advarians (Strepsiptera) with its bee host, Andrena milwaukeensis

Abstract

Specimens of Stylops advarians were sampled by collecting foraging bees of Andrena milwaukeensis along the South Saskatchewan River within Saskatoon, Saskatchewan. As the foraging season progressed from early May till late June over three consecutive years (2016–2018), most stylopized bees possessed endoparasitic adult (neotenic) females of S. advarians protruding from the bee gaster's dorsum. In contrast, very few adult bees stylopized by male puparia, and no free-living males, were encountered. Over the sampling period, prevalence remained around 22% each year; mean intensity was 1.2 (range of 1–3 female parasites per bee); and parasite abundance was 0.27. Also newly reported for Stylops is the occurrence of one bee bearing four Stylops (two neotenic females and two males with puparia), plus another bee with a male puparium extruded from its gaster's sternites. Around 2 May each year, a high proportion of the earliest captured female bees were stylopized. However, non-stylopized female bees typically were not encountered until about 10 days later, suggesting the parasites manipulate female bee hosts to emerge earlier, in close synchrony to male bee emergence. First-instar larvae of S. advarians appeared from 22–25 May, indicating that adults of S. advarians matured and mated at similar times each season.

Phylogenomic species delimitation of the twisted‐winged parasite genus Stylops (Strepsiptera)

“…Here, we add comparative genomic confidence to the conclusion reached based on single gene analyses (Jůzová et al, 2015). The winged Stylops males are poor fliers with a very short lifespan (Balzer & Davis, 2020; Kathirithamby, 2009). Phoretic dispersal by the first instar larva with the stronger flying Andrena hosts is likely the most important mode of dispersal.…”

Anatomical impact and notes on viviparous development related to infestation by neotenic females ofStylops advarians(Strepsiptera: Stylopidae) on adult femaleAndrena milwaukeensis(Hymenoptera: Andrenidae)

“…Most (n = 7) of the 11 stylopised bees investigated anatomically were infected by a single neotenic female, whereas three and one gasters possessed two and three strepsipterans, respectively. Actual collection dates of the sectioned bees are provided by Balzer (2019). One stylopised bee collected on 3 May 2017 also was examined in detail for eggs, embryos, and first-instar larvae within a viviparous neotenic female.…”

Anatomical, phenological and genetic aspects of the host–parasite relationship betweenAndrena vaga(Hymenoptera) andStylops ater(Strepsiptera)

“…1A). Agile primary larvae with a length of around 200 μ m are asynchronously released in high numbers (up to 7000) after ~20–40 days through a ventral brood canal (Linsley and MacSwain, 1957; Jones et al ., 1980; Fraulob et al ., 2015; Balzer and Davis, 2020). They infest new hosts at an early developmental stage (Linsley and MacSwain, 1957; Knauthe et al ., 2016) and have been shown to reach them by phoretic transport in the hair, pollen load or even inside the crop of flower-visiting bees (Ulrich, 1956; Linsley and MacSwain, 1957; Balzer and Davis, 2019).…”

“…At the point of appearance of their host bee, male puparia and female cephalothoraces are already extruded from the host's abdomen, the position regularly being laterally in the intersegmental membrane between the 4th and 5th tergite and rarely between other tergites or even sternites (Linsley and MacSwain, 1957;Jones et al, 1980;Balzer and Davis, 2020). Shortly after host emergence, male Stylops emerge and are immediately able to fly while females permanently remain inside, apart from the cephalothorax, and release strong pheromones to attract mates (Cvačka et al, 2012;Tolasch et al, 2012;Löwe et al, 2016).…”

“…While the latter did not distinguish between male and female hosts and parasites, Pierce ( 1909 ) found females to be over-represented in stylopized individuals in a population of Andrena crawfordi Viereck, 1909. The prevalence of pluristylopization (≥2 Stylops per host) seems to vary greatly across host species, region and year (Jones et al ., 1980 ; Balzer and Davis, 2020 ).…”