Lumps, Bumps and Spines

Everyone loves a treehopper, but what are all those lumps, bumps and spines for? A new study suggest that not only are treehoppers capable of detecting the electric fields emitted by their predators but that the morphology of the pronotum increases their sensitivity to electrical stimuli. 

Electroreception in treehoppers: How extreme morphologies can increase electrical sensitivity. (2025) PNAS 122(30):e2505253122 https://doi.org/10.1073/pnas.2505253122

"The link between form and function of an organism’s morphology is usually apparent or intuitive. However, some clades of organisms show remarkable diversity in their form, often exhibiting extreme morphologies, but with no obvious functional explanation. Treehoppers (Membracidae) are a family of insects that exemplify this, displaying an astounding morphological diversity, resulting in a plethora of extreme forms. The function of these morphological extremities and the reasons for their evolution have thus far remained largely enigmatic. However, this mystery can be considered in light of the capacity of many animals to detect electric fields in air via electrostatic actuation of mechanosensory structures on their body. Importantly, the strength of the electric field experienced by these mechanosensory structures is expected by physics to depend on the animal’s geometry, with sharp and elongated features producing the highest electric fields. Therefore, we hypothesize that the extreme morphologies of treehoppers increase their electrical sensitivity. Here, we show that treehoppers, along with their predators and mutualists, produce electric fields and that the treehopper Poppea capricornis can detect electric fields, responding behaviorally. We also demonstrate that predatory wasps and mutualist bees differ significantly in their electrostatic profiles, pointing to the sophistication of electrical information potentially available to treehoppers. Biophysical, computational, and mathematical techniques are then utilized to provide evidence that the pronotum of treehoppers is the site of electroreception and that its extreme shapes may enhance its sensitivity to electricity."

 

A walk in the park

With much needed rain on the way I took an early morning walk in my local park. I had a target species in mind but didn't find it, so abandoning the Acers, I went off piste. Walking past a large Salix alba, a quick rummage brought up a specimen of Blepharidopterus diaphanus (only a few previous VC55 records).

Before turning for home, I investigated a group of Wellingtonia, and found a few rather indistinctive bugs I took home for further investigation. Closer inspection revealed that one seemed to be Orthotylus caprai. This is a Mediterranean species which has spread across Europe and only has a handful of British records. However, with only a female specimen I couldn't be sure and it was a couple of days before I could go back and look for more. On my second visit I found a male and managed to confirm the first VC55 record for this species.

It's well worth looking out for O. caprai on scaly conifers (Cupressaceae), although you'll need sharp eyes - they're on the small side! 

 

Contradictory spider

I recently wrote about microbiome-mediated spread of the Mirid bug Apolygus lucorum. Hot on the heels of that discovery comes another - the microbiome of the invasive Linyphiid spider Mermessus trilobatus does not contribute to its dispersal and spread. 

Complicated, isn't it? 

The Microbiome of an Invasive Spider: Reduced Bacterial Richness, but no Indication of Microbial-Mediated Dispersal Behaviour. (2025) Microbial Ecology, 88(1), 70. https://link.springer.com/article/10.1007/s00248-025-02565-6

 

Entomology Update - June 2025

It's June, so it's Peak Bioblitz. Much of my activity this month has been dominated by organized group visits and walks. Sadly the results have been dented by the heat and ongoing drought.

The Pattern

In the past, 36 moths of 20 species in the garden moth trap on a warm June evening would have felt like a famine, but now it feels like the best I can hope for.

Got the stomach for it?

Research reveals a possible basis for the arrival of new bug species in VC55. 

Finishing with a bang

A tropical night brings a species I've been waiting to see for years. 

Read previous updates

Latest photos

Finishing with a bang

After what has been a tricky month, the very last night proved to be the highlight. A tropical night (according to the Met Office), and the max-min thermometer I place in my moth trap recorded a minimum temperature of 20C. And the moths responded - 247 moths of 27 species, three new for the garden - the best result I have had in years. But the moths weren't the best bit! When I turned the trap off at 3am there was a swirling cloud of life surrounding it. The by-catch comprises over 20 species of Hemiptera (which I haven't had time to sort through yet), and I didn't even attempt the Diptera or the beetles (some of which looked interesting). The absolute highlight was a species I've been waiting to see for quite a few years, the Eared Leafhopper, Ledra aurita. 

Apart from sleeping, I'd almost welcome more tropical nights.