Britain’s Next Top Pest

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Our Entomology MSc gang have just had two weeks hearing from some of the key players in the biological control industry. While there were many invasive insect pests mentioned that are currently giving UK growers cold sweats in the middle of the night, a few names kept cropping up.

Without further ado, here’s a run-down of just a few of the headline crop-hungry taxa posing new threats on these shores.

Spotted wing drosophila (Drosophila suzukii)

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Not the most appetizing plum, thanks to D. suzukii (photo: Martin Hauser/ Wikimedia Commons)

Despite its catchy name, nobody hopes to catch this fruit fly on their crop. Originally from South East Asia, it’s been rapidly expanding its range in Europe, and was first seen in the UK in August 2012. Unlike like other Drosophila, which tend to go in for decaying and rotten fruit, D. suzukii uses its serrated ovipositor to lay its eggs through the skins of otherwise undamaged fruit. A neat evolutionary advantage for it, really bad news for growers of soft fruit.

The pest control industry is very much all over trying to get the better of this species, though there is no perfect formula. Research has suggested that using biological methods, in this case entomopathic nematodes and fungi, can reduce population development, but can’t stop outbreaks.

South American tomato moth (Tuta absoluta)

Another great name, another insect to strike fear into growers. Unsurprisingly, it’s massively into tomatoes, and can do enormous damage to crops when left unchecked – to the point when they can finish off the lot. Although numbers of outbreaks in the UK are still relatively small, the potential to penetrate all parts of the tomato plant means that any arrivals, such as in imports of Spanish tomatoes, must be taken very seriously indeed.

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The tomato isn’t looking great either (Photo: TNAU Agritech Portal)

Full development from egg to adult has been seen in a wide range of temperatures, and a 2013 study concluded that Tuta is “well able to develop under temperatures that would commonly be experienced in UK glasshouses”.

Other research has highlighted the potential of natural enemies to counter this tomato-loving moth, with Macrolophus and Nesidiocoris tenuis, two Hemipteran egg predators, now seen as having the best potential to make inroads into populations. The problem with this approach is that sometimes a beneficial insect can become a pest, and in this case, the biocontrols have been known to do plant damage themselves. Nothing is ever completely straightforward in the world of pest management, it seems.

Diamondback moth (Plutella xylostella)

There have been recent spikes in numbers of this lover of cabbage and cauliflowers, sparking natural concern among growers. Evidence is mounting that it’s surviving winter here, as well as resistant to pesticides.1280px-Plutella_xylostella1

The fight is by no means over, however. Intercropping – growing a different crop in proximity to the main one – looks like a promising tactic in taking on the pest. A 2010 study showed that planting onion, tomato or pepper with cabbage was as effective as spraying.

Melon thrips (Thrips palmi)

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Photo: Forestry Images/ Wikimedia Commons

Although this thrips species can’t survive the British winter, it can establish with protected crops, and is extremely unfussy in its choice of meal. As such, it’s as much a threat to growers of ornamental plants as it is to those in the fruit and veg business.

What’s more, it’s another insect known for being highly pesticide resistant, so effective biological controls are certainly what’s called for here. It seems likely that a mix of entomopathic nematodes and fungi may well be the dream team for tackling both the larval and adult stages.

 

Is that it?

Far, far from it. The insects featured here are certainly not the only ones that could potentially do significant harm in UK agriculture, should they both get the chance to arrive and find a way to consolidate their numbers here.

DEFRA’s top six of the very latest potentially damaging pests and diseases features a pair of longhorn beetles from the east, while the UK Plant Health Risk Register is a fascinating and somewhat frightening source of information about potential threats to the flora of this island. Currently listing 1,024 pests (not just insects, however), it serves to highlight that amidst the great advantages to global trade come some pretty serious pitfalls.

The prizes for pests that manage to establish themselves in the UK’s famously un-tropical climes are significant – and in an agricultural environment of reducing pesticide effectiveness and use, controlling their proliferation is a multi-faceted and often complex game.

Successful pest management has to take into account factors like the temperatures insects operate in, where they operate in the crop canopy, the need to tackle both adult and juvenile stages, and compatibility of biological control methods with insecticides and fungicides. It also needs to factor in a comprehensive clean-up after the pest has been beaten, to prevent an immediate repeat of the nightmare all over again.

While there are plenty of checks in place to try and prevent invasive pests getting the chance to test their resolve against the UK climate, it’s practically impossible to prevent every insect of potential harm making it past the border. The prerogative is that when they do show up, they are reported quickly, and expert advice sought when needed. If the last fortnight’s lecturers were anything to go by, there certainly is the expertise out there to nip most comers in the bud before scares become crises.

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Spiders and insects: Evolution’s Tom and Jerry chase?

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Among the many interesting points raised during our recent Diversity and Evolution of Insects module was the idea that spiders and insects may have been involved in a sort of cat and mouse pursuit through the fossil record.

It’s certainly the conclusion David Penney reached in his 2004 paper looking at insect and spider family diversity over geological time. It’s suggested here that the rate of exponential increase in diversity was the same for both groups, and that one’s line of rapid diversification – known as radiation – followed the other.

Both insects and spiders tend to be linked with the history of flowering plants, but interestingly, the study also suggests that the major radiations of both these classic antagonists were out of the way a good 100million years before the flora joined the party. This being the case, the arms race began without the need for the habitats that we’d probably associate with the modern tussle of flying insects and web-weavers.

Co-evolution has been proven to be more likely when there’s a direct interaction between groups, and at least one dependency, so the idea of a hunger so profound it transcended the ages certainly sounds plausible. Yet it’s not a view universally shared.

It’s hard to conceive of the struggle between insects and spiders without thinking of webs – and the diversity of arachnid species is linked with the diversity of web design. But in the poetically-titled Tangled in a sparse spider web, researchers at the University of Barcelona muddy the waters of the ‘insects lead, spiders follow’ story of speciation.

They make a case that the diversification of spiders and their web-building approaches was all about moving to different habitats and making use of food resources in an increasingly structurally complex world. To be clear, it’s abundance of prey, they say, that was more significant in driving a species-defining approach to webs rather than its diversity. Loads of flying insects, yes, but not necessarily loads of different ones. They also make the case that the explosion of orb-webs couldn’t have happened at the same time as the insects were on their fiercest period of diversification.

Searching for trends through what remains of the species that have been here and gone is a notoriously tricky business – something that is more than acknowledged by the authors of the different theories offered here. Missing data is one of the foremost problems with scouring the past for clues that may illustrate a trend, while the ‘family trees’ considered in invertebrate evolutionary studies are often complicated and controversial; subject to different interpretations and revisions.

So, has predator chased prey through the ages, or are things a little more complex than that? Well, this is science – never the easiest place to get a neat narrative from. So while you can find shadows of Tom and Jerry, Road Runner and Wile E. Coyote, Bugs and Elmer and the rest if you trace the lineages of Arachnida and Insecta, pinning evolutionary trends on a hunter-hunted analogy alone probably won’t quite cut it.

How Insects Survive in Extreme Cold Winters

Insects survive in many different environmental conditions, across the world. But, when winter hits temperatures can be extreme in places, reaching  -60℃, and colder! So how do insects survive this extreme fluctuation in temperature? Some insects migrate to avoid these temperatures, but some species stay put, and have physiological adaptations to survive the winter months. Thousands of species spanning several orders, including Lepidoptera, Coleoptera and Mecoptera, use two techniques to survive: freeze tolerance and freeze avoidance, which have evolved independently for many species (Dennis, et al, 2015; Duman, et al, 2004; Li, 2016).

1) Freeze Tolerance:

As temperatures start falling in autumn, insects begin to synthesise 3 components key to their winter survival, these are: antifreeze proteins (AFPs), polyols and ice-nucleating agents (INA proteins).

Freeze tolerant species survive by encouraging ice formation in extracellular spaces, using INA proteins. Through osmosis, water is drawn through the cell membrane creating an equilibrium, through these two methods ice is prevented from forming within the insect’s’ cells, which can lead to severe damage and could become lethal (Bale, 2002).

However, the insect is still susceptible to injury from the ice, this is where the polyols come in. These are used to prevent mechanical damage to the insect and have various uses to do this, such as reducing the fluctuation of water across the cell membrane (Bale, 2002).

The insect has one final hurdle to overcome to ensure its survival over winter. As the winter months draw to an end the temperature begins to rise, and water may attach to the ice crystals, within the extracellular spaces, and cause secondary recrystallisation. This is where it gets complicated. Using AFPs, insects can prevent the growth of ice crystals as they preferentially grow from surfaces with a small radius.  AFPs prevent this by adsorbing onto these low radius surfaces of the ice crystal meaning that that they do not grow, unless the temperature reaches the colligative melting point – the Kelvin effect. Essentially the ice crystal will not grow unless the temperature reaches the hysteretic freezing point. Due to the AFPs the water becomes supercooled, and the freezing point is much lower than usual, termed the hysteretic freezing point (Duman, et al, 2004; Zachariassen and Kristiansen, 2000).

2) Freeze Avoidance:

Freeze avoidance is a completely different strategy, using the same materials. Freeze avoidance works by keeping the insects bodily fluids liquid, throughout the entire winter, as opposed to letting the extracellular spaces freeze (Dennis, et al, 2015).

First things first, the insect has its last meal and finds a nice spot to overwinter. Then it begins the process of removing any ice nucleating substances from its body: it’s water content becomes reduced whilst its fat content increases and the digestive system is emptied (Bale, 2002). The insect then synthesises AFPs and polyols which results in the insect having a very low supercooling capacity and thus preventing any bodily fluids from being able to freeze, as long as the temperature remains above their supercooling point (Overgaard and MacMillan, 2017).

To summarise some insects have complex systems allowing them to survive the extreme cold, and it’s pretty cool!

By Linzi Thompson (Email: thompsonlinzi@gmail.com, Twitter: @Apis_linzi )

Harper Adams MSc Entomology Twitter: @EntoMasters

 

References:

Bale, JS. 2002. Insects and Low Temperatures: from Molecular Biology to Distributions and Abundance. Philosophical Transactions of the Royal Society B: Biological Sciences. 357, pp.849-862.

Dennis, AB, Dunning, LT, Sinclair, BJ, and Buckley, TR. 2015. Parallel molecular routes to cold adaptation in eight genera of New Zealand stick insects. Scientific Reports. Nature. 5

Duman, JG, Bennett, V, Sformo, T, Hochstrasser, R, and Barnes, BM. 2004. Antifreeze Proteins in Alaskan Insects and Spiders. Journal of Insect Physiology. 50, pp.259-266.

Li, NG. 2016. Strong Tolerance to Freezing is a Major Survival Strategy in Insects Inhabiting Central Yakutia (Sakha Republic, Russia), the Coldest Region on Earth. Cryobiology. 73, pp.221-225.

Overgaard, J, and MacMillan, HA. 2017. The Integrative Physiology of Insect Chill Tolerance. Annual Review of Physiology. 79, pp.187-208.

Zachariassen KE, and Kristiansen, E. 2000. Ice nucleation and Antinucleation in Nature. Cryobiology. 41, pp.257-279.

An Update (Part 2)

Welcome back peeps! Here’s the second part of the overview/highlights of what we’ve been getting up to so far on the course:

Module 2: Diversity & Evolution of Insects

This module was a nice transition from the previous module content-wise. The first day was a mixed bag, it started with a lecture from Prof. Simon Leather (@EntoProf) on the history of entomology as a subject and insect paleontology (come on, who doesn’t love a bit of Meganeura spp.). Followed by Dr. Andy Cherrill giving a lecture on intraspecific variation. Theeeeen, back to Simon, with a lecture on the super weird, awe-inducing and ever so slightly ridiculous aphid life cycle. The day concluded with the first guest speaker for this module: Professor Tony Dixon! He gave us a lecture on aphid thermobiology and coccinellids (ladybirds, namely on generation time and their usage in biocontrol). He was Simon’s PhD supervisor! It was a privilege to be lectured by someone who has been in the game for so long, is still publishing research and has taught one of our lecturers. The next day was also a healthy mix of topics, covering soil biodiversity to aquatic insects and estimating insect species diversity.

Leading on from the previous day, we had a lecture on Acari (ticks and mites). The study of non-insect arthropods meshes nicely with entomology. As entomologists, it is important for us to be able to identify relatives and to understand their ecological interactions. The rest of the day was full of the mighty Odonata! Starting with a series of lectures from guest speaker Steve Brooks (once again, from NHM) on the identification of British Anisoptera (dragonflies) and Zygoptera (damselfies). The afternoon was spent gleefully identifying odonatans using their larval exuviae with The British Dragonfly Society’s Shropshire County Recorder, Sue Rees Evans!

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The larval exuviae of the Southern Hawker (Aeshna cyanea). Dragonfly larvae are predatory and possess a labial “mask”, a modified labium tipped with pincers. The mask is fired out to grab and immobilise prey. 

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The larval exuviae of a damselfly. The appendages on the rear are called lamellae and they aid gas exchange.

With Odonata checked off the list, we had a day dedicated to an assortment of insect orders with Dr. Mike Copeland. To name a few, we covered the Phasmida, Dermaptera and Neuroptera. The following day started off with a practical session in which we unleashed the fury of lacewing larvae onto some chubby mealybugs; a little taster of what is to come in the Commercial & Practical Biological Control module!

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A lacewing larvae chowing down on a mealy bug. They are voracious predators with specialised mandibles used to extract the bodily fluids of their prey.

The module and week ended on a mellow note, with another chill session of pinning and curation. Practice makes perfect!

Module 3: Experimental Design & Analysis

Being able to design an experiment to test a hypothesis and then analysing the acquired data using the appropriate statistical analyses, holds fundamental importance in science. Once again, the course is full of people with varying levels of experience in different areas, and statistics is no exception. The module reinforced the importance of a robust experimental design, and introduced the cohort to the statistical software R and how to run a range of tests using it. Of course, I would rather have fun practicals over this in a heartbeat, but you can’t replace bread and butter with more filling and expect to have a sandwich! Having just finished this module, we start the Commercial & Practical Biological Control module on Monday! *crowd cheers* HUZZA!!

Soooooo…that’s it from me for now! Linzi will be posting an article on Tuesday on insects which survive in extreme environments and their adaptations to the hostile conditions they live in.

Until next time!

 

By Aqib Ali  (Twitter:@EntoAqib , Email: Aqib1996@hotmail.co.uk , Linkedin: Aqib Ali)

MSc Entomology Twitter: @EntoMasters

An Update (Part 1)

It has been a hot minute since we posted the last article which introduced us, so a little update about what us budding entomologists have been getting up to on the course so far and my thoughts on it seemed rather apt. I present to you part one of the overview/highlights of what we’ve done so far:

Module 1: Biology & Taxonomy of Insects

Following the introductory Research & Information Skills module, this was the first entomology module with two weeks of entomological goodness for the cohort to get stuck into, and boy, we weren’t left disappointed. The module started with a session on Orthoptera and a general run through of insect anatomy led by Dr. Andy Cherrill. This was followed by practical session which involved a delightful dissection of the desert locust (Schistocerca gregaria).

 

The next day we covered the order Thysanoptera (thrips) with Dr Tom Pope (@ipm_tom), followed by a zoom through the superorder Dictyoptera (comprising of the orders Mantodea (mantids) and Blattodea (cockroaches and termites)) with Dr. Rob Graham. With everyone on the course being from varied backgrounds and holding different levels of experience within different things, the session on insect pinning and curation was extremely useful for everyone. The cohort spent the afternoon pinning, micropinning and carding insects in a thrilling practical session led by PhD student Francisca Sconce (@FranciscaSconce).

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Pinned 3rd instar desert locust nymph and carabid (specimens pinned and photographed by Linzi (@Apis_linzi)).

After a whizz through a lecture on sampling methods by Prof. Simon Leather (@EntoProf) we covered a range of methods, ranging from beating to sweep netting and from pitfall traps to malaise traps. The afternoon was spent in the great outdoors sweep netting and getting to use the Vortistm, a vacuum used to suck up and sample insects (and relatives).

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Fellow entomologist Brinna (@BrinnaBarlow) trying her hand at sampling some insects using the Vortis suction sampler.

The first week of this module ended with a bang, with the first guest speaker from the Natural History Museum: hymenopterist Dr. Andy Polaszek (@AndyPolaszek)! In a blitz through the hyper diverse Hymenoptera, we covered several groups, focusing on their identification as well as some tidbits on their biology. We put what we learnt during the morning lecture to test in an intense identification practical.

 

 

 

Week two of the module started with an aphid-packed day on Hemiptera. The next day was Lepidoptera-filled. We had a practical session which involved taking morphometric measurments in waxmoths (Galleria mellonella) and dissecting out the females ovarioles to count the number of eggs.

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A female wax moth (Galleria mellonella) dissected with ovarioles spread out, as part of the Lepidoptera class practical.

Speaker number two from NHM was THE fly girl herself, Dr. Erica McAllister (@flygirlNHM)! She vividly captured our interest and introduced us to the weird and wonderful world of flies. Leading on nicely from the zoom through Diptera, we had a session on Forensic Entomology, full of murder (not literally of course…that’d be bad) and maggots with one of the UK’s leading forensic entomologist’s Dr. Amoret Whitaker. The module ended with shimmer and shine a.k.a beetles, with coleopterist Dr. Max Barclay (@Coleopterist)!

 

This module was certainly a personal favourite of mine (so far), we covered SOOO MUCH in a relatively short space of time. With informative lectures from the university lecturers, plenty of hands on practicals, combined with several external speakers who are experts within their respective fields; I feel as though we thoroughly covered the major insect orders in a very engaging manner! A truly fantastic start to the course!

Make sure to check out the next post “An Update (Part 2)” on Saturday!

 

By Aqib Ali  (Twitter:@EntoAqib , Email: Aqib1996@hotmail.co.uk , Linkedin: Aqib Ali)

MSc Entomology Twitter: @EntoMasters

The larvae emerge…

It’s that time of year again when a new cohort of enthusiastic entomologists begin their journeys at Harper Adams, which of course means new authorship of Mastering Entomology. So, this short post is going to introduce us as the new authors and let you know what you can expect from us across the next year.

We’ve written short pieces introducing ourselves:

Hi guys! My name is Aqib Ali and I am one of two curators of this blog, for this academic year. I’ve had an interest in “creepy crawlies” from a very young age. It began with a childish, albeit slightly morbid, curiosity (yes, I was one of those pulling-off-legs and offering-sacrificial-larvae-to-spider-overlords kind of kids). Although, this interest faded slightly as I moved through the mundane secondary school system, my love for life sciences remained constant and it led to me doing a BSc (Hons) Zoology degree at the University of Derby. As I passed through my undergraduate course, my passion for all things insect was slowly reignited. I did several modules with entomological content, one of which was “Applied Entomology”, taught by the likes of Professor Karim Vahed- a leading expert in the field of sexual selection and insects. With my interests piqued, I decided to do a dissertation on an aspect of sexual selection, namely intrasexual selection (male competition). I looked at whether weapon size affects the outcome of aggressive encounters in a cricket species (Platygryllus primiformis). I also sought out volunteering, such as a research assistant for forensic entomologist Dr. Kate Barnes, to broaden my entomological interests. By the end of my undergraduate degree my heart and head were both set on carrying on down the entomological path. Deciding what my next step would be was a no brainer: the MSc Entomology course at Harper Adams University. What attracted me to this course was its range of modules which cover a variety of topics, the excellent teaching quality and facilities, and that it’s quite literally one of a kind.

My entomological interests at this stage are broad and I am open to the many aspects of this diverse subject. Entering this course open-minded will allow me to fully experience and consider my options before I find my specialism. This journey has started with a bang with the Biology and Taxonomy module! In the short time, I’ve been here I’ve learnt so much! I hope to carry on learning new things, acquiring invaluable skills, amassing great experiences and most importantly, loving what I do.”- Aqib Ali

 

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The new cohort, learning some practical skills in Biology and Taxonomy of Insects (Photo by Aqib)

 

Hi I’m Linzi and I’m a graduate from Keele University studying Applied Environmental Science with Physical Geography. My interest in entomology began when we used aquatic insects as indicator species during a field trip to Cwm Idwal. This developed further throughout more field trips around Staffordshire and into France. When it came to my final year I selected modules that would allow me to focus my interests more and decided to base my dissertation on insects.

After hours of scouring news articles and journal articles I decided to investigate pesticide contamination in honey, particularly neonicotinoids. Although by the end of my experimental work I ended up looking for 91 different pesticides across five honey samples. I loved my dissertation and really wanted to take it further, this is what really set my mind on entomology. Hours and hours of reading articles about honey bees, and other beneficial pollinators had me captivated and after a short google search, my heart was set on Harper.

I have been lucky to be given the opportunity to study at Harper, and since arriving only three weeks ago I’ve already learnt so much and my interests have greatly broadened! I’m excited to keep broadening my interests and eventually find the area that I will  have a career in.Linzi Jay Thompson

So…that’s us! We will be publishing a variety of articles covering; our course, our interests and more. We aim to publish as regularly as possible (schedule permitting) so check back to see which exciting article we have posted. You can expect up to three articles per month covering a variety of topics, meanwhile, please follow us on twitter @EntoMasters for the latest updates, and follow our personal twitter accounts too @EntoAqib and @Apis_Linzi.

Insect flight – an evolutionary development that shaped the world

Flying animals have had a major impact on nonflying organisms. Briefly consider the ecological and evolutionary interrelationships between pollinators and flowers, or between mosquitoes, the parasites they transmit and humans. Even a cursory glance at the manifold relationships flying insects have with all other forms of terrestrial life evaporates any doubt whether the world would be a very different place if they had never evolved.

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