Why do entomologists kill insects?

February 27, 2015 by · Leave a Comment 

A non-taxonomist’s perspective…

Admittedly, this isn’t really a direct user submission per se, but it’s a question which comes up in the entomological world enough to warrant a discussion. Collecting of insects is not controversial amongst entomologists, but seems to strike a chord with many people who are interested in entomology. There’s the perception that entomologists are like big-game hunters and kill insects simply as trophies. Some of the comments regarding this topic can be quite… passionate …and there’s been a lot of heated discussion about why people collect and kill insects.

Anti-collecting comments from Facebook Entomology group, posted under undergraduate collections.
First three easily legible comments were chosen:

User 1: “I live with insects and large animals, so shut up man. I don’t kill flies and mosqitos, nor wasps and roaches. Dna is perishable (or degradable, i don’t know english very well) and certainly no scientist will take dna from theese collections. You are hiding sadism by science. Also, I do not mean the extinction of species, but of higher value of this life in comparison to the attainment of a degree or other useless social conventions. And anyway, I’m sorry to give you this terrible news, but the dna you can get by collecting animals already dead.”

User 2: “You might also want to consider taking photos of butterflies as a recording system, rather than killing and pinning them. You could also educate yourself in the trending decline of butterfly species worldwide? Collecting for scientific purposes is one thing, but to promote the collecting and killing of butterflies as a pastime is abhorrent.”

User 3: “In this page they don’t understand. They said it’s not impossible to find them already dead in “natural way” but it’s too difficult, so they kill’em, probably thinking themselves like gods, only due to their study.”

The reality is a bit different from the perceptions of the posters above. Insects are collected for many reasons, and killed for many more. Taxonomists, the entomologists who describe new species and classify life into systematic groups, often bear the brunt of the blame for insect-killing. Consequently, there’s been a lot of discussion on the internet by taxonomists who explain why collecting is essential to science. Many people are concerned that scientists are helping lead to the destruction of insect species, however the few specimens that scientists do collect for research purposes are not contributing to species loss. A much more pertinent threat to insects is habitat loss and degradation. The posts we linked to are our favorites which explain why killing insects is essential to preserving them, as paradoxical as it may seem. While taxonomists have done an excellent job of discussing why they collect insects, there’s been a lot less attention to why insects need killed in the course of education, pest control, and research…and that’s what we want to mention in this post. We want to discuss the reasons entomologists kill insects in order to further the understanding of their biology among the public, to insure the survival of our agricultural systems, insure our own survival, and so we can further our understanding of their biology.

Why discuss insect killing?

Although we love insects, we’ve always been a bit uncomfortable with entomology as a field. Insect biology is extremely cool, because Lovecraftian or Kafka-esque biology comes standard with most species. Some insects eat their own mothers, while others will essentially age backwards to escape starvation. The majority of insects change into completely different creatures when they turn into adults. They’re so far removed from anything we can identify with, that you can spend hours at a time reading about their biology. Whereas most people have golf magazines by the toilet, Joe’s current reading material is about a group of caddisflies which lay their eggs in the arms of a sea star. Most entomologists are this way, and many of our conversations with our colleagues and co-workers revolve around this sort of stuff because everybody we’ve ever worked with has been as passionate about insect biology as we are. However, a lot of entomologists (ourselves included) must research new ways to kill insects even though we love them as organisms.

So … contrary to what some posters above have said we love insects, but we also research new ways to kill them.
Why do we do this?

1.) Entomologists need collections to educate the public

Nancy with a Malaysian Jungle Nymph.

Nancy with a Malaysian Jungle Nymph.

In order to reduce the chances of introducing invasive species, there are many restrictions to owning live insects. The University of Georgia, where Joe and Nancy obtained their Master’s degrees, (and where Nancy is still working) recently received permits to have and rear exotic insects. The process to obtain the permits was painstaking and specialty rearing facilities had to be obtained. The only other place in the Eastern United States to have these permits is the Smithsonian museum.,

Public outreach with preserved specimens.

Public outreach with preserved specimens.

In contrast to live collections, preserved insects are often for sale and there are fewer laws pertaining to the possession and selling of these items. Therefore, with these artfully done collections, we can captivate the curiosity and wonder of children and the public. We can make people who had been fearful, disinterested, or disenchanted with insects become curious, astounded with their natural beauty, and wonder about their remarkable biology. With collections, it is possible for us, as educators and scientists, to visit rural schools in Georgia, USA and show children what insects in rural Africa look like. And while some of this can be done with photography, having someone see with their own eyes a physical specimen the size of their head cannot be replaced by mere images.

2.) Entomologists protect our food supply

Bt cotton

Farming Bt cotton

Everybody needs to eat. Agriculture is the cornerstone of civilization, and by 2100 we’re going to need to be a lot better at agriculture because there may be as many as 11 billion people on this planet. Unfortunately, agriculture is also extremely inefficient. For every 100 lbs of food which could potentially be harvested, only about 30 lbs is used by consumers. Some of this is waste, but a lot of this is pest damage.

As an agricultural scientist, Joe looks at the situation like this: Of 100 lbs of food grown around the world, 70 lbs of it is lost along the way on average. Of those 70 lbs, 35 lbs of that is lost in the field before harvest. If every farmer stopped all pest control measures, that number would increase to 70 lbs of food lost before harvest. Without any additional increases in efficiency between field and table, the amount of land needed for agriculture would explode…and that would not be a good situation.

Our biggest animal competitors for food, fiber and shelter are insects. Insects attack food products at various points in the production chain. The examples which spring most readily to mind are those which attack plants in the field, but insects also attack food while it’s being stored. On average, pest and disease losses in the field are between 20 and 40% depending on the crop. In storage, 10-15% of the crop can be lost to pests and the value of the harvest can be dropped by up to 50% due to loss of quality. Complete losses of some crops aren’t uncommon either. Insect infestation also leads to other problems by encouraging the growth of mold that produces aflatoxins, so the losses due to infestation can lead to larger losses due to a loss of quality. While this secondary problem might sound minor, aflatoxins are among the most carcinogenic substances known and are thus one of the biggest and most persistent public health challenges.

Damage to raspberry by D. suzukii. Arrows indicate maggots.

Damage to raspberry by D. suzukii. Arrows indicate maggots. (LINK)

To give one very specific example…you might have noticed the increase price and decreased quality of summer berries this year. That’s because a recent invasive species, Drosophila suzukii, has been scaling its way up the eastern United States. Although it has been in Hawaii since the late 1980’s, by 2010 the fly had been spotted in North and South Carolina, Louisana and Utah in addition to Michigan and Wisconsin. D. suzukii deposits its eggs in summer berries like blueberries, raspberries, and blackberries. The maggots eat the flesh of the fruit, but seem to leave unnoticeable damage until the berry is broken into which exposes many the little wriggling maggots. As you can imagine, this makes the fruit unmarketable. In 2008 alone this fly was responsible for $500 million worth of damage, and some farmers lost 80% of their crop. It’s possible that other countries will refuse to buy our fruit out of fear of accidentally introducing this pest, so there are economic consequences beyond yield loss. In order to protect the livelihoods of these farmers, someone has to figure out how to manage this pest and lots of research has gone into understanding its basic biology.

Agricultural scientists work towards solving these problems by developing better tools for controlling insects. In some cases, insects can be controlled by making the environment really tough to live in through the use of biological controls. In some cases, this isn’t a feasible option and insects need to be controlled through other means. Either way, if we didn’t control insects there would likely be widespread starvation or exorbitant food prices.

3.) Entomologists protect human health

Anopheles gambiae, a mosquito responsible for more human suffering than war.  James D. Ganthany, via Wikimedia commons.

Anopheles gambiae, a mosquito responsible for more human suffering than war.
James D. Ganthany, via Wikimedia commons.

Diseases spread by insects are another huge problem for public health, mostly in developing countries. Every year almost a quarter-billion people contract malaria, and well over half a million die worldwide from the disease. In areas where the disease is found, it can affect every conceivable aspect of life from how people make money to how many children they have. It may be difficult to believe, but malaria was in the US as late as the 1940s. In the year 1934, there were 140,000 cases…and the disease was effectively gone from the US by the early 1950s. A combination of a convenient climate, a good economy, pesticide sprays, and habitat elimination facilitated this. Vector control continues to be an extremely important component of public health measures, because we continue to see malaria imported into the US from travelers.

The story of malaria is an important one, because it demonstrates how important vector control is for maintaining a healthy population. Worldwide, over half the population is at risk for contracting a vector-borne disease. The US is no different, although we are relatively fortunate to have the resources to fight these diseases and a climate which makes them easy to combat. Keeping the populations of disease vectors down is really important. In short, medical entomologists work to reduce human suffering by killing insects.

4.) Killing insects is essential to studying biological function

Pan trapping is often used to identify arthropod presence in a given area. Here, pan traps are being used to survey for oceanic island arthropod biodiversity

Pan trapping is often used to identify arthropod presence in a given area. Here, pan traps are being used to survey for oceanic island arthropod biodiversity (LINK)

This last one is admittedly the purpose of killing insects which the posters above were talking about. Collecting insects is essential for documenting their presence for a number of reasons. Many insects (as discussed in our first post) are simply too small to see, and a lot of collection methods kill the insects during the course of collection. In addition, a lot of important insect parts need to be extracted for species-level identification. Often the methods required for this aren’t possible to perform on live insects, and when they are they often injure the insects anyways. The posts written by taxonomists give more details about these methods.

There are a lot of research methods which require live field collected insects. Sometimes, you’re interested in biological characteristics of insects in the real world and captive reared insects just can’t be used to answer those questions. Other times, the insects you’re interested in may be impossible or impractical to rear in captivity. Bee research is a good example of this sort of limitation, there are a lot of bee species which can’t be reared in captivity. In bee research, researchers are often interested in real-world responses and this necessitates the capture of live insects from the field. Questions about presence, life history, abundance, and seasonality are all most effectively answered through collection techniques that kill the insects, but otherwise these questions, like questions about native pollinators, could not be answered.

The Bottom Line?

Entomologists are uncomfortable killing insects, and we don’t take it lightly. If we did, we wouldn’t be very good at our jobs. Most entomologists are deeply concerned about environmental issues, and have thought long and hard about why we’re doing what we’re doing. There are a lot of protocols in place to make sure our experiments don’t result in the extinction of species…and we’re constantly working to make public health and agricultural practices more sustainable in the long-term. Although it may seem paradoxical, wise management of insects for public health and agriculture is an environmental concern, and most entomological conservation research would not be possible without killing insects.

Co-Written by Joe Ballenger and Nancy Miorelli

Plants And The Human Brain

February 7, 2014 by · Leave a Comment 

Why humans think like insects…

Similarities between human and insect brains could be the reason why humans are attracted to plant-derived chemicals, such as tea, coffee, tobacco and drugs, according to a new book.

Professor David Kennedy, of Northumbria University, Newcastle, believes his new book, Plants and the Human Brain, answers the question as to why are affected by .

Despite many studies into how plant-derived chemicals interact with the and affect our behaviour, mood, mental and physical functions, there has been little research into why these chemicals have these effects at all.

Professor Kennedy, Director of Northumbria University’s Brain Performance and Nutrition Research Centre, believes that similarities between human and insect brains can explain why humans are affected by and, in some cases, attracted to plant-derived chemicals.

Professor Kennedy states that human brains are fundamentally just a more complex version of the insect brain, with many striking similarities and patterns of behaviour. These include the use of exactly the same neurotransmitters, receptors and physiological processes.

PlantsBrain

He explained: “Plants evolved to interact with the brains of insects, their closest neighbours, in order to survive, by attracting them for pollination, or repelling them or dissuading them from eating . Therefore, plant chemicals that have evolved to target the brains of insects then have the same effects on the human brain.

“Humans have a long and close relationship with plant-derived chemicals that alter brain function. Most of us reach for a cup of tea or coffee in the morning, many smoke tobacco; a few consume heavyweight drugs such as cocaine, morphine or cannabis.

“If you give the chemicals we think of as social drugs to insects, the change in behaviour is often strikingly similar to that seen in humans. For instance, caffeine and amphetamine make insects more active and less sleepy, LSD makes them confused, cocaine makes bees dance, and morphine kills insect pain. And all of these chemicals also stop insects from eating plant tissue and prove fatal to them at higher doses.”

Professor Kennedy’s book, published by Oxford University Press, explains some of the similarities in the genetics of plants and humans and how these similarities impact on human mental function.

“This book as a whole is novel because it is the first time anyone has tried to answer the question of ‘why’ rather than ‘how’ plant chemicals affect the human brain and behaviour,” said Professor Kennedy.

“Plants and humans share about 3,000 ancestral genes, which underlie a host of unexpected similarities.

“For example, plants synthesise and use most of the ‘neuro-chemicals’ that are found in the human brain, sometimes in concert with similar receptors that allow the chemicals to relay messages. The two also share the same communication processes within cells, and this factor in particular may provide the avenue for the brain performance and health benefits seen after we eat fruit and vegetables.

“We are not as different from plants as we would like to think, and our brains are, in most respects, the same as an insect brain – albeit much more complex.”

More information: Plants and the Human Brain, by David O. Kennedy is published by Oxford University Press and will be released on February 7th in the USA and during March in the UK.

How many species are there?

March 24, 2012 by · Leave a Comment 

An interesting research note just came out in the American Naturalist by Hamilton and colleagues entitled quantifying uncertainty in estimation of tropical arthropod species richness. I retweeted a Science Daily twitter feed on this that had a terribly misleading opening line: “New calculations reveal that the number of species on Earth is likely to be in the order of several million rather than tens of millions“. This is, of course, absolute rubbish because the authors only looked at estimating tropical arthropod richness, not all species on Earth. The number of protists alone is probably > 4 million species, and there are an estimated > 1.5 fungi.

That whinge about crap reporting aside, this is what Hamilton and colleagues concluded:

  • using stochastic models, they predict medians of 3.7 million and 2.5 million tropical arthropod species globally
  • estimates of 30 million species or greater are predicted to have < 0.00001 probability
  • uncertainty in the proportion of canopy arthropod species that are beetles is the most influential parameter
  • in spite of 250 years of taxonomy and around 855000 species of arthropods already described, approximately 70 % await description

Interesting, but I didn’t give it much notice until New Scientist contacted me to get an assessment (their article will appear shortly). This is what I had to say:In general, I commend the authors for attempting to shed some mathematical light on the problem of species richness estimation. I believe that many species richness estimates are inflated for a number of taxa given the paucity of reasonable data with which to make extrapolations. I therefore support the notion that some estimates (e.g., > 30 million tropical arthropod species) are unrealistic.

That said, I believe that the approach potentially underestimates the influence of beta diversity on simple alpha diversity algorithms. Although they acknowledge that changing specialisation across a species’ range is possible (but could not correct for this), their algorithm completely ignores three MAJOR driver of biodiversity patterns: (1) the community of local competitors, (2) the community of local predators and (3) the biogeographical history of a particular ecosystem. These will shift enormously across a species’ range and impose a plethora of constraints that tend to promote speciation (i.e., greater number of niches).

Additionally, but related to the above, taking a single dataset from one island nation and extrapolating it to the entire tropical region is fraught with potential error. It makes for highly uncertain scientific predictions because it cannot capture all the nuances of species distributions elsewhere. Every biological community is different.

My overall conclusion is that while the algorithm provides some direction about the upward bias in existing estimates of arthropod species richness, their prediction is also likely to be far too conservative to be realistic. I would predict the ‘true’ species richness lies somewhere between their estimate of 2.5-3.7 million and existing estimates of > 30 million.

My other concerns include:

  1. It seems to me that the major assumption is the degree of specialisation – this is perhaps the most imprecise parameter and possibly prone to underestimation, especially in light of the high specialisation values observed for most tropical invertebrates.
  2. The sensitivity analysis is basic and does not take into account partial correlations. A multivariate ‘global’ sensitivity analysis using logistic regression is more robust (McCarthy et al. 1995. Biol Conserv 73:93-100); thus, I suspect that their rankings of parameter sensitivity are incorrect.
  3. I very much doubt the parameters in equation 1 (except number of herbivorous canopy beetles) followed uniform distributions. At the very least, I suspect these to be Poisson, log-Normal, Normal or beta (depending on type). The authors discuss this, but I disagree that the Pert is a good alternative distribution. For example, the proportional parameters (i.e., proportion of species that are beetles, the proportion of arthropods in the canopy, etc.) might in fact have a ‘central’ tendency much closer to an extreme between 0 and 1 under say, a beta distribution. Therefore, I believe that the authors have severely underestimated the variance (especially of high richness values), indicating that the upper confidence bounds are too conservative.

Why is any of this important for conservation? Without good estimates of species number and distribution, we have no idea how much we stand to lose/are losing as habitats are destroyed. This is essential information for predictive conservation biology, so we need to get it right. Good on Hamilton and colleagues for stepping in and moving the discipline forward. CJA Bradshaw

Literature:

Hamilton, A., Basset, Y., Benke, K., Grimbacher, P., Miller, S., Novotný, V., Samuelson, G., Stork, N., Weiblen, G., & Yen, J. (2010). Quantifying uncertainty in estimation of tropical arthropod species richness The American Naturalist, 176 (1), 90-95 DOI: 10.1086/652998