The horror of ecological experiments

Lately, me and a PhD researcher in our team were having some struggles in our project. As is often the case when you’re working with live organisms (Ecology, Yay!), things can go wrong, due unexpected organismal misbehavior. And if things CAN go wrong, they DO go wrong. Murphy’s law is the only universal truth in ecology. Plants need care. Insects need care. Everything needs care. If you don’t care, they die. And even if you do care, they sometimes don’t care, and still just decide to die on you. (Although arguably, good care is a good place to start, and to minimize such sudden horror.)

Aphids can be particularly horrible. For an insect group that is generally so abundant, mostly reproduces clonally, and very fast, it is also very (VERY) easy to kill. Sometimes you really can’t tell why. Again, good care can avoid colony collapse, and open the doors to many great new experiments and a whole lot of insight. And generally, good care is what we try to provide. And sometimes, well sometimes they die because we don’t care enough. We’re all learning, aren’t we…

Before I went on parental leave in August, the PhD researcher and I had collected some leftover tansy plants, prepared for past experiments, plants that had gotten old, and, without future plans, would meet a certain death. However, our open-sided greenhouses welcomed a large number of two specialized aphid species to this small group of plants. Given that we were already loosely planning a new experiment in winter, that felt like a golden opportunity. Two species, ready to start new colonies. Let’s save them, and rear them! We brought a plant that contained both species in to our lab, and I personally saved the remaining eleven from death by greenhouse facility employee. I told my colleague I would keep the plants in my garden, just to keep them alive. She could then use them any time for starting her colonies, whenever she would need them. Over the following days, we talked about how to best approach this, while I was on leave.

A couple of days later, I went on leave. To be honest, I hardly thought of aphids at all. My colleague would start her colonies, and we would talk about experimental approaches upon my return. In the meantime, I was busy changing diapers in the French, and/or Italian sun….

Unfortunately, after two months, my leave came to an end.

It turned out that while I was away, the aphids had struggled slightly. The colonies did not look good. It turned out that our aphid-infested plants were also visited by parasitoid wasps, which drastically reduced the numbers of the first species, and in fact, still were hiding inside the aphids, where they would become apparent once the aphid hosts mummified. The second species was turning into black droplets – probably a bacterial or viral entomopathogen. Not good. My colleague, being rather inexperienced, had not recognized the symptoms in time to act accordingly, and during a week of their absence, things had not gotten any better. With substantial input from the professor, they had started growing new colonies from individual adult aphids in petri dishes with detached leaves. Parasitoid and pathogen-free cultures would be started from the nymphs.

This was approximately around the time I returned from my leave. I wasn’t sure how to feel about it. On the one hand, I was slightly disappointed, because I thought I had given the instructions – albeit they may have been inadequate, and therefore I was mostly disappointed in myself. On the other hand, I was understanding about the situation. You cannot teach experience. You can only get experience by doing. By doing things right, but most certainly also by doing things wrong. What made me very happy is that it had clearly been a wake-up call, and the new colonies were cared for with much care and love now. The first aphid species was already doing much much better, but the second still had the pathogen. I had a closer look and then suggested to remove the dead aphid bodies with a brush dipped in ethanol, over the coming days. This appeared to be a successful approach. Within a matter of days, the aphids matured normal-looking, and the colony was finally growing again. It seems that we would manage to get both species back up and running in time for the experiments.

Of course it would not be experimental ecology if it would be that easy! The aphids may have been fine, but the plants, on the other hand, did not like the days becoming shorter, and more importantly, the light becoming weaker. Under lower-light conditions, plants become a bit flimsy. Their defenses are no longer optimized. As a result, some of our plants developed symptoms of mildew. Quickly, we placed all plants in the highest-light conditions we could provide, and a plant-savvy colleague even brought her vegetable growth lights in for us. At least this would make it possible to regulate day length better than using only natural lights, but it wasn’t enough.

Therefore, last week, I decided to rebuild my own light installation, which I had used in the past to grow carnivorous plants. Carnivorous plants need a lot of light, and not to brag, but the sundews and pitcher plants in my care did pretty well. I quickly ordered all the light tubes and fixtures needed to get the high-output tubes glowing. This weekend, I assembled the whole kit, and what can I say. The lights are bright. Tomorrow, I will install the whole deal over our backup plants, and the aphid colonies. I’m confident that they will be much happier, and I think we were still in time to save the plants and the colonies. I hope that by next week we will have enough adult aphids to start cohorts for our climate chamber experiment that is – in fact – currently up and running. We will see soon enough how things pan out! If the colonies are slow, we’ll wait another week. We’ll get there eventually!

In the end, the whole situation, however horrible it felt at its worst point (and I wasn’t even there then!), has been a good learning experience. I think this is true for my colleague, but also for me. I think they now more fully appreciate the great care that is required to rear something seemingly so simple as an aphid. I think they have picked up a couple of lessons about the life history of the aphids, and as I told them last week, I think that makes the whole ordeal of doing a PhD more interesting. For me, it was also a great teaching experience as a supervisor. I’m still rather inexperienced in that regard. Supervision – I suppose – is more than just giving instructions, and assuming everything will sort out by itself. Instead, instructions also require some verification, a check whether you transferred the knowledge appropriately. I will certainly keep this in mind in the future!

Lessons were learned, nothing was damaged beyond repair, which means it was probably totally worth it.

Published by Robin Heinen

Father of two | Husband | Entomologist and Ecologist | Postdoctoral Researcher @ TUM | Traveler | Coffee Addict

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