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The insect sex diaries: Mating disruption in ag

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If you’ve ever been in the military, this will sound all too familiar. During boot camp, the sergeant gave us some very specific directives using colorful euphemisms (which I can’t repeat verbatim), but there was a clear theme: Don’t party like it’s 1999. Don’t develop wanderlust — we’re georestricted like a drone. Turn on that tracking algorithm and immediately turn around if set boundaries are crossed. Despite their availability, don’t engage in vices like drinking and tobacco. And most of all, no amorous encounters.

In the military, it’s all about deprivations rather than indulgences. This makes perfect sense to maintain discipline and good order. But I found it somewhat ironic as a military entomologist. On the pest management front, we often want to encourage steamy (attempted) insect lovin’.

Manage? By playing matchmaker? This sounds counterproductive.

Let me explain. We fully don’t expect the insect pairings that we’re seemly encouraging to actually succeed. We’re playing mind games with desperate males looking for … ahem … intimacy. No offspring will be produced. These failed pairings knock down the next gen population and bring them back to a glorious equilibrium (at least from our vantage point!). Sorry (not sorry) for playing with your emotions insect dudes.

So how do we implement this dating trickery? Simple. Tinker with or otherwise exploit their built-in chemical mojo.

There are a couple of approaches.

Approach No. 1 is mating disruption. We isolate a chemical pheromone (in this case, a sex attractant) from a species of interest and impregnate (bad pun, but appropriate) a lure. Encourage their libido with a little Spanish Fly for insects. We then place these lures at regular intervals in a field, etc.

The pheromone wafts off into the air, broadcasting the equivalent of a fake dating profile (honestly more like Tinder) to all of the males in the immediate area. It effectively says, “Come hither, I’m available.”

The males are intrigued. Their chemical wiring betrays them — it says there must be some willing partner in the area. In fact, their senses tell them this area is certifiably flooded with available females. And they take the bait, endlessly searching for phantom mates. In the process, they exhaust themselves. Score one — for humans. The next gen is stifled.

Pheromones can also be used in a different capacity — to trap and monitor how many males are out and about. With this knowledge in hand, a farmer can make an executive (and informed) decision about whether or not it’s a good time to spray. Basically, has an action threshold been triggered (the uh oh, we need to do something now approach, or can we hold off, because the numbers aren’t enough to be worried about)?

The second approach is sterile insect release (SIR). In this case, we mass rear males in insectaries (insect nurseries) and give them a dose of radiation — just enough to sterilize them. Castration by radiation. Despite this, they’re still in the market. Next, the males are mass released into a known “hot zone.” In this case, they actually find a mate by design. They mate, share a cigarette (not really), both satisfied. One issue: the male is shooting blanks. Again, the next generation takes a hit — all as planned.

Despite being an effective and targeted approach in our pest management arsenal, there’s an unfortunate reality to both approaches — they’re very knowledge intensive.

If we’re using mating disruption, we first have to isolate and characterize the pheromone of interest. This is no small feat in terms of labor or economics. Only the most destructive candidates get the appropriate R&D treatment. These are also species specific. Regrettably, there’s no universal mating disruption pheromone.

Recently, there’s been some work with genetically engineered “sexy plants” that can make insect pheromones themselves. Turns out plants are pretty good biofactories. Just give them blueprints and flip the assembly line switch.

The major issue with SIR is the use of radiation. Not that the insects are radioactive in any way (we’re not after getting an X-ray at the doctor’s, or hopping on a plane), but we have to be mindful of the dose. Nuke them too much, and they’re gimped — not very good at finding females. Nor do they sport the Adonis-like bod females are looking for.

We know through experience that insects can be 1) profoundly destructive and 2) prolifically fertile. We’ve been mired in a never ending gladiator match with them. Fortunately, the salacious underground world of (stifled) insect sex is one key to continued food security.

There’s also gene drive. In this system, a gene basically ensures that it gets passed along to the next generation. Throw Mendel’s rules of inheritance and Punnett Squares out of the window. In this way, we can also take advantage of insect sex to knock down insect populations that vector diseases of human concern.

Insect males — are you looking for a naughty rendezvous? We’re happy to oblige you. Or at least let you think you’re in luck for love. In the sultry world of pest management, sex sells — to our benefit, and your detriment. Won’t somebody please think of the (insect) children? On second thought, please don’t.

 

Tim Durham’s family operates Deer Run Farm — a truck (vegetable) farm on Long Island, New York. As a columnist and agvocate, he counters heated rhetoric with sensible facts. Tim has a degree in plant medicine and is an Assistant Professor at Ferrum College in Virginia.

Any views or opinions expressed in this article are those of the author and do not reflect those of AGDAILY. Comments on this article reflect the sole opinions of their writers.
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