Horticulture Pest Management

Arachnida

In the solitude of the night, the spiders arrived. Arachnida. Creeping up the plants to spin their silken craftsmanship. The spiders fed, weakening the plant.

Elsewhere, spiders hued like blood struck another farm. These creatures had been secretly here for a while, feeding, breeding, lurking… Male mites doted over the cocoons of their loves, waiting for their soulmates to emerge. The most fragrant females attracted the males using a witches’ brew of volatile compounds including the terpenoid nerolidol. [1] The males just couldn’t get enough. More intoxicating nerolidol, more affection.

But this isn’t a spider love story. It’s a story of floral vengeance.

As the mandibles of some of the spider mites penetrated the plant, and as others blatantly laid eggs on a leaf’s underside, the plants silently responded using various chemicals within their armory. Yes, thankfully, the plants had terpenes!

In some cases, the plants’ projecting of the terpenes fouled the mites’ feeding frenzy, and they slunk away, poisoned. But, then, there were the other cases… the cases where the plants’ flexed their molecular muscle and firepower, combined with discreet doses of cunning and expertise. For, these plants possessed terpenes that some other bugs really subscribe to. [2-4] The chemical beacon was cast; the plants earnestly waited in the hopes that their calls would be answered.

And with a thunderous tread, the hired guns arrived, armed with nothing other than their very teeth. Their bulk was impressive; their hunger was endless. They began to devour the herbivore spider mites one by blessed one, saving the plants from death by mastication.

One of the mites escaped with his love. From a safe distance, they looked back upon the carnage, and listened to the sounds of their comrades being devoured. Shuddering, shivering, they found their way to sanctuary. They used the air currents to identify an enticing meal, to regain their strength and composure.

The scent in the air was particularly enticing to the male, as it was nerolidol from a nearby plant. [5] He led his spider-baby to the plant, eager to impress her with his foraging acumen. Almost analogous to clairvoyance, though, the plant sensed the trouble en route, and using the same terpenoid that drew the mites near, sent its own distress signals for help.

The spider mites could hear reverberating, deafening, foreboding sounds. And as their jaws nervously tore another leaf asunder, the predators arrived, hungry for the blood-hued spider mite flesh. Sadly, or poetically, the very molecule that brought the spider mite couple together caused their literal undoing, in a natural story of wicked irony.

Dear Mother Nature: thanks for the stories;

Dear Reader: Happy Halloween.

References

  1. [1] Regev, S. and Cone, W. “Analyses of Pharate Female Two-spotted Spider Mites for Nerolidol and Geraniol: Evaluation for Sex Attraction of Males.” Environmental Entomology, vol. 5, no. 1, 1976, pp. 133–138. [journal impact factor = 1.45; cited by 16]
  2. [2] Arimura, G. et al. “Herbivore-Induced Defense Response in a Model Legume. Two-Spotted Spider Mites Induce Emission of (E)-β-Ocimene and Transcript Accumulation of (E)-β-Ocimene Synthase in Lotus japonicas.Plant Physiology, vol. 135, no. 4, 2004, pp. 1976-1983. [journal impact factor = 5.949; cited by 114]
  3. [3] Shimoda, T. et al. “The Effect of Genetically Enriched (E)-β-ocimene and the Role of Floral Scent in the Attraction of the Predatory Mite Phytoseiulus persimilis to Spider Mite-induced Volatile Blends of Torenia.”New Phytologist, vol. 193, no. 4, 2012, pp. 1009–1021. [journal impact factor = 7.43; cited by 24]
  4. [4] Takabayashi, J., and Dicke, M. “Plant-Carnivore Mutualism Through Herbivore-Induced Carnivore Attractants.” Trends Plant Sci, vol. 1, no. 4, 1996, pp. 109–113. [journal impact factor = 14.006; cited by 423]
  5. [5] Kappers, I. et al. “Genetic Engineering of Terpenoid Metabolism Attracts Bodyguards to Arabidopsis.Science, vol. 309, no. 5743, 2005, pp. 2070-2072. [journal impact factor = 41.063; cited by 417]

Image Credits: Decider, Bug Guide

About the author

Jason S. Lupoi, Ph.D.

Jason S. Lupoi, Ph.D.

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