The Zika virus and Chester County

by Nathaniel Smith, The Times of Chester County, 9/1/16

Getting rid of standing water is more effective than spraying

News has come around lately that “Pennsylvania Is Now One Of The Top States With Zika Virus ” (Phoenixville Patch, 8/23/16). Currently PA ranks 5th in the number of diagnosed Zika cases. Of course, no one knows how many undiagnosed cases there are anywhere.

Quick quiz: how is Zika spread? If you answered “by mosquitoes,” you’re only half right. It’s our fault too.

It’s important to focus on this note in the article: “All of the cases were travel-related, according to the Centers for Disease Control and Prevention.”

That means no human has acquired Zika from a mosquito in PA. Although the prime mosquito host for Zika, aedes aegypti, does exist in Pennsylvania, it doesn’t do well this far north (yet).

The fact is that Zika is spread not only by mosquitoes but also by people, whether through sexual contact (CDC offers explicit advice on this aspect) or from carrying the virus (usually without symptoms) and being bitten by a mosquito that in turn bites someone else, who thus acquires the disease. The aedes albopictus mosquito, often called “Asian tiger,” has become very numerous in PA but fortunately does not seem to transmit Zika very well (yet).

Spraying pesticides is a limited, short-term fix that leaves many adult mosquitoes alive and does not affect eggs and larvae but harms many forms of life and can lead to acquired immunity. Mosquitoes breed over 500 times faster than people, so they will become immune to whatever we do against them much faster than we can evolve to resist them. Mosquitoes in Puerto Rico and Florida are already becoming resistant to permethrin, the standard anti-mosquito pesticide.

This is all not good news, except that in PA we do have some time to get ready for present and future mosquito-borne diseases….

read more at The Times of Chester County

Pyrethroids and insect resistance

excerpt from “Pyrethroids: Not as safe as you think” at Melissa Kaplan’s Herp Care Collection, last updated January 1, 2014:

…Some insects have developed ways to detoxify the naturally occurring pyrethrums encountered when feeding on the nectar of feverfew and chrysanthemums, a not uncommon adaptive response. Unfortunately, while insects and plants have had millions of years to work out these survival pathways, we humans haven’t.

An increasing number of insects have developed high levels of resistance to pyrethroids, such as cockroaches, head lice, and tobacco budworm, pear psylla, fall army-worm, German cockroach, spotted tentiform leafminer, diamondback moth, house fly, stable fly, head lice, and tobacco budworm. Many of these species are resistant to more than one pyrethroid. Because insects reproduce – and adapt – far more quickly than do vertebrates, they are far better able to evolve defenses against the toxins we throw at them, resulting in an ever expanding range of poisons developed and thrown into our environment.

Pyrethroids, like all toxins, are indiscriminate: they affect all the organisms who come into contact with them in the air, on plants, on the ground, in the soil, and in the water. While your local grower – or you – may be applying it to deal with a specific pest, the products affect everything around it. And, since particulates are easily airborne, they travel, often great distances, from the actual point of application….