Invasive Pests Continue to Head Your Way

One of the things I’ve always liked about the field of entomology is there is always something new. Maybe it’s new species, new information, new products or even new procedures. So for the new year, what’s new in the world of pests?

Over the years, plenty of new pests have made it to the U.S. We can go all the way back to early days when roof rats came over on explorers’ ships. Jumping forward a few hundred years, Argentine ants showed up. This was followed by red imported fire ants and Formosan subterranean termites.

A number of factors make these new arrivals so invasive. First, there are no natural enemies (they left all those at home). So the natural balance of predator and prey, or of host and parasite, is completely out of equilibrium. Next is the food sources. While in their native home they may have to compete with others for food or have limited food sources. Here they may have food in abundance with fewer species to compete with or species they easily can outcompete. Lastly, we often don’t have the information to manage these pests. In their home range, many of these may not even be considered pests, so there’s not much research on managing them, biologically or chemically. Considering how fast some species can reproduce, we are at a huge disadvantage!

OTHER RECENT INTRODUCTIONS. Brown marmorated stink bugs were first identified in Pennsylvania in 1998 (though likely introduced earlier) and are native to eastern Asia. They feed mostly on fruit and vegetable crops. Since the original introduction, they have been found in 44 states and are considered an agricultural pest (causing economic damage to the food supply) in 21 states. Aside from the damage to plants, fruits and vegetables, this is also a “nuisance” urban pest. In the fall they gather in huge numbers on sunny sides of buildings and will find entry points to overwinter inside. As PMPs know, the customers calling you for help consider them more than a mere nuisance!

While most new species seem to enter the country on the East Coast, the Turkestan cockroach was first brought in to the West, in California, likely in 1978. These pests are native to northern Africa and central Asia. Since then, they have not only expanded their range to most of the Southwest and all the way east to Georgia, research from 2013 showed that they also have been out-competing the Oriental cockroach (ironically, another introduced species). The Turkestan cockroach is primarily outdoor dwelling, like the Oriental cockroach. However, it develops faster and has more eggs per ootheca than the Oriental cockroach. Like many of our invasive species, the Turkestan cockroach is not listed on any pesticide labels, making exclusion and sanitation especially important.

This past year, a new invasive species appeared on the scene. The Asian longhorned tick was identified in 2017 in New Jersey. Looking back at old specimens, researchers now think this pest arrived as early as 2010 from eastern Asia and is now in 10 eastern states. This species is especially problematic because it has parthenogenic reproduction: females can produce viable offspring without mating (they can clone themselves!). A single female can produce up to 2,000 eggs in just a couple of weeks. Unlike many of our native ticks that can carry a number of human diseases, this tick has not been shown to vector any human pathogens in the U.S. yet. However, it’s still so new in this country; not much is known about how it may affect people, pets and livestock.

While all these species are currently present and established, one more “new” invasive species of note is the Khapra beetle. Native to India, it first appeared in California in 1946. Through much effort (and around $15 million), it was eradicated. This is an extremely damaging pest to stored foods, and one reason it is so hard to manage is because it survives without food for long periods of time. This invasive insect was intercepted more than 470 times at U.S. ports of entry between 1985 and 2004 by Customs and Border Protection agriculture specialists. This year it has been found at Atlanta, Baltimore, Dulles, Detroit and Houston airports as well as many ports on imported grains like rice and dried beans. Currently, no established populations exist in the U.S., but this could be a very serious new pest if it did.

So what’s going to be new this year? Hard to say. How and why a new pest becomes established is based on a number of factors including suitable habitat, food sources and sometimes just bad luck. With global travel and the worldwide movement of goods, new pests have ample opportunity to bug us into the new year.

(If these pests aren’t “new” enough for you...know that last year scientists described 155 new insect and spider species!)

The author is Rollins’ technical services manager.