Bugs and Climate Change
Notes from the Field
By Warren Sconiers, Ph.D.
Climate change is a buzzphrase that has many meanings and possible consequences. Simply put, climate change is just that—a changing climate. But what does that really mean?
First off, let’s start off with a foundational understanding of climate. The “weather” is what you experience day-to-day in your town (hot days, rainy days, etc.), whereas “climate” is the long-term pattern of weather (according to the National Oceanic and Atmospheric Administration). For instance, much of Arkansas is a subtropical, humid climate from its weather pattern across seasons. This includes the hot sunny days and the dusting of snow in November last year.
Global warming describes the warming trend that is being observed around the world. Increasing temperature leads to more energy that drives our climate. Thus, global warming is a driving factor for climate change. More heat means more storms and extreme weather as that energy is released. While global warming and climate change are separate phenomena, they are intertwined.
Climate change, Crops, and Insects
OK, so how can this affect you? Well, growers and farmers in Arkansas may experience changes in how they raise their crops due to behavioral changes in insect pests. That’s right, bugs! The amount of insects depends upon the weather, especially temperature. For instance, insects reproduce faster when temperatures are higher, leading to greater emergences and generations of insects during the growing season.
With warmer temperatures, we can expect warmer and shorter winters between growing seasons. In general, insect pests will continue to reproduce later in the growing season and emerge earlier in the next growing season. Adjusting your planting schedule to accommodate earlier pests may be key to avoiding yield losses. For instance, planting corn before May can help you avoid southwestern corn borer and budworm damage. Western flower thrips are notorious for damaging seedlings and may arrive earlier with warmer temperatures.
Warmer temperatures typically lead to drought. Water deficiency in plants can make insects feed more compared to well-watered plants. From my research, plants suffering from repeated cycles of rain and drought (or water deficiency) may become more nutritious, making some pests prefer these plants. Cotton aphids, cotton fleahoppers, Southern green stinkbugs, and Western flower thrips may become numerous on irrigated cotton recovering from water deficiency.
How does this work? Plants will speed up their recovery from water deficiency by gathering nutrients to vulnerable places. Nutrients such as sugars and proteins will be moved to these places; however, insects use these same nutrients to develop and reproduce, making drier plants more nutritious at times.
How can you tell that your plants are suffering from drought? Unfortunately, the typical sign of wilting plants is one of the last symptoms of a dry plant. Nutritional changes commonly occur before a plant wilts. However, growers and farmers may use a device called a pressure chamber that tests a sample of plants for water deficiency. A pressure chamber can signal the early signs of water deficiency days before plants wilt. I have used them for my research and they are very handy.
What can we do?
In 2017, Arkansas produced over $1.7 billion in soybeans, $380 million in corn and $369 million in cotton, with rice production at over $950 million, according to the USDA. These crops form the cornerstone of Arkansas’s $16 billion agricultural industry with 97% of farms family owned, according to the Arkansas Farm Bureau. Over the next few decades as our population increases, farmers are expected to grow more food and become more productive to feed an estimated 9.7 billion people as of 2050 as estimated by the United Nations.
As it gets warmer and plants dry out, farmers may see more of these insects after they irrigate. If crops are irrigated after they become water deficient, try scouting for pests within a day or two post-irrigation. This will help determine necessary pest-mitigation steps.
One possible pest solution is called Integrated Pest Management (IPM), in which growers use other living organisms such as insect predators, spiders or parasitoid wasps to control crop pests. For example, lady bugs and green lacewings aggressively consume aphids and small armyworms, and can be purchased from insectaries such as Rincon-Vitova (rinconvitova.com). The benefits of natural pest control is that these insects remain on your crops, will reproduce and will not damage crops, providing lasting production.
Along those lines, bioinsecticides such as Helicoverpa NPV are viral infections that only infect the target pests in Helicoverpa, such as soybean podworms, tobacco budworms and corn earworms, the University of Arkansas says. There are also parastoid wasps that lay eggs in and kill a variety of aphid species, and predatory mites that preferentially consume thrips. These approaches are still susceptible to pesticides but can allow for natural and sustainable methods to control pests.
In the end, expect to adjust your routines to accommodate climate change, but this is a gradual process. In some areas of the country, changes may already be here, while others may take longer to notice. Just keep an eye out for thirsty plants, and consider natural pest control.