Great Bend Tribune
Published September 17, 2017
Part I
Corn harvest is slowly ramping up, soybeans are turning color and dropping leaves, milo fields are all over the place and fields are being prepared for the 2018 wheat crop. Milo and wheat producers are considering potential insect and arachnid pest problems. We tend to only think of insects as a negative in food production and they certainly can be. However, let’s take a step back and consider the insects from a broader perspective.
The number of insect species is estimated to be somewhere north of six million. Of that number we have identified approximately 900,000 species. It is thought there are around 200,000,000 for every person on the planet and an acre will contain in the vicinity of 40,000,000 insects. They are members of the order Arthropoda which includes arachnids (spiders, mites, and ticks) and crustaceans. Insects, Hexapoda, are the most numerous class of arthropods. With over six million species it is fortunate that most are not pests. Of all insect species, approximately 3,500 are of real concern as pests and of that number six hundred or so are of concern in the continental U.S. Additionally, the major organisms controlling insect pests are other insects. This may be as predators or parasites. This week let’s discuss the negative impacts of insects in the environment. Next week discusses beneficial insects and the problem agricultural producers face in insect pest control.
- Direct injury to plants by feeding on plant tissue and reducing yield, quality or both. Feeding on seeds and seedlings can significantly reduce plant stands.
- Indirect plant injury includes feeding on unharvested parts that affects the quality and/or quantity of the harvested commodity. The most significant indirect loss is the transmission of diseases by feeding insects, normally those that feed on sap. And injury caused by feeding can leave tissue vulnerable to pathogens.
- After harvest, insects can feed on stored products such as grains and processed foods. They can feed on household items such as wood, wool, paper, and food stuffs.
- For livestock, they may simply be a nuisance making animals uncomfortable and stressed with a result in decreased productivity. The may parasitize livestock and weaken them. Typically, parasites won’t kill the host as it’s not smart for a parasite to kill its host outright but death may result from other causes with a severely weakened animal.
- Indirect damage to livestock is often more severe and is the result of disease transmission when the insect feeds. The outbreak of disease in horses currently in SW Kansas or West Nile in horses and raptors.
- Direct effects of insect pests of human are not typically lethal except in rare cases, think allergic reaction to bee stings or fire ants. Normally the direct effects are discomfort or minor allergic reactions.
- The most negative effects to humans are typically indirect, again disease transmission: West Nile, malaria, Rocky Mountain Spotted Fever, nematodes and so on.
- One last one, insect predators and parasites can attack beneficial insects.
We covered the red ink this week. Next week features the positive.
Part II
Published September 24, 2017
The area is heading into the heart of wheat planting for the 2018 crop and unfortunately our area is listed as in moderate drought surrounded by abnormally dry conditions and an area of severe drought in SW Pawnee and NW Edwards Counties. There is a chance of rain this weekend and into Monday and it is needed. The area, unless you want to cut milo, needs average temperatures to drop into the 70s, which is supposed to happen this week. Now back to discussing the insect dilemma.
Last week we discussed insects in general and the problems they can create. This week focuses on the positives and how critical insects are to agriculture.
- Insects provide direct benefits such as honey, silk, and are used in experimentation, especially genetics and toxicology.
- They are scavengers that help start the process decomposition of organic matter. Everything from carrion and dung beetles to yes, fly maggots.
- They are a food source for wild and domestic animals such as fish, think fly fishing, birds, amphibians, etc. They are often sold as fish bait.
- Insects provide a hobby for many in insect collecting and as an aesthetically pleasing aspect of the environment. In Wichita, the Sedgwick County Zoo and Botanica have butterfly zoos attracting thousands each year.
- Insects are the number one predator for insect pests and can often keep insect pests below economically significant levels in crop fields and greenhouses. This includes ladybugs, parasitic wasps, antlions, dragonflies, and hundreds more. They feed on everything from aphids to various moth larvae and mosquitoes.
- Insects are responsible for the pollination of many dicot (broadleaf) flowers and are necessary for fruit and seed production. Many of your favorite fruits and vegetables wouldn’t be on the table without insects. The list is extensive and includes far more than honeybees. The value of pollination in agriculture is this country runs into hundreds of millions of dollars.
The dilemma faced by agriculture and horticulture is as simple as it is complex and boils down to one question. How can insect pest populations be kept at economically acceptable levels while at the same time, maintaining those beneficial insects critical in helping control insect pests and in pollinating many important plant species. We will tackle that next week but first a tease. The concept is termed IPM, Integrated Pest Management, which uses a wide variety of methods, including insecticides in a manner that protects the crop and livestock while protecting the environment.
Part III
Published October 1, 2017
First, let’s discuss last week’s precipitation a bit. The area received rainfall at the beginning of last week. Western Kansas and much of our area received significant rainfall and areas to the south of Barton County were under a flood watch for a bit. Amounts locally appeared to range for around an inch to over four inches. This certainly helps but doesn’t eliminate for many acres a lack of soil moisture. The top part of the soil profile is in pretty good shape for most but subsoil moisture in many places is short. This is enough to establish the 2018 wheat crop and help perennial plants prepare for winter. It slowed down harvest and shouldn’t result in major loss except for a soybean field or two. It does make following a summer row crop with wheat a bit more challenging. Now back to insects.
The question to answer this week is “Why are we seemingly having more problems with insects in our crop?” We have always dealt with insects “attacking” crops throughout history. With the advent of pesticides following World War II, the problem decreased significantly but returned with a bit of a vengeance from the late 1960s on. Why?
- Natural ecosystems are messy mixes of plants and animals adapted to the region, they typically have great species and genetic diversity. All the ecological niches, places in the environment, are filled. And it is a system that requires the least input of energy to maintain. Managed ecosystems, crop fields, are just the opposite with many niches unfilled (bare ground between rows for example), little species diversity (one crop in a field), and little genetic diversity within species. It takes a great deal of energy and management to maintain this immature, unstable ecosystem. And the crops, compared to the natural environment, are better food sources for insects which leads to the next point.
- There is a theory stating that nature abhors those well-maintained fields lacking diversity that require a lot of energy to maintain and seeks to overturn them and return them to a lower energy state. Insects are part of that problem. Or if you are less esoteric, the next point.
- If you are an insect flying around looking for food and/or a place to lay eggs what would you chose. Would you choose the natural low energy field or would you choose a field with lush, well-maintained, buffet? Probably the buffet where you could supply your needs with little effort.
- The climate is changing. Winters are warmer and more open. Killing frosts are occurring later on average. Plant growth is starting earlier in the spring for plants like winter wheat and canola. Milder winters have expanded the range of many insect pests and allowed those not overwintering in Kansas to move in earlier, often before beneficial insects. And those that overwinter in Kansas lose less of their population overwinter.
- While we are returning to crop rotations, monoculture favors increase in insects, especially as tillage decreases. And the inappropriate and over use of pesticides has resulted in “super” insects resistant to pesticides.
Next week, “What can we do about it?”
Conclusion
Published October 15, 2017
Let’s finish up our discussion of the evolving challenge of controlling insect pressure in a changing environment while protecting that environment and providing a safe food supply. Remember, while there are well over six million insects species worldwide, only a handful of that number are pests while most are benign, and many in fact beneficial as predators, pollinators, etc. The key here is IPM, Integrated Pest Management, which first seeks to understand insects, their life cycles and habits, their place in the ecology, determining what to do and when in an environmentally responsible manner, and use all control methods available, including chemical control. So briefly how do we deal with this pressure in a changing environment? This will have to be general since we are constantly evolving what to do.
- First realize our goal isn’t eradication but control/suppression of pest populations below the economic threshold (where the cost of control equals the cost of the loss). Eradication/elimination is impractical or even impossible and not desirable from an economic and environmental standpoint.
- Adequately fund research at land grant universities to study what is happening and develop strategies/technologies to deal with this challenge. Public and private institutions need to coordinate efforts to provide the best informations/solutions and producers need to pay attention and implement what we already know to do while adopting new programs as they are developed.
- Producers must intensively scout and monitor insect pressure. This is aided where we have a good understanding of life cycles and habits while more difficult where pests are exhibiting new behaviors and moving into new areas.
- Recognize the reality of a changing climate which can either alleviate or exacerbate insect problems. The sugarcane aphid is a prime example. After two years of significant pressure, weather conditions this summer did not favor large number moving north into Kansas. Which is why monitoring is so important.
- Identification of crops and hybrids/varieties of a given crop that have tolerance/resistance to a given pest. This was rapidly done with the sugarcane aphid and those resistant hybrids can be used in breeding programs. In many cases genetic engineering will help this process.
- Crop rotations with crops as dissimilar as possible and practical to interrupt insect life cycles. When that isn’t possible, managing habitat and that may include eliminating crop residue.
- Doing everything possible to minimize stress for crops with proper fertility, planting dates, etc. so crops are better able fight off pressure. Adapt cultural practices such as planting and harvest dates to separate the pest in space and time where practical.
- Develop new insecticide technologies that will target pests and minimize damage to beneficials such as pollinators and predators. And along with this do everything possible to protect beneficial populations.
As this column usually ends there is more but the point is that the agricultural community must become more aggressive in monitoring/managing and the solutions are there even if we may not like them.