Essays on Invertebrate Conservation

WINGS ESSAYS ON INVERTEBRATE CONSERVATION THE XERCES SOCIETY FALL 2015 CONTENTS Pesticides are often the first choice for dealing with a pest, or even with the prospect of one. This issue of Wings suggests that we reassess how we use them and why. Rethinking Pesticides Scott Hoffman Black Page 3. Pursuing a Thoughtful Balance in the Management of Insect Pests Thelma Heidel-Baker and Scott Hoffman Black Managing insect pests is a major concern for all farmers. Integrated pest management offers an effective approach that works in concert with the environment. Page 5. Mosquitoes, Wildlife, and People: Crafting an Integrated Management Plan Celeste A. Searles Mazzacano A mosquito outbreak brought calls for spraying on a national wildlife refuge. Local action forced a review of the proposed plan and led to a new solution. Page 10. Neonicotinoids: Silver Bullets that Misfired Aimee Code Neonicotinoids have rapidly become the world’s most-used insecticides. It’s now apparent that their impact reaches far beyond their intended targets. Page 16. Conservation Spotlight The U.S. Fish and Wildlife Service Pacific Region is seeking to better understand monarch butterflies and native milkweeds in the western United States.Page 22. Invertebrate Notes A roundup of new books and recent research. Page 24. Staff Profile Meet Aimee Code, who directs our pesticide program. Page 26. Xerces News Updates on Xerces Society projects and successes. Page 27. 2 WINGS Rethinking Pesticides Scott Hoffman Black Pesticides have been used to control in- as acutely toxic to humans; no one rec- sects for millennia. We know that the ognized the extent to which DDT would ancient Romans burned sulfur to kill impact the food chain. Once that be- insect pests; centuries later, in the 1600s, came understood, DDT was phased out. people were using a mixture of honey By 1975 it had been replaced by organo- and arsenic to kill ants. By the end of the phosphates and carbamates, although nineteenth century, U.S. farmers were it took decades for bald eagles, ospreys, employing a variety of toxic chemicals and other birds of prey to recover. to control pests, including copper aceto- This cycle repeated itself in the arsenite (known as Paris green), calcium 1990s, when yet another class of insecti- arsenate, and nicotine sulfate. cides were introduced, neonicotinoids, In the 1950s, arsenic-based pesti- once again touted as an improvement cides were replaced by DDT, promoted over prior chemicals. Neonicotinoids as an improvement because it was not have two properties that seemed to jus- Pesticides have become the first option for pest management in intensive agriculture, often applied prophylactically before pests even appear. The reflexive use of chemicals has unhealthy consequences for our ecosystems. Photograph by Tamina Miller, Flickr.com. FALL 2015 3 tify this claim. First, they are less acutely ing suite of chemicals we use. It is the toxic to birds and mammals, including way we use them. Humans constantly humans, which lessened the health im- seek the easiest way to control pests and pacts on people. The second potential weeds. The complexity of ecosystems, benefit was that neonicotinoids were however, means that no single method, “targeted” to kill pests in that they are whether it is a chemical or not, can solve systemic—meaning that once applied a problem in its entirety, and each new they are absorbed by the plant, mak- silver-bullet solution is likely to lead to ing the leaves, stems, and roots toxic to new and unforeseen problems. pests. It was thought that this would be a We need to rethink the ways that we way to keep the insecticide from coming deal with nature and the ecosystems on into contact with beneficial organisms, which we and all other species depend. but that didn’t turn out to be the case. Farms, gardens, parks, and other such The problem is that neonicotinoids are areas are complex systems, and we must taken up into the nectar and pollen, and treat them as such. If we hope to have we now know that pollinators attracted healthy ecosystems we need a new ap- to treated flowers can pick up these in- proach, one that uses their complexity secticides while feeding or gathering to our advantage. The vast majority of supplies for their nest. In some instances animals in the landscape—including in- this can be directly lethal, while in oth- sects—are beneficial, or at least benign. ers it leads to problems with flying, navi- We can use this fact to our advantage by gating, and finding food sources; it also fostering habitats that support the pred- may lead to lower production of young. ators and parasites of crop pests. We also To compound this, neonicotinoids need to spend more time understanding are long-lived and mobile in the envi- actual pests and at what level they will ronment, which is why they are being impact yield or kill a plant. compared to DDT. Indeed, measurable An equally important concern is amounts of residual pesticide have been that many farmers and gardeners use found in woody plants up to six years insecticides when they are not needed. after a single application. Neonicoti- Millions of acres a year are treated with noids can remain in soil for months or neonicotinoids as a kind of “insurance even years after use, and plants planted policy,” even though no pest problems the following year may absorb those are known to be present, and millions chemical residues. Moreover, they move of pounds of insecticides are applied in easily from soil to water, where they urban and suburban areas in the quest have been shown to negatively impact for blemish-free landscapes. Simply aquatic organisms that are the base of moving away from such practices can the food chain. These insecticides may save money and help pollinators as well be leading to declines in everything as other beneficial insects. from aquatic insects to songbirds, and a Rather than seeking the next quick growing body of evidence suggests that fix, we need to look at root causes and neonicotinoids are one factor in declin- address those. By doing so, we can both ing populations of pollinators. produce the food we need and protect But the real issue is not the revolv- the environment we love. 4 WINGS Pursuing a Thoughtful Balance In the Management of Insect Pests Thelma Heidel-Baker and Scott Hoffman Black Looking across lush fields of corn or sects, weeds, or diseases —pesticides fre- cabbages, or rows of ripe tomatoes quently come into play. Often farmers ready for harvest, insect conservation use pesticides prophylactically, apply- may not be the first thing that comes ing insecticides (or fungicides or herbi- to mind. Rather, thoughts of insects cides) to prevent the damage caused by in relation to farming are more likely “pests,” regardless of whether pests are to be about how to control pests and actually in evidence. limit crop damage. For farmers grow- Unfortunately, pesticides, and in- ing food for human consumption and secticides in particular, can also harm feed for animals, insect attacks are a the vast majority of invertebrates that threat to their crops; and in addition are benign or even beneficial—the bees, to insect pests, farmers must deal with flies, beetles, and other insects that live weeds and plant diseases. In seeking to in and around agricultural fields and control these problems—whether in- that often provide such important eco- Integrated pest management (IPM) provides an alternative to the simple wholesale application of pesticides. This multi-faceted approach allows farmers to conserve the “good” insects while controlling the “bad” ones. Photograph by TumblingRun, Flickr.com. FALL 2015 5 system services as pollination and bio- Biological control—usually shortened logical control. to “biocontrol”—makes use of preda- Pest control and insect conservation tors (species that eat other species) and are not mutually exclusive — but how parasitoids (species that complete part does one create a balance between man- of their lifecycle inside a host and in the aging the few insects that actually harm process kill it) to suppress pest popula- crops while still conserving the good tions. In classical biocontrol, beneficial ones? Integrated pest management, or organisms are intentionally brought in IPM, is one approach that brings conser- from elsewhere and released to control vation into the equation, employing a a pest; examples include lady beetles variety of pest control methods instead that eat aphids, weevils that bore into of relying solely upon chemicals. roots or seed heads and stop plants from There are many ways to describe spreading, and nematodes that parasit- IPM, but one of the most concise defi- ize grubs. nitions is from the University of Cali- Often, though, such released “natu- fornia at Davis: “IPM is an ecosystem- ral” enemies of crop pests are not native, based strategy that focuses on long-term having been imported from a country prevention of pests or their damage where the pest species originated, and through a combination of techniques they may become pests in their own such as biological control, habitat ma- right. Conservation biocontrol takes nipulation, modification of cultural a different tack, focusing instead on practices, and use of resistant varieties.” boosting populations of predators and What might these techniques look like parasitoids of pest species that are al- in practice? ready present in the agroecosystem. Potter wasps (Parancistrocerus fulvipes) provision their nests with caterpillars and other soft-bodied prey. Each nest may contain dozens of paralyzed insects. Photograph by Bryan E. Reynolds. 6 WINGS Habitat manipulation is an effective way to support beneficial insects, employing such strategies as planting hedgerows or flower strips alongside crops, or growing insectary flowers between crop plants.

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