2011 Peabody Museum of Natural History, Yale University. All rights reserved.

Transcription

1 2011 Peabody Museum of Natural History, Yale University. All rights reserved.

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4 Operation Vector Find Rangers with the New Haven Parks Department have just discovered an old map. The map shows a remote section of parkland that has not been used for many years. The Parks Department wants to open the section of the park to the public again. But there is a problem. Park rangers know that ticks carrying Lyme disease are common in Connecticut. There are also mosquitoes that can transmit West Nile virus. Before they can open this part of the park they have work to do. Rangers must first collect these vectors and test them for the disease. But they can t afford to waste time looking throughout the entire area. They need to know where to look. As an entomologist, your job is to find the best places to look. You will first pick three places on the map where you think ticks will most likely be found. Forest floors and grassy areas with leaf litter are perfect tick habitats. You will also pick three places that are best for collecting mosquitoes. Mosquito eggs must grow in still water, so you know to look for ponds or vernal pools. The Parks Department wants your final report to include exact measurements and directions. This will allow them to locate these arthropods quickly and collect them. The map shows wooded sections, along with a pond and vernal pool. There is also an entrance to the site. You note that there are grid lines on the map. You decide to use these to help pinpoint the collection spots. The Parks Department has asked that, in addition to marking the map, you submit a written report that contains the following: 1. Three collection sites for ticks, numbered 1, 2 and Three collection sites for mosquitoes, numbered 4, 5, and Distance from the entrance to each site in meters. 4. Relative location from the entrance to each site. (Read Entomology Collecting with LOGS on page 28 to learn about this) 5. Brief comments on why you have chosen each site. Materials Procedure Plot #7 Park Map 30 cm Ruler Entomology Collecting with LOGS Pencil 1. Examine the map and identify the Legend, Orientation, Grid and Scale (Note: Check your notes on Entomology Collecting with LOGS). Figure out how you are going to label your grid. Label the grid. 2. Select 6 collection sites and mark them on the map as numbers 1 through Using the ruler, draw a line to each point from the entrance site. 4. Measure each line with the ruler. 5. Using the scale, figure out the distance in meters to each point from the entrance. 6. Complete your report, making sure to include all of the details listed above.

5 Entomology Collecting with LOGS As an entomologist, some of your work will be collecting specimens to study. It is important for you to know exactly where each specimen was collected. Most scientists who do fieldwork need good maps. Making maps is the work of a group of scientists called geographers. Different kinds of maps show different features of a location. Mapmakers will show various things depending on what the map is used for. A road map shows highways, roads, towns, and cities. It will also show geography such as mountains, lakes, and rivers. A shaded relief map is designed to highlight the land features of a place. A topographic map uses contour lines that show the exact elevation of the land at all points. An easy way to remember some of the basic parts of a map is with the word LOGS: Legend, Orientation, Grid, and Scale. LEGEND: The legend is the key to unlocking the secrets of a map. It identifies the symbols and icons used. There may be special icons for trees, water, town boundaries, or interstate highways. ORIENTATION: Maps use north, south, east, and west to show direction. North is usually towards the top of the map. Geographers use north to mean going toward the North Pole at the top of the Earth. The map direction that points north is called the orientation. This allows you to follow the map Latitude and longitude divide the world into a grid. This grid system was developed during the Middle Ages. This system is written in degrees. On a map, latitude lines run horizontally (left to right) and are about 69 miles apart. The equator is at 0 o. Degrees latitude are numbered from 0 o to 90 o north (above the equator) and 0 o to 90 o south (below the equator). The longitude lines run vertically (up and down) and are known as meridians. 0 o longitude, in Greenwich, England, is called the Prime Meridian. The degrees continue from 180 o east to 180 o west of this meridian. The International Date Line is 180 o from the Prime Meridian. using a compass. Orientation also allows you to describe the relationship of one place to another. One place is north, south, east or west of another. This is known as relative location. For example, you might say Chicago is north-northwest of New York City. This means that you start out by going north from New York City, and then turn at a northwest angle to get to Chicago. GRID: Many maps are divided into longitude and latitude, imaginary grid lines that allow you to pinpoint the absolute location of any place on a globe or map (see text box above). Most globes show these lines, but smaller maps may not. Many basic maps are just divided by grid lines. Grid lines run in the same directions as latitude and longitude. Grid sections can be any size, unlike the exact distances of latitude and longitude. You must check each map legend to see the size of grid for that map. A common way to label a grid is with numbers in one direction and letters for the other direction. This lets you say that a point on the map is in section A3 or F7. SCALE: The relationship between a distance on the map and the real distance on the ground is known as scale. With a distance scale you can figure out the actual distance between two points shown on the map. Some maps use the size of each grid square to show the scale.

6 Discovery File : Oh, Deer! Lyme disease bacteria are transmitted to humans by a tick (Ixodes scapularis). But the story of Lyme disease does not begin with a tick. Ticks don t have Lyme disease when they hatch. They become infected when they bite an infected animal. If the Lyme disease story doesn t start with the tick, where does it begin? The story begins with the white-footed mouse. yscus_leucopus.jpg By PhotoCredit: Content Providers(s): CDC [Public domain], via Wikimedia Commons from Wikimedia Commons Like all zoonoses, Lyme disease must have at least one host. Some hosts provide a home where a pathogen can multiply. Another kind of host can give the pathogen a place to live as it grows. A host can also be the home of a vector. A host is the species in which another species lives while it develops. A host provides food and shelter. Species that play this role do not get sick from the disease. One thing is true for all organisms that host diseases they all help the disease survive. Without hosts or a carrier, a vector-borne disease will disappear. Lyme disease has two major hosts: the white-footed mouse and the white-tailed deer. When a tick egg hatches, its larva is very small. It is so small that it cannot travel far from where it hatched. The larva must first find a tiny animal to bite. It needs a blood meal so it can grow to be a nymph. The white-footed mouse is perfect! Lyme disease bacteria can live and multiply inside the mice and not make them sick. Also, mice are just the right height for a larval tick to climb onto and feed. If the mouse is carrying Lyme disease the tick becomes a carrier, too. It is during this first blood meal when most ticks become infected with Lyme bacteria. Did you know there are more white-footed mice in the Northeastern United States today than when your grandparents were your age? This has happened for a few reasons: o Forest lands that were cleared 300 years ago by colonists have become reforested. o Many of these new forests have been allowed to grow in small patches with lots of stone walls between homes. o These patches give the mice places to hide from medium-sized predators like weasels, owls, and hawks. Mice can find plenty of food there, too. o Predators like wolves, coyotes and mountain lions are mostly gone in these areas. o Tiny white-footed mice are among the last species to leave an area that has lost most of its biodiversity. So, it seems that people have turned the landscape into an ideal Lyme disease habitat! But this isn t the whole Lyme disease story The Ixodes tick that transmits Lyme disease goes by another name most people call it the deer tick. This must mean that deer are important to these ticks too, right? Right! The whitetailed deer is the most common animal an adult tick will bite. Because deer are large animals, hundreds of adult ticks can get their last blood meal from one deer without hurting it. When an adult tick has its final blood meal, it is ready to mate. The mating takes place right on the deer s body. Now the female ticks can fall from the deer and wait. In the spring, they lay thousands of eggs.

7 Like the mice, there are more deer today than there were years ago. Many of the reasons listed above are also true for deer. We have many towns - and even some cities - that provide great places for deer to live. It would be impossible to find and remove every tick in a forest. It is also impossible to remove all the white-footed mice. These little animals can hide from people just like they can hide from weasels, owls and eagles. Besides, every species plays an important role in the ecology of the forest. But deer are larger! Several scientists have asked, Why not control the deer? The number of deer is a lot smaller than the number of mice. And deer are bigger and easier to control. Some towns tried to remove or reduce local deer numbers with hunters. Other people think we should not remove or kill the deer. They suggest there are other ways to reduce the risk of Lyme disease that allow deer to stay in the forested areas. One idea with promising results is a feeding station called a 4-poster. See the pictures below: (photos courtesy of American Lyme Disease Foundation ) 4-poster station tick-infested deer ears treated deer ears Four-poster stations have 4 posts with rollers covered with a pesticide that kills ticks. To get to the food in the station, a deer must reach through the rollers and the pesticide rubs off. It works! Studies have shown very good results. The deer population is not affected but the number of ticks goes down. Problems remain. The 4-poster stations are expensive. It also takes a lot of effort to keep them in good condition full of food and with enough pesticide on their rollers. Some places do not allow 4-poster stations because then pesticide is released into the environment. Other places allow them but not within 100 yards of where children play. You can check out the 4-poster at: Electric fences have been used to control deer around schools, parks, and homes. Gardeners often use deer-resistant plants. These plants aren t tasty to most deer, so deer often choose not to eat them. When deer know there isn t anything tasty to eat, they might not even stop by that location. Do you like one of these deer control methods? Do you have a favorite? Do you have a better idea? 2011 Peabody Museum of Natural History, Yale University. All rights reserved.