The South Florida Aquatic Plant Management Society
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Highlights Florida’s Water Resources: Why Water Resources Are Important Classical Biological Control of Weeds with Insects: Melaleuca Weevil Managing Pestiferous Freshwater Aquatic Midge Emergencies from Storm Water Retention Ponds
Volume 26 Issue 2
Board Members - 2022 Officers 2022
It was amazing seeing everyone at the quarterly meeting. The speakers were excellent as usual, but the best part was seeing everyone catch up in person for the first time in two years. We have all grown accustomed to zoom meetings, but there is no replacement for face to face interactions. Now we get into the heart of the growing season. It is imperative we all work smarter as the cost of fuel and products have increased exponentially. Hopefully when you are around other licensed applicators you are able to bounce ideas off each other and share information on what’s working the best and what’s most cost effective. Even though we may work for different companies or agencies, we all have the same goal. We plan on having another live meeting in June and we hope everyone can attend again as we all work together to improve the quality of the water bodies in our area.
Andy Fuhrman - President South Florida Aquatic Plant Management Society
Andy Fuhrman, President (954) 382-9766 email@example.com Dail Laughinghouse, Ph.D., Vice President (954) 577-6382 firstname.lastname@example.org Colleen Sullivan, Secretary/Treasurer (954) 382-9766 email@example.com Hughie Cucurullo, Immediate Past President (561) 845-5525 firstname.lastname@example.org Board Members 2022 Keith Andreu (239) 694-2174
Rose Bechard-Butman (954) 519-0317 email@example.com James Boggs (352) 521-3538
Norma Cassinari (334) 741-9393
Lyn Gettys, Ph.D. (954) 577-6331
Scott Jackson (561) 402-0682 Rory Roten, Ph.D. (321) 890-4367 Dharmen Setaram (407) 670-4094
firstname.lastname@example.org email@example.com firstname.lastname@example.org
Steven Weinsier (954) 382-9766 email@example.com
The Francis E. “Chil” Rossbach Scholarship Fund
Cover Photo: John Hartzell, City of Coconut Creek
Funds from the scholarship are used to help defray costs for students taking classes related to the study of aquatic environmental sciences or related areas. The scholarship is open to anyone, and all are encouraged to apply. Applications will be accepted throughout the year and the scholarship awarded when a suitable candidate is found. Money raised by the Society during the year partially goes to fund this scholarship, the intent of which is to promote the study of aquatics. For an application, please go to www.sfapms.org.
Figure 1. In November, manatees migrate to warmer coastal waters, such as Crystal River on the west coast of Florida. Credit: UF/IFAS
FLORIDA'S WATER RESOURCES By: Tara Wade and Tatiana Borisova | UF/IFAS
INTRODUCTION: WHY WATER RESOURCES ARE IMPORTANT
"Water is the lifeblood of our bodies, our economy, our nation and our well-being" (Stephen Lee Johnson, Head of EPA under G.W. Bush Administration) This quote sums up the importance of water resources. We use water for drinking, gardening, and other household uses, in agriculture (e.g., for irrigation), and in energy production and industrial processes (e.g., for cooling in thermoelectric power generation). Clean and plentiful water resources are also important for our recreational activities (e.g., boating, swimming, or fishing).
Water also sustains wildlife (such as manatees) and is an integral part of Florida's environment (Figure 1). As of November 2021, record breaking manatee deaths (over 1,000 deaths within 11 months) highlights the importance of clean waterways for wildlife’s survival (Chesnes 2021, FFWCC 2021).
HYDROLOGIC CYCLE: WHERE WATER ORIGINATES AND WHERE IT GOES Toni Morrison, an American novelist, once said that "all water has a perfect memory and is forever trying to get back to where it was." Indeed, water is constantly moving. The hydrologic (or water) cycle is the continual circulation / distribution of water on the surface of the land, in the ground, and in the atmosphere (USGS 2016b). Where water originates and how much water is available are fundamental to how water "cycles" through the environment. There are five basic processes in the hydrologic cycle: (1) condensation, (2) precipitation, (3) infiltration, (4) runoff, and (5) evapotranspiration (Figure 2). These processes can occur simultaneously and, except for precipitation, continuously. We will discuss these five processes in the context of Florida.
Figure 2. Water cycle. Credit: SWFWMD
This process is familiar to any Floridian who leaves his or her car outside at night. In the morning, the car windows are covered with small droplets of water or dew. In general, condensation is the process by which water vapor changes from gas to liquid. This occurs as moist air cools. The cooling water vapor forms tiny droplets that cling to dust, salt, and smoke particles in the air and then form dew or fog. Cloud formation is another example of the condensation process which occurs at higher altitudes where the air is cooler.
Precipitation is the product of condensation of atmospheric water vapor. Rain is an example of precipitation, another stage in the hydrologic cycle. Precipitation occurs as water droplets formed at higher altitudes increase in size and gain weight, causing the droplets to fall due to gravity. Depending upon conditions, precipitation most typically occurs as rain, hail, snow, or sleet.
Figure 3. Florida's average annual rainfall, 1981–2010. Credit: OSU/PRISM
Florida has a subtropical to tropical climate and receives an average of 55 inches of rainfall per year (statewide averages for 1981–2010) (OSU/PRISM 2014; Florida Climate Center 2017). This is almost twice the national average of 31 inches per year, and five times higher than the level of rainfall in the driest US state, Nevada (11 inches per year; averages for 1981–2010) (NOAA/NCEI 2014, 2017). Rainfall varies in amounts and in intensity from one Florida region to another, with the highest mean annual rainfall occurring in northwest Florida (the Panhandle) and in coastal areas of southeast Florida (Figure 3). In these regions, the average precipitation is about 60 inches per year. Other regions receive less rain. For example, the Florida Keys have an average of 40 inches of rainfall annually (average for 1981–2010) (OSU/PRISM 2014; Florida Climate Center 2017a).
Seasonal variations in rainfall are also evident. Traditionally, summer is the wettest season in Florida, with more than half of the annual rainfall occurring during the June to September "wet season" (Figure 4). However, this pattern of seasonal precipitation varies (see minimum and maximum monthly precipitation values in Figure 4). During the wet season, tropical storms are normal in Florida, with some delivering over 10 inches of rainfall during a 24-hour period (causing flooding). Hurricane Easy (in 1950) has the highest estimated rainfall of almost 39 inches in 24 hours in Yankeetown (west-central Florida). Hurricane Jeanne (in 1980) has the highest official measured state record rainfall of approximately 23 inches within a 24-hour period (Florida Climate Center 2017b). Conversely, spring 2017 will be remembered for its widespread drought conditions, where in May, an astonishing 66% of the state registered drought of various severity levels due to low rainfall in the preceding months (Rice 2017).
In Florida, significant volumes of water are used for residential landscape and agricultural crop irrigation. In the dry spring months, residential homeowners rely on supplemental irrigation for landscaping their yards. In turn, many agricultural crops in Florida are planted in the fall season when the air temperatures cool down, with harvesting in the winter and spring seasons, using irrigation during dry winter and spring months for supplemental irrigation and frost protection. Increasing water-use efficiency is a high priority for Floridians. For suggestions related to residential irrigation practices, see Florida Friendly LandscapingTM information at the University of Florida's website (http://fyn.ifas.ufl.edu/homeowners/nine_princi ples.htm). For best management practices (BMP) related to agricultural irrigation, consider exploring the BMP manuals available at the Florida Department of Agriculture and Consumer Services website (https://www.fdacs.gov/Agriculture-Industry/W ater/Agricultural-Best-Management-Practices) Capturing and storing rainfall in reservoirs to reduce the need for pumping water from aquifers during drier months is also a strategy being explored by Florida municipalities.
Figure 4. Statewide monthly precipitation, 1981–2010. Credit: Florida Climate Center
INFILTRATION, PERCOLATION, AND RECHARGES When rainfall reaches the Earth's surface it can enter the ground (infiltration), collect into surface streams and lakes (runoff), or return to the atmosphere as water vapor (evapotranspiration). The phases of runoff and infiltration are highly interrelated, and are influenced by the form of precipitation, the type and amount of vegetative ground cover, topography, and soil permeability. Infiltration occurs when water first enters the soil surface zone. Groundwater collects as the water that is not used by plants percolates (or seeps) downward until it encounters a zone (stratum) where the pores in the soil or rocks are saturated. Underground layers of porous material that are saturated with water are called aquifers. The water level can rise and fall in shallow or surface aquifers, depending upon local rainfall conditions. When a shallow groundwater aquifer is underlain by a stratum of low permeability called a confining unit (e.g., clay) (Figure 5), water is forced to move laterally through the aquifer and emerge into a surface spring, stream, or lake. Conversely, when groundwater levels are low, water may flow in the opposite direction—from surface streams and lakes into the shallow aquifer. Sometimes freshwater exists deep underground in confined aquifers, where the water-bearing aquifer is confined below a stratum of low permeability (e.g., cavities under the clay layer) (Figure 5). A confined aquifer can sometimes hold water under sufficient pressure, allowing water to rise above the confining layer when a tightly cased well penetrates the confining unit (think about how a water fountain works). These are known as artesian aquifers. When tapped, they sometimes produce free-flowing artesian wells. Naturally occurring springs also result from this same phenomenon (Figure 5). Water can also enter aquifers through recharge zones where the water-bearing stratum emerges at the surface or where the confining layer is broken up by faults or natural sinkholes that allow downward infiltration of water (Figure 5). Note that recharge zones may be some distance away from the springs or wells that are fed by the aquifer.
Figure 5. Diagram of the Floridan aquifer system. Credit: USGS
FLORIDA'S AQUIFERS Florida has several prolific aquifers (Figure 6) that yield large quantities of water to wells, streams, lakes, and springs (some of the largest in the world). The principal source of groundwater for most of the state is the Floridan Aquifer—the source of the municipal water supply in north and central Florida. It also yields water to thousands of domestic, industrial, and irrigation wells throughout the state.
Figure 5. Diagram of the Floridan aquifer system. Credit: USGS
Florida Strawberry and Goat Cheese Tarts Recipe from Fresh From Florida Florida Department of Agriculture and Consumer Services
Ingredients 3 cups Florida strawberries, sliced thin
6 ounces goat cheese
½ cup Florida strawberry jam
1 egg, beaten
Florida honey to drizzle
2 (9-inch rounds) prepared pie crust, homemade or store bought
1 tablespoon natural Florida sugar
Preparation Preheat oven to 375 degrees. Cut out three equal-sized circles from each of the two larger pie crusts. Place all the cut outs on one or two lightly greased cookie sheets for baking. Spread an even amount of strawberry jam in the center of each of the cut outs. Have fun evenly arranging or layering the sliced strawberries around the inside of all the cut outs leaving room for a crust. Fold the crust onto itself all the way around to form a crust edge. Crumble an even amount of the goat cheese over each of the strawberry tarts. Brush the crust edges of each of the filled tarts with the beaten egg wash. Lightly sprinkle the sugar evenly over all the crusts where they were just brushed with the beaten egg. Place the tarts in the preheated oven. Cook the strawberry tarts for about 15 to 20 minutes or until the crust is golden brown and the strawberries are bubbling. Remove the strawberry tarts from the oven and let cool slightly. Lightly drizzle strawberry tarts with Florida honey. Serve with fresh whipped cream and extra honey if desired.
A shallow, non-artesian surficial aquifer is present across much of the state, but it is not an important source of groundwater in most areas because a better supply is available from deeper aquifers. However, in rural areas where residential water requirements are relatively smaller by comparison to other areas, this aquifer is tapped by small-diameter wells. The water in this shallow aquifer is derived primarily from local rainfall.
For more information about Florida aquifers, see FDEP (2015). You can learn more about Florida's aquifer system by watching videos collected at the U.S. Geological Service website (https://fl.water.usgs.gov/floridan/visual_gallery. html).
A non-artesian, sand-and-gravel aquifer is the major source of groundwater in the extreme western part of the Florida Panhandle. Water in the sand-and-gravel aquifer is derived chiefly from local rainfall and is of good chemical quality. Wells tapping this aquifer furnish most of the groundwater used in Escambia and Santa Rosa Counties, and part of Okaloosa County.
Except those areas where its limestone formations break the surface of the ground, the Floridan aquifer underlies several hundred feet of sediment, including thick beds of relatively impermeable material that restrict upward movement of the water (Marella and Berndt 2005). This restriction causes the aquifer to have artesian pressure and make the water move through the openings in impermeable layers creating springs (Figure 7).
The non-artesian Biscayne aquifer underlies an area of about 3,000 square miles in Miami-Dade, Broward, and Palm Beach Counties on Florida's lower east coast. Water in the Biscayne aquifer is derived chiefly from local rainfall and, during dry periods, from canals ultimately linked to Lake Okeechobee. The Biscayne aquifer is an important water supply for the lower east coast Florida cities.
In Florida, there are over 1,000 springs, including more than 30 first-magnitude springs with an average flow of over 100 cubic feet per second (64.6 million gallons per day) (Knight 2017). Spring water emerges from cavities in the porous limestone of the Floridan aquifer, and often contributes to the flow or level of water in streams and lakes. The springs depend upon the same resources from which we withdraw water for public water supplies, private water wells, and agricultural production. Increases in water withdrawals for any purpose also reduces spring flows. The Chinese proverb 'when you drink water, remember the spring' applies to Florida literally.
Thick layers of porous limestone of the Floridan aquifer underlie all of the state, and extends beyond the state boundaries, to Georgia, South Carolina, Alabama, and Mississippi. In south Florida, water from the Floridan aquifer is too highly mineralized (i.e., salty) to be usable. Water in the Floridan aquifer is replenished by rainfall in north and central Florida (as well as in south Georgia and south Alabama), where the aquifer emerges at the surface or is covered by permeable materials, or where the confining material is broken up by sinkholes. In these areas, it is especially important to exercise appropriate practices when gardening, managing septic systems, or growing agricultural crops. These practices can directly impact the quality of water in the aquifer, and hence, the quality of water withdrawn for drinking and other purposes, and the quality of water in the springs fed by the aquifer system.
Figure 7. Silver Springs, Florida. Credit: Sally Lanigan, UF/IFAS
SALTWATER INTRUSION Florida's geography as a peninsula between two bodies of saltwater creates the potential for saltwater intrusion into the aquifers (i.e., into the fresh groundwater supply). Saltwater is denser than freshwater and exerts a constant pressure to permeate the porous aquifers. As long as freshwater levels in the aquifers are above sea level, the freshwater pressure keeps saltwater from moving inland and upward into the aquifers. For example, the level of water flowing through south Florida's coastal canals is generally several feet above sea level, which is enough to prevent ocean water from moving inland and upward into the aquifer. However, if during dry periods, the freshwater levels in canals without locks and dams fall to or below sea level, saltwater would move upward in the canals. In some places, excessively pumping a well can increase saltwater intrusion. If water is pumped at a rate faster than the aquifer is replenished, the pressure of freshwater over saltwater in the land mass is decreased. This decrease may cause the level of the saltwater-freshwater interface to rise in the aquifer, degrading water quality. This problem must be controlled by careful attention to well location and pumping rates. The problem of saltwater intrusion is aggravated by drought periods when there is not enough rainfall to replenish the freshwater aquifers.
Increases in the area covered with impermeable surfaces, such as roads, driveways, and houses, can decrease the rate of aquifer recharge while increasing the volume of runoff. Increased runoff volumes can potentially impact the quality of water in rivers, lakes, and canals because runoff can carry a variety of pollutants. Indeed, as Alan Levere, Connecticut Department for Environmental Protection, stated, "A river is the report card for its watershed." In Florida, surface runoff and groundwater discharge feed more than 1,700 streams and rivers (FDEP 2016). Of Florida's five largest streams, four are in the drainage basins of north Florida: Apalachicola, Suwannee, Escambia Rivers and Choctawhatchee (Figure 8). The fifth largest stream is the St. Johns River, which flows north from its headwaters near Vero Beach to its mouth at the Atlantic Ocean in Jacksonville.
Runoff Runoff is water that does not enter the ground but collects in rivers, streams, canals, or lakes. This water evaporates, percolates into the ground, or flows out to the ocean. In turn, groundwater can run close to the surface and then discharge to feed springs, streams, rivers, or lakes. Note that surface runoff, as well as groundwater infiltration and discharge rates, depend upon land use, soils, and weather conditions. With population growth and related changes in land use, we significantly alter the relationship between the rainfall volume that runs off the land and the volume that recharges the aquifers.
Figure 8. Florida rivers. Credit: USGS
The largest of Florida's streams by volume of water (i.e., discharge flow) is the Apalachicola River, which flows south from its headwaters north of Atlanta, Georgia, past the confluence of the Flint and Chattahoochee Rivers at the Georgia-Florida line.
Apalachicola River The Apalachicola River drains 17,200 square miles in Alabama and Georgia, and 2,400 square miles in Florida. From 1978 to 2012, mean discharge of the Apalachicola River at Sumatra, Florida (midpoint of river length in Florida) was 24,000 cubic feet per second (or 15 billion gallons per day), with a variation between approximately 10,000 and 37,000 cubic feet per second (or from 6 billion to 24 billion gallons per day) (USGS 2014a). Despite the fact that the river carries significant volumes of water, the need for water is ever growing due to population growth in all three states. Since the 1990s, the three states have argued over the amount of water each of the states should receive from the river system (priorities: Georgia, Atlanta public water use; Alabama, agricultural irrigation; and Florida, freshwater oyster production in Apalachicola Bay). In other words, wise management and allocation of water is very important.
Suwannee River The Suwannee River (Florida's second-largest river by volume of discharge) drains about 11,000 square miles from its headwaters in Okefenokee Swamp in south Georgia to its mouth at the Gulf of Mexico. At the measuring station in Wilcox, Florida (33 miles north of the Gulf of Mexico), the Suwannee River discharges about 10,000 cubic feet per second (6 billion gallons per day, average for 1930–2013). The variation is between 3,000 and 25,000 cubic feet per second (or from 2 billion to 16 billion gallons per day) (USGS 2014b). The Santa Fe River flows into the Suwannee River, as do several springs, such as Troy, Ichetucknee, Fanning, and Manatee.
Choctawhatchee River The Choctawhatchee River (Florida's thirdlargest river by volume of discharge) drains 3,100 square miles in southeast Alabama and 1,500 square miles in northwest Florida (the Panhandle). Choctawhatchee Bay opens to the Gulf of Mexico in the vicinities of Fort Walton Beach and Niceville. At the measurement station near Bruce, Florida, 21 miles above the Choctawhatchee River's mouth, average discharge is about 7,000 cubic feet per second (more than 4 billion gallons per day, average for 1931–2013). The variation is between 3,000 and 12,000 cubic feet per second (or from 2 billion to 8 billion gallons per day) (USGS 2014c).
Escambia River The Escambia River and its tributaries drain 3,760 square miles in Alabama and 425 square miles in northwest Florida before flowing into Pensacola Bay at a rate of almost 7,000 cubic feet per second (more than 4 billion gallons per day, measured near Molino, Florida, in 1988–2013) (USGS 2014d). Of Florida's five largest rivers, only the St. Johns River is entirely within the borders of the state. Managing the flow or quality of water in the other four largest rivers in Florida requires coordinating efforts with other states. The St. Johns River drains about 9,400 square miles from marshes west of Vero Beach to its mouth at the Atlantic Ocean in Jacksonville. It is one of only a few U.S. rivers that flows north. At its mouth near Jacksonville, flow is about 7,000 cubic feet per second (more than 4 billion million gallons per day, an average for 1970–2011) (USGS 2014e). The St. Johns River connects seven major lakes, from Lake Washington to Lake George. Its tributary, the Ocklawaha River, connects nine lakes, from Lake Apopka to Lake Lochloosa.
www.sfapms.org Other significant streams include the Kissimmee River (with headwaters near Orlando, flowing south and emptying into Lake Okeechobee in the center of the state); the Peace River (flows into Charlotte Harbor), and the Withlacoochee River (flowing to the northwest from the Green Swamp in central Florida and emptying into the Gulf of Mexico near Yankeetown). In addition, the St. Lucie Canal connects Lake Okeechobee to the Atlantic Ocean on the east coast near Stuart, and the Caloosahatchee Canal connects Lake Okeechobee to the Gulf of Mexico on the west coast near Fort Myers. Together, these two canals form a navigable cross-state waterway. Other canals from Lake Okeechobee to the Atlantic Ocean are the Hillsboro, North New River, Miami, and West Palm Beach Canals (Fernald and Purdum 1998). In addition to the rivers, Florida has more than 7,700 lakes, with the largest lake, Lake Okeechobee, being in the top 10 largest lakes in surface areas in the United States (467,200 acres) (Fernald and Purdum 1998; FDEP 2016). Florida also has many types of wetlands, including the Everglades (south Florida) and Green Swamp (central Florida), which provide habitats for a variety of plants and wildlife, and serve as groundwater recharge areas. Overall, the streams, rivers, springs, lakes, and wetlands produced by the runoff phase of Florida's hydrologic cycle are familiar to Floridians as water supply sources, recreational attractions, transportation routes, and havens for the state's abundant fish and wildlife populations.
EVAPOTRANSPIRATION An additional stage of the hydrologic cycle is evapotranspiration. Evapotranspiration is a combined process of evaporation from surfaces and transpiration through plant leaves (Irmak and Haman 2021). Generally, evaporation is the process by which water is changed into its gaseous form (water vapor). Part of the rainfall evaporates from the land surface back to the atmosphere. The potential for evaporation from an area depends upon atmospheric conditions such as temperature and wind speed. Evaporation is also affected by factors such as soil permeability, the type and amount of vegetative ground cover, and slope of the land. For example, evaporation is relatively low in parts of northwest Florida.
page 17 This area is well drained and, compared with other parts of Florida, has steep slopes. Much of the area is covered by permeable soils that readily pass rainfall into a shallow aquifer. An impermeable ground layer underlying the shallow aquifer in this area ensures that most of the rainfall appears in streams. Conversely, for portions of extreme south Florida, where topography is flat and drainage is poor, water is readily available for evaporation. In turn, transpiration is the process whereby moisture in plants is returned to the atmosphere through plant leaves. Many plants rely on rainfall that infiltrates the soil from the surface for moisture. Water deficiency exists when potential evapotranspiration (i.e., evaporation plus moisture demand by plants) exceeds actual evapotranspiration (i.e., soil moisture that is actually available for evaporation and for plant use). Monthly climatic water budgets indicate that in Key West, water deficiency persists throughout the year; in the Panhandle, water deficiencies rarely occur; and in the rest of the state, water deficiencies are common in winter and spring.
CONCLUSIONS The hydrologic water cycle is a useful way to describe and categorize Florida's water resources. The cost and feasibility of making water supplies available for municipal, agricultural, and industrial uses is determined to a great extent by the water cycle patterns of rainfall, runoff, and infiltration over time and space. It is important to remember that while Florida receives significant rainfall every year, most of this water is returned to the environment through evapotranspiration and outflow of the rivers. Only a very small percent infiltrates into the ground to replenish the underground freshwater reservoirs/aquifers that we all depend upon for drinking water. Everyone should be aware that increasing water withdrawals from aquifers for human needs reduces the amount of water available to feed the springs, rivers, and wetlands not only now, but for years to come. For article references see: https://edis.ifas.ufl.edu/publication/FE757
CLASSICAL BIOLOGICAL CONTROL OF WEEDS WITH INSECTS: MELALEUCA WEEVIL By: J. P. Cuda, S. A. Wright, G. R. Buckingham, T. D. Center, and K. T. Gioeli University of Florida
INTRODUCTION This publication presents information about melaleuca weevils, Oxyops vitiosa, introduced to Florida for biological control of the invasive melaleuca tree. It contains information about melaleuca weevil natural history, biology, use as a biological control agent. The intended audience includes homeowners and land managers primarily in south Florida where Melaleuca most is prevalent. General Background Melaleuca, Melaleuca quinquenervia (Cav.) S.T. Blake (Myrtaceae), is an invasive woody plant that is native to Australia, New Guinea, and the Solomon Islands, and is a prohibited species in Florida (Licurance 2013). Melaleuca, also known as the paper bark tree, cajeput, punk tree, or white bottlebrush tree, was introduced into Florida in the late 19th century but apparently failed to naturalize until 1906. It was planted extensively as an ornamental and eventually invaded suitable forested and non-forested wetland habitats in south Florida forming dense monocultures (Figure 1). In 2008, melaleuca occupied over 110,000 ha of wetland ecosystems in this region, most notably the sawgrass marshes that comprise the Florida Everglades. In 2003, total expenditures for melaleuca control in Florida approached $26 million (Carter-Finn et al. 2006). A combination of chemical, mechanical, cultural, and biological control practices have been used to manage melaleuca in south Florida. These methods have been successfully integrated to provide the most effective control.
Figure 1. Stand of melaleuca trees in St. Lucie County, Florida. Credit: Ken Gioeli, UF/IFAS
Melaleuca is not considered a weed in its native Australia because it is attacked by a complex of natural enemies. Classical biological control, which is the introduction of host-specific natural enemies, was investigated as a possible long-term solution to the melaleuca problem. Five insects have been imported into quarantine for host specificity testing by USDA scientists. The first insect released was the melaleuca snout beetle or weevil, Oxyops vitiosa (Pascoe) (Insecta: Coleoptera: Curculionidae) (Figure 2).
Figure 4. Excised shoot tip of melaleuca caused by adult weevil feeding damage. Credit: undefined
Figure 2. Melaleuca weevil Oxyops vitiosa (Pascoe) adult on melaleuca leaf. Credit: Ken Gioeli, UF/IFAS
The presence of adults is usually indicated by the characteristic feeding damage that consists of holes or gouges chewed into the buds, leaves, and stems. Occasionally, young shoot tips are nearly excised when stem feeding occurs on the tender new growth (Figure 4).
ADULT Melaleuca weevils are gray in color and 6 to 9 mm in length. Males are usually smaller than females. The adults are somewhat cryptic in appearance but are usually found on the leaves and stems of saplings (Figure 3) or the new growth of older trees, where they feed, mate, and deposit their eggs.
Figure 3. Two melaleuca weevil adults feeding on melaleuca leaves. Credit: Rob Lowen, USDA-ARS
EGG The eggs of the melaleuca weevil are yellow, 1 mm long, and resemble gel capsules (Figure 5). The female almost always covers the eggs in a secretion as soon as they are deposited to protect them from desiccation or predation. This secretion dries to form a hard protective casing, which is brown to black in color. When the eggs are present, they are usually associated with adult feeding damage.
Figure 5. Eggs of melaleuca weevil on young leaves; uncovered (yellow) and covered with a brown to black secretion. Credit: undefined
CALENDAR OF EVENTS In-Person General Meetings: June 23, 2022 - TBD September 29, 2022 - TBD Zoom Courses: April 28, 2022 November 16, 2022
LARVA The larval stage has four instars, or growth phases. The appearance and size of the larvae vary depending upon their age. Neonates, or newly hatched larvae, are yellow and less than 1 mm long. In contrast, the mature larvae are 14 mm in length, grayish in color, and are slug-like in appearance. Developing larvae are usually covered with translucent yellow or orange oily secretion that turns black after fecal material is incorporated into it. This oily secretion mixed with fecal matter affords the larvae protection from fire ants and possibly other predators. This fecal matter is produced as a long thin coil (Figures 6 and 7). Figure 7. Melaleuca leaf showing feeding damage and larvae of the melaleuca weevil. Credit: undefined
PUPA The pupal stage is not visible because it occurs beneath the soil surface. Larvae develop to the pupal stage inside an earthen capsule formed by the prepupae. The pupal capsule, which is made of soil and an oily secretion produced by the insect, is approximately 10 mm in diameter. The newly formed pupae are of the exarate type (i.e., the legs and wings are free and not glued to the body) and are yellowish in color but turn brown prior to emergence of the adults from the soil. Figure 6. Larva of melaleuca weevil on melaleuca leaf. Note the start of a fecal coil. Credit: Ken Gioeli, UF/IFAS
The feeding damage produced by the larval stage is very different from the adults. Instead of chewing holes in the leaves, the larvae consume all layers of the leaf except for the cuticle on the opposite side. The appearance of the paper-thin feeding trails in the leaves produced by the developing larvae is a clear indication that melaleuca weevils are present (Figure 7). Prior to pupation, the mature larvae, or prepupae, cease feeding and are yellow in color.
DISTRIBUTION AND LIFE CYCLE The melaleuca weevil is native to Australia. This insect was released in Florida in 1997 after Australian field studies and quarantine laboratory testing by the USDA in Florida demonstrated the weevil would reproduce only on melaleuca. Establishment of the weevil has been confirmed in all melaleuca-infested sites except those that are flooded for extended periods.
LARVA Adults feed and reproduce on the leaves and shoots of saplings as well as the new growth of mature melaleuca trees. Females begin to produce eggs when they are approximately 6 weeks old and can live up to 10 months. They will deposit up to 9 eggs per day and produce from 500 to 1000 eggs during their lives. The egg stage lasts approximately 7 days, and larvae begin to feed immediately upon hatching. Larvae will complete their development in approximately 7 weeks and migrate down the stems as they mature. When the larvae become prepupae (cease feeding), they crawl or drop to the ground to complete their development to the adult stage. The larvae will select a suitable site underground to form a pupal capsule from the surrounding soil. The insects will remain in the pupal stage for approximately 2 to 6 weeks. Based on laboratory studies, development from the egg to the adult stage occurs in approximately 12 weeks. In south Florida, new adults appeared in the field 3 months after the weevil was initially released, which suggests the melaleuca weevil is able to produce two to three generations per year in Florida's subtropical climate. As mentioned previously, part of the life cycle of the melaleuca weevil occurs in the soil. While soil type does not appear to preclude establishment, pupation success may be higher at sites with sandy soils. Field and laboratory studies indicate the larvae can pupate under soil conditions ranging from saturated to drier areas with a high relative humidity. However, habitats in south Florida that are characterized by infrequent flooding, moderate melaleuca densities, and dry winters favor weevil establishment. Failure of the weevil to establish at permanently flooded sites suggests these conditions are not conducive to normal pupation, probably because submersed pupae cannot survive without oxygen for any length of time.
Larvae are commonly observed on melaleuca plants in south Florida from October to May, which coincides with flushes of new leaf growth. Adults are present only during the summer months unless the melaleuca is mowed or otherwise damaged. Any activity that stimulates new leaf growth (e.g., shoot regrowth from cut stumps, damaged branches, root suckering, etc.) will support larval populations year-round at a specific site.
IMPORTANCE Both adults and larvae damage melaleuca by disrupting the plants' normal growth processes. Large larvae can destroy most of the leaves on several shoots of an individual plant. At several sites in south Florida where high populations of the larvae have been observed, extensive areas of damaged melaleuca foliage are evident. Reduced flowering (up to 90%) also has been demonstrated experimentally by USDA scientists at several sites in south Florida where the weevil is established. This type of feeding damage may help to reduce seed production and prevent further spread of this highly invasive plant. Because the insect disperses slowly, a coordinated redistribution program was used to establish the insect in all 22 counties in central and south Florida, which are infested with melaleuca. A standardized procedure for collecting and transporting the adult melaleuca weevils to other sites where the weevil is not yet established was first developed and implemented in St. Lucie County (Figure 8). The melaleuca weevil is one of the key components of The Areawide Management and Evaluation of Melaleuca, or T.A.M.E. Melaleuca (TAME Melaleuca 2007). This pest management program, which was initiated in 2001, was designed to promote long-term, biologically-based melaleuca management through partnerships with public agencies and private land managers. The goal of T.A.M.E. melaleuca was to demonstrate the effectiveness of an IPM program for controlling melaleuca in the United States and beyond.
www.sfapms.org Ecosystem recovery has been documented during a 17-year period (1997–2014) following the release of biological control agents of the melaleuca tree. Formerly dense melaleuca stands are gradually changing to more diverse plant communities consisting of mostly native species following an 85% reduction in melaleuca trees. Other melaleuca biological control agents include the melaleuca psyllid (Boreioglycapsis melaleucae) which was released in Florida in February 2002 (Wineriter et al. 2003), and the melaleuca gall midge (Lophodiplosis trifida) in 2008 (Moore et al. 2016). For article references see: https://edis.ifas.ufl.edu/publication/IN172
Figure 8. Procedure for collecting adult melaleuca weevils. Credit: Ken Gioeli, UF/IFAS
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MANAGING PESTIFEROUS FRESHWATER AQUATIC MIDGE EMERGENCES FROM STORM WATER RETENTION PONDS Kenneth T. Gioeli, R. Leroy Creswell, Jeffrey P. Gellermann, Edward A. Skvarch, and Philip G. Koehler University of Florida: St. Lucie County Cooperative Extension Freshwater aquatic midges are mosquito-like Diptera belonging to the families Chironomidae and Chaoboridae (Koehler 2003). Chironomidae are commonly referred to as "Blind Mosquitoes," and Chaoboridae are commonly referred to as "Phantom Predatory Midges" (Figure 1).
Figure 2. Bloodworm. Credit: Lyle Buss, UF/IFAS
Figure 1. Chironomid adult. Credit: James Castner, UF/IFAS
Midge eggs, larva, and pupa are often found in storm water retention ponds, and their larvae thrive in low oxygen zones. These larvae are often referred to as wrigglers, and sometimes as "bloodworms" because some are bright red in color (Figure 2). The adult midges do not bite, suck blood, or carry diseases, and, therefore, are sometimes called "blind mosquitoes." Adult midges become a problem when they emerge from ponds in large numbers, primarily in the warm summer months (Figure 3).
Figure 3. Family: Chironomidae; Genus: Glyptotendipes. Credit: Lyle Buss, UF/IFAS
Unfortunately, the emergence of large numbers of these pestiferous aquatic midges impacts the quality of life of the residents living around many storm water retention ponds in communities throughout Florida. Adult midges prefer to rest in shady areas in the day and are often found in large numbers under eaves, on patio screens, and in foyers.
www.sfapms.org These midges can also find their way inside homes as residents enter and exit the structure. In addition, people have reported damage to paint finishes, airplanes, allergies, and discouraged tourism. A Freshwater Aquatic Midge Integrated Pest Management (FAM IPM) Plan has been developed by the University of Florida to help residents tackle these midge problems. IPM plans are described as a coordinated use of multifaceted pest control strategies. The FAM IPM Plan features the coordinated use of algae control strategies, insectivorous fish, light traps, and insect growth regulators.
HEALTHY PONDS The residents concept of what constitutes a healthy, desirable pond can be taken into account when designing a local FAM IPM Plan. These considerations may include fertilizer and pesticide-free buffers between turf and ponds edge; clean, clear water with no algae and low turbidity; irregular shaped ponds with appropriate native, low maintenance vegetation; and adequate fish and wildlife.
AQUATIC MIDGE IPM PLAN The first strategy in the FAM IPM plan involves the use of algae control. Larval Chironomidae graze on algal detritus that settles to the bottom of these ponds. Ponds can be treated with algaecides, such as those containing copper, to control algae. A nutrient abatement strategy should also be implemented. This strategy involves the enforcement of the Florida Green Industry Standards for fertilizer application to turf around ponds. According to the Florida Department of Environmental Protection (2002), for flat turf adopt the use of three-foot untreated buffers if a fertilizer spreader with a deflector shield is used or a ten foot untreated buffer if a spreader without a deflector shield is used. For steeply sloped turf, larger buffers are recommended. Other environmentally friendly practices such as avoiding blowing grass clippings into the water and using slow-release fertilizers are also featured in the nutrient abatement strategy.
page 29 The second strategy in the FAM IPM plan involves the use of insectivorous fish to biologically control aquatic midges in ponds. Ponds can be stocked with bream and bass to control nuisance aquatic insects and provide recreational fishing opportunities. According to the Florida Fish and Wildlife Conservation Commission (2007), bream should be stocked at a rate of five hundred fingerlings per acre. Bream (70% blue gill / 30% red ear) should be stocked in the fall, allowing them to spawn. One hundred bass fingerlings per acre were stocked in the spring when feeder fish were available. Stocking in the summer is not recommended as high temperatures can potentially stress the fish (Cichra 1995). The third strategy in the FAM IPM plan involves the use of light traps to control adult midges (Ali et al., 1994). Some light traps are able to either trap or kill midges to reduce their numbers. Lights can be used in upland buffers adjacent to the infested ponds in order to divert midges from houses. The fourth strategy in the FAM IPM plan involves the use of insect growth regulators (IGRs) to prevent midge larvae from pupating normally and developing into the adult stage. An IGR labeled for the control of aquatic midges contains (S)- Methoprene and is sold in pellets. These pellets release the IGR for up to 30 days. (S)-Methoprene can effectively stop the formation of midge pupae in the water (Ali 1991). The (S)-Methoprene label recommends a dosage of five to ten pounds per acre which should be applied twenty feet from the waters edge. Always read and follow label directions. Although the use of (S)-Methoprene can effectively manage aquatic midge pupae, it can be expensive.
CONCLUSIONS Implementation of the FAM IPM Plan should result in a significant reduction of pestiferous aquatic midge emergences from storm water retention ponds. An integrated use of algae control strategies, insectivorous fish, light traps, and insect growth regulators can be effective if properly implemented. For article references see: https://edis.ifas.ufl.edu/publication/IN825