Western Plant Diagnostic Network1
First Detector News A Quarterly Pest Update for WPDN First Detectors Spring 2016 edition, volume 9, number 2
In this Issue
Dear First Detectors, For most of us, ants all look the same! Page 1: Editor’s comments Our first response is how to kill them. When one Googles
Pages 2 – 7: Ants and You “ant”, the first links that appear are pest control companies. Ants have been around for approximately 130 million years and have diversified and evolved a complicated social Pages 7 - 10: Phytophthora behavior. With the help of several ant experts, we have and Nursery Plants assembled a workshop on ants with wonderful links. Check out the websites and enjoy the vast and varied world of ants! Page 11: Pest Update: Red Blotch of Grapes Vector It is nursery season, and many of us are planting home Found gardens and commercial plantings. The second article is on the challenges presented by Phytophthora infestations in
nursery stock. Finally, there is a new pest update. A vector has been discovered for a virus disease of grapevines, known
as red blotch. Contact us at the WPDN Regional Center at UC Davis: Please find the NPDN family of newsletters at: Phone: 530 754 2255 Email: [email protected] Newsletters Web: https://wpdn.org Editor: Richard W. Hoenisch @Copyright Regents of the
University of California All Rights Reserved
BrockenInaglory
Western Plant Diagnostic Network News
Ants fossilized in Baltic amber
Ants and You 2
Ants are a true social (eusocial) insect, often appearing suddenly and invading in mass.
They are among the most prevalent pests in households. Ants also invade restaurants, hospitals, offices, warehouses, and other buildings where they can find food and water. On outdoor and sometimes indoor plants, ants protect and care for honeydew-producing insects such as aphids, soft scales, whiteflies, and mealybugs, increasing damage from these pests. Ants also perform many useful functions in the environment, such as feeding Alex Wild Photography Wild Alex on other pests (e.g., fleas, caterpillars, and termites), dead insects, and decomposing
tissue from dead animals. Harvester ants collect and bury seeds, dispersing the local flora
African Driver Ant and thus protecting them from wildfires. See this YouTube Ten awesome facts about ants
and antARK’s Amazing Ant Facts! Ants are in the order Hymenoptera, which includes wasps, bees, and sawflies, and in the family Formicidae, from the Latin for ant, formica. The modern plastic laminate “Formica ,” received its name from formic acid and the derivative formaldehyde compound used in the resin. Ants evolved from wasp-like ancestors in the mid -Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than 12,500 of an estimated total of 22,000 species have been classified. They are easily identified by their elbowed antennae and the distinctive node-like structure that forms their slender waists. Ants undergo complete metamorphosis, passing through egg, larval, pupal, and adult stages. Larvae are immobile, wormlike, and don’t resemble adults. Ants, like many other hymenopterans such as bees and wasps, are social insects with duties divided among different types, or castes, of adults. Queens conduct the reproductive functions of a colony and are larger than other ants; they lay eggs and sometimes participate in feeding and grooming larvae. The sterile female workers gather food, feed and care for larvae, build tunnels, and defend the colony; these workers make up the bulk of the colony. In some species they are all the same size, while others are polymorphic and have small and large workers. Males don’t participate in colony activities; their sole purpose is to mate with the queens. Workers feed and care for males, which are few in number.
TPW Magazine TPW
Control Pest County Sonoma
Above is a diagrammatic of a typical ant queen, male,
soldier and worker. To the right are wonderful actual images of the typical ant egg, larva, pupa, and adult. See the educational website EdVIE: The History of Ants and the fascinating video Ant Metamorphosis
Western Plant Diagnostic Network News
Ant Colonies 3
An ant colony, also called a formicary, is the basic family unit around which ants organize their lifecycle. Ant colonies are eusocial, and are very much like those found in other social Hymenoptera. The typical colony consists of one or more egg-laying queens, a large number of
sterile females (workers) and, seasonally, a large number of winged sexual males and females. Periodically, swarms of the winged males and females, called alates, depart the nest in great nuptial flights. The males
die shortly thereafter, along with most of the females. A small Shane Becker Shane percentage of the females survive to initiate new nests.
Ants usually nest in soil; nest sites vary with species but are often found next to buildings, along sidewalks, or in close proximity to food sources such as trees or plants that harbor honeydew-producing insects. Ants also construct nests under boards, stones, tree stumps, or plants and A plaster cast of a harvester ant sometimes under buildings or other protected places. The primary ant nest with Dr. Walter Tschinkel, that nests indoors is the Pharaoh ant. In temperate climates, this species one of the leading US ant experts nests in warm, moist locations such as inside wall voids, under flooring, or near hot water pipes or heating systems, but is also found nesting outdoors in warmer parts of the West. Food preferences vary among
ant species but may include fruits, seeds, nuts, fatty substances, dead or
live insects, dead animals, and sweets. Although there is some variation among species, a single newly mated queen typically establishes a new colony. After weeks or months of confinement underground, she lays her first eggs. After the eggs hatch,
David Edmondson David she feeds the white, legless larvae with her own metabolized wing
muscles and fat bodies until the larvae pupate. Several weeks later, the pupae transform into sterile female adult workers, and the first workers Ant nest with workers caring dig their way out of the nest to collect food for themselves, the queen for the pupae (who continues to lay eggs), and subsequent broods of larvae. As numbers increase, workers add new chambers and galleries to the nest.
After a few years, the colony begins to produce winged male and female
ants, which leave the nest to mate and form new colonies.
Argentine ants differ from most other ant species in that their nests are often shallow, extending just below the soil surface. However, under dry conditions they will nest deeper in the soil. In addition, Argentine ant colonies aren’t separate but linked to form one large “super colony”
with multiple queens. When newly mated queens disperse to found new Tortoise Trail Images Trail Tortoise colonies, they are accompanied by workers rather than going out on their own as most other species do.
Winged desert leafcutting ants, See these YouTube National Geographic’s Wild City of Ants and Ants: Acromyrmex versicolor, mating Super Soldiers for a fantastic and surreal view of the ant world and ant behavior.
Western Plant Diagnostic Network News
Which Ant is Which? Basic Ant Anatomy 101 4
Flagstaffotos.com.au
antARK
See External Ant Anatomy for further details
UCIPM
UC IPM UC
First Detectors should always
have hand lenses Body parts of a species of ant with two Body parts of a species of ant with one with them! petiole nodes petiole node
Myrmecology is the study of ants. Myrmex is the Greek word for ant. The three most important subfamilies of ants in the West are the Myrmicinae (two petiole nodes), Formicinae (one petiole node) and Dolichoderinae (one petiole node). These three websites have extensive lists of species with good photos for identification. Other sources for ant ID are: Pests of Homes, Structures, People, and Pets , The Three Most Common Ant Species, antARK, and AntWeb, the world’s largest online database of the ant world. Alex Wild Photography - Ants is an exceptional site to get up close and personal with ants. And now, let us look at some of our western ant species. The first step in ant management is identification.
Carpenter ants get their name because they excavate wood, including lumber, in order to build their nests. Their excavation results in smooth tunnels inside the wood. These are large ants ranging in size from one-quarter inch for a worker ant to up to three-quarters inch for Carpenter ant from the side Carpenter Ant, Camponotus spp. a queen. (note the one node)
Western Plant Diagnostic Network News
Asian Citrus Psyllid in Arizona 5
Odorous house ant is one of the most common pests of houses and other structures. In nature it feeds on both living and dead insects, and AntWeb
tends aphids for their honeydew. In homes they forage primarily for sweets, travel in trails. The colonies
can reach up to 10,000 workers and many queens. The antennae of the odorous house Odorous House Ants Tapinoma sessile ant has 12 distinct segments
(one node)
Pavement ants, Tetramorium
Advanced WildlifeControl caespitum, Its common name comes from the fact that colonies usually make their homes in pavement or lawns. It has two nodes on the petiole. They feed on
Alex Wild Photography Photography Wild Alex honeydew, sweets, fruit, grease,
and pet food.
Pavement ant, Tetramorium Pavement ants on the march
caespitum (two nodes)
Argentine ants Linepithema humilis, are ranked among the world's 100 worst animal invaders.
In its introduced range, the Argentine ant often HomeShield
displaces most or all native ants. This can, in
turn, imperil other species in the ecosystem, Penarc
such as native plants that depend on native ants for seed dispersal, or lizards that depend on native ants for food. They sometimes tend aphid
colonies, and their protection of this plant pest Argentine ant with scale from predators and parasitoids can cause Dull-brown Argentine ant. insect problems in agricultural areas. They form huge Note the one erect node “super colonies,” numbering in the millions.
Left, feisty Argentine Alex WildPhotography ants attack a much larger harvester ant. Right, one aggressive Argentine ant
attacking a red
Alex Wild Photography Photography Wild Alex
imported fire ant!
Western Plant Diagnostic Network News
6
Pharaoh ants, Monomorium Alex WildPhotography
pharaonic, are a small (2 mm) yellow or light brown, almost transparent
ant notorious for being a major indoor nuisance pest, especially in
hospitals. They are a tropical
species, but they thrive in buildings Alex Wild Photography Photography Wild Alex almost anywhere, even in temperate
regions provided central heating is A pharaoh ant drinks from a The pharaoh ant has an uneven present. The origin of the name droplet of spilled sugar water thorax and two petiole nodes. “pharaoh” is unknown.
Red imported fire ants (RIFA),
Solenopsis invicta, is native to South America, it has become a
pest in the southern United Coz The States, Australia, the Caribbean, Taiwan, Hong Kong, the southern Chinese provinces of Guangdong, Alex Wild Photography Photography Wild Alex Guangxi and Fujian, and Macau. Since the 1998 RIFA was
discovered in California in Orange, RIFA worker fire ant is shown in stereotypical defensive Los Angeles and Riverside A floating "raft" of RIFA in posture, her sting er extruded, counties. RIFA was found in North Carolina over land that waving a droplet of venom in several locations in Doña Ana normally forms the bank of a the air. (two nodes) County, New Mexico, in July 1998. pond. The land had become Both states have mounted a submerged due to excessive rigorous eradication program. rain and resultant flooding
Fire ants can bite their victims, which inundated the nest. but they are most famous for their painful sting. A RIFA stings by grasping its victim with its mandibles (jaws) and repeatedly jabs the stinger into the skin while pivoting around in a tiny circle.
The distinctive structure of fire ant mounds Young alate RIFA queen in the nest. help ants maintain the humidity and
temperature ideal for brood development.
Western Plant Diagnostic Network News
7 Lurking Invasive Ant Species
Dr. Martin Hauser, an entomologist and ant specialist at CDFA, reports on ant species that have been intercepted on the West Coast and have the potential of invading. The Asian needle ant, Brachyponera chinensis, has invaded the southern states and has been intercepted in houseplants. The electric ant, aka
little fire ant, Wasmannia auropunctata, is a terrible pest in Hawaii, making cats and dogs blind with their stings. In the Galápagos, it eats the hatchlings of tortoises and attacks the eyes and cloacae of the adult tortoises. It is considered to be perhaps the greatest ant species threat in the Pacific region. It has been intercepted several times in parcels from Hawaii.
Photography Wild Alex
The Asian needle ant, is an ecologically The electric ant or little fire ant, is
invasive pest species that displaces one of the world's worst pest ants. native ants in the eastern United States. Phytophthora and Nursery Plants
Species of Phytophthora /Fy-TOFF-thor-uh/ can devastate agricultural crops, nursery crops and forests. Phytophthora diseases are among the most serious problems affecting nursery crops nationwide. The name Phytophthora derives from Greek and literally means "plant destroyer. Phytophthora species resemble fungi but are not. They are an oomycete, with cell walls that are made of cellulose and glucans rather the chitin. The zoospores have two flagella for motility in a wet environment. While they are most closely related to aquatic organisms, such as brown algae and diatoms, they can also exist on land. However, Phytophthora organisms are often referred to as water molds because they need water to complete their life cycle.
Phytophthora species persist in the soil mainly as dormant resting spores (oospores, chlamydospores) or in a vegetative growing form within infected plant tissue.
When the soil is moist or wet reproductive structures (sporangia) are produce. These sporangia are filled with the infective spores of the
Cornell University Cornell fungus (zoospores), which are expelled into the soil in Western Plant Diagnostic Network News significant numbers only when it is completely saturated with water.
8
Phytophthora species are mostly pathogens of dicots, some are relatively host-specific, others have broad host ranges. Many species of Phytophthora are plant pathogens of considerable economic importance. Phytophthora infestans is the causal agent of potato late blight, the disease that caused the Great Irish Famine (1845–1849), and still remains the most destructive pathogen of solanaceous crops, including tomato and potato. The soybean root and stem rot agent, Phytophthora sojae, and Phytophthora cactorum have also caused longstanding problems for agriculture. In general, plant diseases caused by this genus are difficult to control, and fungicides, host resistance, and cultural practices are the main management strategies.
Below are a few key points from Drs. Tedmund Swiecki and Elizabeth Bernhardt of Phytosphere Research from their article Phytophthora in nursery stock and restoration plantings:
1. Phytophthora root rot can develop in susceptible hosts that receive comparatively brief periods of soil saturation, which can occur during normal irrigation or rainfall events. Constant wet conditions are not needed for disease development.
2. Inoculum can be produced and disseminated very rapidly under favorable conditions.
3. Infection occurs long before visible symptoms develop on the above ground parts of the plant. A lack of obvious host symptoms does not mean that plants are not diseased.
Nursery grown plants feature high root density within containers and close spacing of plants, providing near optimum conditions for disease spread and reproduction. Plant handling and frequent rearranging of containers further increase opportunities for pathogen spread. Because of the limited soil volume in containers, plants may be water stressed periodically if irrigation does not keep up with water use. Episodes of water stress or salt stress (also common in container grown plants) can make plants more
susceptible to Phytophthora infection.
MelodiePutnam 2007
Jennifer Parke
In a boxwood nursery, standing or splashing water encourages disease development.
Necrotic, discolored roots can been seen on these boxwood plants.
Western Plant Diagnostic Network News
9
Conditions favorable for infection and disease development commonly persist as long as plants are maintained in the nursery. Plants that are kept in the nursery longer have more chances of being contaminated and more time for reinfection and disease development.
The bottom line is that host and environmental factors in the nursery cannot be altered enough to prevent Phytophthora root diseases. Exclusion of the pathogen provides the only viable option for producing nursery plants that are free of Phytophthora. If the pathogen is not present, disease will not develop even if host and environmental conditions favor disease development.
Unfortunately, few nurseries have instituted all the extensive management practice changes needed to totally exclude Phytophthora. In fact, production practices common in many nurseries have provided many opportunities for contaminating nursery stock with Phytophthora. These practices include:
• use of non-pasteurized potting media • reuse of dirty containers, including those obtained from outside sources • placing containers on the ground • lack of sanitation practices in nursery production • bringing infected (commonly asymptomatic) plants from other sources into the nursery • using systemic fungicides that suppress Phytophthora symptoms but do not eliminate the pathogen
The artificial situation that exists within container nurseries was designed to grow as many plants in as small a space as possible, as quickly as possible. As an unintended consequence, nurseries are also highly favorable for the development and spread of various plant diseases, including Phytophthora root diseases.
See the UC IPM Pests management: Phytophthora Root and Crown Rot in the Garden Drs. John Bienapfl with USDA-APHIS, and Yilmaz Balci at the University of Maryland, studied the Movement of Phytophthora spp. in Maryland's Nursery Trade They surveyed 10 Maryland nurseries over a 3-year period to investigate the presence of Phytophthora spp. on newly arrived plants, mainly from West Coast suppliers. Local nursery plants, irrigation water, and potting media were also sampled for Phytophthora spp. Isolates were identified using a combination of morphological characteristics and DNA sequencing. Species identified included Phytophthora cactorum, P. cambivora , P. cinnamomi, P. citrophthora , P. drechsleri, P. elongata , P. gonapodyides , P. hydropathica , P. irrigata , P. lacustris, P. multivora , P. nicotianae , P. pini , P. plurivora and P. syringae . P.chlamydospora was also isolated from irrigation water. Table 2 on p. 4 of the article lists the Phytophthora species and the hosts they were found on.
A very informative site from Oregon State University is Phytophthora: Training for Nursery Growers. It is a course for nursery growers, nursery managers and field staff. The course consists of three modules with review questions after each. The entire course is 4 hours, and one can stop at any point to resume at any time.
Western Plant Diagnostic Network News
Phytophthora
10 Some New and Devastating Phytophthora Species
As detection methods advance, more Phytophthora species have been detected. Phytophthora ramorum, is the causal organism of sudden oak death (SOD). SOD was first discovered in California in 1995 when large numbers of tanoaks died mysteriously, and was described as a new species of Phytophthora in 2000. It was also found in nurseries in Europe in the early 1990’s and has subsequently been found in many other areas, including Britain, Germany, and some other U.S. states, either accidentally introduced in nursery stock, or already present undetected. P. ramorum also infects a great number of other plant species, significantly woody ornamentals such as Rhododendron, Viburnum, and Pieris, causing foliar symptoms known as ramorum dieback or ramorum blight. Such plants can act as a source of inoculum for new infections, with the pathogen-producing spores that can be transmitted by rain splash and rainwater. See the WPDN Summer 2013 News for more info.
Phytophthora tentaculata, was isolated in Germany in a nursery in 1993. It was found in Spain in 2001, in China in 2008, and in California native plant nurseries in sticky monkey flower, Diplacus aurantiacus (syn. Mimulus aurantiacus ) in 2012. Recent detections of plant pathogens in California native plant nurseries and restoration sites are raising concerns about forest pathogens being introduced from native plants out-planted from restoration nurseries.
Phytophthora hibernalis was formerly a disease of citrus, one of the many pathogens generally known as citrus brown rot of fruit. It was found on Rhododendron, variety “Rocket,” in 2002, while surveying for P.
ramorum. See the story and the methods at Phytophthora hibernalis, A New Pathogen on Rhododendron
USFS5 Region
Cheryl Blomquist CDFA CherylBlomquist
It’s easy to see how tanoak mortality from sudden oak Rhododendron ‘Rocket’ infected with death can have effects on the whole forest community. Phytophthora hibernalis from a Del Norte This photo was taken in Marin County, CA. County, California nursery.
See this brand new website, Phytophthoras in Native Habitats. Inadvertent planting of Phytophthora-infected nursery stock into native habitats has the potential to introduce these pathogens into wildlands. Furthermore, many of these Phytophthora species appear to have wide host ranges, capable of causing disease on plants across many families.
Western Plant Diagnostic Network News
Pests Updates 11
University of California researchers find vector for Red Blotch in grapes In the Fall 2013 WPDN News, pages 6 to 8, Dr. Mysore “Sudhi” Sudarshana, a plant virologist with the USDA-ARS at UC Davis, reported on a new virus disease of grapes, Grapevine red blotch-associated virus (GRBaV), popularly called “red blotch.” This virus disease was found in many vineyards and was a complete mystery – about the type of virus it is and if it had a vector or vectors, if any. Dr. Sudarshana, Dr. Frank Zalom, a UC Davis professor of Entomology, and their post-doctoral researcher, Dr. Brian Bahder, together confirmed that the three-cornered alfalfa treehopper (Spissistilus festinus) was able to transmit GRBaV to grapevines in greenhouse tests. The treehopper has been known to cause minor damage to grapevines by way of girdling young shoots and leaf petioles which may turn red. The discovery is the first confirmation of a vector for the virus. Mysore “Sudhi” Sudarshana and Dr. Zalom obtained a grant from Specialty Crops Research Initiative Block Grant to fund the project and worked together with several farm advisors and UC researchers, including Rhonda Smith, UCCE Sonoma County; Mike Anderson, Oakville station; and Lynn Wunderlich, UCCE Central Sierra, monitored and mapped vineyards where patterns of red blotch spread were evident. See their article in the Journal of Phytopathology: Spissistilus festinus as a vector of Grapevine re blotch-associated virus.
.
Three-cornered Bugguide.net alfalfa hopper, Spissistilus
festinus
Lynn Wunderlich Lynn
Lynn Wunderlich Lynn
Brian Bahder and Frank Zalom at a red blotch study site in Amador County. USDA-ARS virologist Mysore Western Plant Diagnostic Network News "Sudhi" Sudarshana