B.C. Pest Monitor — Former Newsletter of IPM in British Columbia
Vol. 4 No. 1 June 1995
Garry Oak Pest Update: Jumping Gall Wasps and Oak Leaf Phylloxera
The following article was compiled from research summaries provided by Dr. Bob Duncan, Canadian Forest Service, Victoria, B.C.
 During the past several years, the Garry oak trees of Vancouver Island and the Gulf Islands have been under attack, once again, by introduced pests. In the early 1980's the oaks were infested by the winter moth, which is now largely kept in check by introduced parasitic insects and by native predators, such as ground beetles. This time the problem species are a tiny gall wasp (Neuroterus saltatorius) and a phylloxeran (Phylloxera nr. glabra), which is a tiny aphid-like insect.
Jumping Gall Wasps
Jumping gall wasps are native to the western states, but were not known in B.C. before they were found in Victoria in 1986. They have spread considerably in the last 9 years and are now found attacking Garry oak in much of the Capital Regional District. They have recently spread northward to Nanaimo and onto Saltspring Island.
Leaves attacked by the jumping gall wasp appear scorched along the edges and have large numbers of small (1 to 2 mm), round, cream-coloured galls attached to the lower surface. These galls mature in June and July, then drop to the ground, where they appear to "jump" for several weeks before burying themselves in the soil. Movement of the tiny larvae within the galls causes them to jump (sometimes surprisingly high) and produces a soft, swishing sound similar to a light rain shower. The larvae remain in the gall to pupate in the fall. The dark brown adult wasps (1-2 mm long) emerge in March-April to lay eggs in the expanding oak buds. Blister galls of the first generation develop on newly expanded leaves. Within a month the next generation of adults emerges to lay eggs on the lower surface of oak leaves. Feeding by the larvae that hatch from these eggs induces the leaves to form galls, which provide shelter and food for the developing larvae.
Damage to most oak trees is limited to scorching of foliage, although some trees turn brown completely and drop their leaves early. Some of these trees produce a second growth of leaves. Although heavily affected trees may be less vigorous, at this time no trees are expected to die from the long-term infestation. Hope is at hand for the future, as eight species of parasitic wasps have been found to be established in the gall wasp population. There was a general reduction in gall wasp damage in 1993 and 1994 in areas where the gall wasp had been established the longest. This was due to a combination of factors, including parasites, predators, diseases and the failure of galls to develop completely. The level of parasitism in the summer generation of wasps average 9.6% in 1993 and 15.3% in 1994. Surprisingly, for those people that dislike earwigs, they, along with other predators, accounted for significant mortality of the gall wasps. Researchers looking for differences in susceptibility found that Garry oak seedlings from Vancouver Island are more susceptible to jumping gall wasp damage than seedlings of California origin.
Oak Leaf Phylloxeran
Oak phylloxera are believed to have been come from Europe and have been present in the Victoria area since the early 1960's. They didn't seem to be perceived as a problem by the public, however, until the jumping gall wasp damage started to occur. The small, pear-shaped insect is 1 mm long and an orangeish yellow colour. It feeds by sucking the plant sap. Like its aphid relatives, phylloxera have several generations per year.
The phylloxera mainly attack Garry oak and English Oak. They are distributed throughout the entire range of Garry oak in B.C., including the Greater Victoria area, the east coast of Vancouver Island north to Comox, the Gulf Islands and Sumas Mountains in the Fraser River Valley. About 10% of trees in the area are currently being attacked, but over the last 8 years there has only been a slight increase the number of trees attacked.
 The damage is first visible as yellow spots on the leaves in May and June. This gradually progresses to complete browning and defoliation of some trees by late July. By late July or early August heavily affected trees lose their leaves. Often the trees produce a second flush of leaves in August. Most trees with phylloxera seem to have light infestations without damage, while a few trees are heavily attacked, year after year, becoming severely weakened. Many infested trees are cut down by the owners, but for the first time in 1993, chronically attacked trees were found to have died from phylloxera infestations. It is likely that all heavily attacked trees will eventually die.
At least 10 species of predators have been recorded feeding on the phylloxeran, but they do not appear to control it. In Europe, the phylloxeran is a minor pest, causing discoloration to some trees in some years. This means there may be some hope that European predators can be introduced to eventually suppress the phylloxeran numbers. A new predator, the lady beetle Harmonia axyridis has been released experimentally, but it is too early to tell whether it will become established and have an impact on the pest population. There is also another species of ladybird beetle and a lacewing that control the phylloxeran in Europe that may be effective if introduced.
Research and Prognosis
The high public profile of the damage to native oaks by both pests stimulated the formation of a Garry Oak Steering Committee in 1991 to advise and assist in research and surveys on these two pests. The committee has representatives from the Municipalities of Saanich, Victoria, Oak Bay and Esquimalt, the Capital Regional District, University of Victoria, Canadian Forest Service, Royal B.C. Museum as well as professional arborists and public interest groups. The municipalities, CRD and Canadian Forest Service have jointly funded annual surveys and research projects, including the work conducted by two University of Victoria graduate students from 1992-95. These studies have led to a better understanding of the complex of predators, parasites and other factors that reduce the pest populations. They have clarified the biology of the pests, their distribution pattern and the genetic basis for differences in the attack by phylloxera.
The prognosis for gall wasp damage is that it is expected to continue to decline in areas where the wasps have been established the longest. The populations of native parasites are expected to continue to increase, although damage will continue to get worse along the expanding front of the infestations before it improves. For the oak leaf phylloxeran, it is expected that the 10% of trees that are genetically susceptible to attack will eventually die from continuous defoliation. The native predators do not seem to be controlling this species and it is too early to tell whether introducing predators from Asia or Europe will provide effective control.
Biological Control of Aphids in Vancouver City Trees
Dr. Debbie Henderson, E.S. Cropconsult, Ltd. Vancouver, B.C.
A research project was carried out last year from May to September to try to control aphids on boulevard trees in three different Vancouver neighbourhoods. Approximately 400 households were involved in a project initiated by the City of Vancouver in response to complaints about honeydew. Honeydew is a sticky substance excreted by aphids as they feed on plant sap. It leaves a sticky residue on sidewalks and cars parked beneath city trees. The objective of the project was to determine if there was a non-toxic or biological way to control aphids and thereby reduce property damage from honeydew. The City wanted to find alternatives to chemical controls that did not involve removing aphid affected trees.
Two methods were tested in 1994:
1. Encasing tree trunks with plastic bands covered with a thin layer of Tanglefoot, which is a sticky glue for trapping insects.
2. Releasing a commercially produced native aphid predator, Aphidoletes aphidimyza, into trees.
The sticky bands were tested because they stop ants from climbing the tree trunks. Ants collect the sweet honeydew and protect aphids by removing predators from the aphid colony. It was hoped that controlling the ants would allow natural enemies to control the aphids.
Plastic clipboards were laid on the ground under the trees to collect honeydew dropping from trees. Each week during the summer, the amount of honeydew was monitored. Trees were also periodically sampled for aphids. Neighbourhood residents assisted by preventing passersby from vandalizing the tree bands or removing clipboards.
Early results showed that aphid numbers and honeydew quantity appeared to be lower in the areas where the Aphidoletes were released. The sticky bands seemed to have little or no effect. Insects other than aphids (such as scale insects) may have been contributing to the honeydew deposit. More work is needed to assess this method of controlling aphids and a similar project will continue in 1995 through the City of Vancouver.
Cooperators on the project were: E.S. Cropconsult, Ltd., Applied Bio-Nomics, Ltd., The City of Vancouver and the federal Pest Management Alternatives Office.
Ladybug, Ladybug, Don't Fly Away Home!
Dr. Linda A. Gilkeson BC Environment, Victoria, B.C.
When people think of ladybird beetles, it is usually the familiar orange "ladybug" with black spots that springs to mind. There are, however, many other beetles in the lady beetle family or Coccinellidae, that are native to B.C. Many species are bright orange or yellow with black spots or marks, but others range in colour from the all-black spider mite destroyers (Stethorus species) to the common, ash-grey lady beetles. The common names are often a clue to the pattern of the spots, such as nine-spotted lady beetle, five-spotted lady beetle, three-banded lady beetle, parenthesis lady beetle and others equally descriptive. There are about 400 species in North America, and many of these are native to B.C. Generally, lady beetles are shiny, round or oval in shape, with short legs and very short antennae. They fly, albeit awkwardly, by lifting the rigid wingcovers on their backs and extending the pair of transparent, cellophane-like wings folded underneath.
In the fall, the adult beetles creep into the leaf litter or under garden debris to spend the winter. After feeding for a short period in the spring, they start to lay their eggs. The female lays oval white or yellow eggs, usually in upright clusters of a dozen or more on the undersides of leaves. The eggs hatch in 3-5 days. If there is no other prey immediately available, the first larvae to emerge may eat the other eggs. The larvae look nothing like beetles as they are soft, wingless and elongated. They look a bit like miniature brown, purplish and black-mottled alligators. Some species have a few, short spines while others are quite spiny. They feed on insects or mites for 2 to 3 weeks, then fasten themselves to a twig or a protected leaf to pupate. After a pupation period of a week to 10 days, the adult splits open the pupa case and emerges.
Some species of lady beetles are limited in their tastes, but most feed on small, soft insects, especially aphids, eggs and small larvae of other insects. Several native species are spider mite predators. Both adults and larvae are predators. The adults also feed on pollen, especially when prey is scarce. Lady beetles are excellent predators, especially good at quickly reducing a high aphid population because they are so voracious. Other natural enemies of aphids (such as aphid midges or the many species of parasitic wasps) are better at controlling low levels of aphids. Some aphids escape being eaten by lady beetles because the relatively large, clumsy beetles accidentally knock the aphids off of the leaf as they blunder through crowded aphid colonies.
The convergent lady beetle (Hippodamia convergens), is collected from the wild in the Sierra mountains of California and sold commercially in garden centres or by mail order. Harvesting these wild insects may be depleting their numbers and some conservation groups are against the practice. For a home garden, these beetles can be a waste of money because they fly away as soon as they are released outdoors. Some people try to prevent them from leaving by coating the beetles with 7UP soda to glue their wings down. This doesn't hurt the beetles (it is probably even be good for them to have a quick meal of liquid and sugar), but this has not been shown to keep them from dispersing as soon as they get their wings unstuck. A recently published University of California study (Flint, et al., 1995), found that most ladybeetles left aphid infested plants within 24 hours of release, regardless of how they were treated to prevent them from leaving. The few beetles, however, that stayed on plants for several days did significantly reduce the aphid numbers. In a University of Maryland study (Raupp, et al., 1994), researchers found that lady beetles released on aphid infested firethorn plants in greenhouses quickly left the plants. Beetles released outdoors on Russian olive,however, flew up into the tree canopy and were still present 15 days later, having significantly reduced the aphid numbers. The beetles showed distinct preferences between species of aphids and there were other complex factors involved in whether or not they dispersed. Clearly more research is needed before we know whether, or under what conditions, releasing collected lady beetles is worth while in landcapes.
For the home gardener, conserving and attracting the many native lady beetles is likely the most effective and economical course. Ladybeetles (and a myriad of other aphid predators) quickly show up when there is an aphid outbreak in home gardens. The first step in conserving them is to learn to recognize lady beetles and their various life stages so that they aren't mistaken for pests. Avoid using pesticides in the garden or use only the least-toxic products. The University of Maryland study found that dried, weathered residues of malathion and carbaryl on leaves still killed newly-released lady beetles up to 2 weeks after the sprays were applied. In contrast, insecticidal soap and horticultural oils had no effect on beetles 1 hours after spraying and residues of a pyrethrins mixture had no effect after 1 day. Gardeners may also want to plant flowers to provide a source of pollen to attract and supplement the diet of adult beetles. Calendula, daisies, aster and other composites supply pollen, while dill, parsley (in flower), alyssum, and many herbs supply pollen and nectar. Allowing a few weeds to remain in the borders, such as dandelions, yarrow and wild carrot also provides them with food.
IPM in BC Agriculture
Since 1991, the Pesticide Management Section has been tallying the total acreage ofagricultural crops in the province monitored by IPM consultants (see Table). In 1991 there were 6 services operating (2 in the Okanagan Valley, 3 on the Lower Mainland and 1 on Vancouver Island). These numbers remain the same in 1994, although one service had gone out of business and a new one had begun. There was more than a 50% increase in acreage between 1991 (a total of 2262 ha) and 1993 (a total of 3440 ha). The overall area decreased by about 7% in 1994, largely due to the end of research projects for monitoring pear and raspberry acreages, which had been included in previous year's figures. A greater variety of crops were monitored in 1994 than in previous years. New crops include grapes, ginseng, Christmas trees and a variety of field vegetables (tomatoes, peppers, celery and beans). Also, for the first time, 96 hectares of seed potatoes were grown under an IPM program. For more information on agricultural IPM in the province see the following reports:
Agricultural Crops Grown Under Integrated Pest Management Programs in British Columbia: 1991
Integrated Pest Management Programs in British Columbia Agriculture:1993
Both reports available from:
Pesticide Management Section, 2nd Floor, 777 Broughton St.,
Victoria, B.C., V8V 1X4 Fax: 387-8897
Table of B.C. Agricultural crops and area monitored by IPM consultants: 1991-94 (in acres).
Update File
Integrated Pest Management Information System
BC Environment's IPM Information System (IPMIS) on the Internet continues to expand. Over the winter, with the help of funding from Environment Canada and Agriculture and Agri-foods Canada, four IPM consultant companies in B.C. compiled information to be entered into the database. Subjects included apples and tree fruit, field and greenhouse vegetables, berries, landscapes, biological control and other pest management subjects. Abstracts and bibliographic information were entered for the copyrighted materials. References that are in the public domain and that can be carried in full, on-line were kept aside. They will be entered starting in June, when the enhanced version of IPMIS will be ready to handle pictures and book-length text files. The Branch has purchased a scanner and the work on the new version of the system has been completed, although testing continues. This summer, with the assistance of funding from Agriculture and Agri-foods Canada, we will start scanning in insect identification sheets and reclaiming other useful and out-of-print information.
PMAO Closes
After two years of operation, the national Pest Management Alternatives Office closed its doors on March 31, 1995. Funding is being reallocated to the new Pest Management Regulatory Agency to deliver the program for the Alternatives Office within that organization (see below). At the time of closing, 44 research projects funded by the PMAO were expecting a second year of funding. As many of these as possible are receiving funding to complete work in progress. Copies of reports and other documents generated by the PMAO continue to be available from:
Coordination Directorate, Research Branch, Agriculture and Agri-Food Canada Tel: 613-995-7084 Fax: 613-947-0334.
New Pest Management Regulatory Agency
As of April 1, 1995, the responsibilities and resources for pest management regulation at the federal level were consolidated into one agency. The new Pest Management Regulatory Agency is entirely under one ministry, Health Canada. It is now in a transition period, with interim Director General, Dr. Sol Gunner, overseeing the process. A more efficient pesticide registration process is expected to be developed as a result of the changes. All staff that were previously responsible for pesticide product management from Agriculture Canada and for submission evaluation from Health Canada and Environment Canada will now report to one person in the new agency. For additional information on the new agency, contact:
Pest Management Regulatory Agency, Tenth Floor, 473 Albert Street, Ottawa, Ont. K1A 0C5 Tel: 613-991-0216 Fax.: 613-991-0231.
New Products
Products are listed for reader information only. This does not constitute an endorsement of either quality or effectiveness by B.C. Environment.
Weed Wrencher
 A weed removing tool highly recommended by Dr. Sheila Daar at the recent IPM Conference in Kelowna is the Weed WrenchTM. It is a manually operated, all-steel tool with a long lever. It has jaws that grips the stem of a plant so that it can be easily uprooted. This minimizes disturbance to the soil and to desirable plants nearby. The wrench was particularly designed for pulling out scotch broom, gorse, and other plants where uprooting is an end to that plant. It can be used for clearing established blackberry thickets as well, although follow-up work will be needed as underground runners send up new shoots.
The tool comes in 4 sizes, from heavy duty (US$140, shipping additional) to the 'mini' for smaller plants (US$50), which can even be used by children. The 'medium' size (US$110) can be handled by anyone of ordinary strength, while the weight of the heavier model makes it a tool for stronger people. The supplier encourages prospective buyers to contact them to make sure that the tool is the right one for the vegetation they plan to control.
Available from: New Tribe, 5517 Riverbanks Road, Grants Pass, Oregon 97527 Tel. & Fax: (503)-476-9492.
Hot Water Vegetation Control Systems
People attending the IPM conference in Kelowna in March had the opportunity to see a demonstration of the Waipuna System hot-water weed control technology from New Zealand. The system consists of computer controlled boilers and a pump that dispenses hot water through application heads. The operator applies the hot water through a long wand with a roller head attachment that is easy to slide back and forth over pavement, soil and other surfaces. The application heads come in various widths from 3 inches wide upwards. The company leases the equipment, provides training and maintains the equipment and has recently appointed a distributor in the Lower Mainland. For information contact:
Ron Murphy, Waipuna B.C., Tel: 604-731-4971, Fax: 604-732-1745.
The Aqua Heat Jr., a hot water vegetation control machine from Minnesota, has recently become available in B.C. The hot water is applied through booms or insulated hand-held sprayers, which can be individually designed for various applications. The unit is self-contained, with a 9 HP gas engine and a diesel fuel burner to heat the water. It comes on a 3'x4' skid that can be mounted on a tractor, trailer or other vehicle. The cost of the system is in the $20,000 range, depending on how the application head is configured.
Distributed by: Kerry Doyle, Joonas Agritech, 3046 McMillan Road, Abbotsford, B.C. V2S 6A5.
Net Resources
New Urban IPM On-line Service
The Integrated Pest Management Practitioners Association in Eugene, Oregon has developed an interactive, on-line computer service called IPM Access. This will be of interest for anyone working on urban, structural, rights-of-way and residential IPM programs. The service offers both newsgroups and information files to give IPM practitioners and interested people the opportunity to share information. Contributions from members through the forums will help update the information in the databases. The use of the system is free, however, a recommended donation of US$25 per year is requested to help defray costs. It is available through the Internet (WWW or telnet) or through direct dial-up.
World Wide Web address: http://www.ipmaccess.com/
For more information and to subscribe: I.P.M.P.A., P.O. BOX 10313, Eugene, Oregon 97440 E-mail: ipmpa@efn.org Tel: 503-345-2272.
National IPM Network (USA)
The National IPM Network in the US is a system of four information servers located in different parts of the country. They are linked to make up the network and can be reached through the Internet World Wide Web. There is a lot of information available on the different servers, primarily agricultural and horticultural IPM and also some home gardening information.
World Wide Web address: http://www.ipmcenters.org/
Publications
Safe and Sensible Pest Control. 1992 - 1994
By. L. Gilkeson
This is a series of brochures developed by BC Environment to encourage the use of safe, practical alternatives to the overuse of pesticide against common pests of home and garden. Titles available:
Aphids, Bats, Beneficial Insects, Carpenter Ants, Caterpillars, Fleas, Household Insects, Rats and Mice, Lawn and Yard Weeds, Yellowjackets
|
