Following the observations that whitefly adults are readily caught on
yellow surfaces whitefly traps have been used for many years. Their use
was suggested both as monitoring and as controlling instruments, but no
standardization of either the necessary trap design and architecture,
or of the placement and the mathematical treatment of the trapping results
have been dealt with systematically. Nevertheless, traps are used for
the benefit of both researchers and applied entomologists in many countries.
Therefore, we decided to try and review the present situation and present
an overview of current trap use. We sent out questionnaires, of which
14 were answered (1 from India, 1 from Jordan, 1 from Switzerland, 3 from
Israel, and the rest from the USA). A summary of the results is given
herewith. We also added some comments of our own and listed the addresses
of the scientists to facilitate contact among them and to enable those
interested to contact them.
Except for two, colorless, or neutral traps, all were yellow. They applied
permanent sticky material (Tanglefoot or the like) except for groups in
India or Israel who applied vegetable or castor oil. Most traps were rectangular
or square and their size varied from 9x9 to 33xl8 or 30x30 cm. Cylindrical
traps of ca. 15x10 and flat, round traps with a diameter of 9cm were also
used for monitoring research. In three cases the traps were hung vertically,
in 9 they were placed horizontally (the rest did not specify). With two
exceptions (S. Naranjo and Dan Gerling) all traps were placed above ground,
usually about canopy height or higher. The traps were used either for
field research (to learn if whitefly levels could be determined with trap
counts instead of field counts and to study whitefly dispersal and movements),
for practical monitoring and registering movements of whiteflies, or for
pest control in the greenhouses. They were applied in cotton fields, vegetables,
and ornamentals. Each of these has different requirements which express
themselves particularly in the placement density, length of exposure times
and frequency of trap placements. Trap exposure times range from 2-3 hours
for research, to 1-7 days for monitoring whitefly presence. Traps for
control are replaced when they are full with insects, this may occur several
or even only one time per season. The main drawbacks mentioned were: that
traps may be expensive, the numbers of whiteflies caught represent the
true field situation only early in the season, particularly in the case
of insecticide treatments after which the trap-field relationship is poor.
Correlation between trap catches and whitefly levels in the field pertain
only to the particular situation, precluding the drawing of general conclusions
as to the meaning of different whitefly levels. In the greenhouses, the
use of traps both monitoring and controlling depends upon grower persistence
in examining and changing the traps, which may be a problem. At times,
natural enemies are also caught under these situations, and measures to
reduce this problem must be taken.
Comments:
Yellow traps are most efficient when placed horizontally on the ground
in full sun.
Numbers of whiteflies caught on the same trap diminishes rapidly with
rise in trap height. Therefore, it is not possible to compare the trapping
results of different stations, and each researcher establishes his own
standards empirically in order to obtain the best results. In the field,
ground-height placement of traps can result in a catch of many thousands
of whiteflies per day. Such quantities will eventually fill the trap
and bar the adherence of additional individuals that may arrive during
the next days. Therefore, ground-level traps should be places for short
durations only. The short duration means also that there is no need
for a long-lasting, weather resistant sticky material and a thin layer
of oil will serve the need quite adequately. Placing traps at plant
canopy height has other advantages since canopy level is the region
at which the whiteflies arrive when landing on the plants.
Price considerations are quite relevant, and high expenses were overcome
in, at least two ways. Using oils instead of expensive sticky material
both reduces the price of each application and facilitates reuse of
the traps following wiping off the old oil film and applying a new one.
A second approach is that of Berlinger, to use disposable plastic petri
dishes as the trapping surface. These are placed upon a yellow surface,
can be exchanged easily and reused numerous times at very low cost
The problem of trap reliability and its suitability for monitoring
of whitefly populations in the field has not yet been solved. Steve
Naranjo suggests to carry out comparisons of traps at multiple sites
and over many years. Only with a large body of such data will it be
possible to develop robust relationships between the catches of standardized
traps and the populations within the field. The findings of others that
the traps are mainly reliable as whitefly population indicators before
early in the season and before the first insecticide treatment, add
to the problem.
It is evident that, although traps are used to the benefit of the
grower and scientists, their utilization could gain from the exchange
of information standardization of the methods and better analysis of
larger samples.
Some questionnaires arrived too late to be included in the summary. We
thank you all for your participation.
Contributors
Experiments and monitoring > Dr. Steve Naranjo
Dispersal > Dr. D. N. Byrne
Monitoring > Dr. M. Ciomperlik, Dr. Eric Natwick, Dr. John Goolsby,
Dr. S. Cohen, Dr. B. V. Patil, Prof. Dan Gerling, M. J. Berlinger
Greenhouses > Dr. Marc E. Schmidt, Dr. Massimo Benuzzi, Dr. Volkmar
Hasse
Submitted by: Chang-chi Chu & Thomas J. Henneberry
USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ, USA.
The "CC Trap" was designed to capture whitefly (Bemisia
spp.) adults for survey, monitoring and sampling in the field and in the
greenhouse. The trap design was based on whitefly adult behavioral attraction
to yellow color, flight orientation to sky light when leaving host plants,
and walking to shade when landing on a new host for feeding and egg laying.
The trap does not use sticky materials or bait. It can be placed in greenhouses
or fields for extended periods of time without saturation catches of whitefly
adults. The trap does not catch other insects in large numbers and is
not affected by dust contamination. It is washable, reusable, inexpensive,
and easy to use. Whiteflies caught can be counted against a dark background
without the aid of a microscope. It may also be used for supplementary
adult whitefly control in greenhouses where parasites are released for
the control of whitefly nymphs (larvae). It did not catch Eretmocerus
spp. parasites. The trap can also be used as a research tool for studying
whitefly activity in the field.
Submitted by: Maria Regina Vilarinho de Oliveira. EMBRAPA.
Until the 80's Bemisia tabaci was not considered a problem in
Brazil, it attacked soybeans, cotton and beans (Gemini virus problem).
There was not much concern about this pest. Around 1991, an increase was
detected in the Bemisia populations in the State of Sao Paulo (where
we have many producers of ornamentals). Up to 1995 this included, poinsettia,
weeds, and Cucurbitaceae in general. There was also a problem in soybean
in the north part of the State of Paraná. From that period on we
can now find this pest in the majority of the Brazilian States attacking
mainly tomatoes, melons, watermelon and grapes. There is a serious risk
in the tomato production as geminivirus is spreading very quickly. We
have not yet calculated the economic loss due to this pest but I can tell
you that the situation in northeast of Brazil is very worrying as the
many large tomato companies are already thinking of leaving the area and
buying tomato production from Mexico. That's one of the reasons we decided
to have a meeting in Brazil in November to talk about this situation and
take some steps and begin using methods already developed elsewhere to
control this pest.
Submitted by: Paul De Barro. CSIRO Entomology Unit
Since the detection of the silverleaf whitefly (SLW) in October 1994
in Darwin, Northern Territory, the whitefly has spread throughout Queensland,
northern New South Wales, the Darwin region of the Northern Territory
and most recently to a single nursery in Western Australia where attempts
to eradicate it are having encouraging success. The whitefly has been
effectively distributed on poinsettia, duranta and hibiscus via the nursery
industry.
Nursery Industry > SLW is found
in many nurseries in the Northern Territory, Queensland and Northern
New South Wales. It tends to vary from nursery to nursery in the level
of damage caused and in individual nurseries will vary from season to
season depending on weather and the crops grown. Management varies,
but most successful management is based around the control of weeds,
removal of infested plants and judicious use of insecticide, with oil
sprays of various forms often providing better control than conventional
insecticides.
Horticulture > In the past
12 months the SLW has started to damage crops in the dry tropics region
of Queensland. In particular, melon, eggplant and okra crops in the
Burdekin/Bowen and Mt. Isa regions. Crops on which the whitefly can
be found are tomato, cabbage, melon, broccoli, capsicum, lettuce, silverbeet,
squash, zucchini and beans. In addition, backyard vegetables are being
attacked from Townsville down to Bundaberg. The damage ranges from severe
soiling to uneven ripening in tomatoes. The outbreaks in the Burdekin/Bowen
region were most likely precipitated by several growers deciding to
grow over the summer period, when in the past this was normally a crop
free period. At present there are few management options for growers.
In melons, there are no insecticides registered that are effective against
the SLW. In solanaceous crops, Confidor is registered for use against
aphids, but not whitefly. It is known that SLW in Australia already
has some tolerance to Confidor and that the rates used for aphids may
be below the dose required to kill heterozygotes. None of the other
novel insecticides are close to registration and resistance remains
a major concern.
Cotton > Unlike cotton grown
in parts of the USA, most of the Australian cotton growing regions do
not have continuous cropping of suitable hosts. SLW is found in all
the cotton growing regions. Numbers are very low, but a close watch
is being kept on the situation.
Research
The introduction of SLW to Australia has lead to the initiation of several
research programs by a number of different agencies. These are all funded
through the cotton and/or horticulture industries. The aim has been to
address those areas where immediate information is needed as well as commence
some strategic research. The various agencies involved interact on a regular
basis to ensure that overlaps do not occur so as to make the best use
of the limited funds available. Currently there is research on the identification
and biology of parasitoids, insecticide resistance, monitoring the numbers
of SLW in at risk areas, the distribution and identification of Geminiviruses,
and the ecology of SLW on commercial horticultural crops in the dry tropics.
Researchers, crop consultants and extension officers, growers and industry
are kept informed by the twice yearly distribution of the Whitefly Report.
CSIRO Entomology has several research projects. The major research program
is on assessing the potential of parasitoids currently in Australia to
control SLW. Australia has its own native biotype of Bemisia tabaci
which is genetically distinct from other known biotypes. Research to date
shows that it and the SLW are parasitized by several, possibly 10 different
species of Encarsia and 2, possibly more species of Eretmocerus.
The project is split into taxonomy and biology. The taxonomic study involves
the use of both morphological and molecular systematics being undertaken
side by side so that there is a direct link between the two. Of the parasitoids
found to date, 4 appear to show promise as control agents. The biologies
of these will be determined prior to field cage studies to assess their
potential. In addition, research into the biology of SLW and its interaction
with the Australian native Bemisia is being undertaken. Also, a
survey of the Pacific Islands for Bemisia tabaci is nearing completion.
SLW in cotton and horticulture regions are also being monitored.
Research into geminiviruses is being carried out by CSIRO Horticulture
in conjunction with the Queensland Department of Primary Industry. Here,
surveys for geminiviruses, especially the Australian tomato leaf curl
Gemini virus and development of virus resistant tomatoes is well under
way.
New South Wales Agriculture is measuring and monitoring insecticide resistance
levels in SLW to a range of conventional and novel insecticides as well
as monitoring SLW numbers in the New South Wales cotton growing regions.
Queensland Department of Primary industry is monitoring SLW in Queensland
cotton and is commencing research into the ecology of SLW on a range of
horticultural crops in the Burdekin/Bowen region.
Planned Research
A review of the current research into SLW, given the outbreaks in Queensland
is underway and a workshop in June is planned to help focus research directions
over the next 3 years.
CGIAR Whitefly IPM Project >
Submitted by: Pamela Anderson, Centro Internacional de Agricultura Tropical
- CIAT, Colombia.
The Consultative Group on International Agriculture (CG System) Whitefly
IPM Project has been approved and the project has been funded. The project
was described in the previous Bemisia Newsletter. We have been given
start-up funding of $1,200,000 for 2 years. It is being distributed
among 5 international centers, 6 advanced research institutions, and
26 regional/national programs (12 countries in Latin America and 10
countries in Africa).
Course on Whiteflies and their Natural Enemies
>
Submitted by: The Training Officer, International Institute of Entomology.
United Kingdom.
A short intensive course to impart knowledge and skills to facilitate
identification of whiteflies and their natural enemies and the use of
natural enemies in biological control was held 23- 26 September 1997,
at the International Institute of Entomology, London. For more information
contact:
Pest Management Resource Centre >
Submitted by: Peter McEwen. School of Pure & Applied Biology, University
of Wales, United Kingdom.
The Pest Management Resource Centre (PMRC) has moved to: http://www.pestmanagement.co.uk,
and includes a number of new and expanded features. Please take a look,
link your sites, and send your comments. Ideas for new resources, URLs
to connect to, etc, should be sent.
International Workshop on the Silverleaf
Whitefly, Bemisia argentifolii Submitted by: Dra. Luzia Helena Corrêa Lima. EMBRAPA/CENARGEN.
Brasil. The International Workshop on the Silverleaf Whitefly, Bemisia
argentifolii (ENCONTRO INTERNACIONAL SOBRE A MOSCA BLANCA, I) was
held November 4-6, 1997 at the auditorium of EMBRAPA in Brasilia, DF.
Invited speakers from around the world presented research and management
tactics conducted in their respective regions of the world. Objectives
were to hear about methods of prevention and control being conducted
in other affected countries, develop a national program involving diverse
organizations in Brazil, and to develop and distribute written technical
assistance on various methods to control the pest. Collaborative projects
were also developed. Attendees from Brazil and neighboring countries
included government and university researchers, extension personnel,
growers and marketers, and students. Several workshops were conducted.
Annual USA Bemisia Meeting > A new USA 5-year plan was devised in San Diego, California last year.
The First Annual Progress Review of the 5-Year Silverleaf Whitefly Research,
Action and Technology Transfer Plan will take place in South Carolina.
This meeting of Bemisia workers from across North America, will
be the first to report progress on research, action and technology transfer
activities under the new plan. Similar meetings have been conducted for
the previous five years under the original plan. The upcoming gathering
will be held February 3-5, 1998, at the Francis Marion Hotel in Charleston,
South Carolina, USA. As in previous years, abstracts from this meeting
will be published.
2nd International Workshop on Bemisia and Gemini
viral Diseases >
At the 1st International Bemisia Workshop held in Israel in 1994,
it was unanimously decided that a 2nd workshop should be held in 3 to
4 years. The 2nd International Workshop on Bemisia and Gemini viral
Diseases will be jointly sponsored by the International Bemisia
Working Group and the International Geminiviruses and their Vectors Working
Group, and is planned for June 7-12, 1998 in San Juan, Puerto Rico. Attendance
at this meeting is expected to be 250 to 300 participants. There are a
limited number of rooms available at the San Juan Marriott at a special
meeting rate of $110/night double occupancy. Interested parties are encouraged
to make their reservations as soon as possible. Although a program has
been planned, additional topics can be suggested to Dr. Menachem Berlinger
in Israel. There will be opportunities for specialty meetings and these
should be coordinated through Mrs. Deanna Guy in Orlando, Florida. The
organizing committee is trying to obtain institutional and private funding
to assist with supporting the meeting and assisting with travel costs
for participants and invited speakers. Anyone wanting to make a contribution
to the workshop should do so through the International Bemisia Working
Group, in care of Richard T. Mayer in Orlando, Florida. Donations (in
US$) are tax deductible and a receipt will be issued upon request.
The Center for Strategic Agribusiness Information, dependent from the
Universidad de Chile (Chile, South America), social objective is to assist
producers in their decisions, is looking for an expert in whitefly (Bemisia
tabaci) at the request of a tomato producing company in Chile. The
company is offering a consultantship in Perú for the control of
Bemisia tabaci in tomatoes. Please send us your references, honoraries
and possible date for the travel. Submitted by: Lucía Aravena M.,
Agronomist
The following URLs are just a sampling. Most contain additional links
to more information. If there are important web pages missed, please notify
Walker Jones at the address at the back of this newsletter. The following
sites are linked on the Web version of this Bemisia Newsletter
at:
If you have e-mail access, you can send and receive information among
a large group of whitefly workers by joining the Whitefly Listserver.
To automatically join, send a message with no Subject to:
