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Project News 06.2004

A new whitefly species emerges as
a pest of cereals in Central America

All available newsletters > | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 |

  • Whitefly Trap Survey Results
  • Development of a new whitefly trap
  • Bemisia in Brazil
  • Bemisia in Australia
  • Projects and Courses
  • Recent meetings, workshops, etc.
  • Upcoming meetings
  • Opportunities
  • Websites of interest
  • Whitefly Listserver


Summary by Dan Gerling

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:

listserv@listserv.tamu.edu

In the body, type subscribe. To get off the network, type the message unsubscribe to the same address above.

After getting subscribed, messages to the group must be sent to a different address:

whitefly-l@tamu.edu

For friendly help, contact Reyes Garcia III, Whitefly Net Administrator

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