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Distribution of Scirtothrips Dorsalis in the Carribbean Region and the Development of Chemical and Biological Methods to Manage this Pest

Seal, Dakshina
University of Florida
Start date
End date
  1. Determine distribution of S. dorsalis in different countries in Caribbean Region.
  2. Determine an efficient but accurate method of trapping S. dorsalis.
  3. Develop sampling method for each host crop depending on the distribution of S. dorsalis and identify feeding and reproductive status on those hosts.
  4. Develop a control method using conventional insecticides labeled for use on fruits, ornamentals and vegetable. The efficacy of some bio-rational insecticides, such as neem, neem oil, garlic barrier and hot pepper wax, will also be evaluated in various crop systems.
  5. Various native biological agents will be identified in each country of Caribbean Basin. Their potentiality will be assessed in the laboratory condition. The efficient biocontrol agent will be mass reared for inundated release at the beginning of S. dorsalis infestation.
  6. Gain the goodwill and cooperation of agricultural personnel in each country, present talks and poster on S. dorsalis damage and train them with necessary knowledge on pest management to continue further studies on sampling, insecticide evaluation and biocontrol.
  7. Disseminate information to research, extension and regulatory personnel, and also to growers in Florida and Caribbean countries. Report progress at the annual meetings of the Florida Entomological Society and the Caribbean Food Crops Society. Attempts will be made to facilitate adoption of this proven control technologies in the management of fruits, ornamental and vegetable production system.
  8. Two manuscripts will be published in refereed journals on the distribution, bionomics and management of S. dorsalis in the Western Hemisphere.
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NON-TECHNICAL SUMMARY: Scirtothrips dorsalis is a major pest of vegetable, fruit and ornamental crops in Asia and other areas invaded by this highly invasive species. It has become established on several Caribbean islands and threatens to enter the USA through shipments of peppers, etc. Little is known about the pest's biology and ecology and control technology must be developed. This investigation will seek to (1) determine the distribution of S. dorsalis in different countries of the Caribbean Region, (2) develop an efficient but accurate method of detection and trapping, (3) develop an optimal sampling method for the pest on each host plant, (4) develop methods of control including use of conventional and bio-rational insecticides already labeled for use on fruits, ornamentals and vegetables, (5) identify native biological agents attacking the pest in each country of Caribbean Basin, and assess approaches for increasing their effectiveness, (6) train scientific personnel and growers appropriately, and (7) disseminate information to research, extension and regulatory personnel, and to growers in Florida and Caribbean countries.

APPROACH: To determine the pest's geographical distribution the Ministry of Agriculture of each Caribbean country or Territory will be contacted for permission to conduct a survey for S. dorsalis, or to assist qualified personnel in a given country to carry out the survey. In each country a group of people will be trained to collect and identify S. dorsalis, and prepare specimens for microscopic examination. This group will also receive preliminary training on chemical control, biological control and disinfestations of commodities to be exported. Determination host distribution will be informed by previous studies conducted by various researchers in Asia. This knowledge will be used to identify those hosts in various countries of Caribbean Basin. A standard trapping method will be developed, which can be used by others in different locations. Initially yellow sticky cards will be used to trap and monitor S. dorsalis presence and population densities. Other types of traps will be evaluated. Improved sampling methods will be developed to augment direct relative sampling, which entails the collection of parts of plants assess the presence of this insect on host plants. This may provide information on the feeding and reproductive behavior of S. dorsalis on that species of plant. In order to manage S. dorsalis, chemical control will be developed using approaches successfully developed against Thrips palmi. A list of candidate insecticides has been prepared. Also the use of a number of the less harsh biorational chemicals will be developed. The use of biocontrol agents will be investigated. A number of potentially effective predators have already been identified, and their effectiveness in the field will be assessed. These objectives will be conducted in close cooperation with CARDI scientists and personnel from Ministry of Agriculture in each country, especially St. Vincent and the Grenadines and St. Lucia, where most of the work on chemical, biorational cultural and biological control will be conducted. Every year, one meeting will be organized in one Caribbean country to share data with various stakeholders including the Caribbean Community Secretariat (CARICOM), USDA-APHIS and the Department of Homeland Security. Sessions may be organized at the annual meetings of the Caribbean Food Crops Society and the Florida Entomological Society. Information will also be disseminated through Pest Alert and EDIS. Data on various studies will be published as peer-reviewed articles. In collaboration with f Cooperative Agricultural Pest Survey, we will organize an active surveillance program to detect the pest in south Florida

PROGRESS: 2005/09 TO 2008/09
OUTPUTS: Life table and other parameters of the chilli thrips, Scirtothrips dorsalis were studied in a greenhouse at Homestead, Florida. Mean numbers of larvae per plant were significantly higher on pepper and on the rose cultivar, Knockout, than on bean, eggplant, squash and tomato. Mean numbers of pupae were also higher on pepper and Knockout rose than on these other hosts. Adult S. dorsalis were abundant on pepper and rose and less so on eggplant, and absent on bean, squash and tomato. Larval duration was longer than pupal duration irrespective of the host plant. The duration of the immature stages varied within a narrow range on all host crops. The sizes of all of the developmental stages of S. dorsalis were quite similar on all host plants. The preoviposition period on pepper (3.60 d) was the same as on rose. The oviposition period on rose 13.20 d) was longer than on pepper (12.60 d). The longevities of both males and females were greater on pepper than on rose. The net reproduction rate (Ro) was higher on pepper (11.50) than on rose (9.47). The innate capacity for natural increase (rm) and the mean duration of a generation (T) of S. dorsalis did not differ between those reared on pepper or on rose. The population density was highest during March through June with a peak in April and lowest during January and February. Adults were most active during 10.00 - 04.00 EST. Females oviposited most eggs during 10.00 - 04.00 EST. On `Jalapeno' pepper plants BotaniGard ES (Beauveria bassiana) at 0.5 l/100 l at weekly intervals significantly reduced mean numbers of S. dorsalis adults and larvae. TriCon (a blend of borax, orange oil and biodegradable surfactants) at 391 ml/100 l also reduced S. dorsalis populations on pepper and cotton. Metarhizium anisopliae (green muscardine fungus) at 227 ml/100 l effectively reduced S. dorsalis adults on cotton. All treatments of M. anisopliae and B. bassiana significantly reduced populations of chilli thrips larvae, and were comparable to spinosad (Spintor), which provides excellent control of S. dorsalis larvae. Imidacloprid provided significant reduction of S.dorsalis when applied as Admire as a soil drench or when applied as Provado to the foliage. Thiamethoxam (Actara) was more effective when used as a foliar application than when applied as a soil drench as Platinum. Foliar application of dinotefuran (Venom) provided significant reduction of S. dorsalis on pepper. Acetamiprid (Assail) applied to the foliage of pepper plants did not provide significant reduction of S. dorsalis in the present study. The spinosyns, spinosad (SpinTor) and spinetoram (Radiant), when applied to the foliage were highly effective against S. dorsalis larvae and adults. Neither adult nor larval populations were substantially suppressed by any of the following pyrethroids: cyfluthrin (Baythroid), zeta-cypermethrin (Mustang), cyhalothrin-lambda (Warrior), and esfenvalerate (Asana XL). In 2008 S. dorsalis was found in the Greater Caribbean Region in Barbados, Florida, Jamaica, Puerto Rico, Texas, Trinidad & Tobago, St. Lucia, St. Vincent, Venezuela and Suriname, but not in the French West Indies, Guyana, Hispaniola and Costa Rica.
PARTICIPANTS: Dr. Matt A. Ciomperlik, Entomologist, USDA,APHIS,PPQ, Pest Detection Diagnostics and Management Laboratory, Moore Air Base, Edinburg, TX was very helpful in conducting studies on St. Vincent, and in conducting surveys for the chilli thrips in Barbados, Guyana and Suriname. Dr. Ciomperlik also surveyed the infestations found in the Rio Grand Valley and at Houston, TX. Dr. Lance S. Osborne, Mid-Florida Research & Education Center, Apopka, FL, Dr. Amanda Hodges, Entomology and Nematology Department, University of Florida, Gainesville, FL took the lead in educating county agents and growers in Florida and in assembling host records. Dr. Adam Silagyi, Cooperative Agricultural Pest Surveys, supervised surveys for S. dorsalis in Florida. Authoritative taxonomic determinations were provided by Dr. G. B. Edwards, Florida Department of Agriculture and Consumer Services.
TARGET AUDIENCES: The target audiences include professional entomologists in educational, research and regulatory agencies and in private firms which supply advisory services or chemical and biological controls to growers. Since in Florida, the pest is particularly troublesome on landscape plants in urban settings, master gardners, county agents and employees of parks departments need to become familiar with S. dorsalis and how to cope with it.
PROJECT MODIFICATIONS: Since we received funding only for the first two years of this study, we had to curtail travel in the Caribbean Region to determine the current geographic distribution of the pests and how damage by the pest is manifested in different geographical settings. In addition we were unable to pursue much of the planned research on biological controlof S. dorsalis.

IMPACT: 2005/09 TO 2008/09
Information obtained on life table and demographic parameters and on daily activity patterns of the pest provides the foundation for understanding the capacity of the pest to rapidly build large large populations on hosts such as cotton, peanut, pepper, and ornamentals such as lisianthus. On the otherhand it is not clear why the pest is not yet destructive on tropical fruits in Puerto Rico but not in Florida. The pest's flight activity during the windiest hours of the day facilitates it dispersal by wind. A number of nicotinoid and spinosyn insecticides that are highly effective in suppressing chilli thrips populations have been identified. None of the pyrethroid insecticides investigated provided effective control of this pest. The entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae proved to be effective in suppressing the pest, as did Tricon, a mixture of natural products.This information has significant bearing on the efforts of the fruit, ornamental and vegetable industries to protect their crops from damage by S. dorsalis infestations. Moreover, this information will enable growers to use neonicotinoid insecticides more selectively to avoid the decimation of populations of natural enemies.

Funding Source
Nat'l. Inst. of Food and Agriculture
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Chemical Contaminants