Progress 10/01/99 to 09/30/04
Outputs
We studied the toxicity of pesticides to adult Diaprepes abbreviatus L. Weevils were exposed to field rates of pesticide-treated bouquets of fully-expanded, mature citrus leaves. At a field rate, only Supracide was effective producing 100% mortality within 24 h after exposure. Field rates of Avaunt, Baythroid, Capture, Furdan, Fury, Lannate, and Supracide produced 100% mortality of males and females in 72 h. Sevin and Carzol, currently used for D. abbreviatus, produced mortality levels of about 95% after 72 h. LC50 toxicity was in the order Baythroid = Fury = Capture = Pounce = Asana > Avaunt = Furadan > Lannate > Supracide > Danitol > Vydate = Sevin = Carzol = Guthion > Imidan = Lorsban. We examined the reproductive potential of field populations from five Florida geographical locations and one laboratory population of Diaprepes abbreviatus (L.). The life span for female weevils taken from field populations ranged from 116 to 300 d compared to 268 to 330 d for the
laboratory population. Field-collected females oviposited a maximum of 11,414 eggs in 181 egg masses. The laboratory population produced a maximum of 20,048 eggs in 265 egg masses and may have been selected for egg production. The mean number of eggs, egg masses, and eggs/mass declined with female age for the laboratory-reared population. Compared to previous studies, our data increased the estimate of the maximum egg laying potential of individual females in field populations of D. abbreviatus from 7,000 to about 11,000 eggs. However, over a 6-wk period, the estimated life span for adults in the field, there was no difference in mean egg production between populations, and the overall mean +- S.E. was only 1954 +- 102 eggs (n = 184). Our data confirmed previous reports that females require fertilization by a male for egg development into a first-instar larva. We developed a technique to compare the consumption of baits by individual Anastrepha suspensa Loew. By improving consumption
and determining individual dose, we could lower pesticide concentration while retaining bait/pesticide efficacy and potentially reduce the environmental impact of fruit fly bait/pesticide eradication methods. Fluorescein, measured at 491 nm, and cresol red, measured at 573 nm, were efficiently extracted with 0.1 M NaOH and quantified with a spectrophotometer. The lower limit for this method with 0.1% dye concentration is 300 nl consumed by an individual fly. Dye movement to the hindgut and possible defecation occurred in about 4 h; maximum ingestion occurred in about 1 h. Maximum experimental time is limited to 4 h. Flies preferred feeding upside down compared to right side up when given a choice; consumption was equal when flies were given no choice of feeding position. Maximum bait/pesticide efficacy might be achieved with an upside-down presentation. Regurgitation led to a 100% overestimation of actual consumption with the J-tube method for presenting and measuring consumption of
food.
Impacts
These studies provide the data for choosing pesticides for management of diaprepes abbreviatus and for controlling the adult, particularly the female. Our individual fly consumption technique is a powerful technique for comparing consumption in phagostimulant studies, estimating dose in oral toxicity tests, differentiating behavioral and physiological resistance in toxicant studies, ultimately leading to improved bait/pesticide methods and reduced environmental impact of area wide fruit fly eradication programs. This technique could be applied to studies of tephritid consumption, to the consumption of other insects and to regurgitation studies.
Publications
- Nigg, H. N., S. E. Simpson, R. J. Stuart, L. K. Yang, R. C. Adair, B. Bas, S. UR-Rehman, N. W. Cuyler, and J. I. Barnes. 2004. Reproductive potential of Florida populations of Diaprepes abbreviatus (Coleoptera: Curculionidae). J. Entomol. Sci. 39(2):251-266.
- Nigg, H. N., S. E. Simpson, R. A. Schumann and S. Fraser. 2004. Toxicity of pesticides to adult Diaprepes abbreviatus L. (Coleoptera: Curculionidae). J. Entomol. Sci. 39(4):654-669.
- Nigg, H. N., R. A. Schumann, J. J. Yang, L K. Yang, S. E. Simpson, E. Etxeberria, R. E. Burns, D. L. Harris, and S. Fraser. 2004. Quantifying individual fruit fly consumption with Anastrepha suspensa (Diptera: Tephritidae). J. Econ. Entomol. 97(6):1850-1860.
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Progress 10/01/02 to 10/01/03
Outputs
We have completed the development of a technique for determining the consumption of an individual fruit fly. This has enabled us to determine that sucrose is a preferred sugar by Caribbean fruit fly, Anastrepha suspensa. This technique has enabled us to show that A. suspensa prefers 0.2 m sucrose (6.8% sucrose). Commercial lures for this fly contain 1% or less sucrose or 14% sucrose dependent on the lure. We have determined that a preferred amino acid is lysine.
Impacts
We have developed, for the first time, an insect consumption technique that can compare various baits and lures and can be used to examine resistance to ingested pesticides. Data in progress will lead to improved baits, stronger fly management programs and environmental benefits through reduction in pesticide use.
Publications
- Nigg, H. N., S. E. Simpson, R. J. Stuart, L. W. Duncan, C. W. McCoy, and F. G. Gmitter, Jr. 2003. Abundance of Diaprepes abbreviatus (L.) Neonates Falling to the Soil Under Tree Canopies in Florida Citrus Groves. J. Econ. Entomol. 96:835-843
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Progress 10/01/01 to 10/01/02
Outputs
We have completed our work on a Diaprepes larval abundance estimation method. The range of larval numbers falling to the soil ranged from 10-67 per square meter with an average of 401 larvae per square meter for the season. These findings, coupled with our previous work with Diaprepes larvae, emphasize the importance of the proper larval challenge in plant resistance experiments. The correspondence between adult presence and larval numbers obtained in our experiment teaches that control of the adult or the larval life stage should begin when either stage is found in a citrus grove. We have completed the development of a technique for determining the consumption of an individual fruit fly. This has enabled us to determine that sucrose is a preferred sugar by Caribbean fruit fly, that this fly prefers to feed upside down, that there is most likely resistance to malathion in the population, and that this fly prefers certain baits.
Impacts
We have now provided, in a bit more than 3 years, a tolerant rootstock for Diaprepes abbreviatus and a scientifically based approach to determine the tolerance of other rootstock-an approach based on natural larval pressure. Rootstock resistance is a sustainable long-term solution for Diaprepes. We have developed, for the first time, an insect consumption technique that can compare various baits and lures and can be used to examine resistance to ingested pesticides.
Publications
- Nigg, H. N., S. E. Simpson, R. J. Stuart, L. W. Duncan, C. W. McCoy, and F. G. Gmitter, Jr. 2002. Abundance of Diaprepes abbreviatus (L.) Neonates Falling to the Soil Under Tree Canopies in Florida Citrus Groves. J. Econ. Entomol. (in press).
- Nigg, H. N., S. E. Simpson, D. G. Hall, L. R. Ramos, S. U. Rehman, B. Bass, and N. Cuyler. 2002. Sampling Methods as Abundance Indices for Adult Diaprepes abbreviatus (Coleoptera: Curculionidae) in Citrus. J. Econ. Entomol. 95:856-861.
- Futch, S. H., C. W. McCoy, H. N. Nigg. 2002. A Guide to Soil Insect Pests Identification. Gainesville, FL: University of Florida, EDIs HS 130. 5 pg.
- Futch, S. H., C. W. McCoy, H. N. Nigg. 2002. A Guide for Identification of Soil Insect Pests. Citrus Industry Magazine. 83(4): 4 pp. (insert).
- H. N. Nigg, S. E. Simpson, R. A. Schumann, E. Exteberria, and E. B. Jang. 2002. Kairomones for the Management of Anastrepha spp. Fruit Flies. Proc. 6th Intl. Fruitfly Symp. on Fruit Flies of Economic Importance, Stellenbosch, South Africa, May 2002 (in press).
- H. N. Nigg, S. E. Simpson, J. L. Knapp. 2002. The Caribbean Fruit Fly Fly-Free Zone Program in Florida, USA. Proc. 6th Intl. Fruitfly Symp. on Fruit Flies of Economic Importance, Stellenbosch, South Africa, May 2002 (in press).
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Progress 10/01/00 to 10/01/01
Outputs
We have completed our work with the toxicity of fipronil to Diaprepes abbreviatus larvae. This indicated that soil incorporated fipronil at 5-25 ppm would control these larvae over a two-year period. We investigated the movement of adult D. abbreviatus in a commercial citrus grove. These data indicated that adult D. abbreviatus distribute themselves evenly throughout a grove and do not move beyond about 100 m from the site of release. We completed a study of the tolerance of citrus cultivar seedlings to D. abbreviatus larvae. These results indicated that too many larvae have been used in tests of cultivar tolerance to this weevil. We determined that Caribbean fruit fly does not appear to perceive sodium tetraborate in baits at up to 5% concentration.
Impacts
The impacts of our work include better IPM programs for D. abbreviatus, a lead for resistant and tolerant rootstocks for D. abbreviatus, and fruit fly control with effective and safe natural products.
Publications
- Nigg, H. N., S. E. Simpson, H. E. Anderson, and L. K. Yang. 2001. Fipronil Toxicity to Diaprepes abbreviatus L. (Coleoptera: Curculionidae) Larvae. Proc. Florida State Hort. Soc. (peer reviewed section) 114:(in press).
- Nigg, H. N., S. E. Simpson, N. E. El-Gholl, and F. G. Gmitter, Jr. 2001. Response of Citrus Seedlings to Diaprepes abbreviatus L. (Coleoptera: Curculionidae) Larvae Feeding. Proc. Florida State Hort. Soc. (peer reviewed section)114:(in press).
- Nigg, H. N., S. E. Simpson, L. E. Ramos, T. Tomerlin, J. M. Harrison, and N. Cuyler. 2001. Distribution and Movement of Adult Diaprepes abbreviatus L. (Coleoptera: Curculionidae) in a Florida Citrus Grove. Florida Entomol. (in press).
- Yang, L. K., H. N. Nigg, S. E. Simpson, S. Fraser, and R. E. Burns. 2001. Discrimination of Sodium Tetraborate by Anastrepha suspensa Loew. (Diptera: Tephritidae). J. Entomol. Sci. 36:268-284.
- Knapp, J. L., H. N. Nigg, and H. E. Anderson. 2001. Update on Petroleum Oil for Citrus Rust Mite Control. Proc. Florida State Hort. Soc. 114:(in press).
- Nigg, H. N., S. E. Simpson, R. A. Schumann, and E. B. Jang. 2001. Anastrepha spp. Kairomones. Proc. 2nd Asia-Pacific Conferences on Chemical Ecology, Aug. 11-18, 2001, Penang, Malaysia, 18 pp.
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