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Introduction to Botanical Insecticides Introduction to Botanical

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Introduction to Botanical Insecticides Introduction to Botanical Powered By Docstoc
					Parasitology and Entomology Research Laboratories
School of Public Health and Tropical Medicine
James Cook University Townsville Australia
                                                                              Introduction to Botanical Insecticides
                                                                                Reconsideration of botanical insecticides is increasing
          THE EFFICACY OF SEVERAL                                               due to:
          PROMISING MOSQUITOCIDAL                                               –   The lack of novel insecticides
          PHYTOCHEMICALS                                                        –   The high cost of synthetic pyrethroids
                                                                                –   Concern for the environment
                                                                                –   Concern for food safety
                                                                                –   The unacceptability of many organophosphates and
  The 74th Florida                        by                                        organochlorines
  Mosquito Control Association            Essam Shaalan                         –   Increasing insecticide resistance on a global scale
  Annual Fall Meeting
  16-19 November
                                          Deon Canyon
  Biscayne Bay                            Mohamed Wagdi Faried Younes
                                          Hoda Abdel-Wahab
                                          Abdel-Hamid Mansour




     Introduction to Botanical Insecticides                                   Introduction to Botanical Insecticides
         Evidence looks good…                                                   Any one of these effects taken alone is usually not
          –   Large number of different plant species                           impressive, but…
          –   Most geographical areas around the world                          –   Combined ovicidal, larvicidal and IGR effects possessed by
                                                                                    many of phytochemicals can produce impressive results.
          –   Cause a range of acute and chronic toxic effects

                                                                                Joint action
         A phytochemical typically exhibits a range of                          –   Regularly synergistic and effective at LC25 doses
         deleterious effects                                                    –   May well prolong the usefulness of synthetic insecticides that
          –   Larvicidal                                                            will eventually be unusable due to resistance
          –   Reduced fecundity
          –   Reduced viability of mosquito eggs
          –   Growth regulation effects




     Purpose of Study                                                         Materials

         To evaluate the efficacy of:                                           Glassware and pipettes

          –   Khaya senegalensis (African mahogany)
                                                                                Mosquitoes
                 Hexane extracts quite effective against Cx. annulirostris
                 (LC50 5.1 mg/L) Alfazairy et al. 1994                          –   Aedes aegypti
                                                                                       From Townsville colony -
          –   Dacus carrota (carrot) seed                                              2002
                 Shown to be equitoxic against Ae. aegypti and Cx. fatigans     –   Culex annulirostris
                 (LC50 = 36 and 30 mg/L respectively) Sharma et al. 1994               From QIMR colony -
          –   Callitris spp (cypress)                                                  1996
                 Wood is highly effective against termites – no previous        –   4th instar larvae
                 efficacy studies




                                                                                                                                                     1
      Materials and Methods                                                                         Method

       Phytochemicals                                                                                      Preliminary screening
                                                            Manpower                                        –    1000, 500, 100, 50, 5 mg/L – 4 replicates
                                                                A productive student                       Standard WHO methodology for LC50 determination
            Khaya senegalensis (African
            mahogany seed)                                                                                  –    4 reps per dose
                                                                                                            –    Each beaker
             –   Hexane, Ethanol, Acetone, Methanol
                                                                                                                    99 ml deionized water
                 - Soxhalet apparatus & rotary
                                                                                                                    1 ml active (extract + ethanol solvent)
                 evaporator
                                                                                                                    25 4th instar larvae
            Dacus carrota (carrot seed)                                                                     –    Assessment after 24 hrs
             –   Hexane, Ethanol, Acetone, Methanol                                                                 Number alive, dead, pupae
                 - Soxhalet apparatus & rotary                  Mr Essam Shaalan                                    Discard and repeat if control mortality > 2 in a replicate
                 evaporator                                     Doctoral candidate                                  or if > 2 pupae in controls
                                                                Associate Lecturer                                  – Abbott's correctional formula not necessary.
            Callitris (cypress wood)                            Aswan faculty of science                    –    Analysis using SPSS Probit – Regression program
             –   Steam distillation, Liquefied                  South Valley University
                 refrigerant gas, Methanol reflux               Egypt




      Preliminary Results – Aedes aegypti                                                           Preliminary Results – Culex annulirostris

Botanical                      1000 mg/L    500 mg/L    100 mg/L      50 mg/L     5 mg/L    Botanical                           1000 mg/L       500 mg/L   100 mg/L     50 mg/L          5 mg/L
Callitris (steam distl.)          100         100         100           100        100      Callitris (steam distl.)                 100          100          100          100            100
Callitris (refridg. gas)          100         100         100           100         42      Callitris (refridg. gas)                 100          100          100          100             10
Callitris (methanol reflux)       100         100          2             --         --      Callitris (methanol reflux)              100          100          100          96               --
Khaya (hexane)                    100         100         100            41         --      Khaya (hexane)                           100          100          100          100             43
Khaya (ethanol)                   89           7           --            --         --      Khaya (ethanol)                          100          100          100          100              --
Khaya (acetone)                   83          11           --            --         --      Khaya (acetone)                          100          100          100          100              --
Khaya (methanol)                  83          10           --            --         --      Khaya (methanol)                         100          100          100          100             53
Carrot (ethanol)                   --         77           --            --         --      Carrot (ethanol)                         100          100          97            --              --
Carrot (methanol)                  --         62           --            --         --      Carrot (methanol)                        100          100          99            --              --
Carrot (hexane)                    --         60           --            --         --      Carrot (hexane)                          100          100          99            --              --
Carrot (acetone)                   --         34           --            --         --      Carrot (acetone)                         100          100          84            --              --




                                                                                                                 Probit Transformed Responses
                                                                                                          2.0
      LC50 Results                                                                                  LC50 Results
                                                                                                          1.5


 Botanical                    Species        LC50          95% FL             Slope ± SE                  1.0


                                                                                                            .5                                                             Botanicals
 Callitris (steam distl.)     Ae. aegypti      0.62         (0.44 - 0.77)     1.35 ± 0.16
 Callitris (refridg. gas)     Ae. aegypti      5.21         (2.14 - 7.54)     0.07 ± 0.01                                                                                         Khaya Me Cx
                                                                                                          0.0
 Callitris (methanol reflux) Ae. aegypti     306.44    (282.97 – 333.56)      0.01 ± 0.00                                                                                         Khaya He Cx
                                                                                                           -.5
                                                                                                                                                                                  Callitris2 Cx
 Callitris (steam distl.)     Cx. annul.       0.24        (0.18 – 0.30)      4.72 ± 0.41                 -1.0
                                                                                                                                                                                  Callitris1 Cx
 Callitris (refridg. gas)     Cx. annul.       9.54       (7.77 – 11.13)      0.23 ± 0.02
 Callitris (methanol reflux) Cx. annul.       38.96      (35.49 – 42.57)      0.07 ± 0.00                 -1.5                                                                    Callitris2 Ae
                                                                                                 Probit




                                                                                                          -2.0                                                                    Callitris1 Ae
 Khaya (hexane)               Ae. aegypti     57.33      (54.70 – 60.13)      0.05 ± 0.00                    -10       0        10         20      30         40      50
 Khaya (hexane)               Cx. annul.       4.83        (4.10 – 5.66)      0.26 ± 0.02
 Khaya (methane)              Cx. annul.       7.70       (4.88 – 12.61)      0.13 ± 0.01                        DOSE mg/L




                                                                                                                                                                                                  2
                                                                           LC50/90 (mg/L) Results Compared
How do they compare?
     On average, botanical insecticides, most of which are                 Botanical                  Species       LC50          LC90
     secondary compounds produced by plants to protect                     Propoxur                   Ae. aegypti          3.97          7.67
     themselves against herbivorous insects, are                           Piper nigrum               Ae. aegypti           2.6             -
     considerably less active than their synthetic pyrethroid              BTI VectoBac (600 ITU)     Ae. aegypti          0.76          1.66
     counterparts by a factor ranging from 100 to 1000.                    Callitris (steam distl.)   Ae. aegypti          0.62          1.57
                                                                           Malathion                  Ae. aegypti          0.51          0.69
     In contrast to synthetic chemicals, the amount of
                                                                           BTI dry (1200 ITU)         Ae. aegypti          0.25          0.75
     phytochemical required to achieve 100% mortality is
                                                                           Callitris (steam distl.)   Cx. annul.           0.24          0.51
     often far higher than the LC50, (i.e. the slope of the
                                                                           Fenthion                   Ae. aegypti          0.18          0.25
     response curve is low).
                                                                           Temephos                   Ae. aegypti          0.03          0.10
     –   This equates to a considerable and often uneconomical
         increase in cost thus rendering the potential products unviable   Permethrin                 Ae. aegypti     0.002         0.004
         for commercial operators.                                         Bioresmethrin              Ae. aegypti     0.001         0.004
                                                                           Lambda-cyhalothrin         Cx. annul.     0.0001        0.0002




Points to remember

1.    The steam distilled extract of Callitris is the
      most active mosquitocidal larvicide yet
      discovered.
2.    We tested raw extracts – fractionation and
      isolation should result in higher toxicity.
3.    These are preliminary results
          Environmental impact unknown
          Action specificity unknown
          Mode of action unknown




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