Fig 1.
Chemical structures of chemicals used in this study.
A-C) Chemical structures of insect growth regulators: pyriproxyfen (PPF) or Sumilarv (Sumil.), Triflumuron (Trifl.), and novaluron (noval.) or Rimon EC10 D) Chemical structure of the Kir channel inhibitor, VU041.
Fig 2.
Experimental design for laboratory and semi-field studies.
A) Schematic diagram showing the methodology used to expose Anopheles quadrimaculatus to the IGRs in the laboratory. B) Schematic diagram showing the methodology for testing the efficacy of IGRs and adulticides to control the mosquito population in a semi-field environment.
Table 1.
HPLC analysis of IGR chemicals in oviposition habitats of Anopheles females exposed by contact immediately after blood feeding.
Fig 3.
Toxicity of IGRs and VU041 to An. quadrimaculatus.
A) Concentration-response curves of triflumuron (closed circles), pyriproxyfen (open squares), and novaluron (open circles) as determined by inhibition of adult emergence after exposure to 4th instars. Each data point represents an average (n = 3) toxicity and each replicate consisted of 30 larvae; totaling 90 mosquitoes. Error bars represent SEM. B) Toxicity in blood fed, adult An. quadrimaculatus 24h after contact exposure to netting treated with VU041. Data points represent a mean mortality (n = 4–8 replicates of 25 mosquitoes tested per dose) and error bars represent SEM.
Fig 4.
Influence on fecundity and larval survivorship after adult exposure to IGRs.
A) Total number of eggs laid per female 72 hours after adult contact exposure to IGRs immediately after blood feeding. Control treatment was netting treated with acetone only. Each data point represents the egg output of an individual mosquito. Red bars indicate the median number of eggs laid for each treatment. Asterisks represent statistical significance (P<0.05) when compared to the control (solvent only) treatment. B) Percent hatch of the eggs. Solid bars represent the mean % egg hatch in habitats that were contaminated by the adult mosquito during oviposition (horizontal transfer) whereas the checkered bars represent egg hatch of eggs laid in water contaminated with an IGR at the IE50 concentration. Bars represent a mean % hatch (n = 25) and error bars represent SEM. Asterisks represent statistical significance (* P<0.05, **P<0.01) when compared to the control treatment for each group, horizontal transfer and IGR treated water. C) % survivorship of larvae hatched from a habitat that was oviposited in by adults treated with IGRs. Mortality was measured by counting number of alive 1st-instar larvae compared to 2nd-instar larvae. Bars represent average survivorship (n = 25) and error bars represent SEM. D) % emergence of ultimate instar larvae added into oviposition sites that had eggs laid. Bars represent means (n = 4, 10 mosquitoes per rep) and error bars represent SEM. For all panels, letters indicate statistical categorization of the means as determined by a one-way ANOVA with a multiple comparisons test (P < 0.05). Bars not labeled by the same letter as the control bar represents statistical significance when compared to the control value (P<0.05).
Fig 5.
Larval toxicity and time course of horizontal transfer capabilities of Rimon EC10.
A) Concentration-response curves of Rimon EC10 when exposed to 1st-instars (closed circles), 3rd-instars (open circles), and pupae (open squares) as determined by inhibition of adult emergence. Each data point represents a mean % emergence derived from 3 replicates and each replicate consisted of 3 replicates of 20 larvae. Error bars represent SEM. B) % survivorship of larvae hatched into a habitat that was oviposited in by adults exposed to control (black bars) or Rimon EC10 treated netting (checkered bars) immediately after blood feeding. Mortality was measured by counting number of alive 1st-instar larvae compared to 2nd-instar larvae. Bars represent average survivorship (n = 25) and error bars represent SEM.
Fig 6.
Autodissemination efficacy of novaluron and PPF and toxicity of VU041 in a semi-field environment.
A) % recapture of adult mosquitoes when exposed to a VU041- or deltamethrin-treated resting boxes. Deltamethrin was tested at an LC99 to determine the visitation rates of mosquitoes to the resting box. Bars represent mean (n = 6) % recapture and error bars represent SEM. B) Fecundity and adult emergence of control-, VU041+novaluron-, and VU041+PPF-treated groups. Bars represent mean (n = 15) and error bars represent SEM.