Frédéric Darriet - Academia.edu (original) (raw)

Papers by Frédéric Darriet

Recent Advances and Issues in Environmental Science, 2011

The American journal of tropical medicine and hygiene, 2009

In the Caribbean, insecticide resistance is widely developed in Aedes aegypti and represents a se... more In the Caribbean, insecticide resistance is widely developed in Aedes aegypti and represents a serious obstacle for dengue vector control. The efficacy of pyrethroid and organophosphate ultra-low volume space sprays was investigated in Martinique where Ae. aegypti has been shown to be resistant to conventional insecticides. In the laboratory, a wild-field caught population showed high levels of resistance to deltamethrin, organophosphate (naled), and pyrethrum. Simulated-field trials showed that this resistance can strongly reduce the knock-down effect and mortality of deltamethrin and synergized pyrethrins when applied by thermal-fogging. Conversely, the efficacy of naled was high against insecticide-resistant mosquitoes. Chemical analyses of nettings exposed to the treatments showed a decrease in residues over distance from release for the pyrethroids, and naled was not detected. This finding has important implications for dengue vector control and emphasizes the need to develop i...

Malaria journal, 2006

Recent field studies indicated that insecticide-treated bednets (ITNs) maintain their efficacy de... more Recent field studies indicated that insecticide-treated bednets (ITNs) maintain their efficacy despite a high frequency of the knock-down resistance (kdr) gene in Anopheles gambiae populations. It was essential to evaluate ITNs efficacy in areas with metabolic-based resistance. Bifenthrin was used in this experiment because it is considered a promising candidate for bednets impregnation. Nets were treated at 50 mg/m2, a dose that has high insecticidal activity on kdr mosquitoes and at 5 mg/m2, a dose that kills 95% of susceptible mosquitoes under laboratory conditions with 3 minutes exposure. Bednets were holed to mimic physical damage. The trial was conducted in three experimental huts from Pitoa, North-Cameroon where Anopheles gambiae displays metabolic resistance and cohabits with An. funestus. Bifenthrin at 50 mg/m2 significantly reduced anophelines' entry rate (>80%). This was not observed at 5 mg/m2. Both treatments increased exophily in An. gambiae, and to a lesser ext...

Malaria journal, 2005

Pyrethroid resistant mosquitoes are becoming increasingly common in parts of Africa. It is import... more Pyrethroid resistant mosquitoes are becoming increasingly common in parts of Africa. It is important to identify alternative insecticides which, if necessary, could be used to replace or supplement the pyrethroids for use on treated nets. Certain compounds of an earlier generation of insecticides, the organophosphates may have potential as net treatments. Comparative studies of chlorpyrifos-methyl (CM), an organophosphate with low mammalian toxicity, and lambdacyhalothrin (L), a pyrethroid, were conducted in experimental huts in Côte d'Ivoire, West Africa. Anopheles gambiae and Culex quinquefasciatus mosquitoes from the area are resistant to pyrethroids and organophosphates (kdr and insensitive acetylcholinesterase Ace.1R). Several treatments and application rates on intact or holed nets were evaluated, including single treatments, mixtures, and differential wall/ceiling treatments. All of the treatments were effective in reducing blood feeding from sleepers under the nets and i...

Journal of the American Mosquito Control Association, 2002

A new strain of Bacillus circulans isolated from a larva of Culex quinquefasciatus showed larvici... more A new strain of Bacillus circulans isolated from a larva of Culex quinquefasciatus showed larvicidal activity on 3 mosquitoes of medical importance. Compared to Bacillus sphaericus strain 2362, this B. circulans isolate proved less toxic to Cx. quinquefasciatus and Anopheles gambiae but was 107 times more toxic to Aedes aegypti. Moreover, in comparison to other studies, B. circulans was at least as pathogenic as B. thuringiensis var. israelensis in Ae. aegypti. The tests have showed that the toxicity of the bacterial culture of B. circulans resulted from its spores and not from the insecticidal effect of chitinases or exotoxins.

The American journal of tropical medicine and hygiene, 2002

Agricultural use of insecticides is involved in the selection of resistance to these compounds in... more Agricultural use of insecticides is involved in the selection of resistance to these compounds in field populations of mosquitoes in Burkina Faso. Anopheles gambiae s.l. was resistant to permethrin and DDT in cotton-growing and urban areas, but susceptible in areas with limited insecticide selection pressure (rice fields and control areas). Nevertheless, resistance to these insecticides was observed in a village on the outskirts of the rice fields at the end of the rainy season, suggesting that the latter population of mosquitoes had migrated from the surrounding cotton villages into the rice fields. A seasonal variation of resistance observed in the cotton-growing area is related to the distribution of the molecular M and S forms of An. gambiae, since resistance to pyrethroids has so far only been reported in the S form. Pyrethroid resistance in west African An. gambiae was conferred by target site insensitivity through a knockdown resistance (kdr)-like mutation, which was present ...

Trends in Parasitology, 2002

Vector control remains an important component of malaria control, particularly in Africa where mo... more Vector control remains an important component of malaria control, particularly in Africa where most infant deaths occur. Among the different methods, insecticide-treated bednets seem to be a suitable way to reduce morbidity and child mortality in endemic areas. To facilitate their large-scale use and to investigate alternative vector control methods, the authors propose these current directions of research that are already being explored in Africa through a collaborating network involving several African countries: (1) vector genetics, (2) insecticide resistance and (3) vector control strategies.

Transactions of the Royal Society of Tropical Medicine and Hygiene, 1998

Journal of the American Mosquito Control Association, 2008

In this study, the activity of cyromazine was evaluated following WHO standard procedures against... more In this study, the activity of cyromazine was evaluated following WHO standard procedures against susceptible and resistant mosquito strains of Anopheles gambiae, Culex quinquefasciatus, and Aedes aegypti. The dose for 50% and 90% inhibition of adult emergence (IE 50 and IE 90 ) ranged from 0.028 mg/liter to 0.17 mg/liter and from 0.075 mg/liter to 0.42 mg/liter, respectively. The effects of cyromazine were closer to that of chitin synthesis inhibitors rather than that of juvenile hormone analogues, with only 10-20% pupal mortality. The toxicity of cyromazine was not strongly affected by the presence of common resistance mechanism, i.e., Kdr mutation and Ace.1 R (resistance ratio from 0.5 to 2.3). The absence of cross resistance with common insecticides (pyrethroids, carbamates, organophosphates) makes cyromazine a potential candidate for disease vector control, especially for the management of insecticide resistance.

Journal of the American Mosquito Control Association, 2005

Among the characteristics of spinosad that are worth noting is its environmentally favorable toxi... more Among the characteristics of spinosad that are worth noting is its environmentally favorable toxicity profile. It is a compound of biological origin, whose insecticide action is highly effective against a great number of insects. Laboratory larval bioassays of spinosad on Aedes aegypt| Culex quinquefasciatus, and Anopheles gambiae (specimens that were either susceptible or resistant to pyrethroids, carbamates, and organophosphates) showed that this product had a lethal action (mortality after 24 h of exposure) regardless of the original status, susceptible or resistant, of the mosquito larvae.

PLoS Neglected Tropical Diseases, 2011

Background: Dengue fever is reemerging on the island of Martinique and is a serious threat for th... more Background: Dengue fever is reemerging on the island of Martinique and is a serious threat for the human population. During dengue epidemics, adult Aedes aegypti control with pyrethroid space sprays is implemented in order to rapidly reduce transmission. Unfortunately, vector control programs are facing operational challenges with the emergence of pyrethroid resistant Ae. aegypti populations.

Pest Management Science, 2004

The efficacy of insecticide mixtures of permethrin (pyrethroid) and propoxur (carbamate) was test... more The efficacy of insecticide mixtures of permethrin (pyrethroid) and propoxur (carbamate) was tested by larval bioassays on two strains of Culex quinquefasciatus (Say), one resistant to pyrethroids and the other resistant to carbamates. The method consisted in combining one insecticide at the highest concentration causing no mortality (LC 0 ) with increasing concentrations of the second one. The concentration-mortality regression lines were determined for permethrin and propoxur alone and in combination, and synergism ratios (SR) were calculated in order to determine the magnitude of an increase or decrease in efficacy with use of the mixtures. With the pyrethroid-resistant strain (BK-PER), the results showed that propoxur at LC 0 significantly enhanced the insecticidal activity of permethrin (SR 50 = 1.54), especially on the upper range of the concentration-mortality regression. Conversely, when permethrin at LC 0 was tested with propoxur against the carbamate resistant strain (R-LAB), an antagonistic effect was observed (SR 50 = 0.67). With the BK-PER strain, an increased oxidative detoxification (MFO) appeared to be the main mechanism responsible for the synergistic interaction. Nevertheless, antagonism in the R-LAB strain is probably due to a physiological perturbation implying different target sites for pyrethroid (ie sodium channel) and carbamate insecticides [ie acetylcholinesterase (EC 3.3.3.7) and choline acetyltransferase (EC 2.3.1.6)].

Medical and Veterinary Entomology, 2000

Medical and Veterinary Entomology, 2001

15, 105±112 ITN treatment, 6±8% An. gambiae and 12±14% Cx. quinquefasciatus with pyrethroid alone... more 15, 105±112 ITN treatment, 6±8% An. gambiae and 12±14% Cx. quinquefasciatus with pyrethroid alone. Mosquitoes that entered the huts were killed sooner by nets with combined treatment than by pyrethroid alone. Mortality-rates in response to ITNs with carbosulfan (alone or combined with pyrethroid) were signi®cantly greater for Cx. quinquefasciatus, but not for An. gambiae, compared to ITNs with only pyrethroid. About 20% of sleepers reported potential side-effects (headache and/or sneezing) from use of ITN treated with carbosulfan alone. Further development of this new`two-in-one' ITN concept requires a range of investigations (choice of effective products, cost-bene®t analysis, safety, etc.) leading to factory production of wash-resistant insecticidal nets treated with complementary insecticides.

Medical and Veterinary Entomology, 2001

Pyrethroid-impregnated bednets are advocated for personal protection against malaria vectors. To.... more Pyrethroid-impregnated bednets are advocated for personal protection against malaria vectors. To. avoid the need for periodic re-treatment, it would be advantageous to have nets that retain insecticidal efficacy for years and withstand repeated washing. Such a type of commercially produced bednet with permethrin 2% incorporated in polyethylene fibres (trademark Olyset Net@ supplied by Sumika Life-Tech Co., Osaka, Japan) was evaluated against mosquitoes in veranda-trap huts at Yaokoffìkro, near Bouaké, Côte d'Ivoire, by standard WHOPES phase II procedures. Four Olyset Nets were compared with a standard untreated polyester net as control. They comprised three examples previously used in a village for over 3years (one washed, one dirty, one very dirty) and a previously unused Olyset Net, newly unwrapped, from the same original batch. Bioassays with 3min exposure of susceptible Anopheles gambiae Giles (Diptera: Culicidae) gave > 99% mortality of female mosquitoes tested on the 'new' Olyset Net. The used Olyset Nets gave mortality rates averaging 83% for the washed net, 85% for the dirty net and 55% for the very dirty net (within 24-h following 3min exposure). Thus, Olyset Nets were found to remain remarkably effective against susceptible An. gambiae for at least 3 years under field conditions. Wild pyrethroid-resistant populations of Culex quinquefasciatus Say and An. gambiae (savanna cytotype with 96% kdr) were assessed during June-August 1999 for their responses to sleepers protected by nets in the experimental huts. With regard to hut entry by foraging female mosquitoes, Olyset Nets showed some deterrency against An. gambiae (44% reduction by the new net, -20% by the dirty nets, none by the washed net), but not against Cx, quinquefasciatus. Among mosquitoes entering the hut with untreated control net, 30-34% tried to leave (exophily) but were caught in the verandah trap. The permethrin repellency of Olyset Nets increased exophily by 19% for An. gambiae and 14% for Cx. quinquefasciatus. Blood-feeding rates were 16% An. gambiae and 35% Cx. quinquefasciatus in the hut with sleeper under the untreated net (showing considerable prevention of biting), 22-26% of both species in huts with washed or dirty used Olyset Nets (not significantly different from control), while the biting success rate of Cx. quinquefasciatus (but not kdr An. gambiae) was more than halved by the 'new' Olyset Net. Mortality rates of pyrethroid-resistant An. gambiae and Cx. quinquefasciatus from the huts were, respectively, 3% and 8% with the untreated polyester net, 27.5% and 17% with the 'new' Olyset, 15% and 17.5% with the washed Olyset, 16-25% and 17-20% with dirty old Olyset Nets. Kill differences between nets are significantly different for both An. gambiae and Cx. quinquefasciatus. Unfortunately the washed used Olyset Net showed least 97 98 R. "Guessan et al.

Medical and Veterinary Entomology, 2003

To see if synergism occurs between carbamate and pyrethroid insecticides, we tested permethrin an... more To see if synergism occurs between carbamate and pyrethroid insecticides, we tested permethrin and propoxur as representatives of these two classes of compounds used for mosquito control. Larvicidal activity of both insecticides was assessed separately and together on a susceptible strain of the mosquito Culex quinquefasciatus (Diptera: Culicidae) by two methods. When mixed at a constant ratio (permethrin : propoxur 1 : 60 based on LC 50 ) and tested at serial concentrations to plot dose/mortality regression, significant synergy occurred between them (co-toxicity coefficient ¼ 2.2), not just an additive effect. For example, when the mixture gave 50% mortality, the same concentrations of permethrin and propoxur alone would have given merely 2 Â 1% mortality. When a sublethal dose (LC 0 ) of permethrin or propoxur was added to the other (range LC 10 -LC 95 ), synergism occurred up to the LC 80 level. Synergistic effects were attributed to the complementary modes of action by these two insecticide classes acting on different components of nerve impulse transmission. Apart from raising new possibilities for Culex control, it seems appropriate to consider using such mixtures or combinations for insecticide-treated mosquito nets in situations with insecticide-resistant Anopheles malaria vectors.

Medical and Veterinary Entomology, 2003

Resistance to carbosulfan, a carbamate insecticide, was detected in field populations of the mala... more Resistance to carbosulfan, a carbamate insecticide, was detected in field populations of the malaria vector mosquito Anopheles gambiae Giles (Diptera: Culicidae) from two ecologically contrasted localities near BouakeÂ , Ivory Coast: rural M'beÂ with predominantly M form of An. gambiae susceptible to pyrethroids; suburban Yaokoffikro with predominantly S form of An. gambiae highly resistant to pyrethroids (96% kdr). The discriminating concentration of 0.4% carbosulfan (i.e. double the LC 100 ) was determined from bioassays with the susceptible An. gambiae Kisumu strain. Following exposure to the diagnostic dosage (0.4% carbosulfan for 1 h), mortality rates of female An. gambiae adults (reared from larvae collected from ricefields) were 62% and 29% of those from M'beÂ and Yaokoffikro, respectively, 24 h post-exposure. Exposure for 3 min to netting impregnated with the operational dosage of carbosulfan 200 mg/m 2 gave mortality rates of 88% of those from M'beÂ and only 12.2% for Yaokoffikro. In each case the control untreated mortality rate was insignificant. Biochemical assays to detect possible resistance mechanism(s) revealed the presence of insensitive AChE in populations of An. gambiae at both localities, more prevalent in the S form at Yaokoffikro than in M form at M'beÂ , as expected from bioassays results. Our study demonstrates the need to monitor carbamate resistance among populations of the An. gambiae complex in Africa, to determine its spread and anticipate vector control failure if these insecticides are employed.

Medical and Veterinary Entomology, 2006

The knock-down, mortality and ' irritancy ' effects of three synthetic repellents (DEET, IR3535 a... more The knock-down, mortality and ' irritancy ' effects of three synthetic repellents (DEET, IR3535 and KBR 3023) on Aedes aegypti (L) (Diptera: Culicidae) were evaluated in the laboratory in the absence of animal bait. Filter paper tests were carried out to assess the knock-down effect (KDt 50 and KDt 95 ) and mortality (LC 50 and LC 95 ) induced by each repellent. ' Irritancy ' tests were carried out to compare the flight response (time to first take-off, or FT) to increasing concentrations of repellents (2 -7%) and at five distances from the treated surface (0 -40 mm). DEET had an insecticidal effect (KDt 50 = 9.7 min at 7%; CL 50 = 1165 mg/m 2 ), whereas IR3535 and KBR 3023 did not. Relative to an untreated control, IR3535 was an irritant (relative irritancy or RI > 1) at doses of 5% and 7% (RI = 17.7 and 9.9, respectively), whereas DEET was an irritant at lower concentrations (RI = 12.3 at 2% DEET). KBR 3023 was the weakest irritant over the same range of concentrations (RI max = 3.6 at 6%). DEET was more of an irritant (RI 20 = 9.4) than IR3535 (RI 20 = 2.9) over a range of distances (0 -20 mm), and KBR 3023 was not an irritant unless mosquitoes made contact with the treated surface. All three repellents had a significant effect on mosquitoes, but DEET exhibited a more complex mode of action than the others due to its insecticidal properties. The repellents do not behave as a single class of compounds with a common mode of action, but most probably affect different physiological systems in insects. The physiological and molecular mechanisms of repellents, especially DEET, should be investigated to ensure a better use of these molecules for skin applications and/or for treating materials against mosquitoes.

Medical and Veterinary Entomology, 1998

Pyrethroid resistance was investigated in thirty-three samples of Culex quinquefasciatus Say from... more Pyrethroid resistance was investigated in thirty-three samples of Culex quinquefasciatus Say from twenty-five cities in Côte d'Ivoire and Burkina Faso. Permethrin resistance ratios at LC 50 ranged from 9.5-to 82-fold in Côte d'Ivoire and from 17-to 49-fold in Burkina Faso. For deltamethrin, resistance ratios were lower and ranged from nine to thirty-eight in both countries. A strain was selected with permethrin to investigate resistance mechanisms. After forty-two generations of selection, permethrin resistance level reached 3750-fold, but deltamethrin resistance remained unexpectedly unchanged. This indicated that a specific mechanism was involved in permethrin resistance. Synergist assays and biochemical tests indicated that resistance was partly due to P450-dependent oxidases. A target site insensitivity (kdr) was also involved, associated with DDT cross resistance and a dramatic loss of permethrin knockdown effect on adults. This resistance should be taken into consideration when planning the use of pyrethroid-impregnated materials in urban areas, as Culex is by far the main source of nuisance. Any failure in nuisance control due to resistance is likely to demotivate people in using impregnated materials.

Journal of Medical Entomology, 2006

In this study, the efÞcacy of pyriproxyfen and spinosad, alone and in combination, was evaluated ... more In this study, the efÞcacy of pyriproxyfen and spinosad, alone and in combination, was evaluated against the dengue vector Aedes aegypti (L.). Larval bioassays were carried out on susceptible mosquito larvae to determine the concentrationÐmortality responses of mosquitoes exposed to each insecticide alone and in mixture. Synergism between pyriproxyfen and spinosad was determined by the calculation of a combination index (CI) by using the isobologram method. For pyriproxyfen, LC 50 and LC 95 were 1.1 ϫ 10 Ϫ4 (1.0 ϫ 10 Ϫ4 Ð1.1 ϫ 10 Ϫ4 ) and 3.2 ϫ 10 Ϫ4 (2.9 ϫ 10 Ϫ4 Ð3.6 ϫ 10 Ϫ4 ) mg/liter, respectively. Pyriproxyfen acted at very low concentrations by inhibiting the adult emergence of Ae. aegypti (97% inhibition rates at 3.3 ϫ 10 Ϫ4 mg/liter). Spinosad activity was Ϸ500 times lower than that of pyriproxyfen against the Bora strain, with LC 50 and LC 95 values estimated at 0.055 (0.047Ð 0.064) and 0.20 (0.15Ð 0.27) mg/liter, respectively. A binary mixture of pyriproxyfen and spinosad was realized at the ratio 1:500 by considering the values of the LC 50 obtained for each product. The LC 50 and LC 95 of the mixture were 0.019 (0.016 Ð 0.022) and 0.050 (0.040 Ð 0.065) mg/liter, respectively. The mixture combined both the larvicidal activity of spinosad and the juvenoid action of pyriproxyfen. From the LC 70 to LC 99 , a signiÞcant synergism effect was observed between the two insecticides (CI ranged from 0.74 to 0.31). This strong synergism observed at high concentrations allows a reduction by Þve and nine-fold of pyriproxyfen and spinosad amounts to kill almost 100% mosquitoes. Combination of pyriproxyfen and spinosad may then represent a promising strategy to improve mosquito control in situations with insecticide-resistant Aedes dengue vectors.

Recent Advances and Issues in Environmental Science, 2011

The American journal of tropical medicine and hygiene, 2009

Malaria journal, 2006

Malaria journal, 2005

Journal of the American Mosquito Control Association, 2002

The American journal of tropical medicine and hygiene, 2002

Trends in Parasitology, 2002

Transactions of the Royal Society of Tropical Medicine and Hygiene, 1998

Journal of the American Mosquito Control Association, 2008

Journal of the American Mosquito Control Association, 2005

PLoS Neglected Tropical Diseases, 2011

Pest Management Science, 2004

Medical and Veterinary Entomology, 2000

Medical and Veterinary Entomology, 2001

Medical and Veterinary Entomology, 2003

Medical and Veterinary Entomology, 2006

Medical and Veterinary Entomology, 1998

Journal of Medical Entomology, 2006