A verandah-trap hut for studying the house-frequenting habits of mosquitos and for assessing insecticides. II.—The effect of dichlorvos (DDVP) on egress and mortality of Anopheles gambiae Giles and Mansonia uniformis (Theo.) entering naturally

1965 ◽  
Vol 56 (2) ◽  
pp. 275-282 ◽  
Author(s):  
Alec Smith
Keyword(s):  
Anopheles Gambiae ◽  
Chemical Analyses ◽  
Window Traps ◽  
Anopheles Gambiae Giles ◽  
Mansonia Uniformis

Assessment of the effects of dichlorvos (DDVP), released from a Ciba XI dispenser, on females of Anopheles gambiae Giles and Mansonia uniformis (Theo.) entering a verandah-trap hut in the Umbugwe area of Tanzania was made over a period of two months in 1964. Of the numbers of A. gambiae that entered one treated and one untreated hut, 27 per cent, of those entering the hut treated with dichlorvos and 48 per cent, of those entering the untreated hut left again. Of the numbers leaving each hut, 38 per cent, left through the eaves of the treated hut as compared with 9 per cent, in the untreated one. In the case of M. uniformis, 88 per cent, of those entering the treated hut and 94 per cent, of those entering the untreated hut left again. Of the numbers leaving each hut, 59 per cent, left through the eaves of the treated hut as compared with 61 per cent, in the untreated one.Over-all mortalities were 56 per cent, for A. gambiae and 34 per cent, for M. uniformis when the eave-egress fraction from the treated hut was taken into account, compared with 62 per cent, for A. gambiae and 43 per cent, for M. uniformis when the eave-egress fraction was ignored.The results of bioassays and of chemical analyses showed that the problem of mortality from fumigation in situ was considerably less in verandah traps than indoors or in window traps fitted with funnels of cotton netting.

Preliminary louvre-trap hut studies on the egress of Anopheles gambiae Giles, Mansonia uniformis (Theo.) and Culex pipiens fatigans Wied. from untreated huts

1972 ◽  
Vol 61 (3) ◽  
pp. 415-419 ◽  
Author(s):  
A. Smith ◽  
J. E. Hudson ◽  
W. O. Obudho
Keyword(s):  
Anopheles Gambiae ◽  
Culex Pipiens ◽  
Window Trap ◽  
Culex Pipiens Fatigans ◽  
Window Traps ◽  
Anopheles Gambiae Giles ◽  
Mansonia Uniformis

The louvre-trap hut was designed to be cheaper and simpler to use than the verandah-trap hut. The eaves are closed, and mosquitoes enter by way of a row of five louvre frames and leave by a window fitted with a window trap. In three trials at Magugu, Tanzania, window traps fitted over one or all louvre frames showed that the efficiency of the louvres in preventing egress was 66–79% for Anopheles gambiae Giles, 51–73% for Mansonia uniformis (Theo.) and 74–78% for Culex pipiens fatigans Wied. Egress through the louvres of A. gambiae is only slightly more, and of M. uniformis much less, than through the eaves of a verandah-trap hut.

A verandah-trap hut for studying the house-frequenting habits of mosquitos and for assessing insecticides. I.—A description of the verandah-trap hut and of studies on the egress of Anopheles gambiae Giles and Mansonia uniformis (Theo.) from an untreated Hut

1965 ◽  
Vol 56 (1) ◽  
pp. 161-167 ◽  
Author(s):  
Alec Smith
Keyword(s):  
Anopheles Gambiae ◽  
East Africa ◽  
Window Trap ◽  
Anopheles Gambiae Giles ◽  
Mansonia Uniformis

A description is given of a verandah-trap hut designed to assess the egress and survival of mosquitos escaping through the eaves of the type of window-trap hut used in insecticide testing in East Africa.Fifty-one per cent. of females of Anopheles gambiae Giles in all gonotrophic stages and 19 per cent. of those recently fed left the hut each night, with 15 and 30 per cent., respectively, of the egress occurring through the eaves.Ninety per cent of females of Mansonia uniformis (Theo.) in all gonotrophic stages and 91 per cent. of those recently fed left the hut each night, with 69 and 66 per cent., respectively, of the egress occurring through the eaves.It was concluded that, owing to the high proportion of individuals of M. uniformis that leaves by the eaves, the verandah-trap hut was of a more suitable design for studying the house-frequenting habits of this species, and of other species with similar habits, than the simple window-trap hut.

The effects of smoke from mosquito coils on Anopheles gambiae Giles and Mansonia uniformis (Theo.) in verandah-trap huts at Magugu, Tanzania

1971 ◽  
Vol 61 (2) ◽  
pp. 247-265 ◽  
Author(s):  
J. E. Hudson ◽  
S. Esozed
Keyword(s):  
Anopheles Gambiae ◽  
Anopheles Gambiae Giles ◽  
Mansonia Uniformis

The effects of smoke from mosquito coils containing pyrethrins or DDT on Anopheles gambiae Giles and Mansonia uniformis (Theo.) were investigated by burning coils for five nights per week in three man-baited verandah-trap huts. Three other verandah-trap huts served as controls. Smoke from 004–0–3% pyrethrins coils deterred 24–84% of A. gambiae and 71–93% of M. uniformis from entering treated huts, and that from 7–3–130% DDT coils deterred 91 % of A. gambiae and 92% of M. uniformis.In pyrethrum-treated huts 62–76% A. gambiae were unfed (33–67% in the controls) and 80–99% were in the exit traps (43–79% in the controls). In DDT-treated huts 85% A.gambiae were unfed (48% in the controls) and 100% were in the exit traps (55% in the controls). With M. uniformis, 61–84% in the pyrethrum-treated huts were unfed (38–54% in the controls) and in the DDT-treated huts 71 % (69% in the controls). The effects of the smokes on the egress of M. uniformis could not be assessed since 82–100% were in the exit traps in the treated and in the control huts. Overall mortalities never exceeded 22% of A. gambiae and 12% of M. uniformis, but some dead mosquitoes may have been removed by ants. With pyrethrum coils, feeder-survivor indices were 15–84% for A. gambiae and 90–98% for M. uniformis, and with the DDT coils, 94% and 96%, respectively. When caged A. gambiae females were exposed all night in the huts, 24-h delayed mortalities caused by 019–0–30% pyrethrins coils were 38–56%, by 009% pyrethrins coils 12–27%, and by 004% pyrethrins coils 3–5%. DDT coils produced 99–100% mortality in 24 h, but this may have been due to contact with contaminated mosquito netting.

scholarly journals Human biting rhythm of Anopheles gambiae Giles, 1902 (Diptera: Culicidae) and sleeping behaviour of pregnant women in a lagoon area in Southern Benin

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Armel Djènontin ◽  
Aziz Bouraima ◽  
Christophe Soares ◽  
Seun Egbinola ◽  
Gilles Cottrell
Keyword(s):  
Plasmodium Falciparum ◽  
Pregnant Women ◽  
Anopheles Gambiae ◽  
Early Morning ◽  
Allelic Frequency ◽  
Malaria Vectors ◽  
Mosquito Nets ◽  
Anopheles Gambiae Giles ◽  
Almost All ◽  
Southern Benin

Abstract Objective In the framework of EVALMOUS study aiming to assess the use and effectiveness of mosquito nets by pregnant women and other members of their household in a lagoon area in southern Benin, the behaviour of pregnant women relative to the time they go to bed using the net were recorded. Malaria vectors biting rhythm, Plasmodium falciparum infection and insecticide resistance genes in malaria vectors were also determined. Results Overall, 3848 females of Anopheles gambiae s. l were collected and 280 pregnant women responded to the survey. Almost all Anopheles gambiae s. l. tested were Anopheles coluzzi Coetzee and Wilkerson 2013 (Diptera: Culicidae). The CSP index in malaria vector was 1.85% and the allelic frequency of kdr gene was 74.4%. Around 90% of bites and Plasmodium falciparum Welch, 1897 (Haemosporida: Plasmodiidae) transmission occurred between 10 p.m. and 6 a.m., which coincides with the period when more than 80% of pregnant women were under bednet. Despite a slight early evening and early morning biting activity of malaria vectors in the study area, the good use of nets might remain a useful protection tool against mosquito biting and malaria transmission.

Studies of House Leaving and Outside Resting of Anopheles gambiae Giles and Anopheles funestus Giles in East Africa. I.—The Outside Resting Population

1954 ◽  
Vol 45 (2) ◽  
pp. 361-373 ◽  
Author(s):  
M. T. Gillies
Keyword(s):  
Anopheles Gambiae ◽  
Anopheles Funestus ◽  
Drastic Reduction ◽  
Natural Conditions ◽  
Resting Sites ◽  
Lowland Area ◽  
Set Up ◽  
Anopheles Gambiae Giles ◽  
Gravid Females ◽  
Periodic Examination

The behaviour of Anopheles gambiae Giles and A. funestus Giles was studied under natural conditions in a lowland area of Tanganyika.Studies on the outside resting population were carried out by direct searching for natural resting sites, and by the use of artificial box shelters partly buried in the ground in shaded localities. Catches in these give a valid sample when set up at some distance from houses.Fed and gravid females comprised 67 per cent. of the outside resting gambiae population, the latter group being between 12 and 4·5 times as numerous as the former. Rather less than half the funestus females caught were unfed, the remainder of the population being mainly composed of gravid females.Precipitin tests on the small numbers of fed females caught outside were nearly all positive for man.The identification of gravid funestus females was confirmed by periodic examination of the eggs.Entry of females into outside shelters did not occur solely in the period around sunrise. An appreciable number of funestus females did not enter before 07.00 hours and this was particularly so in shaded shelters.The building of a hut in the vicinity of a box shelter caused a drastic reduction in the numbers of mosquitos resting in the latter.Outside biting activity in these two species is of negligible importance as a source of females resting outside.

Nutrient and hormone levels in Douglas-fir corrosion cavities, megagametophytes, and embryos during embryony

2005 ◽  
Vol 35 (10) ◽  
pp. 2447-2456 ◽  
Author(s):  
John G Carman ◽  
Gordon Reese ◽  
Rodney J Fuller ◽  
Timnit Ghermay ◽  
Roger Timmis
Keyword(s):  
Pseudotsuga Menziesii ◽  
Dry Mass ◽  
Douglas Fir ◽  
Chemical Analyses ◽  
Dynamic Changes ◽  
Hormone Levels ◽  
Corrosion Cavity ◽  
Novel Method ◽  
Indole 3 Acetic Acid

Gymnospermous embryos are nourished by fluids secreted from the megagametophyte. During early embryony, these fluids occupy the newly formed corrosion cavity. We describe a novel method for extracting corrosion cavity fluid and provide chemical analyses based on extractions from approximately 120 000 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) megagametophytes. Levels of potassium, phosphorus, calcium, zinc, and iron were higher in corrosion cavity fluid than in whole tissue, but levels of sulphur and manganese were lower. Levels of cyclitols, sucrose equivalents, erythrose, and arabinose were many-fold higher in corrosion cavity fluid than in whole tissues. Ala, Ser, Arg, Glx, and NH3 exceeded 80 mmol/kg dry mass in corrosion cavity fluid. These levels were about 100-fold higher than those found in whole tissues. During early embryony, hormone levels in corrosion cavity fluid were higher than levels observed in whole megagametophytes by 120-fold for indole-3-acetic acid, 53-fold for abscisic acid, and 8- to 10-fold for cytokinins. Nutrient and hormone levels tended to be much higher in the corrosion cavity fluid than would have been predicted based on whole-tissue analyses. Dynamic changes in nutrient and hormone levels occurred over time in the corrosion cavity, and these changes may normalize embryony in situ.

scholarly journals Characterizing Permethrin and Etofenprox Resistance in Two Common Laboratory Strains of Anopheles gambiae (Diptera: Culicidae)

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 146 ◽  
Author(s):  
Aaron Gross ◽  
Jeffrey Bloomquist
Keyword(s):  
Anopheles Gambiae ◽  
Pyrethroid Resistance ◽  
Laboratory Strain ◽  
Pyrethroid Insecticide ◽  
Sub Saharan Africa ◽  
Cross Resistance ◽  
Type I ◽  
Mosquito Vector ◽  
Sub Saharan ◽  
Anopheles Gambiae Giles

Anopheles gambiae Giles (Diptera: Culicidae) is the most prolific malaria vector in sub-Saharan Africa, where widespread insecticide resistance has been reported. An. gambiae laboratory strains are commonly used to study the basic biology of this important mosquito vector, and also in new insecticide discovery programs, where insecticide-susceptible and -resistant strains are often used to screen new molecules for potency and cross-resistance, respectively. This study investigated the toxicity of permethrin, a Type-I pyrethroid insecticide, and etofenprox, a non-ester containing pyrethroid insecticide, against An. gambiae at three life stages. This characterization was performed with susceptible (G3; MRA-112) and resistant (Akdr; MRA-1280) An. gambiae strains; the Akdr strain is known to contain the L1014F mutation in the voltage-sensitive sodium channel. Surprisingly, etofenprox displays a lower level of resistance than permethrin against all stages of mosquitoes, except in a headless larval paralysis assay designed to minimize penetration factors. In first-instar An. gambiae larvae, permethrin had significant resistance, determined by the resistance ratio (RR50 = 5), but etofenprox was not significantly different (RR50 = 3.4) from the wild-type strain. Fourth-instar larvae displayed the highest level of resistance for permethrin (RR50 = 108) and etofenprox (RR50 = 35). Permethrin (PC50 = 2 ppb) and etofenprox (PC50 = 9 ppb) resulted in headless larval paralysis (5-h), but resistance, albeit lower, was still present for permethrin (RR50 = 5) and etofenprox (RR50 = 6.9). In adult female mosquitoes, permethrin displayed higher resistance (RR50 = 14) compared to etofenprox (RR50 = 4.3). The level of etofenprox resistance was different from that previously reported for a similar Akron An. gambiae laboratory strain (MRA-913). The chemical synergists piperonyl butoxide (PBO) and diethyl maleate (DEM) were able to synergize permethrin, but not etofenprox in the resistant strain (Akdr). In conclusion, multiple mechanisms are likely involved in pyrethroid resistance, but resistance profiles are dependent upon selection. Etofenprox is an effective insecticide against An. gambiae in the lab but will likely suffer from resistance in the field.

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