Toxicity of several botanical essential oils and their combinations against females of Aedes albopictus (Skuse) and Anopheles minimus (Theobald): Oviposition deterrent, ovicidal and adulticidal efficacies

Objective:To investigate the efficacies of 12 essential oil (EO) formulations from three Zingiberaceae plants (Alpinia galanga,Curcuma zedoaria,and Zingiber cas.sumunar) individually and in combination with an augmenting Eucalyptus globulus (E.globulus) EO against females of Aedes albopictus (Ae.adbopictus) and Anopheles minimus (An.minimus).Methods:These formulations were evaluated for their ovicidal,oviposition deterrent and adulticidal activities against Ae.albopictus and An.minimus by a topical method,a double-choice method and a WHO susceptibility test,respectively.Results:It was found that all formulations of Zingiberaceae plants EOs augmented with E.globulus EO were more effective in oviposition deterrent,ovicidal,and adulticidal activities against the two mosquito species than all of the formulations used without E.globulus EO.Their oviposition deterrent,ovicidal and adulticidal activities were equivalent to those of 10％ w/v cypermethrin.In contrast,70％ v/v ethyl alcohol as a control alone was not effective at all.The highest synergistic effect in effective repellency against Ae.albopictus was achieved by 5％ Alpinia galanga EO + 5％ E.globulus EO and against An.minimus was 5％ Zingiber cassumunar EO + 5％ E.globulus EO.Moreover,the highest synergistic effects in ovicidal activities against Ae.albopictus and An.minimus were achieved by 10％ Zingiber cassumunar EO + 10％ E.globulus EO and 5％ Curcuma zedoaria EO + 5％ E.globulus EO,respectively.For the adulticidal activities,the highest synergistic effect against two mosquitoes was achieved by 5％ Gurcuma zedoaria EO + 5％ E.globulus EO.Conclusions:These results suggest that Zingiberaceae plant EOs augmented with E.globulus EO have a high potential to be developed into oviposition deterrent,ovicidal,and adulticidal agents for controlling populations of Ae.albopictus and An.minimus.

Toxicity of several botanical essential oils and their combinations against females of Aedes albopictus (Skuse) and Anopheles minimus (Theobald): Oviposition deterrent, ovicidal and adulticidal efficacies

Objective: To investigate the efficacies of 12 essential oil (EO) formulations from three Zingiberaceae plants (Alpinia galanga, Curcuma zedoaria, and Zingiber cassumunar) individually and in combination with an augmenting Eucalyptus globulus (E. globulus) EO against females of Aedes albopictus (Ae. albopictus) and Anopheles minimus (An. minimus). Methods: These formulations were evaluated for their ovicidal, oviposition deterrent and adulticidal activities against Ae. albopictus and An. minimus by a topical method, a double-choice method and a WHO susceptibility test, respectively. Results: It was found that all formulations of Zingiberaceae plants EOs augmented with E. globulus EO were more effective in oviposition deterrent, ovicidal, and adulticidal activities against the two mosquito species than all of the formulations used without E. globulus EO. Their oviposition deterrent, ovicidal and adulticidal activities were equivalent to those of 10% w/v cypermethrin. In contrast, 70% v/v ethyl alcohol as a control alone was not effective at all. The highest synergistic effect in effective repellency against Ae. albopictus was achieved by 5% Alpinia galanga EO + 5% E. globulus EO and against An. minimus was 5% Zingiber cassumunar EO + 5% E. globulus EO. Moreover, the highest synergistic effects in ovicidal activities against Ae. albopictus and An. minimus were achieved by 10% Zingiber cassumunar EO + 10% E. globulus EO and 5% Curcuma zedoaria EO + 5% E. globulus EO, respectively. For the adulticidal activities, the highest synergistic effect against two mosquitoes was achieved by 5% Curcuma zedoaria EO + 5% E. globulus EO. Conclusions: These results suggest that Zingiberaceae plant EOs augmented with E. globulus EO have a high potential to be developed into oviposition deterrent, ovicidal, and adulticidal agents for controlling populations of Ae. albopictus and An. minimus.

Larvicidal efficacy of crude and fractionated extracts of Dracaena loureiri Gagnep against Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Anopheles minimus mosquito vectors

Objective: To evaluate the larvicidal efficacy of crude and fractionated extracts of Dracaena loureiri endocarp against Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Anopheles minimus mosquitos. Methods: Larvicidal activity was tested according to World Health Organization standard protocol.The third-stage larvae of each mosquito species were exposed to various concentrations of Dracaena loureiri crude extract and six groups of Dracaena loureiri fractionated extracts (RC-DT 009–014). Larval mortality rates were observed after 24 h and 48 h of exposure.Then, a computerized probit analysis of the mortality data was performed to determine lethal concentration 50 (LC50) and lethal concentration 90 values. Results: Anopheles minimus larvae (24-h LC5077.88 mg/L) had the highest susceptibility to crude extract, whereas others (Aedes aegypti, 24-h LC50224.73 mg/L; Aedes albopictus, 24-h LC50261.75 mg/L; and Culex quinquefasciatus, 24-h LC50282.86 mg/L) were significantly less susceptible. The most effective groups of fractionated extracts were RC-DT 012 and RC-DT 013. The mosquito species most susceptible to fractionated extracts was Culex quinquefasciatus, with 24-h LC50 values of 0.66 and 0.94 mg/L for RC-DT 012 and RC-DT 013, respectively. Conclusions: The larvicidal activity of fractionated extracts is more effective than that of crude extract against all tested mosquito species. For the most effective alternative larvicide, purification and a phytochemical constituent analysis must be performed.

Larvicidal efficacy of crude and fractionated extracts of Dracaena loureiri Gagnep against Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Anopheles minimus mosquito vectors

Objective: To evaluate the larvicidal efficacy of crude and fractionated extracts of Dracaena loureiri endocarp against Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Anopheles minimus mosquitos. Methods: Larvicidal activity was tested according to World Health Organization standard protocol. The third-stage larvae of each mosquito species were exposed to various concentrations of Dracaena loureiri crude extract and six groups of Dracaena loureiri fractionated extracts (RC-DT 009-014). Larval mortality rates were observed after 24 h and 48 h of exposure. Then, a computerized probit analysis of the mortality data was performed to determine lethal concentration 50 (LC

Estimation of vectorial capacity of Anopheles minimus Theobald & An. fluviatilis James (Diptera: Culicidae) in a malaria endemic area of Odisha State, India.

Background & objectives: Anopheles minimus and An. fluviatilis were incriminated as the major malaria vectors in Keonjhar district of Odisha State recently. This study was carried out to elucidate the potential role of these two vector species in transmission of malaria during different seasons, and vectorial capacity of these species was also estimated. Methods: Three hilly and forested villages of Keonjhar district were randomly selected. Vectorial capacity (C) was calculated using the Macdonald’s formula as modified by Garret-Jones. The human landing density of the vector species was obtained from all night human landing collections (bait protected by bed-net). Man feeding habit was estimated by multiplying the human blood index with feeding frequency, which was obtained on daily basis from the duration of gonotrophic cycle. The probability of survival through the extrinsic incubation cycle was calculated from the probability of survival through one day and duration of sporogonic cycle. Results: The estimated vectorial capacity of An. minimus varied between 0.014 and 1.09 for Plasmodium falciparum (Pf) and between 0.1 and 1.46 for P. vivax (Pv). The C of An. minimus for both Pf and Pv was higher during rainy season than the other two seasons. The estimated C of An. fluviatilis varied between 0.04 and 1.28 for Pf and between 0.20 and 1.54 for Pv. Interpretation & conclusions: Based on the estimated values of vectorial capacity of the two vector species, the area could be stratified and such stratification would reflect the difference in the intensity of transmission between different strata and accordingly the appropriate control strategy could be adopted for each stratum.

Genetic diversity and gene structure of mitochondrial region of Anopheles minimus (Diptera: Culicidae) - major malaria vector of North east India

Objective: To depict mitochondrial genetic variation for the first time among Anopheles minimus (. An.minimus) (Diptera: Culicidae) species from two malaria endemic states of NE India. Methods: Phylogeographic analysis was carried at 9 out of 12 sites of An.minimus confirmed malaria endemic places. Results: All sequences were Adenine-Thymine rich regions. Transitions were observed in 6 sequences where 5 mutations were synonymous substitutions and in 1 case non synonymous mutation was observed. Three distinct clusters of haplotypes were generated. Haplotype diversity and low nucleotide diversity were studied. Overall negative values obtained from Tajima's D test and Fu'sF

Genetic diversity and gene structure of mitochondrial region of Anopheles minimus (Diptera: Culicidae) - major malaria vector of North east India

OBJECTIVE@#To depict mitochondrial genetic variation for the first time among Anopheles minimus (An.minimus) (Diptera: Culicidae) species from two malaria endemic states of NE India.@*METHODS@#Phylogeographic analysis was carried at 9 out of 12 sites of An.minimus confirmed malaria endemic places.@*RESULTS@#All sequences were Adenine-Thymine rich regions. Transitions were observed in 6 sequences where 5 mutations were synonymous substitutions and in 1 case non synonymous mutation was observed. Three distinct clusters of haplotypes were generated. Haplotype diversity and low nucleotide diversity were studied. Overall negative values obtained from Tajima's D test and Fu'sFS test indicate a recent genetic population expansion. Network analysis has explained sequence diversity that was also shown by mutations in 6 sequences.@*CONCLUSIONS@#High genetic diversity observed within the populations of An.minimus species has several possible implications for vector control in the region.

Risk assessment of re-emerging Plasmodium falciparum on Ishigaki Island using a stochastic transmission model

On Ishigaki Island, <I>Plasmodium falciparum</I> and <I>Plasmodium vivax</I> epidemics occurred in 1945-1946 and were successfully suppressed. The epidemic re-emerged in 1949 because many settlers immigrated to the former endemic areas, but it terminated in 1961. The present study aimed at predicting an outbreak of a new epidemic based on the situation in which <I>P. falciparum</I> malaria patients stay on Ishigaki Island and also examined the re-emergence of the <I>P. falciparum</I> epidemic in 1951-1960 to determine the reliability of the model.<br>A stochastic transmission model of <I>P. falciparum</I> was constructed to detect a small number of infected persons. The seasonal fluctuation of the <I>Anopheles minimus</I> population obtained by observational data and meteorological data through statistical processing was introduced into the model.<br>Simulations were carried out to predict the risk of a new epidemic with scenarios in which the attribute of index patient, visiting season, and reduced inoculation rates of <I>An. minimus</I> were assumed. When an infected person visited the island in summer, a small number of patients with primary infections derived from the index patient appeared for all 1,000-iterations. On the other hand, when an infected person visited the island in winter, few or no patients with primary infections appeared for any of the 1,000-iterations because of the low mosquito density. In realistic conditions, the simulation results showed that there was little possibility of the occurrence of <I>P. falciparum</I> infection.

The efficacy of integrated method controlling Xenopsylla cheopis and Anopheles minimus in Hoa Binh province

A research was conducted in 2001 and 2002 to evaluate the efficacy of remaining spray by using Permethrin 50EC to kill both kinds of vectors: Xenopsylla cheopis and Anopheles minimus, responsible for plague and malaria transmission, respectively. The results showed that Permethrin 50EC at the concentration of 0.5g/m2 was highly effective to kill Xenopsylla cheopis and Anopheles minimus and remained effective for 4 months

Effects of temperature and source of blood on development of Anopheles minimus in laboratory

Experiments were caried out on An.minimus F98 in laboratory conditions of 22+/- 1°C, 25+/- 1°C and 28 +/- 1°C, 70-80% RH. The time required for egg stage and egg hatching rate were negatively correlated with temperature. At 22 +/- 1°C, egg hatching rate was 84.1 %, the duration of the egg stage was 3-4 days. At 25+/-1°C and 28 +/-1oC, egg hatching rate was 77.3% and 65.5%, respectively, the time of the egg stage were 2-3 days. At higher temperature, the duration of larvae stage was shorter than at the lower temperature. 25°C was optimum temperature for larvae with 38% of larvae developed to adults. 1 day after molting, mosquitoes started feeding at all tested temperatures. At 22°C, blood feeding rate higher than at the higher temperatures. Number of eggs and egg hatching rate of mosquitoes that fed human blood were higher than mosquitoes fed on mice

Physicochemical factors affecting the breeding of Anopheles minimus var. flavirostris

A selected number of physicochemical factors were studied to determine their effect upon the breeding of A. minimus var. flovirostris, the chief vector of malaria in the Philippines. To this end, a comparison was made between one portion of a stream found to be constantly positive for A. minimus and another portion of the same stream consistently negative for the larvae of this mosquito. Comparisons were also made between two positive and two negative wells. The results of a total of 233 observations indicate the preference of A. minimus for water of high purity with high oxygen but low carbon dioxide contents. (Summary and conclusions)

The occurence of Anopheles minimus flavirostric (Ludlow) in the City of Manila

1) The first recorded occurrence of Anopheles minimus flavirostris breeding within the city limits of Manila is reported2) A total of 66 larvae, 1 pupa and 1 adult of A. minimus flavirostris was obtained in two streams situated in the vicinity of the North Cemetery, a hundred yards or so from the thickly populated areas. In addition to A. minimus flavirostris, other species of anophelines were also found, such as A. manalangi, A. hycranus nigerrimus, A. hycranus lesteri, A. filipinas, A. tessellatus, A. litoralis, A. subpictus indefinitus3) This study has demonstrated that, as Holt and Russell have said, "A. minimus is a versatile creature and does not limit itself to the classical breeding places"4) The great losses suffered by the animal population during the war greatly reduced the animal barriers and allowed the vector to wander far and wide for blood and gave it an opportunity to migrate to other breeding places5) With this discovery of the malaria vector within the confines of the city it is impossible to deny the likelihood that malaria may be contracted in Manila6) The history of a 2-year old child living near the breeding place, whose blood was found positive for P. falciparum, strongly suggests an infection contracted in Manila. (Summary and Conclusion)

Sporozoites of plasmodium sp. in anopheles mangyanus and oocysts in A. kochi

Dissections of anopheles mosquitoes in Tabla Valley, Cauayan, Occidental Negros (Philippines), conducted to determine the existence of malaria vectors other than A. minimus flavirostris in the Philippines, showed the following results: 1) Oocysts and sporozoites were found in A. mangyanus2) Infected guts and glands in A. minimus flavirostris were also demonstrated3) Oocysts were found in A. kochiAlthough it was not possible to ascertain if the sporozoites and oocysts found were those of human, avian or simian malaria, there is a strong presumption to incriminate A. mangyanus as a vector of human malaria in the Philippines. (Summary)

Observation on Polytene Chromosomes of the Ovarian Nurse Cell of Anopheles minimus from Yuanjiang / 中国寄生虫学与寄生虫病杂志

Anopheles minimus collected from Yuanjiang, Yunnan Province, were bred with standard methods in lab. The ovarian nurse cells of A.minimus were separated and stained, and the whole polytene chromosomes were photographed under light microscope and compared with A.minimus from Guangxi. 365 samples of ovarian nurse cells were observed. The chromosomes included one telocentric sex-chromosome X, two submetacentric autosomes II(autosome II right arm, 2R and autosome II left arm, 2L) and two metacentric autosomes III(autosome III right arm, 3R, and autosome III left arm, 3L). The X is the shortest chromosome and the 2R is the longest one. In comparison with the pattern of polytene chromosomes of A. minimus from Guangxi, difference at 12 positions has been found at the parts of arms in banding sequences.

Study on a Grey Model for Evaluation of Anopheles minimus Density / 中国寄生虫学与寄生虫病杂志

wet season temperature_max. The An. minimus density evaluation model was derived as follows: y=0

Molecular Variation Based on mtDNA-COII Gene of Members of the Anopheles minimus Group / 中国寄生虫学与寄生虫病杂志

Objective To investigate intra and inter species molecular variations and phylogeny of the five members of the Minimus Group of Anopheles subgenus Cellia in China: An. aconitus, An.varuna, An.jeyporiensis, An.minimus A and An.minimus C, and to report the DNA sequence divergence among these species at a mitochondrial locus (cytochrome oxidase II). Methods Single mosquito′s legs were digested to extract DNA. COII gene was amplified, sequenced and analysed; and the phylogenetic tree of members of An.minimus group was reconstructed by maximum likelihood method (DNAML). Results and Conclusion The data confirmed the presence of two cryptic species, A and C, within An.minimus complex in the research localities; and two species differed by 2.3% in the COII sequences owing to 16 nucleotide substitutions. There was less variation between the two species than other members of the Minimus Group.