Carlos Granados-Echegoyen

Inhibition of the growth and development of mosquito larvae of Culex quinquefasciatus (Diptera: Culicidae) treated with extract from leaves of Pseudocalymma alliaceum (Bignonaceae).

OBJECTIVE To determine larvicidal activity of the essential oil, hydrolat and botanical extracts derived from leaves of Pseudocalymma alliaceum on mosquito larvae of Culex quinquefasciatus. METHODS Groups of twenty larvae were used in the larvicidal assays. The mortality, relative growth rate, the larval and pupal duration and viability was estimated. The essential oil was analyzed by solid phase microextraction using gas chromatography coupled to mass spectrometry. RESULTS Essential oil at 800 ppm showed larvicidal activity at 24 h with lethal values of LC50 and LC90 of 267.33 and 493.63 ppm. The hydrolat at 20% and 10% on 2nd stage larvae showed 100% effectiveness after 24 h. The aqueous extract at 10% had a relative growth index of 0.58, while the ethanolic and methanolic extract obtained values of 0.76 and 0.70 and control reached 0.99. Larvae treated with 10% of methanol, ethanol and aqueous extract showed a reduction in larval duration of 5.00, 2.20 and 4.35 days; ethanol extract at 1% provoke decrease of 2.40 days in the development and exhibited an increment of 3.30 days when treated with 0.01%. Aqueous, ethanol and methanol extracts at 10% reduced in 6.15, 3.42 and 5.57 days pupal development. The main compounds were diallyl disulfide (50.05%), diallyl sulfide (11.77%) and trisulfide di-2-propenyl (10.37%). CONCLUSIONS The study demonstrated for the first time, the larvicidal activity of the essential oil and hydrolat of Pseudocalymma alliaceum; aqueous, ethanol and methanol extracts inhibited the normal growth and development of mosquito larvae, prolonging and delaying larval and pupal duration.

Chemical characterization and mosquito larvicidal activity of essential oil from leaves of Persea americana Mill (Lauraceae) against Culex quinquefasciatus (Say)

Abstract Objective To determine chemical composition and mosquito larvicidal activity of essential oil from dried leaves of Persea americana against Culex quinquefasciatus. Methods About 20 larvae in each group were used for larvicidal assays. The mortality, relative growth index, larval and pupal duration and viability were estimated. The essential oil was analyzed by solid phase microextraction using gas chromatography coupled to mass spectrometry. Results The most abundant compounds were estragole (61.86%), sabinene (15.16%) and 1R-α-pinene (14.25%). The essential oil inhibited mosquito larvae growth up to 26.73% [relative growth index (RGI) = 0.74)] and 16.83% (RGI = 0.84) at 800 and 50 mg/L respectively, while the untreated control and group treated with polysorbate 20 showed the RGI of 1.01. The viability of larvae to pupae decreased 53.75% when used 800 mg/L essential oil causing prolongation of development of 14.14 days, while the control had durability in its development of 12 days. In the pupae-adult phase, when used 800 and 50 mg/L of essential oil, 22.36% and 21.81% adults were formed, and there was prolongation of 15.88 days and delay of 13.62 days respectively; however the control showed duration of 14.63 days. Mortality at the end of the experiment was recorded as 57.50% with treatment of 800 mg/L and gradually decreased to 40% with treatment of 50 mg/L essential oil. Conclusions The study demonstrated that the larvicidal activity of essential oil of Mexican avocado inhibited the normal growth and development of mosquito larvae, prolonged larval and pupal duration.

Insecticidal Effect of Botanical Extracts on Developmental Stages of Bactericera cockerelli (Sulc) (Hemiptera: Triozidae)

Abstract. Insecticidal effect of aqueous and ethanol extracts of dried leaves of Ambrosia artemisiifolia L., Piper auritum Kunth, and Taraxacum officinale F. H. Wiggwere determined on developmental stages of potato/tomato psyllid, Bactericera cockerelli (Sulc). When aqueous extract at 0.2 g/ml was applied to psyllid nymphs, A. artemisiifolia extract was most toxic, P. auritum was moderately toxic, and T. officinale was slightly less toxic. Ethanol extract of A. artemisiifolia killed more than 50% of 2nd, 3rd, and 5th instar nymphs treated with 0.001, 0.01, and 0.1 g/ml, respectively. P. auritum was effective on 3rd and 4th instars and T. officinale on 5th and 3rd instars at 0.01 and 0.1 g/ml, respectively. Ethanol extracts of the three plant species killed 50 to 60% of adults with 0.1 g/ml and 30 to 45% with 0.01 g/ml. Extracts of Argemone mexicana L., Azadirachta indica A. Juss, Petiveria alliacea L., and Tagetes filifolia Lag. were evaluated on 4th and 5th instar nymphs. Ethanol extract of leaves of A. mexicana at 0.2 g/ml killed 100% of 5th instar nymphs at 24 hours and 93% of 4th instars at 72 hours. A. indica, P. alliacea, and T. filifolia at 0.2 g/ml killed 85, 88, and 87%, respectively, of 5th instar nymphs.

Effects of aqueous and ethanol extract of dried leaves of Pseudocalymma alliaceum (Bignonaceae) on haematological and biochemical parameters of wistar rats

Abstract Objective To perform the toxicological evaluation of aqueous and ethanol extract of dried leaves of Pseudocalymma alliaceum ( P. alliaceum ) in male Wistar rats by oral administration for 14 days, and to determine the biochemical and haematological status of blood. Methods The animals were completely randomized into four groups of three rats each. Results No deaths were reported after oral administration of the extracts, no physical signs of toxicity or adverse effects were observed. Hematological indices of red blood cell count, hemoglobin concentration and mean corpuscular hemoglobin showed no significant abnormality; however, white series levels decrease presenting a leukopenia. Glucose, creatinine and albumin increased, while urea decreased; aspartate aminotransferase values decreased with the aqueous extract at 50 and 100 mg/kg and increased with dose of 200 mg/kg, in contrast ethanol extract caused an increase in this parameter to the doses used. The alanine aminotransferase decreased with aqueous extract and increased with ethanol extract. Triglycerides decreased when used aqueous extract and reduced with ethanol extract at 100 and 200 mg/kg, in contrast to 50 mg/kg decreased to be compared with control group. Conclusions The daily intake of P. alliaceum did not produce acute toxicity to 50 mg/kg which may be interpreted as toxic signs or biological damage, but liver and renal function changes at dosages of 100 and 200 mg/kg; however, the reduction ability of white blood cells count could be used as a basis for specific studies on the treatment of patients with leukemia.

Effects of Salinity and pH on the Infective Capacity of Romanomermis iyengari and Romanomermis culicivorax in Larvae of Culex quinquefasciatus Mosquito

Abstract. Effects of salinity and pH were assessed on the infective capacity of parasitic nematodes of mosquitoes Romanomermis culicivorax Ross & Smith and Romanomermis iyengari (Welch), on larvae of southern house mosquito, Culex quinquefasciatus Say. Thirteen pH levels (3.6, 3.8, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.2, and 8.4) were evaluated. Six salinity levels (NaCl concentrations) were evaluated, with values of 0.01 M (584 mg/L), 0.02 M (1,169 mg/L), 0.03 M (1,753) mg/L), 0.04 M (2,338 mg/L), 0.05 M (2,922 mg/L), and a 0.00 M check, with three replications. Percentage of infection (of parasitized larvae) and infestation intensity (average nematodes parasitizing a mosquito larva) were recorded for both factors. To determine effects of pH and salinity on percentage of infection and infestation intensity, a sample (n = 20, IV instar) of larvae surviving at high salinity levels was extracted 5 days after application. The greatest percentage of infection statistically significant in R. iyengari was 75 to 91.7 for pH 5.0 to 7.5, and 86.7 to 100 for R. culicivorax between pH 6.0 and 7.0. The greatest infestation intensity statistically significant in R. iyengari was 4.42 to 8.45 between pH 4.5 and 8.0. The greatest levels of infestation statistically significant in R. culicivorax were between pH 5.0 and 7.5 with 3.07 and 3.63 nematodes per mosquito larva.

Larvicidal effect of Clinopodium macrostemum essential oil extracted by microwave-assisted hydrodistillation against Culex quinquefasciatus (Diptera: Culicidae)

INTRODUCTION In the present study, we determined the chemical composition of Clinopodium macrostemum essential oil obtained by microwave-assisted hydrodistillation and its effect on the growth and development of Culex quinquefasciatus mosquito larvae. METHODS The essential oil compounds were identified by gas chromatography-mass spectrometry analysis, and bioassays were conducted to evaluate the influence on the developmental stages of early second instar larvae of Cx. quinquefasciatus until the emergence of adults, using essential oil concentrations of 50, 100, 200, 400, and 800mg/L. RESULTS The gas chromatography-mass spectrometry analyses revealed that the leaf essential oil of C. macrostemum contained 32 compounds and the major chemical compounds identified were linalool (55.4%), nerol (6.4%), caryophyllene (6.25%), menthone (5.8%), geraniol acetate (4.1%), terpineol (3.7%), and pulegone (2.8%). The essential oil yield obtained by microwave-assisted hydrodistillation was 0.8% at 20 min. The treatments showed lethal concentrations (LC50 and LC90) of 22.49 and 833.35mg/L, respectively, after the final measurement of the total number of dead larvae (second, third, and fourth instars), and LC50 and LC90 of 6.62 and 693.35mg/L, respectively, at the end of the experimental period. The essential oil inhibited the growth and development of the mosquito larvae by 32% (relative growth index = 0.68) at 50mg/L, and up to 47% (relative growth index = 0.53) at 800mg/L. CONCLUSION The present study demonstrated the larvicidal effect of C. macrostemum essential oil on Cx. quinquefasciatus, which can be attributed to the oxygenate compounds obtained by the extraction method.

Argemone mexicana (Papaverales: Papavaraceae) as an Alternative for Mosquito Control: First Report of Larvicidal Activity of Flower Extract

Abstract Culex quinquefasciatus Say (Diptera: Culicidae), an arboviral and filarial vector, is one of the most widespread mosquitoes in the world. The indiscriminate use of synthetic chemical insecticides has led to the development of resistance in mosquito populations worldwide. The effect of continuous exposure to crude extracts of Argemone mexicana, the Mexican poppy, on the development and growth stages of second-instar larvae of the mosquito was studied, along with qualitative chemical analysis of the different plant parts. Inhibition, mortality, and larval and pupal duration phases were assessed. Second-instar mosquito larvae were exposed to crude ethanol extracts of flowers, stems, and seeds. Flower extract exhibited the strongest larvicidal activity with LC50 and LC90 values after 24 h of exposure of 18.61 and 39.86 ppm, respectively, and 9.47 and 21.76 ppm after 48 h. Extracts from stem and seeds were significantly less effective. The flower extract registered a Growth Inhibition Index of 0.01 at 25 ppm, with stems and seeds registering 0.05 and 0.08, respectively, at 100 ppm (control group 1.02). Qualitative chemical analysis by thin-layer chromatography showed characteristic spots indicating the presence of alkaloids and flavonoids and phytochemical screening showed the presence of alkaloids, anthraquinones, flavonoids, tannins, and terpenoids in the various crude extracts. This is the first report of the effectiveness of an ethanol flower extract of A. mexicana on Cx. quinquefasciatus; it can be considered a promising alternative control for this mosquito species.

Antimicrobial engineered nanoparticles in the built cultural heritage context and their ecotoxicological impact on animals and plants: a brief review

Nanoparticles (NPs) of metal oxides, sometimes referred to as engineered nanoparticles have been used to protect building surfaces against biofilm formation for many years, but their history in the Cultural Heritage world is rather short. Their first reported use was in 2010. Thereafter, a wealth of reports can be found in the literature, with Ti, Ag and Zn oxides being the major protagonists. As with all surface treatments, NPs can be leached into the surrounding environment, leading to potential ecotoxicity in soil and water and associated biota. Dissolution into metal ions is usually stated to be the main mode of toxic action and the toxic effects, when determined in the marine environment, decrease in the order Au > Zn > Ag > Cu > Ti > C60, but direct action of NPs cannot be ruled out. Although ecotoxicity has been assessed by a variety of techniques, it is important that a suitable standard test be developed and the European Unions’s Biocidal Product Registration group is working on this, as well as a standard test for antimicrobial efficacy to determine their impact on ecological processes of surrounding non-target organisms and their transformation products under realistic scenarios.