Atila Yanikoglu

A study of the larvicidal activity of Origanum (Labiatae) species from southwest Turkey

ABSTRACT The insecticidal activity of essential oils isolated from two species of Origanum (Origanum onites L. and Origanum minutiflorum (O. Schwarz and P.H. Davis) (Labiate)) was investigated against 3rd and 4th instar larvae of the mosquito, Culex pipiens L. (Diptera: Culicidae). The LC50 and LC90 values were 24.8 and 61.3 ppm, and 73.8 and 118.9 ppm, respectively. This activity was attributed to the carvacrol, the major constituent of these oils.

Acaricidal activity of Satureja thymbra L. essential oil and its major components, carvacrol and γ-terpinene against adult Hyalomma marginatum (Acari: Ixodidae)

The acaricidal activity of a volatile essential oil hydrodistillate of Satureja thymbra L. (Lamiaceae) and its major constituents, carvacrol and gamma-terpinene, were evaluated against field-collected unfed adult Hyalomma marginatum. The distillate was tested against this tick species at 5, 10, 20, and 40 microL/L while the two major components were each tested at 10 microL/L. Generally, tick mortality to the S. thymbra distillate increased with concentration and exposure time. Ticks exposed to vapors from cotton wicks containing at least 40 microL/L resulted in complete (100%) mortality at 3h. The lower concentrations provided >or=90% mortality at 3h post treatment with complete mortality at 24h. Knockdown was observed only in the carvacrol and gamma-terpinene treatments. Ticks exposed to carvacrol-treated wicks produced >93% knockdown at 3h but at 24h approximately 57% were dead. The gamma-terpinene treatment produced >or=90% knockdown at 105 min through 3h but at 24h only about 87% of the ticks were dead.

Acaricidal effects of the essential oil of Origanum minutiflorum (Lamiaceae) against Rhipicephalus turanicus (Acari: Ixodidae)

The acaricidal effects of the volatile essential oil Origanum minutiflorum O. Schwarz & P.H. Davis (Lamiaceae) against adult Rhipicephalus turanicus was evaluated at a variety of concentrations and exposure times. Generally tick mortality increased with concentration and exposure. Ticks exposed to vapors from cotton wicks containing at least 10mul/L resulted in complete (100%) mortality at 120min. The major constituent of essential oil obtained from the plant material of O. minutiflorum was carvacrol.

Insecticidal activity of major lichen compounds, (−)- and (+)-usnic acid, against the larvae of house mosquito, Culex pipiens L.

In this research, (−)-usnic acid and (+)-usnic acid, commonly encountered lichen secondary metabolites, were evaluated for their insecticidal effects against the larvae of Culex pipiens L. (Diptera: Culicidae) under laboratory conditions. Both compounds showed strong larvicidal activity and caused 100% mortality on third–fourth larval stages of the species at 24xa0h at the doses of 5 and 10xa0ppm. Bioassays with (−)- and (+)-usnic acids against larvae of C. pipiens revealed that the LC50 values were 0.8 and 0.9xa0ppm, respectively. The results suggest that lichen compounds could be useful in the search of new insecticides.

Genotoxicity testing of five herbicides in the Drosophila wing spot test.

Four triazine herbicides: amitrole, metribuzin, prometryn and terbutryn, and the bipyridal compound diquat dibromide have been evaluated for genotoxicity in the wing somatic mutation and recombination test of Drosophila melanogaster, following standard procedures. Third-instar larvae trans-heterozygous for the third chromosome recessive markers multiple wing hairs (mwh) and flare-3 (flr(3)) were chronically fed with different concentrations of the test compounds. Feeding ended with pupation of the surviving larvae. Genetic changes induced in somatic cells of the wings imaginal discs lead to the formation of mutant clones on the wing blade. Point mutation, chromosome breakage and mitotic recombination produce single spots; while twin spots are produced only by mitotic recombination. Exposure to 0.5 mM and 1 mM of amitrole clearly increased the frequency of small single, large single and total spots. Terbutryn, at the concentration of 5 mM, induced a slight increase in the frequency of small single and total spots, but this result could be false positive. The other three herbicides tested did not show any genotoxic effect. When heterozygous larvae for mwh and the multiple inverted TM3 balancer chromosomes were treated, significant increases in the frequency of mutant spots were only detected for amitrole. The observed spot frequencies were lower than those found in mwh/flr(3)50%) of the total spot induction was due to mitotic recombination.

Larvicidal activity of selected plant hydrodistillate extracts against the house mosquito, Culex pipiens , a West Nile virus vector

The larvicidal activity of hydrodistillate extracts from Chrysanthemum coronarium L., Hypericum scabrum L., Pistacia terebinthus L. subsp. palaestina (Boiss.) Engler, and Vitex agnus castus L. was investigated against the West Nile vector, Culex pipiens L. (Diptera: Culicidae). Yield and identification of the major essential oils from each distillation was determined by GC-MS analyses. The major essential oil component for each plant species was as follows: α-pinene for P. terebinthus palaestina, and H. scabrum (45.3% and 42.3%, respectively), trans-β-caryophyllene for V. agnus castus (22.1%), and borneol for C. coronarium (20.9%). A series of distillate concentrations from these plants (that ranged from 1xa0ppm to 500xa0ppm, depending on plant species) were assessed against late third to early fourth C. pipiens larvae at 1, 6, and 24xa0h posttreatment. In general, larval mortality to water treated with a distillate increased as concentration and exposure time increased. H. scabrum and P. terebinthus palaestina were most effective against the mosquito larvae and both produced 100% mortality at 250xa0ppm at 24-h continuous exposure compared with the other plant species. Larval toxicity of the distillates at 24xa0h (LC50 from most toxic to less toxic) was as follows: P. terebinthus palaestina (59.2xa0ppm) > H. scabrum (82.2xa0ppm) > V. agnus castus (83.3xa0ppm) > C. coronarium (311.2xa0ppm). But when LC90 values were compared, relative toxicity ranking changed as follows: H. scabrum (185.9xa0ppm) > V. agnus castus (220.7xa0ppm) > P. terebinthus palaestina (260.7xa0ppm) > C. coronarium (496.3xa0ppm). Extracts of native Turkish plants continue to provide a wealth of potential sources for biologically active agents that may be applied against arthropod pests of man and animals.

Use of the drosophila wing spot test in the genotoxicity testing of different herbicides.

Four herbicides, namely propanil, maleic hydrazide, glyphosate, and 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T), were investigated for genotoxicity in the wing spot test of Drosophila melanogaster. The herbicides were administered by chronic feeding to 3‐day‐old larvae. Two different crosses, a standard (ST) and a high‐bioactivation (HB) cross, involving the flare‐3 (flr3) and the multiple wing hairs (mwh) markers, were used. The HB cross uses flies characterized by an increased cytochrome P‐450–dependent bioactivation capacity, which permits a more efficient biotransformation of promutagens and procarcinogens. In both crosses, the wings of the two types of progeny, which are inversion‐free marker heterozygotes and balancer heterozygotes, were analyzed. Maleic hydrazide and glyphosate proved to be more genotoxic in the ST cross, whereas propanil appeared to be slightly more genotoxic in the HB cross. On the other hand, the herbicide 2,4,5‐T increased the mutation frequency for only the small single spots in the ST cross. Environ. Mol. Mutagen. 36:40–46, 2000.

Genotoxicity is modulated by ascorbic acid studies using the wing spot test in Drosophila

The ability of ascorbic acid (Vitamin C) to modulate the genotoxic action of several mutagens was investigated in the wing spot test of Drosophila melanogaster. In this assay, 3-day-old transheterozygous larvae for the multiple wing hairs (mwh, 3-0.3) and flare (flr, 3-38.8) genes were treated with three reference mutagenic compounds, namely cobalt chloride (CoCl2), 4-nitroquinoline 1-oxide (4-NQO) and potassium dichromate (K2Cr2O7). The results obtained show that the three reference mutagens tested were clearly genotoxic in the Drosophila wing somatic mutation and recombination test (SMART). None of the three concentrations tested of ascorbic acid (25, 75 and 250mM) induced significant increases in the frequency of the mutant clones recorded. When co-treatment experiments with ascorbic acid were carried out, different results were found. Thus, ascorbic acid was effective in reducing the genotoxicity of K2Cr2O7 virtually to the control level; on the contrary, it did not show any antigenotoxic effect on the genotoxicity of 4-NQO. Finally, co-treatments with CoCl2 and ascorbic acid show a significant increase in the frequency of mutant clones over the values obtained with CoCl2 alone.

Larvicidal activity of novaluron, a chitin synthesis inhibitor, against the housefly, Musca domestica

Abstract A chitin synthesis inhibitor, novaluron, was evaluated under laboratory conditions for its larvicidal activity against a field population of the housefly, Musca domestica L. (Diptera: Muscidae), by feeding and dipping methods. The concentrations used were 1, 2.5, 5, 10 and 20 mg a.i./kg in both methods. The product caused >80% larval mortality at 10 and 20 mg a.i./kg. Of the two methods, feeding was more effective for larvicidal activity at doses above 2.5 mg a.i./kg. After 72 hours, the LC50 and LC90 values were 1.66 and 8.25 mg a.i./kg, respectively, with the feeding method; and 2.72 and 17.88 mg a.i./kg, respectively, using the dipping method. The results showed that the product provided good control of housefly larvae and would greatly reduce adult emergence.

Genotoxicity studies on the phenoxyacetates 2,4-D and 4-CPA in the Drosophila wing spot test.

The phenoxyacetates 2,4-D and 4-CPA were evaluated for genotoxicity using the Drosophila melanogaster wing spot test, which assesses for somatic mutation and recombination events. Third-instar larvae trans-heterozygous for two recessive mutations affecting the expression of wing trichomes, multiple wing hairs (mwh), and flare (flr) were treated by chronic feeding with different concentrations of the two chemicals. Feeding lasted until pupation of the surviving larvae and the genotoxic effects induced were evaluated in adults for the appearance of wing-blade cell clones with the mwh, flr, or mwh-flr phenotypes. Exposure to 2,4-D, at the highest concentration evaluated (10 mM), induced a weak but significant increase in the frequency of two of the categories of recorded spots: large single and total spots; in contrast, the 4-CPA treatments failed to induce any significant increase in the frequency of evaluated spots. When the heterozygous larvae for mwh and the multiple inverted TM3 balancer chromosome were treated with the chemicals, no increases were detected, either after the 2,4-D nor the 4-CPA treatments.