Evaluation of larvicidal activity of Pongamia pinnata extracts against three mosquito vectors

Objective

To evaluate the mosquito larvicidal activity of Pongamia pinnata (P. pinnata) extracts against three mosquito vectors.

Methods

The methanol and hydroalcohol extracts of bark part of P. pinnata L were tested against fourth instar larvae of Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi. The mortality was observed 24 h and 48 h after treatment, data was subjected to probit analysis to determine lethal concentration (LC₅₀ and LC₉₀) to kill 50 and 90 percent of treated larvae of tested species.

Results

The larval mortality was found in both methanol and hydroalcohol extracts of P. pinnata against Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi with LC₅₀ values of 84.8, 118.2 and 151.7 ppm; 97.7, 128.3 and 513 ppm. The highest larval mortality was found in methanol extract of P. pinnata when comparable to the hydroalcohol extract.

Conclusions

These results suggest that both methanol and hyrdoalcohol extracts have the potential to be used as an ideal ecofriendly approach for the control of disease vectors. This could lead to isolation of novel natural larvicidal compounds.     

Larvicidal and irritant activities of hexane leaf extracts of Citrus sinensis against dengue vector Aedes aegypti L.

Objective

To assess the larvicidal and irritant activities of the hexane extracts of leaves of Citrus sinensis (C. sinensis) against the early fourth instars and female adults of Aedes aegypti (Ae. aegypti).

Methods

The larvicidal potential of the prepared leaf extract was evaluated against early fourth instar larvae of Ae. aegypti using WHO protocol. The mortality counts were made after 24 h and LC₅₀ and LC₉₀ values were calculated. The efficacy of extract as mosquito irritant was assessed by contact irritancy assays. Extract-impregnated paper was placed on a glass plate over which a perspex funnel with a hole on the top was kept inverted. Single female adult, 3-day old unfed/blood-fed, was released inside the funnel. After 3 min of acclimatization time, the time taken for the first take-off and total number of flights undertaken during 15 min were scored.

Results

The citrus leaf extracts from hexane possessed moderate larvicidal efficiency against dengue vector. The bioassays resulted in an LC₅₀ and LC₉₀ value of 446.84 and 1 370.96 ppm, respectively after 24 h of exposure. However, the extracts were proved to be remarkable irritant against adults Ae. aegypti, more pronounced effects being observed on blood-fed females than unfed females. The extract-impregnated paper was thus proved to be 7–11 times more irritable as compared with the control paper.

Conclusions

The hexane extracts from C. sinensis leaves are proved to be reasonably larvicidal but remarkably irritant against dengue vector. Further studies are needed to identify the possible role of extract as adulticide, oviposition deterrent and ovicidal agent. The isolation of active ingredient from the extract could help in formulating strategies for mosquito control.     

Bioactivity of seagrass against the dengue fever mosquito Aedes aegypti larvae

Objective

To identify the larvicidal activity of the seagrass extracts.

Methods

Seagrass extracts, Syringodium isoetifolium (S. isoetifolium), Cymodocea serrulata and Halophila beccarii, were dissolved in DMSO to prepare a graded series of concentration. Batches of 25 early 4th instars larvae of Aedes aegypti (Ae. aegypti) were transferred to 250 mL enamel bowl containing 199 mL of distilled water and 1 mL of plant extracts (0.01 mg – 0.1 mg). After 24 h the mortality rate was identified with the formulae [(% of test mortality – % of control mortality)/(100 – % of control mortality)] × 100. Each experiment was conducted with three replicates and a concurrent control group. A control group consisted of 1 mL of DMSO and 199 mL of distilled water only.

Results

: The root extract of S. isoetifolium showed maximum larvicidal activity with minimum concentration of extract of LC₅₀= 0.0 604 ± 0.0 040)µg/mL with lower confidence limit (LCL) – upper confidence limit (UCL) = (0.051–0.071) and LC₉₀=0.0 972µg/mL followed by leaf extract of S. isoetifolium showed LC₅₀= (0.062 ± 0.005)µg/mL. The regression equation of root and leaf extract of S. isoetifolium for 4th instar larvae were Y= 4.909 + 1.32x (R²= 0.909) and Y= 2.066 + 1.21x (R² =0.897) respectively. The results of the preliminary phytochemical constituents shows the presence of saponin, steroids, terpenoid, phenols, protein and sugars.

Conclusions

From the present study the ethanolic extracts of seagrass of S. isoetifolium possesses lead compound for development of larvicidal activity.     

Bioefficacy of Mentha piperita essential oil against dengue fever mosquito Aedes aegypti L

Objective

To assess the larvicidal and repellent potential of the essential oil extracted from the leaves of peppermint plant, Mentha piperita (M. piperita) against the larval and adult stages of Aedes aegypti (Ae. Aegypti).

Methods

The larvicidal potential of peppermint oil was evaluated against early fourth instar larvae of Ae. aegypti using WHO protocol. The mortality counts were made after 24 and 48 h, and LC₅₀ and LC₉₀ values were calculated. The efficacy of peppermint oil as mosquito repellent was assessed using the human-bait technique. The measured area of one arm of a human volunteer was applied with the oil and the other arm was applied with ethanol. The mosquito bites on both the arms were recorded for 3 min after every 15 min. The experiment continued for 3 h and the percent protection was calculated.

Results

The essential oil extracted from M. piperita possessed excellent larvicidal efficiency against dengue vector. The bioassays showed an LC₅₀ and LC₉₀ value of 111.9 and 295.18 ppm, respectively after 24 h of exposure. The toxicity of the oil increased 11.8% when the larvae were exposed to the oil for 48 h. The remarkable repellent properties of M. piperita essential oil were established against adults Ae. aegypti. The application of oil resulted in 100% protection till 150 min. After next 30 min, only 1-2 bites were recorded as compared with 8-9 bites on the control arm.

Conclusions

The peppermint essential oil is proved to be efficient larvicide and repellent against dengue vector. Further studies are needed to identify the possible role of oil as adulticide, oviposition deterrent and ovicidal agent. The isolation of active ingredient from the oil could help in formulating strategies for mosquito control.     

Tagetes erecta Linn. and its mosquitocidal potency against Culex quinquefasciatus

Objective

To investigate mosquitocidal effects of ethanolic extract of flowers of Tagetes erecta (T. erecta) and its chloroform and petroleum ether soluble fractions against the larvae of Culex quinquefasciatus (Cx. quinquefasciatus).

Methods

The fresh flowers of T. erecta were extracted in cold with ethanol (5.0 L) and after concentration, the ethanol extract was fractionated with chloroform and petroleum ether to afford a brownish syrupy suspension of ethanol extract (50.0 g), petroleum ether soluble fraction (18.6 g) and chloroform soluble fraction (23.8 g). The larvicidal effect of ethanol extract and their solvent fractions were determined by the standard procedure of WHO against different instars of Cx. quinquefasciatus.

Results

Among the tested samples the chloroform soluble fractions showed the highest toxicity and consequently, the lowest LC₅₀ values (14.14 µg/mL, 17.06 µg/mL, 36.88 µg/mL and 75.48 µg/mL) for all the instars larvae of Cx. quinquefasciatus. The larvae showed comparative tolerance in the course of increasing age and time.

Conclusions

It can be concluded that the flowers of T. erecta are very effective natural larvicide and could be useful against Cx. quinquefasciatus.     

Control of human filarial vector,Culex quinquefasciatus Say 1823 (Diptera: Culicidae) through bioactive fraction of Cayratia trifolia leaf

Objective

To investigate the mosquito larvicidal activity of Cayratia trifolia (L.) Domin (Vitaceae: Vitales) (C. trifolia) which is distributed in many parts of India with medicinal properties as vector control is facing threat due to the emergence of resistance to synthetic insecticides.

Methods

Young and mature leaves of C. trifolia were investigated for larvicidal activity against 3rd instars larvae of Culex quinquefasciatus in different seasons throughout the year. The active fractions were extracted using six different solvents in a non-polar to polar fashion viz petroleum-ether, benzene, chloroform: methanol (1:1 v/v), acetone, absolute alcohol and distilled water. Dose dependent mortality was recorded against each solvent extract. Determination of LD₅₀ and LD₉₀ were executed through log-probit analysis using the most bioactive fraction. The fluctuations in mortality were statistically co-related through ANOVA analyses concerning different seasons and types of leaves as random variables. Justification of larvicidal activity was established through student''s t-test. Costing effects were evaluated on the non-target water fauna under laboratory conditions. Thin layer chromatographic techniques were performed for phytochemical analysis and categorization of chemical personality of the active fractions using the most effective solvent extract following standard methods.

Results

Significant variations in mortality rate were noted with respect to the type of leaves (mature and senescence), concentration of leaf extract and between seasons. The water extract among all the solvent extracts was found to induce cent percent mortality at 50 mg/L in test mosquito species within 24 h with a LD₅₀ and LD₉₀ value of 10.70 mg/L and 27.64 mg/L respectively. No significant mortality was recorded in non-target water population. Chromatographic analyses of the water extract revealed the presence of steroids, triterpene glycosides, essential oil, phenolics and diterpenes as secondary phytochemicals.

Conclusions

Water extract of C. trifolia leaf promised as a cost effective and potent larvicidal agent against Culex quinquefasciatus.     

Larvicidal and repellent potential of Moringa oleifera against malarial vector,Anopheles stephensi Liston (Insecta: Diptera: Culicidae)

Objective

To evaluate the larvicidal and pupicidal potential of the methanolic extracts from Moringa oleifera (M. oleifera) plant seeds against malarial vector Anopheles stephensi (A. stephensi) mosquitoes at different concentrations (20, 40, 60, 80 and 100 ppm).

Methods

M. oleifera was collected from the area of around Bharathiar University, Coimbatore. The dried plant materials were powdered by an electrical blender. From each sample, 100 g of the plant material were extracted with 300 mL of methanol for 8 h in a Soxhlet apparatus. The extracts were evaporated to dryness in rotary vacuum evaporator to yield 122 mg and 110 mg of dark greenish material (residue) from Arcang amara and Ocimum basilicum, respectively. One gram of the each plant residue was dissolved separately in 100 mL of acetone (stock solution) from which different concentrations, i.e., 20, 40, 60, 80 and 100 ppm were prepared.

Results

Larvicidal activity of M. oleifera exhibited in the first to fourth instar larvae of the A. stephensi, and the LC₅₀ and LC₉₀ values were 57.79 ppm and 125.93 ppm for the first instar, 63.90 ppm and 133.07 ppm for the second instar, 72.45 ppm and 139.82 ppm for the third instar, 78.93 ppm and 143.20 ppm for the fourth instar, respectively. During the pupal stage the methanolic extract of M. oleifera showed that the LC₅₀ and LC₉₀ values were 67.77 ppm and 141.00 ppm, respectively.

Conclusions

The present study indicates that the phytochemicals derived from M. oleifera seeds extracts are effective mosquito vector control agents and the plant extracts may be used for further integrated pest management programs.     

Lead levels of Culex mosquito larvae inhabiting lead utilizing factory

Objective

To determine lead level primarily in Culex quinquefasciatus (Cx. quinquefasciatus), and Culex gelidus (Cx. gelidus) larvae inhabiting lead consuming factories, and to putatively estimate eco-toxicological impact of effluents from the firms.

Methods

Third instars larvae were sampled by standard dipping method and lead concentrations in the larvae and their respective surrounding factory aquatic environments were determined through standard atomic absorption spectrophotometry (AAS).

Results

Cx. quinquefasciatus was the most abundant species followed by Cx. gelidus. The levels of lead were higher in the Cx. quinquefasciatus (1.08-47.47 µg/g), than in the wastewaters surface (0.01-0.78 µg/mL) from the factories or closer areas around factories. Other species were not reaching the criteria for lead determination.

Conclusions

The Cx. quinquefasciatus larvae can bio-accumulate the metal and can potentially serve as a biomarker of lead contamination, to complemente conventional techniques.     

Isolation and efficacy of entomopathogenic fungus (Metarhizium anisopliae) for the control of Aedes albopictus Skuse larvae: suspected dengue vector in Pakistan

Objective

To isolate the entomopathogenic fungus Metarhizium anisopliae (M. anisopliae) in the local environment, and evaluate its efficacy against the suspected dengue vector Aedes albopictus in Pakistan.

Methods

According to the standard procedure, M. anisopliae was isolated from the dead mosquitoes which were collected from the field or dead after the collection. Bioassay was performed to determine its efficacy.

Results

The results indicated that M. anisopliae had larvicidal effect with LC₅₀ value 1.09×10⁵ and LC₉₀ value 1.90×10¹³ while it took 45.41 h to kill 50% of tested population.

Conclusions

Taking long time to kill 50% population when compare with the synthetic insecticides, is the only drawback for the use of entomopathogenic fungus but these bio-pesticides are safe for the use.     

Laboratory assessment of the molluscicidal and cercariacidal activities of Balanites aegyptiaca

Objective

To assess the molluscicidal and cercariacidal activities of aqueous extracts of Balanites aegyptiaca (B. aegyptiaca) against Ethiopian Biomphalaria pfeifferi (B. pfeifferi), Lymnaea natalensis (L. natalensis) and Schistosoma mansoni (S. mansoni) cercariae.

Methods

Extracts of seeds, endocarp, mesocarp, and fruit of B. aegyptiaca were tested for their activities against adult B. pfeifferi and L. natalensis. The cercariacidal activity of the seeds of the plant was also evaluated against S. mansoni. Bioassays were carried out following the methods recommended by WHO. Snail mortalities were compared between each plant part and snail species, and LC₅₀ and LC₉₀ values for the plant parts tested were computed. The cercariacidal activity of the plant was assessed by exposing the mice to the cercariae pre-exposed to aqueous extract of B. aegyptiaca seeds.

Results

For the molluscicidal activities of seeds, endocarp, mesocarp and whole fruit, the LC₅₀ values against B. pfeifferi were 56.32, 77.53, 65.51 and 66.63 mg/L, respectively, while the respective LC₉₀ values were 77.70, 120.04, 89.50 and 97.55 mg/L. Similarly, the LC₅₀ values for the seeds, endocarp, mesocarp and whole fruit against L. natalensis were 80.33, 92.61, 83.52 and 87.84 mg/L, respectively, while the respective LC₉₀ values were 102.30, 138.21, 115.42 and 127.69 mg/L. B. pfeifferi were found to be more susceptible to B. aegyptiaca than L. natalensis. S. mansoni cercariae exposed to 15 mg/L of extract of seeds were incapable of infecting mice. The mean egg load of tissue was reduced in mice infected with the cercariae exposed to 5 and 10 mg/L of the extract.

Conclusions

The aqueous extracts of different parts of B. aegyptiaca exhibited reasonable molluscicidal activity against B. pfeifferi and L. natalensis, as well as cercariacidal activity against S. mansoni cercariae. However, comprehensive laboratory evaluation is recommended prior to field tests of the plant parts since their impact on other aquatic biota is not known.     

Repellent properties of Cardiospermum halicacabum Linn. (Family: Sapindaceae) plant leaf extracts against three important vector mosquitoes

Objective

To determine repellent activity of hexane, ethyl acetate, benzene, chloroform and methanol extract of Cardiospermum halicacabum (C. halicacabum) against Culex quinquefasciatus (Cx. quinquefasciatus), Aedes aegypti (Ae. aegypti) and Anopheles stephensi (An. stephensi).

Methods

Evaluation was carried out in a net cage (45 cm×30 cm×25 cm) containing 100 blood starved female mosquitoes of three mosquito species and were assayed in the laboratory condition by using the protocol of WHO 2005; The plant leaf crude extracts of C. halicacabum was applied at 1.0, 2.5, and 5.0 mg/cm² separately in the exposed area of the fore arm. Only ethanol served as control.

Results

In this observation, the plant crude extracts gave protection against mosquito bites without any allergic reaction to the test person, and also, the repellent activity was dependent on the strength of the plant extracts. The tested plant crude extracts had exerted promising repellent against all the three mosquitoes.

Conclusions

From the results it can be concluded the crude extract of C. halicacabum was potential for controlling Cx. quinquefasciatus, Ae. aegypti and An. stephensi mosquitoes.     

Residual effects of TMOF-Bti formulations against 1st instar Aedes aegypti Linnaeus larvae outside laboratory

Objective

To evaluate the effectiveness and residual effects of trypsin modulating oostatic factor-Bacillus thuringiensis israeliensis (TMOF-Bti) formulations against Aedes aegypti (Ae. aegypti) (L.) larvae at UKM Campus Kuala Lumpur.

Methods

Twenty first instar Ae. aegypti larvae were added in each bucket containing 4 L of water supplied with crushed dried leaf powder as their source of food. Combination of TMOF-Bti in rice husk formulation with the following weights viz 10, 25, 50 and 100 mg, respectively in duplicate was distributed in the buckets; while TMOF-Bti in wettable powder formulation each weighing viz 2, 5, 10 and 20 mg, respectively in duplicate was also placed in the buckets. The control buckets run in duplicate with 4 L of water and 20 first instar Ae. aegypti larvae. All buckets were covered with mosquito netting. Larval mortality was recorded after 24 hours and weekly for five weeks. A new batch of 20 1^st instar larvae Ae. aegypti was introduced into each bucket weekly without additional TMOF-Bti rice husk formulation or wettable powder. The experiment was repeated for four times.

Results

The result of the study showed that all formulations were very effective on the first two weeks by giving 100% larval mortality for all concentrations applied. The TMOF (2%) + Bti (2%) had a good residual effect until the end of 3^rd week, TMOF (4%) + Bti (4%) until 4^th week, wettable powder TMOF (20%) + Bti (20%) until the third week.

Conclusions

From the results it can be concluded that the TMOF-Bti formulations can be utilized in dengue vector control.     

Evaluation of aqueous and ethanol extract of bioactive medicinal plant,Cassia didymobotrya (Fresenius) Irwin & Barneby against immature stages of filarial vector,Culex quinquefasciatus Say (Diptera: Culicidae)

Objective

To evaluate aqueous and ethanol extract of Cassia didymobotrya leaves against immature stages of Culex quinquefasciatus.

Methods

The mortality rate of immature mosquitoes was tested in wide and narrow range concentration of the plant extract based on WHO standard protocol. The wide range concentration tested in the present study was 10 000, 1 000, 100, 10 and 1 mg/L and narrow range concentration was 50, 100, 150, 200 and 250 mg/L.

Results

2nd instar larvae exposed to 100 mg/L and above concentration of ethanol extract showed 100% mortality. Remaining stages such as 3rd, 4th and pupa, 100% mortality was observed at 1 000 mg/L and above concentration after 24 h exposure period. In aqueous extract all the stages 100% mortality was recorded at 1 000 mg/L and above concentration. In narrow range concentration 2nd instar larvae 100% mortality was observed at 150 mg/L and above concentration of ethanol extract. The remaining stages 100% mortality was recorded at 250 mg/L. In aqueous extract all the tested immature stages 100% mortality was observed at 250 mg/L concentration after 24 h exposure period. The results clearly indicate that the rate of mortality was based dose of the plant extract and stage of the mosquitoes.

Conclusions

From this study it is confirmed and concluded that Cassia didymobotrya is having active principle which is responsible for controlling Culex quinquefasciatus. The isolation of bioactive molecules and development of simple formulation technique is important for large scale implementation.     

Acaricidal activity of different extracts from Syzygium cumini L. Skeels (Pomposia) against Tetranychus urticae Koch

Objective

To investigate the acaricidal activity of different extracts from Syzygium cumini (S. cumini) (Pomposia) againsst Tetranychus urticae Koch (T. urticae) and the biochemical changes in antioxidants enzymes.

Methods

Six extracts of S. cumini (Pomposia) at concentrations of 75, 150 and 300µg/mL were used to control T. urticae (Koch).

Results

The ethanol extract showed the most efficient acaricidal activity agent against T. urticae (98.5%) followed by hexane extract (94.0%), ether and ethyl acetate extract (90.0%). The LC₅₀ values of the promising extract were 85.0, 101.0, 102.0 and 98.0µg/mL, respectively. The activities of enzymes including ascorbate peroxidase (APX), peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) in susceptible mites were increased. The activities of all antioxidant enzymes reach the maximum value in mites at LC₅₀ with ethanol and ethyl acetate extracts, respectively.

Conclusions

The extract of S. cumini has acaricidal acivity against T. urticae, and the ethanol extract is the most efficient.     

Unusual developing sites of dengue vectors and potential epidemiological implications

Objective

To identify the unusual breeding sites of two dengue vectors, i.e. Aedes albopictus (Ae. albopictus) and Aedes aegypti (Ae. aegypti).

Methods

During the second half of 2010, we performed an occasional survey in rural (Teluk Tempoyak) and urban (Gelugor) areas of Penang Island, Malaysia, to identify cryptic breeding sites.

Results

In the rural area, we found heterogeneous immature stages of Ae. albopictus in the water bowl of an encaged bird. We also observed Ae. aegypti eggs deposited in the flush tank of a toilet in the urban area.

Conclusions

It can be concluded that both breeding patterns can increase contact with hosts (humans and birds) and presumably population densities of Ae. albopictus and Ae. aegypti, thereby potentially boosting the risks for spread and transmission of arboviral diseases.     

Ovicidal and repellent activities of botanical extracts against Culex quinquefasciatus,Aedes aegypti and Anopheles stephensi (Diptera: Culicidae)

Objective

To determine the ovicidal and repellent activities of methanol leaf extract of Ervatamia coronaria (E. coronaria) and Caesalpinia pulcherrima (C. pulcherrima) against Culex quinquefasciatus (Cx. quinquefasciatus), Aedes aegypti (Ae. aegypti) and Anopheles stephensi (An. stephensi).

Methods

The ovicidal activity was determined against three mosquito species at various concentrations ranging from 50-450 ppm under the laboratory conditions. The hatch rates were assessed 48 h after treatment. The repellent efficacy was determined against three mosquito species at three concentrations viz., 1.0, 2.5 and 5.0 mg/cm² under the laboratory conditions.

Results

The crude extract of E. coronaria exerted zero hatchability (100% mortality) at 250, 200 and 150 ppm for Cx. quinquefasciatus, Ae. aegypti and An. stephensi, respectively. The crude extract of C. pulcherrima exerted zero hatchability (100% mortality) at 375, 300 and 225 ppm for Cx. quinquefasciatus, Ae. aegypti and An. Stephensi, respectively. The methanol extract of E. coronaria found to be more repellenct than C. pulcherrima extract. A higher concentration of 5.0 mg/cm² provided 100% protection up to 150, 180 and 210 min against Cx. quinquefasciatus, Ae. aegypti and An. stephensi, respectively. The results clearly showed that repellent activity was dose dependent.

Conclusions

From the results it can be concluded the crude extracts of E. coronaria and C. pulcherrima are an excellent potential for controlling Cx. quinquefasciatus, Ae. aegypti and An. stephensi mosquitoes.     

Household survey of container-breeding mosquitoes and climatic factors influencing the prevalence of Aedes aegypti (Diptera: Culicidae) in Makkah City,Saudi Arabia

Objective

To investigate the prevalence of container breeding mosquitoes with emphasis on the seasonality and larval habitats of Aedes aegypti (Ae. aegypti) in Makkah City, adjoining an environmental monitoring and dengue incidence.

Methods

Monthly visits were performed between April 2008 and March 2009 to randomly selected houses. During each visit, mosquito larvae were collected from indoors and outdoors containers by either dipping or pipetting. Mosquitoes were morphologically identified. Data on temperature, relative humidity, rain/precipitations during the survey period was retrieved from governmental sources and analyzed.

Results

The city was warmer in dry season (DS) than wet season (WS). No rain occurred at all during DS and even precipitations did fall, wetting events were much greater during WS. Larval survey revealed the co-breeding of Aedes, Culex and Anopheles in a variety of artificial containers in and around homes. 32 109 larvae representing 1st , 2nd, 3rd, and 4th stages were collected from 22 618 container habitats. Culicines was far the commonest and Aedes genus was as numerous as the Culex population. Ae. aegypti larval abundance exhibited marked temporal variations, overall, being usually more abundant during WS. Ten types of artificial containers were found with developing larvae. 70% of these habitats were located indoors. 71.42% of indoor containers were permanent and 28.58% was semi-permanent during WS. Cement tanks was the only container type permanent during DS. Ae. aegypti larval indices (CI, HI, BI) recorded were greater during WS.

Conclusions

Taken together, these results indicate a high risk of dengue transmission in the holy city.     

Control of Tetranychus urticae Koch by extracts of three essential oils of chamomile,marjoram and Eucalyptus

Objective

To evaluate the acaricidal activity of extracts of three essential oils of chamomile, marjoram and Eucalyptus against Tetranychus urticae (T. urticae) Koch.

Methods

Extracts of three essential oils of chamomile, marjoram and Eucalyptus with different concentrations (0.5%, 1.0%, 2.0%, 3.0% and 4.0%) were used to control T. urticae Koch.

Results

The results showed that chamomile (Chamomilla recutita) represented the most potent efficient acaricidal agent against Tetranychus followed by marjoram (Marjorana hortensis) and Eucalyptus. The LC₅₀ values of chamomile, marjoram and Eucalyptus for adults were 0.65, 1.84 and 2.18, respectively and for eggs 1.17, 6.26 and 7.33, respectively. Activities of enzymes including glutathione-S-transferase, esterase (α-esterase and β-esterase) and alkaline phosphatase in susceptible mites were determined and activities of enzymes involved in the resistance of acaricides were proved. Protease enzyme was significantly decreased at LC₅₀ of both chamomile and marjoram compared with positive control. Gas chromatography-mass spectrometer (GC-MS) proved that the major compositions of Chamomilla recutita are α-bisabolol oxide A (35.251%), and trans-β-farersene (7.758%), while the main components of Marjorana hortensis are terpinene-4-ol (23.860%), p-cymene (23.404%) and sabinene (10.904%).

Conclusions

It can be concluded that extracts of three essential oils of chamomile, marjoram and Eucalyptus possess acaricidal activity against T. urticae.     

Bioefficacy of crude extract of Cyperus aromaticus (Family: Cyperaceae ) cultured cells,against Aedes aegypti and Aedes albopictus mosquitoes

Objective

To evaluate the growth inhibition activity of the crude extract of Cyperus aromaticus (C. aromaticus) cultured cells against the 3rd instar larvae of Aedes aegypti (Linn.) and Aedes albopictus Skuse (Ae. albopictus) under laboratory conditions, and determine the sublethal effects (EI₅₀) of the crude extract of C. aromaticus cultured cells on some biological and morphological parameters of both Aedes mosquito species during two generations as well.

Methods

The cell suspension cultures of C. aromaticus were activated from five callus lines (P4, Pa, Z1, Z6 and Ml) derived from the root explants of in vitro plantlets. The cultured cells were extracted in chloroform and used as plant material for the present study. For detection of juvenile hormone III, the crude extracts were analyzed by HPLC. Then the crude extracts of the three C. aromaticus cultured cell lines which contained varied amounts of juvenile hormone III [high level (P4 cell line), medium level (Z1 cell line) and low level (Ml cell line)] were tested against Aedes mosquito species. Laboratory evaluation was performed against late third instar larvae of the Vector Control Research Unit strains of Ae. aegypti and Ae. albopictus using the standard WHO method. The effects of EI₅₀ of the C. aromaticus cultured P4 cells on fecundity, fertility, growth period, sex ratio, adult size and longevity of Aedes mosquitoes were assessed.

Results

Bioassay tests presented the remarkable growth inhibition activity of the crude extracts of C. aromaticus cultured cells against the two Aedes mosquitoes. Between the two mosquito species, Ae. albopictus was more susceptible to the crude extracts with lower EI₅₀ values. EI₅₀ of the crude extract of C. aromaticus cultured cells (P4) increased the sterility indices in the parental generation females in both Aedes mosquito species. A significant delay in the pupal formation and adult emergence were observed in the parental generation of the both mosquito species. The sex ratio of the adult population either parental or F1 generation of the Aedes mosquito species was not significantly affected by the EI₅₀ dosage of the crude extract of C. aromaticus cultured P4 cells. A significant decrease in the wing length of the treated adult (female and male) of Aedes aegypti as well as the treated female of Ae. albopictus were observed. Longevity of the adult female of the parental generation of both Aedes mosquitoes as well as females of F1 generation of Ae. albopictus were significantly decreased.

Conclusions

The present study revealed the potential of the crude extract of C. aromaticus cultured cells in controlling vector mosquito populations in the effort to reduce the transmission of vector borne diseases.     

Cytotoxicity of the rhizome of medicinal plants

Objective

To investigate the cytotoxicity of the crude ethanol extract of the rhizome of Zingiber zerumbet (Z. zerumbet) (L) Smith. and Curcuma zedoaria (C. zedoaria) Rosc. against Artemia salina Leach.

Methods

Fresh rhizomes of Z. zerumbet (L) Smith. and C. zedoaria Rosc. were extracted separately in cold with ethanol (2.5 L) and after concentration a brownish syrupy suspension of ethanol extracts of Z. zerumbet (L) Smith. and C. zedoaria Rosc. was obtained. The cytotoxic effect of the crude ethanol extracts of both plants was determined by brine shrimp lethality bioassay.

Results

Crude ethanol extracts of the rhizome of Z. zerumbet (L) Smith. showed the highest cytotoxicity (LC₅₀ was 1.24 µg/mL) against brine shrimp nauplii as compared with C. zedoaria Rosc. (LC₅₀ was 33.593 µg/mL) after 24 h of exposure.

Conclusions

It can be concluded that the rhizome of Z. zerumbet (L) Smith. and C. zedoaria Rosc. can be used as a source of cytotoxic agent.