Culex Quinquefasciatus Mosquito Larvae Research Articles

Potential efficacy of bimetallic nanoparticles synthesized from extracellular cell-free extract of Penicillium citrinum against Culex quinquefasciatus mosquito larvae, and their photocatalytic activity

The biological synthesis of nanoparticles finds application in the development of novel insecticides and bioremediation agents. In this study, bimetallic nanoparticles were synthesized using copper and zinc salts along with Penicillium citrinum secondary metabolite. The synthesized nanoparticles were analyzed for their insecticidal and photocatalytic efficacy on Culex quinquefasciatus larvae and organic dyes, respectively. The synthesized nanoparticles were characterized by UV spectroscopy, FTIR, XRD, SEM, EDX, and HR-TEM. The results showed fungal metabolite synthesized bimetallic nanoparticles were too toxic for Culex quinquefasciatus larvae, with LC50 and LC90 values of 1016.51 ppm, 4948.12 ppm for 24 h exposure; 184.80 ppm, 718.16 ppm for 48 h exposure, and 59.07 and 338.76 ppm for 72 h exposure, respectively. The Cu–Zn bimetallic nanoparticles showed mild photocatalytic activity on Xylenol orange (36%). This study shows that bimetallic NPs synthesized from Penicillium citrinum are advantageous for mosquito control as well as having photocatalytic dye degradation properties.

Assessing the possibility of using entomopathogenic fungi for mosquito control in Hawaii

Currently, the Hawaiian government uses chemical pesticides and Bti, a bacterial agent applied to larval pools, for mosquito control. These methods can pose a threat to the environment and be expensive. Additionally, mosquitoes usually develop a resistance toward these pesticides. An alternative agent for mosquito control is entomopathogenic fungi, which can kill or disable insects while they are non-pathogenic to plants and mammals. The purpose of this research is to investigate the use of entomopathogenic fungi as a more sustainable mosquito-control method. We isolated Metarhizium anisopliae from local soil samples in Honolulu, Hawaii. We hypothesized that this entomopathogenic fungus from Hawaii would effectively kill Culex quinquefasciatus mosquito larvae. We tested the fungus on the larvae of C. quinquefasciatus at concentrations of 1 x 104 and 1 x 105 conidia/mL. We found that the more concentrated fungal solution was more virulent to the larvae. Hence, this entomopathogenic fungus may offer a sustainable approach to mosquito control.

Toxic and synergetic effect of plant essential oils along with nano-emulsion for control of three mosquito species

Nano-emulsion containing Eucalyptus grandis (W. Hill ex Maiden) and Corymbia citrodora (Hook.) K.D.Hill & L.A.S.Johnson (common synonym Eucalyptus citriodora Hook.) leaf essential oils individual, combination was evaluated its larvicidal activity against Anopheles stephensi, Aedesaegypti and Culex quinquefasciatus mosquito larvae at 24 h post treatment. Nano-emulsion had low polydispersivity index and mean droplet size was below 66 nm. After 24 h E. grandis essential oil exhibited significant larvicidal activity with LC50 and LC90 values in A. aegypti (23.667; 438.797 ppm in A. aegypti A. stephensi (10.984; 277.535 ppm) and C. quinquefasciatus (4.676; 106.415 ppm). Similarly in C. citrodora showed low LC50 and LC90 values in A. aegypti (18.430; 1048.599 ppm), A. stephensi (6.573; 176.737 ppm) and C. quinquefasciatus (7.917; 287.720 ppm) respectively. The combination of E. grandis and C. citrodora essential oils showed higher mortality rates than individual essential oils, with low LC50 and LC90 values in A. aegypti (3.625; 58.962 ppm), A. stephensi (3.245; 34.473 ppm) and C. quinquefasciatus (3.002; 30.153 ppm). Nano-emulsion exhibited toxic effects similar to combination group with LC50 and LC90 values in A. aegypti (5.344; 113.362 ppm), A. stephensi (3.183; 83.112 ppm) and C. quinquefasciatus (2.832; 166.665 ppm). Chemical constituents of both essential oil were analyzed using GC-MS and FT-IR, result showed E. grandis contain different compounds namely; alpha-pinene, (31.74%); o-cymene, (17.84%); Eucalyptol (16.24%); Bicyclo[2.2.1]heptane (3.2%) and C. citrodora showed Citronellol (49.31%); dl-Isopulegol (25.39%) as a major compound while their synergistic action may be due to type’s composition of EOs might produce the synergist effect along with nanoemulsions. Our findings suggest that combination of essential oil E. grandis and C. citrodora can be used for mosquito control as green approach.

In vitro Bioactivity Evaluation of Ziziphus mauritiana Lam. (Bidara) Leaves Extract against Vector Mosquitoes Aedes spp. and Culex quinquefasciatus

Ziziphus mauritiana methanol crude extract was evaluated for its insecticidal properties against Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus mosquito larvae. Bioassays against larvae mosquitoes were done following World Health Organization’s guidelines. Late third and/or early fourth instar of mosquito larva were assayed for five different concentrations viz. 100, 150, 200, 250, and 300 mg ml–1 of Z. mauritiana crude extracts. From the results obtained, Aedes aegypti was the most susceptible to Z. mauritiana crude extracts. The percentage of mortality exhibited above 50% of 200, 250, and 300 mg ml–1 in 24, 48, and 72 hr exposure. Thus, it gives the lowest LC50 within 24 hr of exposure (121.98 mg L–1), followed by Ae. albopictus (189.89 mg L–1) and Cx. quinquefasciatus (246.22 mg L–1). Observation of the morphology effect of the dead larvae shows Ae. aegypti was the most affected, followed by Ae. albopictus and Cx. quinquefasciatus. A ruptured midgut was observed in 100 and 200 mg ml–1 concentrations. In contrast, in higher concentrations of 300 mg ml–1, the abdominal segments were indistinguishable, and the head and thorax regions were severely damaged. This study suggested that Z. mauritiana methanolic crude extracts were potent against Ae. aegypti larvae mosquitoes and have the potential to be used as an alternative larvicide in population control. However, further studies are required to establish the potential of Z. mauritiana larvicidal effects in the field setting.

Cys183 and Cys258 in Cry49Aa toxin from Lysinibacillus sphaericus are essential for toxicity to Culex quinquefasciatus larvae.

The two-component Cry48Aa/Cry49Aa toxin produced by Lysinibacillus sphaericus shows specifically toxic to Culex quinquefasciatus mosquito larvae. Cry49Aa C-terminal domain is responsible for specific binding to the larval gut cell membrane, while its N-terminal domain is required for interaction with Cry48Aa. To investigate functional role of cysteine in Cry49Aa, four cysteine residues at positions 70, 91, 183, and 258 were substituted by alanine. All mutants showed similar crystalline morphology and comparable yield to that of the wild type except that the yield of the C91A mutant was low. Four cysteine residues did not involve in disulfide bond formation within or between Cry49Aa molecules. Cys91, Cys183, and Cys258 are essential for larvicidal activity against C. quinquefasciatus larvae, while Cys70 is not. Substitution at C91, C183, and C258 caused weaker Cry48Aa- Cry49Aa interaction, while mutations at C183 and C258 reduced the binding capacities to the larval gut cell membrane. Thus, Cysteine residues at position 91, 183, and 258 in Cry49Aa are required for full toxicity of Cry48Aa/Cry49Aa toxin.

Larvicidal activity of novel anthraquinone analogues and their molecular docking studies.

To investigate the larvicidal activities of novel anthraquinones (1a-1k) against Culex quinquefasciatus mosquito larvae. Novel anthraquinones (1a-1k) derivatives were synthesis via condensation method. The compounds were confirmed through FT-IR spectroscopy, 1H & 13C NMR spectrum, and mass spectral studies. The larvicidal activity of compound 1c was highly active LD50 20.92 µg/mL against Culex quinquefasciatus compared standard permethrin with LD50 25.49 µg/mL. Molecular docking studies were carried out for compound 1c against Odorant-binding protein of Culex quinquefasciatus. The compound 1c (−9.8 Kcal/mol) was a potent larvicide with more binding energy than control permethrin (−9.7 Kcal/mol). Therefore, compound (1c) may be more significant inhibitors of mosquito larvicidal.

The Cry48Aa N-terminal Domain is Responsible for Cry48Aa-Cry49Aa Interaction in Lysinibacillus sphaericus Toxin.

The Cry48Aa/Cry49Aa binary toxin from Lysinibacillus sphaericus is composed of a three-domain Cry-like toxin (Cry48Aa) and a binary-like protein (Cry49Aa) that work together to kill Culex quinquefasciatus mosquito larvae through a novel interaction between its two components. The aim of this study was to identify the functional regions of Cry48Aa that were involved in the interaction with Cry49Aa. Eight Cry48Aa truncated fragments were constructed from both N- and C-termini and expressed in Escherichia coli. Only the individual or combined N69K truncated fragment, a Cry48Aa N-terminal derivative consisting of three domains, showed larvicidal activity against C. quinquefasciatus larvae, while the other fragments exhibited significant loss of biological activity. Far-Western dot blot analysis showed that Cry48Aa N-terminal regions had the ability to bind to Cry49Aa protein. These results demonstrate that the N-terminal domain of Cry48Aa plays a crucial role in responsible for the full virulence to mosquito larvae and the interaction with Cry49Aa as a binary toxin.

Fresh leaf extract’s efficacy of twelve medicinal plants against Culex quinquefasciatus mosquito larvae

Fresh leaf extract’s efficacy of twelve medicinal plants against Culex quinquefasciatus mosquito larvae

Toxicity of Silybum marianum and Nerium oleander extracts against Mosquito Larvae of Culex quinquefasciatus (Say)

Toxicity of two plant extracts against Culex quinquefasciatus mosquito larvae was measured in this work. The plants include the species; Silybum marianum and Nerium oleander. Their Lc50 and Lc90 after 4-hrs were evaluated against three instars of the mosquito. S. marianum Lc50 values were: 57, 214, and 379 ppm for the three instars respectively. S. marianum Lc90 values were: 2422, 2936, and 3161 ppm for the three instars respectively. N. oleander Lc50 values were: 161, 194, and 360 for the three instars respectively. N. oleander Lc90 values were: 1968, 2004, and 4203 for the three instars respectively. The results showed that the 1st instar larvae were more sensitive than the 2nd instar larvae, and this was more sensitive than the 3rd instar larvae. The results of recent work showed high correlation rate between logs of S. marianum and N. oleander concentrations and C. quinquefasciatus mortality percentage probits for all three larvae stages with high R values (0.911, 0.914 and 0.997) (0.993, 0.970 and 0.943) respectively. The aim of this study is to screen plant materials sources can be used in mosquito control.

UTILIZATION OF ROSMARIN LEAF OIL (Rosmarinus officinalis L) ON Culex Quinquefasciatus MOSQUITO LARVA AS A FILARIASIS VECTOR (ELEPHANT FOOT DISEASE)

Elephantiasis (filariasis / elephantiasis) is still endemic in hundreds of districts in Indonesia and has become a health problem for the world community in accordance with the resolution of the World Health Assembly (WHA) in 1997. This is caused by Culex quinquefasciatus mosquitoes as one of many filariasis vectors found in urban areas (Gandahusada et al., 1998), while the number of filariasis chronic cases reported until 2009 was 11,914 cases. Filariasis / elephantiasisi is a chronic infectious disease caused by filarial worm infection transmitted by various types of mosquitoes in the lymph nodes, this disease is chronic (chronic) and if it does not get treatment can cause permanent disability in the form of enlargement of the legs, arms and genitals both women and men man. Rosmarin (Rosmarinus officinalis L.) is a multifunctional plant in Indonesia especially abroad, one of its benefits is as larvicides. Because rosmarin has a chemical compound, one of them is essential oil which has larvicidal effectiveness on Culex quinquefasciatus mosquito larvae as vector filariasis (elephantiasis) Essential oil was obtained by distillation of fresh rosmarin leaves, then each extract was made with 1000 ppm stock solution and then made 6 series of concentration of 12.5 ppm to 300 ppm then tested on 20 larvae of instar III Culex quinquefasciatus, Observations were made after 24 hours and calculated LC90 uses an analysis of the orbit. The results obtained were only essential oils of Rosmarin leaves (Rosmarinus officinalis L.) which had larvicidal activity against Culex quinquefasciatus mosquito larvae, with LC90 182,9756 ppm.

Larvicidal potential of Asteraceae family endophytic actinomycetes against Culex quinquefasciatus mosquito larvae

Pakistan is blessed with plants of Asteraceae family with known medicinal background used for centuries by Hakims (traditional physicians). Keeping in mind the background of their anti-larval potential, a total of 21 endophytic actinomycetes were isolated from four Asteraceae plants and screened against the first and fourth instar stages of Culex quinquefasciatus Say mosquito larvae. Of the 21 isolates, 6 of them gave strong larvicidal activity (80–100% mortality) in the screening results and 4 isolates gave a potent larvicidal activity (100% mortality) at the fourth instar stage. These isolates belonged to different species within the actinomycetes group, namely Streptomyces albovinaceus and Streptomyces badius. This communication reports the larvicidal potential of endophytic actinomycetes residing within the native Asteraceae plants in Pakistan. The study suggests further exploration through large-scale productions leading to the identification of the larvicidal compounds.

Mosquito larvicidal activity of some common spices and vegetable waste on Culex quinquefasciatus and Anopheles stephensi

Objective To investigate the larvicidal activities of crude and chloroform: methanol (1:1 v/v) extracts of some common spices ( Cuminum cyminum, Allium sativum, Zingiber offinale, Curcuma longa) and vegetable waste ( Solanum tuberosum germinated tuber) against Anopheles stephensi and Culex quinquefasciatus mosquito larvae. Methods Larval mortality of above mosquito species were observed after 24, 48 and 72 h of exposure to five concentrations of aqueous extract (0.1%, 0.2%, 0.3%, 0.4% and 0.5%) and four concentrations (25, 50, 75 ppm) of chloroform: methanol (1:1 v/v) extract. The lethal concentration of individual spices or vegetable waste was determined by log-probit analysis (at 95% confidence level) and effect of crude and chloroform: methanol (1:1 v/v) extracts were recorded on non target organisms. Results Relative mortality rate of both larval mosquito species were recorded in the following sequences: Cuminum cyminum > Allium sativum > Zingiber offinale, Curcuma longa > Solanum tuberosum germinated tuber for crude extract, and efficacy of chloroform: methanol (1:1 v/v) extract were as follows: Curcuma longa > Zingiber offinale > Solanum tuberosum germinated tuber > Cuminum cyminum > Allium sativum. Conclusions Crude and chloroform: methanol (1:1 v/v) extract of Cuminum cyminum, Allium sativum, Zingiber offinale, Curcuma longa and Solanum tuberosum germinated tuber can be recommended effectively in mosquito control programmes at very low concentrations. No mortality and other abnormalities were noticed on non target organisms and further studies are needed to investigate the chemical structure of active principal which are responsible for larvicidal activity.

The Cry48Aa‐Cry49Aa binary toxin from Bacillus sphaericus exhibits highly restricted target specificity

The Cry48Aa/Cry49Aa binary toxin of Bacillus sphaericus was recently discovered by its ability to kill Culex quinquefasciatus mosquito larvae through a novel interaction between its two components. We have investigated the target specificity of this toxin and show it to be non-toxic to coleopteran, lepidopteran and other dipteran insects, including closely related Aedes and Anopheles mosquitoes. This represents an unusually restricted target range for crystal toxins from either B. sphaericus or Bacillus thuringiensis. Gut extracts from Culex and Aedes larvae show differential processing of the Cry48Aa protein, with the location of cleavage sites in Culex reflecting those previously shown for the activation of Cry4 toxins in mosquitoes. Pre-activation of Cry48Aa/Cry49Aa with Culex extracts, however, fails to induce toxicity to Aedes larvae. Co-administration of Cry49Aa with Cry4Aa gives higher than predicted toxicity, perhaps suggesting weak synergism against Culex larvae between Cry49Aa and other three-domain Cry toxins.

Marginal cross-resistance to mosquitocidal Bacillus thuringiensis strains in Cry11A-resistant larvae: presence of Cry11A-like toxins in these strains.

Culex quinquefasciatus mosquito larvae resistant to the Cry11A toxin showed marginal cross-resistance to the multiple toxin crystals from B. thuringiensis subsp. israelensis and also to toxin crystals from three other mosquitocidal strains, i.e. B. thuringiensis subsp. fukuokaensis, subsp. jegathesan, and subsp. kyushuensis. Cross-resistance patterns of the Cry11A-resistant larvae to mosquitocidal strains of B. thuringiensis together with the immunological screening using antisera raised against Cry11A indicated the presence of Cry11A-like toxins in these strains and could be used as a screening tool for the identification of novel toxins. The Cry11A-resistant larvae had significantly less resistance to the Cry11B toxin from B. thuringiensis subsp. jegathesan. The occurrence of cytolytic toxins in all of these mosquitocidal strains partially explains the marginal cross-resistance observed with multiple toxin crystals since each of these crystals also contains cytolytic toxins.

Marginal cross-resistance to mosquitocidal Bacillus thuringiensis strains in Cry11A-resistant larvae: presence of Cry11A-like toxins in these strains

Culex quinquefasciatus mosquito larvae resistant to the Cry11A toxin showed marginal cross-resistance to the multiple toxin crystals from B. thuringiensis subsp. israelensis and also to toxin crystals from three other mosquitocidal strains, i.e. B. thuringiensis subsp. fukuokaensis, subsp. jegathesan, and subsp. kyushuensis. Cross-resistance patterns of the Cry11A-resistant larvae to mosquitocidal strains of B. thuringiensis together with the immunological screening using antisera raised against Cry11A indicated the presence of Cry11A-like toxins in these strains and could be used as a screening tool for the identification of novel toxins. The Cry11A-resistant larvae had significantly less resistance to the Cry11B toxin from B. thuringiensis subsp. jegathesan. The occurrence of cytolytic toxins in all of these mosquitocidal strains partially explains the marginal cross-resistance observed with multiple toxin crystals since each of these crystals also contains cytolytic toxins.

Mosquitocidal activity of the CryIC delta-endotoxin from Bacillus thuringiensis subsp. aizawai.

The cloned 135-kDa CryIC delta-endotoxin from Bacillus thuringiensis is a lepidopteran-active toxin, displaying high activity in vivo against Spodoptera litoralis and Spodoptera frugiperda larvae and in vitro against the S. frugiperda Sf9 cell line. Here, we report that the CryIC delta-endotoxin cloned from B. thuringienesis subsp. aizawai HD-229 and expressed in an acrystalliferous B. thuringiensis strain is also toxic to Aedes aegypti, Anophles gambiae, and Culex quinquefasciatus mosquito larvae. Furthermore, when solubilized and proteolytically activated by insect gut extracts, CryIC is cytotoxic to cell lines derived from the first two of these dipteran insects. This activity was not observed for two other lepidopteran-active delta-endotoxins, CryIA(a) and CryIA(c). However, in contrast to the case with a lepidopteran and dipteran delta-endotoxin cloned from B. thuringiensis subsp. aizawai IC1 (M.Z. Haider, B. H. Knowles, and D. J. Ellar, Eur. J. Biochem. 156:531-540, 1986), no differences in the in vitro specificity or processing of CryIC were found when it was activated by lepidopteran or dipteran gut extract. The recombinant CryIC delta-endotoxin expressed in Escherichia coli was also toxic to A. aegypti larvae. By contrast, a second cryIC gene cloned from B. thuringiensis subsp. aizawai 7.29 (V. Sanchis, D. Lereclus, G. Menou, J. Chaufaux, S. Guo, and M. M. Lecadet, Mol. Microbiol. 3:229-238, 1989) was nontoxic. DNA sequencing showed that the two genes were identical. However, CryIC from B. thuringiensis subsp. aizawai 7.29 had been cloned with a truncated C terminus, and when it was compared with the full-length CryIC delta-endotoxin, it was found to be insoluble under alkaline reducing conditions. These results show that CryIC from B. thuringiensis subsp. aizawai is a dually active delta-endotoxin.

Persistence and recycling of Bacillus sphaericus 2362 spores in Culex quinquefasciatus breeding sites in West Africa

A flowable concentrate of Bacillus sphaericus strain 2362 was applied at 10 g/m2 against Culex quinquefasciatus mosquito larvae in cesspools. Complete control of larvae was maintained during 5 to 6 weeks, due to a very low settling of B. sphaericus spores, and was related to the presence of at least 100 to 500 spores per ml in upper water layers. Larval cadavers sedimented within 48 h after treatment. B. sphaericus was shown to recycle in dead larvae but not in mud. Spore persistence exceeded 5 months in bottom mud and the concentration of persistent spores was higher in cesspools, the bottom of which was cemented. Depth, temperature, pH, dissolved oxygen and suspended matter content of the water remained relatively constant throughout 4 months. In laboratory experiments, the final amounts of spores recycled in larvae was not influenced by spore concentration in water or by detergent, but it was affected by organic matter. Projected costs of B. sphaericus formulation indicates that its use even at high dosages, would be more cost effective than the use of chemical insecticides, especially where c. quinquefasciatus is resistant to these latter. A new strategy for controlling this vector could be deployed, using B. sphaericus and insect growth regulators in alternation.