Preliminary evaluation of mosquito larvicidal efficacy of plant extracts

Mosquitoes are the most important single group ofinsects in terms of public health importance, whichtransmit a number of diseases, such as malaria, filariasis,dengue, Japanese encephalitis, etc. causing millionsof deaths every year. Repeated use of syntheticinsecticides for mosquito control has disrupted naturalbiological control systems and led to resurgencesin mosquito populations. It has also resulted in thedevelopment of resistance1, undesirable effects onnon-target organisms and fostered environmental andhuman health concern2, which initiated a search foralternative control measures. Plants are considered asa rich source of bioactive chemicals3 and they may bean alternative source of mosquito control agents.Natural products of plant origin with insecticidalproperties have been tried in the recent past for controlof variety of insect pests and vectors. Essentialoils of leaf and bark of Cryptomeria japonica demonstratedhigh larvicidal activity against Aedesaegypti (Diptera: Culicidae) larvae4. Insecticidalactivity of plant essential oils has been well-describedby Isman5. Azadiractin, the active ingredient of neemhas long been recognised for its mosquito larvicidalcapability. The extracts of Murraya koenigii, Coriandrumsativam, Ferula asafetida and Trigonella foenumgraceum were found to be effective and showedencouraging results against Ae. aegypti6 and Culex(Diptera: Culicidae) mosquito larvae7. It is also reportedthat many compounds with insecticidal potentialhave been isolated from the genus Piper—Pipercide,isolated from Piper negrum (black piper) hasbeen found to be just as active against adjuki beanweevils as the pyrethroides8. Phytochemicals derivedfrom plant sources can act as larvicide, insect growthregulators, repellent and ovipositor attractant andhave different activities observed by many researchers9–11. However, insecticides of plant origin havebeen extensively used on agricultural pests and to avery limited extent, against insect vectors of publichealth importance.Northeastern region of India is considered as a majorbiodiversity hot spot. The eastern Himalayas range,which extends all through the northern border ofAssam, is a rich treasure house of many promisingmedicinal and aromatic plants. In the present communication,an attempt has been made to evaluate themosquito larvicidal efficacy of methanol and ethanolextracts of different parts of five indigenous plantsagainst Ae. albopictus (Diptera: Culicidae) and Culexquinquefasciatus larvae in laboratory conditions.Plant materials were collected from the foothill forestsof Sonitpur district, Assam bordering ArunachalPradesh during April and May 2005. They were segregatedas leaf, stem, bark, root and fruit/pericarp andair-dried in a shady place. Dried materials wereground in a table model grinder. The ground plant materialswere dipped in solvents (methanol and ethanol)Short Research Communications146 J VECT BORNE DIS 44, JUNE 2007in tightly capped jars separately for 48 h. The solventsalong with extracts were drained out, filtered andsemisolid extracts were obtained in vacuum usingrotary evaporator. The semisolid extracts were lyophilisedto obtain solid extracts. Stock solutions of desiredconcentration were prepared in distilled waterusing 1 ppm teepol as emulsifying agent and subsequentdilutions were made as per requirement. Larvicidalbioassay was carried out as per standard WHOtechniques in 500 ml glass beakers containing 250 mlof water and 25 numbers of late III or early IV instarmosquito larvae for various concentrations. Threedifferent concentrations of each extract were tried outat a time with six replicates. One control was kept witheach set of experiment and mortality was recordedafter 24 h. Five sets of experiments were conductedfor each extract. Tests were carried out under controlledlaboratory conditions (temperature 27 ± 2oC)against laboratory reared Ae. albopictus and Cx. quinquefasciatus(Diptera: Culicidae) larvae. Values obtainedwere subjected to log probit regression analysisto obtain LC50 and LC90 values with 95% confidencelimit12.The results showed that the larvicidal activity ofmethanol and ethanol extracts of five aromatic plantspecies against Ae. albopictus and Cx. quinquefasciatuslarvae varied according to plant species (Tables 1& 2). Methanol extract of Aristolochia saccata rootswas found to be the most effective against Ae. albopictuslarvae followed by ethanol extracts of A. saccata,Annona squamosa leaf and methanol extract ofA. squamosa leaf respectively. LC90 values of methanolextract of fruit/pericarp of Gymnopetelumcochinchinensis, bark of Caesalpinea species andethanol extract of stem of Piper species were obtainedat <200 ppm but methanol extract of seeds of G.cochinchinensis and stem of Piper species gave at<358 ppm against Ae. albopictus larvae (Table 1).Ethanol extract of leaf of A. squamosa was found tohave the most promising larvicidal activity againstCx. quinquefasciatus larvae. Methanol and ethanolextracts of A. saccata (root), methanol extract of A.squamosa (leaf) showed LC90 values at <100 ppmwhile methanol extract of G. cochinchinensis (fruit/pericarp), methanol and ethanol extract of Piper speciesshowed at <200 ppm and methanol extract of G.cochinchinensis (seed) showed at >302 ppm againstCx. quinquefasciatus larvae (Table 2).Long before the advent of synthetic insecticides,plants and their derivatives were used to kill pest ofagriculture, veterinary and public health. Sosan et al13reported larvicidal activities of essential oils of Ocimumgratissium, Cymbopogon citrus and Ageratumconyzoides against Ae. aegypti and achieved 100%mortality at 120, 200 and 300 ppm concentrationsrespectively. Similarly, it was reported that the essentialoil of Ipomoea cairica Linn. possesses remark-Table 1. Larvicidal efficacy of plant extracts against Ae. albopictus larvaeName of plant Part used Solvent used LC50 LC90 Regression equationAristolochia saccata Root Methanol 14.52 42.68 Y = 2.5683 *X+2.0164-do- Root Ethanol 17.30 58.51 Y = 2.3633 *X+2.0721Annona squamosa Leaf Methanol 20.26 86.59 Y = 1.9392 *X+2.4637-do- Leaf Ethanol 20.70 76.73 Y = 2.1991 *X+2.1020Gymnopetelum cochinchinensis Fruit/Pericarp Methanol 50.67 155.12 Y = 2.5821 *X+0.5927-do- Seed Methanol 100.42 312.45 Y = 2.3014 *X+0.3481Caesalpinea species Bark Methanol 53.66 169.41 Y = 2.3429*X+0.8638Piper species Stem Methanol 144.22 357.32 Y = 3.1826 *X–1.9688-do- Stem Ethanol 76.35 180.42 Y = 3.2525 *X–1.1333DAS et al : HERBAL MOSQUITO LARVICIDES 147able larvicidal properties as it could produce 100%mortality in the larvae of Cx. tritaeniorhynchus, Ae.aegypti, An. stephensi and Cx. quinquefasciatus mosquitoesat concentrations ranging from 100 to 170ppm14. Dwivedi & Kawasara15 found acetone extractof Lantana camara to be most effective against Cx.quinquefasciatus larvae at the dose of 1 ml/100 ml.Latha et al16 reported Piper longum and Zingiberwightianum extracts at 80 mg/l causing completemortality in Cx. quinquefasciatus and 60 mg/l for Cx.sitiens. In the present investigation LC90 values ofmethanol and ethanol extracts of roots of A. saccata,leaf of A. squamosa and fruits/pericarp of G.cochinchinensis against Ae. albopictus and Cx. quinquefasciatuslarvae ranged between 31.80 and 155ppm. Studies with essential oil of Ocimum americansand O. gratissium showed LC50 at 67 and 60 ppmrespectively against Ae. aegypti larvae17. In contrast,in the present study methanol and ethanol extracts ofroots of A. saccata, leaf of A. squamosa and fruits/pericarp of G. cochinchinensis against Ae. albopictusand Cx. quinquefasciatus larvae showed LC50 valuesbetween 6.96 and 57.4 ppm. Larvicidal activities ofthe plant extracts vary according to the plant species,the parts of the plant, the geographical location wherethe plants were grown and the application method.Plant could be an alternative source for mosquitolarvicides because they constitute a potential sourceof bioactive chemicals and generally free from harmfuleffects. Use of these botanical derivatives inmosquito control instead of synthetic insecticidescould reduce the cost and environmental pollution.Further studies on identification of active compounds,toxicity and field trials are needed to recommend theactive fraction of these plant extracts for developmentof eco-friendly chemicals for control of insect vectors.AcknowledgementThe authors are thankful to Dr. S.N. Dube, Director,Defence Research Laboratory, Tezpur, Assam, Indiafor extending necessary facilities, continuous supportand guidance in the study.References1. Brown AWA. Insecticide resistance in mosquitoes:pragmatic review. J Am Mosq Control Assoc 1986; 2: 123–40.2. Hayes JB Jr, Laws ER Jr. Handbook of pesticidetoxicology, v. 1. San Diego, CA: Academic Press 1991.3. Wink M. Production and application of pytochemicalsfrom an agricultural perspective. In: Van Beek TA, BretelerH, editors. Phytochemistry and agriculture. Oxford, UK:Clerendon Press 1993; p. 171–213.Table 2. Larvicidal efficacy of plant extracts against Cx. quinquefasciatus larvaeName of plant Part used Solvent used LC50 LC90 Regression equationAristolochia saccata Root Methanol 31.91 81.06 Y = 3.3086 *X-0.0062-do- Root Ethanol 19.83 60.44 Y = 2.5791 *X-1.6605Annona squamosa Leaf Methanol 17.70 64.29 Y = 2.1180 *X+2.3457-do- Leaf Ethanol 6.96 31.80 Y = 1.9441 *X+3.3592Gymnopetelum cochinchinensis Fruit/pericarp Methanol 57.4 108.3 Y = 4.1627 *X+2.3501-do- Seed Methanol 199.0 301.6 Y = 1.7586 *X+11.0557Caesalpinea species Bark Methanol 42.27 207.13 Y = 1.7586 *X+2.0573Piper species Stem Methanol 70.10 113.90 Y = 5.669 *X+5.4992-do- Stem Ethanol 57.4 108.3 Y = 4.1627 *X+2.3501148 J VECT BORNE DIS 44, JUNE 20074. Cheng SS, Chang HT, Chang ST, Tsai KH, Chen WJ.Bioactivity of selected plant essential oils against theyellow fever mosquito Aedes aegypti larvae. BioresTechnol 2003; 89(1): 99–102.5. Isman MB. Pesticides based on plant essential oils.Pesticide Outlook 1999; p. 68–72.6. Harve G, Kamath V. Larvicidal activity of plant extractsused alone and in combination with known syntheticlarvicidal agents against Aedes aegypti. Indian J ExptlBiol 2004; 42: 1216–9.7. Desai ST. Potency of larvicidal properties of plantextracts against mosquito larvae under laboratoryconditions (M.Sc. Dissertation submitted to MumbaiUniversity Mumbai, India 2002).8. Mwangi RW, Mukiama TK. Evaluation of Melia volkensiextract fractions as mosquito larvicides. J Am MosqControl Assoc 1988; 4: 442–7.9. Babu R, Murugan K. Interactive effect of neem seed kernaand neem gum extract on the control of Culex quinquefasciatusSay. Neem Newsletter 1998; 15(2): 9–11.10. Venketachalam MR, Jebasan A. Repellent activity ofFerronia elephantum Corr. (Rutaceae) leaf extract againstAedes aegypti. Biores Technol 2001; 76(3): 287–8.11. Venketachalam MR, Jebasan A. Larvicidal activity ofHydrocotyl javanica Thunb (Apiaceae) extract against Cx.quinquefasciatus. J Exptl Zool India 2001; 4(1): 99–101.12. Finney DJ. Probit analysis, III edn. Cambridge: CambridgeUniversity Press 1971.13. Sosan MB, Adewoyin FB, Adewunmi CO. Larvicidalproperties of three indigenous plant oils on the mosquitoAedes aegypti. Nigerian J Natl Prod Med 2001; 5: 30–3.14. Thomas TG, Rao S, Lal S. Mosquito larvicidal propertiesof an indigenous plant, Ipomoea cairica Linn. JapaneseJ Infect Dis 2004; 57: 176–7.15. Dwivedi SC, Karwasara K. Larvicidal activity of fiveplants extracts against Culex quinquefasciatus. Indian JEntomol 2003; 65(3): 335–8.16. Latha C, Vijhayakumar PD, Velayudhan S, Joseph A.Biological activity of indigenous plant extracts as mosquitolarvicides. Indian J Exptl Biol 1999; 37: 206–8.17. Cavalcanti ESB, Morais SM, Lima MAA, Santana EWP.Larvicidal activity of essential oils from Brazilian plantsagainst Aedes aegypti L. Mem Inst Oswaldo Cruz 2004;99(5): 541–4.Corresponding author: Dr. N.G. Das, Medical Entomology Division, Defence Researc

A New Method for the Economic Laws of Extinction Using the Fox-Wright-type Function

In this note, we deal with the possibility of optimal economic extinction. We employ the Fox-Wright-type function to characterize the probability of transference from optimal selection to the economic laws of extinction. For the extinction, we shall utilize the fractional Poisson process

Fluorescent Pseudomonas influence palisade mesophyll development and spatial root development in Phaseolus vulgaris

Three strains of plant growth promoting fluorescent Pseudomonads (HPR6, RRLJ008 and RRLJ134) were studied for their effect on growth and yield of French bean (Phaseolus vulgaris L.) under field conditions. The effect of these strains on nature of root development and leaf palisade tube length were also examined. The strains induced positive response on growth and physiological parameters resulting in higher yield in P. vulgaris. Strain HPR6 produced the most promising results in thickening of leaf palisade layer, spreading of lateral roots and production of root hairs. The increase in specific leaf weight (SLW), net assimilation rate (NAR) and relative growth rate (RGR) by these strains were 68%, 152% and 167%, respectively. The growth and yield parameters were also significantly improved compared to the uninoculated control. Antibiotic resistant mutant strains demonstrated that these bacteria effectively colonized the rhizosphere of French bean. The results suggest that the strains could be developed for field application on a large scale

Local fractional system for economic order quantity using entropy solution

Abstract The economic order quantity (EOQ) model describes the quantity that minimizes the aggregate sum of all cost functions. We propose an assembly for EOQ, nonlinear local fractional differential models with costs functions with respect to time in a cyclic period. For this system, using fractional entropy, we study the related optimization problem and improve a relaxed method for calculating a bounded interval containing the optimal cycle length. Also, for a special class of transportation functions, we study these consequences and introduce processes to compute the optimal size and the matching optimal order stage

A Proposed Vision of the Transformation of the Arab Universities into Smart Digital Universities

This research develops a proposed vision to transform Arab universities into smart digital universities. The descriptive research approach is used to achieve the research objectives. The research sample consists of 450 faculty members and 75 educational experts randomly selected by stratified random method. The questionnaire is adopted as a research instrument. The findings indicate that a proposed vision can be developed to transform Arab universities into smart digital universities by addressing several themes; the philosophical premises of the proposed vision, the features of the proposed vision “smart university administration, smart people, smart university environment, and knowledge network”, determining the requirements necessary to implement the proposed vision, setting the appropriate foundations for the proposed implementation and success in Arab universities, and demonstrating the potential challenges and threats that may stand in the way of implementing the proposed vision and methods to overcome them

Increased 30-Day Mortality in Very Old ICU Patients with COVID-19 Compared to Patients with Respiratory Failure without COVID-19

Purpose: The number of patients ≥ 80 years admitted into critical care is increasing. Coronavirus disease 2019 (COVID-19) added another challenge for clinical decisions for both admission and limitation of life-sustaining treatments (LLST). We aimed to compare the characteristics and mortality of very old critically ill patients with or without COVID-19 with a focus on LLST. Methods: Patients 80 years or older with acute respiratory failure were recruited from the VIP2 and COVIP studies. Baseline patient characteristics, interventions in intensive care unit (ICU) and outcomes (30-day survival) were recorded. COVID patients were matched to non-COVID patients based on the following factors: age (± 2 years), Sequential Organ Failure Assessment (SOFA) score (± 2 points), clinical frailty scale (± 1 point), gender and region on a 1:2 ratio. Specific ICU procedures and LLST were compared between the cohorts by means of cumulative incidence curves taking into account the competing risk of discharge and death. Results: 693 COVID patients were compared to 1393 non-COVID patients. COVID patients were younger, less frail, less severely ill with lower SOFA score, but were treated more often with invasive mechanical ventilation (MV) and had a lower 30-day survival. 404 COVID patients could be matched to 666 non-COVID patients. For COVID patients, withholding and withdrawing of LST were more frequent than for non-COVID and the 30-day survival was almost half compared to non-COVID patients. Conclusion: Very old COVID patients have a different trajectory than non-COVID patients. Whether this finding is due to a decision policy with more active treatment limitation or to an inherent higher risk of death due to COVID-19 is unclear.info:eu-repo/semantics/publishedVersio

Accelerometer Measured Levels of Moderate-to-Vigorous Intensity Physical Activity and Sedentary Time in Children and Adolescents with Chronic Disease: a Systematic Review and Meta-Analysis

Context: Moderate-to-vigorous physical activity (MVPA) and sedentary time (ST) are important for child and adolescent health. Objective: To examine habitual levels of accelerometer measured MVPA and ST in children and adolescents with chronic disease, and how these levels compare with healthy peers. Methods: Data sources: An extensive search was carried out in Medline, Cochrane library, EMBASE, SPORTDiscus and CINAHL from 2000–2017. Study selection: Studies with accelerometer-measured MVPA and/or ST (at least 3 days and 6 hours/day to provide estimates of habitual levels) in children 0–19 years of age with chronic diseases but without co-morbidities that would present major impediments to physical activity. In all cases patients were studied while well and clinically stable. Results: Out of 1592 records, 25 studies were eligible, in four chronic disease categories: cardiovascular disease (7 studies), respiratory disease (7 studies), diabetes (8 studies), and malignancy (3 studies). Patient MVPA was generally below the recommended 60 min/day and ST generally high regardless of the disease condition. Comparison with healthy controls suggested no marked differences in MVPA between controls and patients with cardiovascular disease (1 study, n = 42) and type 1 diabetes (5 studies, n = 400; SMD -0.70, 95% CI -1.89 to 0.48, p = 0.25). In patients with respiratory disease, MVPA was lower in patients than controls (4 studies, n = 470; SMD -0.39, 95% CI -0.80, 0.02, p = 0.06). Meta-analysis indicated significantly lower MVPA in patients with malignancies than in the controls (2 studies, n = 90; SMD -2.2, 95% CI -4.08 to -0.26, p = 0.03). Time spent sedentary was significantly higher in patients in 4/10 studies compared with healthy control groups, significantly lower in 1 study, while 5 studies showed no significant group difference. Conclusions: MVPA in children/adolescents with chronic disease appear to be well below guideline recommendations, although comparable with activity levels of their healthy peers except for children with malignancies. Tailored and disease appropriate intervention strategies may be needed to increase MVPA and reduce ST in children and adolescents with chronic disease

Geometric Study of 2D-Wave Equations in View of K-Symbol Airy Functions

The notion of k-symbol special functions has recently been introduced. This new concept offers many interesting geometric properties for these special functions including logarithmic convexity. The aim of the present paper is to exploit essentially two-dimensional wave propagation in the earth-ionosphere wave path using k-symbol Airy functions (KAFs) in the open unit disk. It is shown that the standard wave-mode working formula may be determined by orthogonality considerations without the use of intricate justifications of the complex plane. By taking into account the symmetry-convex depiction of the KAFs, the formula combination is derived