Control Of Larvae Research Articles

Biolarviciding implementation in southern Tanzania: Scalability opportunities and challenges

BackgroundThe resistance to insecticides among malaria vectors poses a global challenge in the efforts towards malaria elimination. This calls for an addition of larval control methods such as biolarviciding. However, the implementation of biolarviciding in Tanzania has been very low. Therefore, this study explored factors affecting the implementation of biolarviciding in the councils of Southern Tanzania.MethodsA mixed method descriptive qualitative, cross-sectional study design was used to collect data from 32 community leaders through key informant interviews and 12 Vectors Control Coordinators through in-depth interviews and questionnaire interviews and document review of implementation reports in 12 councils. Data were analysed using ATLAS.ti version 8, where content analysis was performed and SPSS for the quantitative data.ResultsThe study found low implementation of biolarviciding intervention in 9 out of 12 (75%) surveyed councils. All Vector Control Coordinators reported a shortage of at least one type of resources: funds, trained personnel, transport, supply of biolarvicide, and equipment; low community involvement (50%) and low level of community participation 83.3% (10/12).ConclusionThis study highlights resource inadequacy and low community participation as main barriers to the implementation of biolarviciding. Availing adequate resources and strengthening community participation through involvement in all stages of implementation is crucial for successful and sustainable implementation.

Programmatic review of the mosquito control methods used in the highly industrialized rice agroecosystems of Sacramento and Yolo Counties, California

In the Sacramento Valley (California, USA), rice (Oryza sativa L.) fields are an economically important crop and productive habitats for the mosquito species Culex tarsalis and Anopheles freeborni. Since 2010, approximately 150 km2 of conventional and 16 km2 of organic rice have been grown in Sacramento and Yolo Counties. These fields are often within mosquito flight-range of both rural towns and urban centers. Culex tarsalis are highly competent vectors of West Nile virus, and An. freeborni are aggressive, mammalophagic, nuisance biters. The Sacramento–Yolo Mosquito and Vector Control District provides mosquito control for the two counties in its jurisdiction. The principles of Integrated Pest Management are used to control mosquitoes in rice growing areas, relying upon a range of surveillance and control interventions. Larvae are controlled by limiting habitats that enable development of immature mosquitoes while balancing agricultural and wildlife needs, applying larvicides, and the use of Gambusia affinis (mosquitofish). Adult mosquitoes are controlled by ultra-low volume pesticide applications. The program was assessed for larval and adult mosquito control efficacy and areas of programmatic improvement identified. Because rice fields are productive habitats for mosquitoes, complete elimination of the habitat is not a feasible goal, thus efforts are aimed at interrupting disease transmission and reducing the number of mosquitoes that traverse into populated areas.

Direct development of the catfish pectoral fin: An alternative pectoral fin pattern of teleosts.

The study of the teleosts' pectoral fin development touches on many crucial issues of evolutionary biology, from the formation of local adaptations to the tetrapod limbs' origin. Teleosts' pectoral fin is considered a rather developmentally and anatomically conservative structure. It displays larval and adult stages differing in the skeletal and soft tissues' composition. Larva-adult transition proceeds under the thyroid hormone (TH) control that defines pectoral fin ontogeny as an indirect development. However, the outstanding diversity of teleosts allows suggesting the existence of lineage specific developmental patterns. We present a description of the North African catfish, Clarias gariepinus, pectoral fin development. It lacks a clear larval stage and directly develops the adult skeleton with the associated musculature and innervation. Interestingly, the development of catfish pectoral fin appears not to be under the TH dependence. This catfish displays a direct pectoral fin developmental trajectory differing from the stereotyped teleost pattern. In the absence of the larval endoskeletal disk and TH control, the catfish's proximal radials arise in a manner somewhat similar to the metapterygial radials in basal actinopterygians and humerus in sarcopterygians. Thus, the catfish fin pattern seems homoplastic, arising by convergence with, or reversion to the ancestral developmental mechanisms.

A Review on Vector Borne Disease Transmission: Current Strategies of Mosquito Vector Control

.In this review, the mosquito vector borne diseases (VBD) majorly malaria, dengue, filariasis, chikungunya, Japanese encephalitis, Zika were presented to comprehend the global disease incidence as the control of these disease transmitting vectors are challengeable globally nowadays. It has been found that malaria affects nearly 500 million people and lymphatic filariasis about 100 million people worldwide every year. About 25 million people are infected by dengue, with approximately 25,000 deaths annually. For mosquito larval adult control measures, synthetic pesticides playing major role but owing to resistance development its application is impeded. Alternatively, bacterial biopesticides are very useful for larval control mainly due to environment friendliness and lack of resistance development. As of now, Bacillus sphaericus (Bs) and B. thuringiensis israelensis (Bti) are in use but Bs is nowadays not recommended for field application due to resistance. Significant results on resistance development are noticed in India, Brazil and France. Due to these situations, there is a growing interest in discovering novel biological agents from natural sources. In the present review, the current global scenario of VBDs were discussed.

Habitat characteristics and spatial distribution of Anopheles mosquito larvae in malaria elimination settings in Dembiya District, Northwestern Ethiopia

The persistence and productivity of larval habitat is a major factor that regulates adult Anopheles mosquitoes’ density and malaria transmission intensity. A study on Anopheles mosquitoes breeding habitat diversity, distribution, characteristics and larval density in different seasons across various habitat types is important to design effective larval control strategies. This study was aimed to investigate the Anopheles species composition, the productivity of larval breeding habitats, and their spatial distribution in selected localities of Dembiya District. A longitudinal study on characteristics and productivity of Anopheles larval breeding habitats was conducted from June 2018 to May 2019 in selected localities of Dembiya District. Anopheles larvae were collected using standard WHO dipper (350 ml capacity) and droppers depending on the size of the breeding habitats. Physicochemical characteristics of breeding habitats were measured and Anopheles mosquitoes were identified by using morphological keys and polymerase chain reaction (PCR). Logistic regression was used to assess the association of environmental factors with the presence or absence of Anopheles mosquitoes larvae. A total of 1,629 Anopheles larvae and 185 pupae were collected from both localities. These comprise Anopheles arabiensis, An. pharoensis, An. coustani, An. christyi, An. squamosus, An. demeilloni, An. danicalicus, and An. cinereus. The highest density of Anopheles larvae was collected from at a drying water canal (14.7 ± 3.5 larvae/dip) and the lowest larval density was recorded in rain water pools (0.2 ± 0.2 larvae/dip). The presence or absence of Anopheles larvae were significantly associated with physical characteristics of the breeding habitats such as turbidity (mid turbid) (AOR = 66.03; 95% CI: 2.01-2168.24, p = 0.019) and presence of grasses (AOR = 12.62; 95% CI: 1.29-122.78, p = 0.029). This study indicated that breeding sites persist and support Anopheles mosquito breeding activities and impact malaria control and elimination programs. Incorporating vector control strategies targeting Anopheles larvae as a part of malaria intervention strategies could enhance the malaria control and elimination program in the study area.

Defining the mechanisms of action and mosquito larva midgut response to a yeast-encapsulated orange oil larvicide

BackgroundYeast-encapsulated orange oil (YEOO) is a novel, ingestible larvicide that combines the benefits of a low-cost essential oil with yeast, an attractive food source for mosquito larvae. In this work, we investigated the underlying mechanisms of action associated with YEOO ingestion by Aedes aegypti larvae.MethodsAedes aegypti third-stage larvae (L3) were treated with sublethal or lethal concentrations of YEOO. Genes associated with apoptosis, autophagy and innate immune responses were investigated by RT-qPCR in guts and carcasses dissected from treated and control larvae. Differential expression of cytochrome P450 genes in the CYP6 and CYP9 families were also investigated. Confocal and transmission electron microscopy were used to assess damage caused by YEOO throughout the larval alimentary canal. TUNEL was used to assess apoptosis via DNA fragmentation.ResultsThe apoptosis genes IAP1 and IAP2 in larvae displayed opposing effects following exposure to lethal doses of YEOO, with a 26-fold induction of IAP1 at 8 h post YEOO ingestion. The effector caspase CASPS8 displayed a 6.7-fold induction in the gut and concomitant 70-fold induction in the carcass at 8 h post YEOO ingestion. The midgut epithelia regenerator, Vein, had an 11-fold induction in the gut after 4 h and was repressed 7.6-fold in the carcass at 24 h. Sublethal concentrations (< LC50) led to significant differential expression of CYP6 and CYP9 genes. Midgut epithelial damage was highlighted by the destruction of microvilli, vacuolization of midgut cells and damage to cell junctions and basal lamina as early as 30 min. Larval type 2 peritrophic matrix structural integrity and porosity remain unchanged.ConclusionOur results strongly suggest that the robust larvicidal activity of YEOO is due to a generalized broad-acting mechanism combining epithelial damage and apoptosis, with concomitant expression of multiple innate response genes involved in epithelial regeneration and detoxification. YEOO’s amenability for use as part of an integrated vector management program makes this novel larvicide a practical approach for mosquito larval control in the future.Graphical

Effect of pyriproxyfen on development and survival of Anopheles gambiae sensu stricto under forested and deforested areas

BackgroundThe land cover changes in the form of deforestation are known for their impact on enhancing Anopheline life-history traits. In most cases, these traits depend on environmental parameters such as temperature and light. Pyriproxyfen is an insect growth regulator juvenile hormone (JH) designed to inhibit adult mosquito emergence. It is an effective biolarvicide in controlling immature stages of malaria vectors and many other insects. Despite the known efficiency of pyriproxyfen in malaria vector control, but the understanding of its performance under deforested or afforested areas is not clear. The present study aimed at evaluating the impact of pyriproxyfen on development and survivorship of Anopheles gambiae s.s. in forested and deforested areas. Tests of two dosages (0.03 ppm.ai. and 0.3 ppm.ai.) of pyriproxyfen were done in standardized semi-field conditions under ambient temperature and light in netting screened environment. The plastic artificial microcosms containing 1 kg of soil and 2000 mL of dechlorinated water were used. First instars larvae were distributed in densities of 20, 40, and 60 in six replicates each, to form a total of 18 microcosms per each land cover type. Larvae mortality, development, and survival time were monitored and recorded after every 24 h until pupation. Emerging adults from pupa were recorded, and their sexes were identified.ResultsPyriproxyfen increased Anopheles gambiae larvae mortality rates and larvae developmental time of first instar larvae to pupal at densities of 20, 40 and 60 larvae in forested area (p < 0.05). Also, the larvae survival time was found to be longer in forested area compared to deforested area (p < 0.05) except at the density of 20 larvae. Pyriproxyfen reduced larvae pupation rates by 88% in forested area and it had 100% adult emergence inhibition regardless of land cover type and pyriproxyfen concentration, except at the density of 60 larvae exposed to 0.03 ppm, where adult emergence rate of 6.7% was detected.ConclusionThese findings suggest that, the efficacy of pyriproxyfen against Anopheles gambiae s.s. larvae and pupae is dependent on land cover types and its larvicidal effect can be increased by presence of trees canopy covers. Therefore, reviving forestry schemes and community afforestation programmes could have a positive impact on mosquito larval control by using larvicides. Also, increasing land canopy cover can be opted as a way to discourage the development and survival of potential malaria vectors.

Strong Larvicidal and Molluscicidal Activities of the (E)-β-caryophyllene-rich Chemotype of Callicarpa macrophylla Vah Leaf Essential Oil Growing Wild in Vietnam

Essential oils have been shown to effectively control vectors and intermediate hosts of disease transmission. The essential oil from the leaves of the Vietnamese species Callicarpa macrophylla was investigated for chemical composition, and evaluated for the pesticidal activities of both the essential oil and its major components. The essential oils were obtained by hydrodistillation (Clevenger apparatus) and analyzed by gas chromatography/mass spectrometry (GC/MS). The main components identified in the essential oil were (E)-β-caryophyllene (24.1%), caryophyllene oxide (18.7%), β-pinene (17.8%), and myrtenal (9.3%). The essential oil was screened for mosquito larvicidal activity and molluscidical activity. The essential oil showed promising potential for larval control of Aedes aegypti and Aedes albopictus with LC50 values of 34.01 and 48.45 µg/mL after 48 h of exposure, respectively. Furthermore, this essential oil demonstrated excellent molluscidical activity against Pomacea canaliculata with an LC50 value of 8.09 µg/mL. The essential oil did not exhibit toxicity to the non-target organism Diplonychus rusticus with mortality rates of only 10.0% and 11.25% after 24 h and 48 h of exposure, respectively, at a concentration of 100 μg/mL. The good acetylcholinesterase (AChE) enzyme inhibitory activity could be a mechanism responsible for the potent larvicidal activities of the essential oil. The essential oil of the leaves of Callicarpa macrophylla may be considered as an environmentally-friendly source of pesticide.

Dengue virus transovarial transmission detection in Aedes aegypti from dengue hemorrhagic fever patients' residences in Denpasar, Bali.

Background and Aim:To effectively control dengue hemorrhagic fever (DHF), it is necessary to assess the risk of vertical virus transmission in Aedes aegypti mosquitoes. This study aimed to detect dengue virus (DENV) transovarial transmission in A. aegypti collected from DHF patients’ residences in Denpasar, Bali.Materials and Methods:A. aegypti samples were acquired by rearing A. aegypti eggs collected from ovitraps placed in the homes of DHF patients. Ovitraps were installed for 7 days and viewed using a loupe to determine whether there were Aedes spp. eggs present. An immunocytochemical method was utilized with 200 samples, and virus detection was performed using a reverse transcriptase-polymerase chain reaction (RT-PCR).Results:Of the 10 DHF patient houses fitted with ovitraps, four produced positive ovitraps from which larvae developed (house index=40%). Of the 50 ovitraps mounted in the 10 homes, 14 ovitraps were positive and contained A. aegypti eggs (ovitrap index=28%). Of these 14 positive ovitraps containing A. aegypti eggs, 10 ovitraps produced larvae. Immunocytochemical tests were conducted on A. aegypti eggs from the four houses under study. It was found that from the 200 samples collected, 197 samples could be observed, and 11 samples (5.6%) were positive for DENV antigen. RT-PCR examination conducted on mosquitoes reared from the four houses studied obtained a negative virus content result.Conclusion:This study found the presence of DENV antigen to be as high as 5.6%. This means that potential for transovarial transmission exists within DHF patients’ homes in Denpasar, Bali. Aedes control strategy in Denpasar should address this finding, in addition to the current approaches which have focused primarily on the elimination of larval breeding habitats and control of adults using insecticidal fogging during outbreaks.

PREDATORY EFFECT AND SELECTIVITY OF PREY OF NOTONECTA PERUVIANA (HEMIPTERA: NOTONECTIDAE) ON THE LARVAL CONTROL OF MOSQUITOES (DIPTERA: CULICIDAE)

The larval stage of culicid mosquitoes are the main food resource of notonectides in aquatic systems. Prey alternation and abundance can significantly affect predator-prey interaction and functional response (FR). We evaluated the effect of predation and prey selectivity of Notonecta peruviana in fourth-stage larvae (F1) of Aedes aegypti and Culex quinquefasciatus at different densities and two test systems: one prey and the combination of both (ratio 1: 1). We used the FR protocol to measure predation and the Manly preference index () to evaluate the selectivity of prey, in a CRD experimental design. N. peruviana generated type II RF (“concave model”) of greater impact in larvae of Ae. aegypti (p ≤ 0.01). Predation capacity was similar in both of the prey, 17 ± 4 larvae / day in Cx. quinquefasciatus and 21 ± 4 in Ae. aegypti. The attack coefficient (a), turned out to be similar for both prey species in both test systems and the handling time (Th) was lower for Ae. aegypti than for Culex. Notonecta peruviana demonstrated selectivity for larvae of Ae. aegypti especially at the highest densities (≥ 0.5), attributed to the inefficient anti depredation response, active mobility and smaller size compared to those of Cx. quinquefasciatus. The FR demonstrated the success of N. peruviana in the larval control of culicid mosquitoes, prioritizing the type of prey; thus, promoting the need for its applicability in the field.

Polymer-based nanostructures loaded with piperine as a platform to improve the larvicidal activity against Aedes aegypti

Piperine is an alkaloid extracted from the seed of Piper spp., which has demonstrated a larvicidal effect against Ae. aegypti. The incorporation of piperine into nanostructured systems can increase the effectiveness of this natural product in the control of Ae. aegypti larvae. In this study, we evaluated the effectiveness of piperine loaded or not into two nanostructured systems (named NS-A and NS-B) prepared by the nanoprecipitation method. The Ae. aegypti larvae were exposed to different concentrations of piperine loaded or not (2 to 16 ppm) and the mortality was investigated after 24, 48, and 72 hours. The nanostructures prepared were spherical in shape with narrow size distribution and great encapsulation efficiency. The lethal concentration 50 (LC50) for non-loaded piperine were 13.015 ppm (24 hours), 8.098 ppm (48 hours), and 7.248 ppm (72 hours). The LC50 values found for NS-A were 35.378 ppm (24 hours), 12.091 ppm (48 hours), and 8.011 ppm (72 hours), whereas the values found for NS-B were 21.267 ppm (24 hours), 12.091 ppm (48 hours), and 8.011 ppm (72 hours). Collectively, these findings suggested that non-loaded piperine caused higher larval mortality in the first hours of exposure while the nanostructured systems promoted the slow release of piperine and thereby increased the larvicidal activity over time. Therefore, loading piperine into nanostructured systems might be an effective tool to improve the larval control of vector Ae. aegypti.

Knowledge, Attitudes, and Behavior of Larva Monitoring Interpreter (Jumantik) Cadre as Efforts to Prevent Dengue Cases

Background: Efforts to prevent and control DHF in Palu City are still inadequate. The lack of community participation in the implementation of 3M causes the density of Aedes aegypti larvae to be high.&#x0D; Objective: To analyze the knowledge, attitudes and behavior of larva monitoring interpreters before and after being given health education in reducing dengue cases.&#x0D; Methods: This type of research is a quasi-experimental, with one group pre and posttest design. Carried out in Palu City, Central Sulawesi Province and Pasang Kayu Regency, West Sulawesi Province. The sample size is 98 Jumantik cadres. The interview study instrument used a set of previously validated and tested questionnaires. Informed consent was taken from all respondents and confidentiality was guaranteed throughout the study. Data were analyzed using SPSS with Paired T-test dependent &#x0D; Results: Knowledge about ways to prevent DHF increased the highest from the pre-test (20.10) post-test (51.77) which means that it increased by 32.3% p = 0.000, the smallest increase in knowledge about the spread of DHF was the pre-test value ( 12.9) post-test (14.2) means an increase of 1.3% p=0.003. The attitude that increased the most was the effort to control DHF with a pre-test value (9.4) post-test (48.2%) increased by 38.8% p = 0.000, while the smallest increase was the attitude of responsibility for controlling DHF with a pre-test value. -test (53.32) post-test (53.50) increased by 0.18% p=0.737. The behavior with the highest increase in value was about larval control with a pre-test score (4.75) post-test (37.78) means an increase of 33.0% p = 0.000, while the smallest increase is the behavior of draining the water tank with the pre-test (26.87) post-test (35.83) increasing 8.96% p = 0.002.&#x0D; Conclusion: Health education through counseling methods is effective in increasing the knowledge, attitudes and behavior of Jumantik Cadres in preventing dengue fever in Palu City, Central Sulawesi and Pasangkayu Regency, West Sulawesi

Antimicrobial and Larvicidal Activities of Different Ocimum Essential Oils Extracted by Ultrasound-Assisted Hydrodistillation.

Infectious diseases and their vectors have remained a concern for human population from their historical origin. Microbial pathogens have also emerged as a potent threat to the healthcare systems even in developed countries. Essential oils remain a less explored method for infectious disease control; besides, the ultrasound-assisted extraction (UAE) of essential oil production has emerged as promising source of bioactive volatiles over conventional methods. This study analyzed the possible use of UAE- Essential oils (EOs) from different species of Ocimum plants (Ocimum basilicum (OB), O. gratissimum (OG), O. tenuiflorum (OT), and O. canum (OC)) in the management of microbial pathogens and mosquito larval control. The antibacterial activity was estimated in terms of a disc diffusion assay and minimum inhibitory concentrations against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enteritidis. The larvicidal property was found using three important mosquito vectors and the LC50 value was determined. Furthermore, antioxidant and anti-inflammatory properties were estimated in terms of radical scavenging activities and the inhibition of lipoxygenase enzyme activity. The EOs exhibited significant DPPH radical scavenging (high in OG), hydrogen-peroxide scavenging (OB) and lipoxygenase inhibition (OB). The antibacterial activity was high in OB and OG (p < 0.05) and the larvicidal activity was of higher sensitivity against Aedis and Culex, whereas Armigeres was more resistant. However, no sign of toxicity in the Allium cepa model or non-targeted organism Guppy fishes was observed. Overall, the UAE extracted Ocimum essential oils were found to be effective against various human pathogenic microbial organisms, with OB and OG being highly active. Likewise, the EOs was also able to induce mortality in the larval forms of various mosquito vectors.

Temporal Evaluation of Insecticide Resistance in Populations of the Major Arboviral Vector Aedes Aegypti from Northern Nigeria.

Simple SummaryOutbreaks of dengue and yellow fever are fast becoming normal in Nigeria. Transmitted by mosquito vectors, Aedes aegypti and/or Aedes albopictus, control of these arboviral diseases depends largely on control of the above vectors. This requires knowledge of the identity/composition and insecticide resistance profile of the vector species—knowledge which is inadequate across Nigeria. In this study we characterised two populations of Aedes aegypti from north-western Nigeria (BUK/Kano and Pantami). Bioassays with Kano larvae suggest resistance to temephos (an important insecticide for larval control) is low but increasing, while deltamethrin resistance is high, and increased 6-fold between 2018 and 2019, and 11-fold by 2020. Adult bioassays established high pyrethroid resistance (the bed net insecticides) and extreme resistance to DDT (an indoor residual spraying insecticide). Bioassays with piperonylbutoxide and diethylmaleate (synergists which block activity of the enzymes that confer insecticide resistance) resulted in significant recovery of mortalities, implicating CYP450s and GSTs—enzymes which confer pyrethroid and DDT resistance, respectively. Tests with pyrethroid-containing bed net, PermaNet® 3.0 (side panels) revealed high resistance, in contrast to the areas also containing piperonylbutoxide (PermaNet® 3.0, roof panel). These findings highlight the challenges associated with the control of this arboviral vector of public health importance in Nigeria.To support evidence-based control measures, two Nigerian Aedes populations (BUK and Pantami) were characterised. Larval bioassay using temephos and deltamethrin revealed a significant increase in deltamethrin resistance, with LC50 of 0.018mg/L (resistance ratio compared to New Orleans, RR = 2.250) in 2018 increasing ~6-fold, by 2019 (LC50 = 0.100mg/L, RR = 12.5), and ~11-fold in 2020 (LC50 = 0.198mg/L, RR = 24.750). For the median deltamethrin concentration (0.05mg/L), a gradual decrease in mortality was observed, from 50.6% in 2018, to 44.9% in 2019, and 34.2% in 2020. Extremely high DDT resistance was observed, with <3% mortalities and LT50s of 352.87 min, 369.19 min and 406.94 min in 2018, 2019 and 2020, respectively. Significant temporal increase in resistance was observed towards ƛ-cyhalothrin (a type II pyrethroid) over three years. Synergist bioassays with diethylmaleate and piperonylbutoxide significantly recovered DDT and ƛ-cyhalothrin susceptibility respectively, implicating glutathione S-transferases and CYP450s. Cone bioassays revealed increased resistance to the PermaNet® 3.0, side panels (mortalities of 94% in 2018, 66.4% in 2019, and 73.6% in 2020), while full susceptibility was obtained with the roof of PermaNet® 3.0. The F1534C kdr mutation occurred in low frequency, with significant correlation between heterozygote genotypes and DDT resistance. This temporal increase in resistance is a major challenge for control of this vector of public health importance.

The Larval Scaffold Controls Fascicle Number But is Not Required for Formation of the Dorsolongitudinal Flight Muscles in Manduca Sexta

The Larval Scaffold Controls Fascicle Number But is Not Required for Formation of the Dorsolongitudinal Flight Muscles in Manduca Sexta

Evaluation of Liquid and Granular Insecticide Formulations at Planting for Larval Corn Rootworm Control, 2021

Evaluation of Liquid and Granular Insecticide Formulations at Planting for Larval Corn Rootworm Control, 2021

Sustainable control of malaria employing Gambusia fishes as biological control in Jalore and Barmer districts of Western Rajasthan

Sardar Sarovar Irrigation Canal system was constructed by Narmada Valley Development Authority (NVDA) to cater to drinking water as well as for irrigation purposes in Jalore and Barmer districts of Western Rajasthan. To cater to the needs of water for the villagers in the command areas, 'Diggies' (surface water tanks) with 'Sumpwells' (water supply surface tanks) were installed. In a health impact assessment study of the irrigation canals from December 2010 to February 2016, the breeding of two major malaria vectors. An. culicifacies and An. stephensi were observed in diggies and sumpwells. As a biological control, Gambusia affanis fishes were employed for larval control in such stagnated water sites during the intervention phase viz. February 2012 in 251 diggies and 251 sumpwells. A significant reduction of breeding in diggies (99.54%) and sumpwells (97.81%) was observed. The positivity and larval density (dip index) were monitored in the control from up to February 2016 for their sustainability.

Isolation and biocontrol efficacy of entomopathogenic nematodes Steinernema carpocapsae, Steinernema monticolum and Rhabditis blumi on lepidopteran pest Spodoptera litura

Entomopathogenic nematodes (EPN) are an important component of biological control of agricultural pests. Depending on the ambient temperature, EPNs efficacy may be affected by high temperature between 30 and 40°C is usually featured in tropical and subtropical regions. In the present study, we isolated three EPN strains, namely GNAF1, NBS1 and MAF2, exhibiting high virulence on Spodoptera litura larvae and tested their lepidopteran larval control efficacy at temperatures ranging from 20 °C to 40 °C. Results show that larval control efficacy of the isolated nematodes was not affected at higher temperatures, higher emergence of infective juveniles was observed at higher temperatures, showing that EPN multiplication is not affected at higher temperatures. Based on 18s rDNA sequence these strains were identified as Steinernema carpocapsae -MK350941; Steinernema monticolum -MK503674; Rhabditis blumi -MN453373. The present study shows that these EPN can be used for controlling lepidopteran insect pest in tropical and subtropical agroecosystems.

LETHAL TIME BIOLARVA PADA LARVA AEDES AEGYPTI

Aedes aegypti is a Dengue Hemorrhagic Fever (DHF) vector caused by mosquitoes bites from DHF patients to healthy humans. Aedes aegypti needs an optimized temperature to continue their generation. At the larval stage, the temperature required by the larva is 37 ° C with a pH of 7. At optimal temperature, the larvae can become adult mosquitoes that harm humans. Larval control through chemical insecticides can pollute the environment so that natural insecticides are needed. This study aims to identify LT50 biolarvacide 2% concentration. This study is carried out through a systematic review. Of the 125 articles, nine were selected, which were used as the main library. The nine articles use biological larvicides to control Aedes larvae aegypti with lethal time (LT50) varies from 1 hour to 24 hours. Legundi leaves in a concentration of 2% have the fastest LT50, which is 1 hour, while zodia has the longest lethal time of 24 hours with the same attention.

Validation of the Early Warning and Response System (EWARS) for dengue outbreaks: Evidence from the national vector control program in Mexico.

BackgroundDuring 2017, twenty health districts (locations) implemented a dengue outbreak Early Warning and Response System (EWARS) in Mexico, which processes epidemiological, meteorological and entomological alarm indicators to predict dengue outbreaks and triggers early response activities.Out of the 20 priority districts where more than one fifth of all national disease transmission in Mexico occur, eleven districts were purposely selected and analyzed. Nine districts presented outbreak alarms by EWARS but without subsequent outbreaks (“non-outbreak districts”) and two presented alarms with subsequent dengue outbreaks (“outbreak districts”). This evaluation study assesses and compares the impact of alarm-informed response activities and the consequences of failing a timely and adequate response across the outbreak groups.MethodsFive indicators of dengue outbreak response (larval control, entomological studies with water container interventions, focal spraying and indoor residual spraying) were quantitatively analyzed across two groups (”outbreak districts” and “non-outbreak districts”). However, for quality control purposes, only qualitative concluding remarks were derived from the fifth response indicator (fogging).ResultsThe average coverage of vector control responses was significantly higher in non-outbreak districts and across all four indicators. In the “outbreak districts” the response activities started late and were of much lower intensity compared to “non-outbreak districts”. Vector control teams at districts-level demonstrated diverse levels of compliance with local guidelines for ‘initial’, ‘early’ and ‘late’ responses to outbreak alarms, which could potentially explain the different outcomes observed following the outbreak alarms.ConclusionFailing timely and adequate response of alarm signals generated by EWARS showed to negatively impact the disease outbreak control process. On the other hand, districts with adequate and timely response guided by alarm signals demonstrated successful records of outbreak prevention. This study presents important operational scenarios when failing or successding EWARS but warrants investigating the effectiveness and cost-effectiveness of EWARS using a more robust designs.