Control de larvas de Aedes aegypti con extractos de Allium sativum y Annona muricata como larvicidas / Control of larvae Aedes aegypti with extracts of Allium sativum and Annona muricata as larvicides

RESUMEN Objetivo Evaluar el efecto larvicida en éter de petróleo de los extractos de Allium sativum (ajo) y Annona muricata (guanábana) sobre larvas en IV estadio de Aedes aegypti en condiciones de laboratorio. Métodos Se realizaron diferentes bioensayos (tratamientos) en 6 concentraciones para Annona muricata y 7 concentraciones de Allium sativum, con cuatro repeticiones y un control. Se tuvo lecturas de mortalidad a las 2, 12, 24, 36 y 48 horas. Se validaron los datos obtenidos estadísticamente (corrección de Abbott y Análisis ANOVA). Además, se determinaron las concentraciones y tiempos letales para ambos extractos con un análisis Probit. Resultados Se obtuvo que, en un periodo de 48 horas, el tratamiento de 500 ppm del extracto de Annona muricata logró una mortalidad del 97%, mientras que el tratamiento de 2000 ppm con Allium sativum logró alcanzar una mortalidad del 85%. El tiempo letal 50 (50% de mortalidad) para Annona muricata, se obtuvo en el tratamiento de 200 ppm antes de 24 horas, para el caso de Allium sativum fue en el tratamiento de 1200 ppm antes de 48 horas. Para el tiempo letal 90 (90% de mortalidad) para Annona muricata, se obtuvo en el tratamiento de 400 ppm antes de 40 horas. Para el caso de Allium sativum, el tiempo letal 90 no fue posible obtenerlo experimentalmente. Se determinó por medio de un modelo matemático lineal, que dio como resultado 51 horas. Conclusión Ambas especies poseen efecto larvicida. Sin embargo, el extracto más eficiente y efectivo como larvicida es el de Annona muricata, lo que permite dar una alternativa natural, viable, económica y biodegradable para el control de larvas de esta especie.

ABSTRACT Objective To evaluate the larvicidal effect in petroleum ether of the extracts of Allium sativum (garlic) and Annona muricata (soursop) on larvae in stage IV of Aedes aegypti under laboratory conditions. Methods Different bioassays (treatments) were performed in 6 factors for Annona muricata and 7 concentrations of Allium sativum, with four replications and one control. Mortality readings were taken at 2, 12, 24, 36 and 48 hours. The data obtained statistically (Abbott correction and ANOVA analysis) were validated, in addition, the concentrations and lethal times for both extracts were determined with a Probit analysis. Results It was obtained that, in a 48 hour period, the treatment of 500 ppm of the extract of Annona muricata resulted in a mortality of 97%, while the treatment of 2000 ppm with Allium sativum reached a mortality of 85%. The lethal time 50 (50% mortality) for Annona muricata, was obtained in the treatment of 200 ppm within 24 hours, in the case of Allium sativum it was in the treatment of 1200 ppm before 48 hours. For the lethal time 90 for Annona muricata, obtain the treatment of 400 ppm before 40 hours, for the case of Allium sativum, the lethal time 90 (90% mortality) could not be obtained experimentally, it was determined by means of a linear mathematical model, resulting in 51 hours. Conclusion Both species affected larvicidal effect. However, the most efficient and effective extract as a larvicide is that of Annona muricata, which allows giving a natural, viable, economical and biodegradable alternative for the control of larvae of this species.

Carmenta theobromae (), pest of guava in Colombia: biology, life cycle and natural enemies.

In 2006, the presence of a pest in guava was detected for the first time in the Province of Vélez, Santander, Colombia, known as the bander worm. Research on the biology of this pest is scarce and no natural enemies have been registered. The aim of the study was to establish the taxonomy, life cycle, damage (distribution, incidence, and severity) and natural enemies of this pest to be used in future integrated management programs. This study was carried out between May 2013 and December 2014. The taxonomy and morphological descriptions of the life stages of the bander worm correspond to Carmenta theobromae ( Busck, 1910). The life cycle in the field was 120-150 days, with 2-3 generations per year: egg, 15-30 days; larva, 60 days; pupa, 25 days; adult, 10-30 days. In the laboratory, the life cycle was 90-110 days: egg, 10-20 days; larval stages 6-7, 50-60 days; pupa, 20-22 days; adult, 5-7 days. The incidence was 98% in 124 farms with 9.87 ± 1.94 infested trees in relation to 40.74 ± 5.52 observed trees (n = 4,970). Severity was moderate (n = 48). The damage involves the removal of the bark to reach the vascular cambium. Biological control associated with the parasitoids Brachymeria pedalis and Telenomus sp., the entomopathogens Lecanicillium lecanii, Beauveria bassiana and B. brongniartii, and the practices like weeding and pruning represent a potential control strategy.

Deltamethrin resistance in Chagas disease vectors colonizing oil palm plantations: implications for vector control strategies in a public health-agriculture interface.

BACKGROUND: Triatomine bugs are responsible for the vectorial transmission of the parasite Trypanosoma cruzi, etiological agent of Chagas disease, a zoonosis affecting 10 million people and with 25 million at risk of infection. Several triatomine species of the genus Rhodnius have been found inhabiting palm crowns where insects can find shelter in leaves axils and blood from palm-associated vertebrates. Rhodnius prolixus insects have been collected in oil palms in Colombia, and high T. cruzi infection rates were found. Since pest control is carried out in oil palm plantations, continuous exposure to insecticides could be occurring in these triatomines. Some insecticides suggested for pest control in oil palm plantations are also recommended for triatomine control in human dwellings. In this study, our objective was to assess if triatomines inhabiting oil palms exhibit resistance to deltamethrin, an insecticide used for vector control. METHODS: Rhodnius prolixus nymphs were sampled in oil palms located in Tauramena, Colombia. To determine deltamethrin resistance, biological and biochemical assays were carried out on fifth-instar nymphs from the F1 generation. For biological assays, pure and commercial deltamethrin were used, and in biochemical assays, activities of detoxifying enzymes related to pyrethroid resistance, such as oxidases, esterases and transferases, were quantified. RESULTS: Deltamethrin lethal dosage 50 and 90 in R. prolixus from oil palms was significantly higher than in those from a susceptible colony suggesting possible deltamethrin resistance. Moreover, mortality with commercial deltamethrin was very low in insects from oil palms. In biochemical assays, the activity of evaluated detoxifying enzymes was significantly higher in R. prolixus from oil palms than in those from the susceptible colony. CONCLUSIONS: Possible deltamethrin resistance found in R. prolixus insects from oil palms could threaten traditional vector control strategies in urban settings if insecticide-resistant triatomines can migrate from oil palms plantations. In palm oil producer countries such as Colombia, the oil palm plantations are growing constantly during the last years. We suggest that pest control strategies in oil palm crops should include triatomine surveillance and toxicological monitoring, especially in zones with several Chagas disease cases.

Deltamethrin resistance in Chagas disease vectors colonizing oil palm plantations: implications for vector control strategies in a public health-agriculture interface / Resistência à deltametrina em vetores da doença de Chagas que colonizam plantações de dendezeiros: implicações para estratégias de controle de vetores em uma interface saúde pública-agricultura

Background: Triatomine bugs are responsible for the vectorial transmission of the parasite Trypanosoma cruzi, etiological agent of Chagas disease, a zoonosis afecting 10 million people and with 25 million at risk of infection. Several triatomine species of the genus Rhodnius have been found inhabiting palm crowns where insects can fnd shelter in leaves axils and blood from palm-associated vertebrates. Rhodnius prolixus insects have been collected in oil palms in Colombia, and high T. cruzi infection rates were found. Since pest control is carried out in oil palm plantations, continuous exposure to insecticides could be occurring in these triatomines. Some insecticides suggested for pest control in oil palm plantations are also recommended for triatomine control in human dwellings. In this study, our objective was to assess if triatomines inhabiting oil palms exhibit resistance to deltamethrin, an insecticide used for vector control. Methods: Rhodnius prolixus nymphs were sampled in oil palms located in Tauramena, Colombia. To determine deltamethrin resistance, biological and biochemical assays were carried out on ffth-instar nymphs from the F1 generation. For biological assays, pure and commercial deltamethrin were used, and in biochemical assays, activities of detoxifying enzymes related to pyrethroid resistance, such as oxidases, esterases and transferases, were quantifed. Results: Deltamethrin lethal dosage 50 and 90 in R. prolixus from oil palms was signifcantly higher than in those from a susceptible colony suggesting possible deltamethrin resistance. Moreover, mortality with commercial deltamethrin was very low in insects from oil palms. In biochemical assays, the activity of evaluated detoxifying enzymes was signifcantly higher in R. prolixus from oil palms than in those from the susceptible colony. Conclusions: Possible deltamethrin resistance found in R. prolixus insects from oil palms could threaten traditional vector control strategies in urban settings if insecticide-resistant triatomines can migrate from oil palms plantations. In palm oil producer countries such as Colombia, the oil palm plantations are growing constantly during the last years. We suggest that pest control strategies in oil palm crops should include triatomine surveillance and toxicological monitoring, especially in zones with several Chagas disease cases

Influence of physicochemical factors on environmental availability and distribution of semiochemicals that affect Varroa destructor and phylogenetically close organisms: classification by VHWOC PCA-clustering.

Varroa destructor parasites Apis mellifera larvae following the interception of the semiochemicals involved in bee communication; thus, the semiochemical availability and distribution pathways take place within different physicochemical environments. The structure of 172 molecules with semiochemical activity on Varroa destructor was used to compute the representative physicochemical descriptors of the thermodynamic partition among different physicochemical environments: vapor pressure (V), Henry's coefficient (H), water solubility constant (W), octanol-water partition coefficient (O) and organic carbon partition coefficient (C); VHWOC. The principal component analysis (PCA) and hierarchical clustering of VHWOC descriptors allowed us to establish the trend in availability and distribution of the semiochemicals resulting in a 4 classes model of physicochemical environments: Class 1, Soluble/Volatile; Class 2, Soluble; Class 3, Contact; Class 4, Adsorbed/Volatile. Our results suggest that semiochemicals can transit between different thermodynamic equilibrium phases depending on environment conditions. The classification prediction of the model was tested on 6 new molecules obtained from ketonic extracts of L5 Apis mellifera drone larvae; locating them in class 4, which was consistent with their molecular structure. This study can be the starting point for the design of synthetic semiochemicals or for the control of Varroa destructor. In addition, the method can be used in the analysis of other semiochemical groups.

A Simulation Model of the Mass Rearing of Tetranychus urticae Koch (Acari: Tetranychidae) on Beans.

The supply of predatory mites as natural enemies is a key component to guarantee the success of biological pest control programs as alternatives to chemical control in commercial crops. To meet the demand for a supply of biologicals, the mass rearing of natural enemies is an option, and the first step must be to develop a standardized system that maximizes the production of prey. One choice for this first step is to use simulation models that can evaluate scenarios that are difficult or complex to address experimentally. In this work, a model was developed to evaluate the current management conditions for the mass rearing of the pest mite Tetranychus urticae Koch. Our aim was to identify alternative scenarios to maximize mite production through mass rearing that could be evaluated in real systems. We assumed that populations of T. urticae were regulated by the conditions of supply-demand theory and modeled the age structure, temperature effects, and individual phenology of T. urticae. The supply-demand theory of resources was used to regulate populations, which involved structured ages and temperature effects for the different stages in the development of individuals. We used the functional response and the paradigm of metabolic pool models to describe resource acquisition and allocation. We demonstrated that 7- to 14-day-old plants infested with 45 or 62 T. urticae/plant could reach 25,000 individuals/plant, being 50% of these preys at the preferred stages by the predator Phytoseiulus persimilis Athias-Henriot. Our theoretical model requires validation in experimental/real systems of mass rearing to better verify the validity of all of the parameters and predictions before commercial implementation.

Effect of mini-sprinkler irrigation system on Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae) infective juvenile

Entomopathogenic nematodes (EPNs) are currently being used as successful biological control agents of soil-dwelling insect pests. Previous field and greenhouse studies demonstrated that application techniques and non-biotic factors (temperature and pressure) have a significant effect on EPNs efficacy. The objective of this study was to evaluate the influence of an irrigation spray application system on the viability, infectivity and host search capability of Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae) infective juveniles (IJ). Two assays were proposed. Their viability was evaluated under the microscope after the IJ passed through the irrigation system. Infectivity on Galleria mellonella larvae, and host search capability, as evidenced by larval mortality, were evaluated in containers (Experiment 1). In the field (Experiment 2), mortality of G. mellonella larvae was evaluated under different nematode concentrations (0, 100,000, 300,000 and 500,000 IJ per tree). No differences were recorded on the viability, infectivity and host search capability of the IJ in Experiment 1. In Experiment 2, differences were recorded among the different concentrations used (p 0.05), and a higher mortality was observed at the highest nematode concentration (28.3% and 37% in each one of the two experiment repetitions). This irrigation system did not affected adversely the viability, infectivity and host search capability of H. baujardi LPP7.

Nematóides entomopatogênicos (NEPs) vêm sendo usados com sucesso como agentes do controle biológico de pragas de solo. Estudos anteriores mostraram que técnicas de aplicação e fatores abióticos (temperatura e pressão) afetam a eficiência dos NEPs em testes de campo e casa-de-vegetação. O objetivo deste trabalho foi avaliar a influência de condições geradas por um sistema de irrigação por microaspersão, na viabilidade, infectividade e na capacidade de busca de hospedeiros nos juvenis infectantes (JI) de Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae). Dois experimentos foram propostos. A viabilidade dos juvenis infectantes (JI) foi avaliada no microscópio imediatamente após sua passagem pelo sistema de irrigação. A infectividade e a capacidade de busca pelo hospedeiro em larvas de Galleria mellonella foram avaliadas em vasos (Experimento 1). A campo (Experimento 2), foi avaliada a mortalidade de larvas de G. mellonella sob diferentes concentrações do nematóide (0, 100.000, 300.000 e 500.000 JI por árvore). A viabilidade, infectividade e a capacidade de busca dos nematóides após a passagem pelo sistema não foi diferente da testemunha. No Experimento 2, houve diferença entre os tratamentos (p 0.05) e se observou maior mortalidade na maior concentração de nematóides, com mortalidade de 28,3% e 37% em cada uma das duas repetições do experimento. Este sistema de micro-aspersão não afeta a viabilidade, infectividade e capacidade de busca dos JIs de H. baujardi LPP7 até o inseto-alvo.

Effect of mini-sprinkler irrigation system on Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae) infective juvenile

Entomopathogenic nematodes (EPNs) are currently being used as successful biological control agents of soil-dwelling insect pests. Previous field and greenhouse studies demonstrated that application techniques and non-biotic factors (temperature and pressure) have a significant effect on EPNs efficacy. The objective of this study was to evaluate the influence of an irrigation spray application system on the viability, infectivity and host search capability of Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae) infective juveniles (IJ). Two assays were proposed. Their viability was evaluated under the microscope after the IJ passed through the irrigation system. Infectivity on Galleria mellonella larvae, and host search capability, as evidenced by larval mortality, were evaluated in containers (Experiment 1). In the field (Experiment 2), mortality of G. mellonella larvae was evaluated under different nematode concentrations (0, 100,000, 300,000 and 500,000 IJ per tree). No differences were recorded on the viability, infectivity and host search capability of the IJ in Experiment 1. In Experiment 2, differences were recorded among the different concentrations used (p 0.05), and a higher mortality was observed at the highest nematode concentration (28.3% and 37% in each one of the two experiment repetitions). This irrigation system did not affected adversely the viability, infectivity and host search capability of H. baujardi LPP7.

Nematóides entomopatogênicos (NEPs) vêm sendo usados com sucesso como agentes do controle biológico de pragas de solo. Estudos anteriores mostraram que técnicas de aplicação e fatores abióticos (temperatura e pressão) afetam a eficiência dos NEPs em testes de campo e casa-de-vegetação. O objetivo deste trabalho foi avaliar a influência de condições geradas por um sistema de irrigação por microaspersão, na viabilidade, infectividade e na capacidade de busca de hospedeiros nos juvenis infectantes (JI) de Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae). Dois experimentos foram propostos. A viabilidade dos juvenis infectantes (JI) foi avaliada no microscópio imediatamente após sua passagem pelo sistema de irrigação. A infectividade e a capacidade de busca pelo hospedeiro em larvas de Galleria mellonella foram avaliadas em vasos (Experimento 1). A campo (Experimento 2), foi avaliada a mortalidade de larvas de G. mellonella sob diferentes concentrações do nematóide (0, 100.000, 300.000 e 500.000 JI por árvore). A viabilidade, infectividade e a capacidade de busca dos nematóides após a passagem pelo sistema não foi diferente da testemunha. No Experimento 2, houve diferença entre os tratamentos (p 0.05) e se observou maior mortalidade na maior concentração de nematóides, com mortalidade de 28,3% e 37% em cada uma das duas repetições do experimento. Este sistema de micro-aspersão não afeta a viabilidade, infectividade e capacidade de busca dos JIs de H. baujardi LPP7 até o inseto-alvo.