RESUMEN
Old world bollworm Helicoverpa armigera (Hübner) is one of the serious pests of agricultural crops with more than 184 recorded hosts including cotton. In cotton, H. armigera usually causes yield losses up to 40% with 20-80% damage intensity. In the Indian context it has already developed resistance to most conventional classes of insecticide and its survival on Bt cotton also has been reported in some isolated places. Under such situation, application of semiochemicals can serve as an alternative management option. Among the semiochemicals, oviposition deterrent ones are known to be the most effective as they minimize the infestation at first line of attack by deterring the female moths and protecting the host from oviposition. However, before applying at field level, it is important to develop and standardize a bioassay method for evaluation of oviposition deterrent compounds under laboratory condition. Here, we report a suitable improved bioassay method for evaluation of effect of oviposition deterrents against H. armigera. The five days duration of bioassay method was finalized according to the peak activity of adult moth in terms of mating and fecundity. This investigation presents a method, for finding promising oviposition deterrent compound which will be helpful for researchers to identify the most potent molecule/compounds against H. Armigera
RESUMEN
Aim: The present study was carried out to identify and explore novel areas of semiochemical based pest management like oviposition deterrents.Methodology: The oviposition deterrents were identified from larval faecal pellets of pink bollworm using methanol as solvent and analysed in GC-MS. Three fatty acids were identified and evaluated for oviposition deterrent effect. Results: In the present study, three major compounds namely; oleic, linoleic and palmitic acids were identified for the first time from larval faecal pellets of pink bollworm. Their oviposition deterrent effect was confirmed in bioassays carried out with different concentrations of identified compounds. The avoidance index (Ai) 0.78 ± 0.05 and per cent effective deterrency (PED) 87.42% was recorded in oleic acid at highest concentration followed by linoleic acid (Ai: 0.77 ± 0.03; PED: 86.61%) in reducing the egg laying by conspecific female. This clearly showed the role of these compounds as oviposition deterrent. Interpretation: The compounds, oleic and linoleic acids evaluated in laboratory showed oviposition deterrent effect on female pink bollworm reducing egg laying considerably. However, further field studies need to be conducted to validate these observations.
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Este trabalho teve por objetivo avaliar a bioatividade de óleos essenciais de sassafrás (Ocotea odorifera) e eucalipto (Eucalyptus viminalis) no controle de larvas e adultos de cascudinho (Alphitobius diaperinus), comparando-se seu potencial inseticida. Os óleos essenciais foram obtidos por meio de extração por arraste a vapor de água em escala piloto. Foi empregada a técnica de papel de filtro contaminado para a avaliação do número de insetos mortos. No bioensaio definitivo, foram selecionadas 11 concentrações e um controle (solvente) para determinação da taxa de mortalidade e CL50 dos dois óleos testados. As larvas foram mais suscetíveis que os adultos ao óleo essencial de sassafrás e menos suscetíveis que os adultos, quando expostas ao óleo de eucalipto. Tanto larvas quanto adultos de A. diaperinus foram mais suscetíveis ao óleo essencial de sassafrás (CL50 adulto 0,26mL l-1 e larva 0,12mL l-1) que ao de eucalipto (CL50 adulto 1,37mL l-1 e larva 1,72mL l-1), por via de intoxicação por contato (Ocotea odorifera: Larva y=3,3916+1,4699logx; Adulto; y=0,9486+2,8576logx; e Eucaliptus viminalis: Larva y=1,3643+1,6254logx; Adulto y=1,4487+1,6623logx). Conclui-se que os óleos essenciais de sassafrás e eucalipto podem ser empregados para o controle do cascudinho como uma nova estratégia no manejo integrado dessa praga.
This research aimed to evaluate the sassafras (Ocotea odorifera) and eucalyptus (Eucalyptus viminalis) essential oils on the control of larvae and adults of lesser mealworm (Alphitobius diaperinus), comparing their insecticide potential. The essential oils were produced through water vapor extraction in a semi industrial scale. Contaminated paper filter technique was applied to evaluate the insect mortality. In the current experiment twelve concentrations were included for evaluation and among them one control (solvent) in order to settle the mortality rate and LC50 of the two tested essential oils. The larvae were more susceptible then the adults to sassafras essential oil exposure and less susceptible than the adults, when exposed to eucalypt essential oil. Larvae as well as adults of A. diaperinus were more susceptible to the sassafras (LC50 adults 0.26mL l-1 and larvae 0.12mL l-1) than the eucalyptus essential oil (LC50 adults 1.37mL l-1 and larvae 1.72mL l-1), by contact intoxication (Ocotea odorifera: Larvae y=3,3916+1,4699logx; Adult y=0,9486+2,8576logx; e Eucaliptus viminalis: Larvae y=1,3643+1,6254logx; Adult y=1,4487+1,6623logx). It is concluded that the essential oils of sassafras and eucalyptus can be used to control lesser mealworm and used as a new integrated strategy for management of this pest.
RESUMEN
A broca-do-café é a praga mais importante do cafeeiro. Provoca prejuízos em quantidade e qualidade da produção. Normalmente, é controlada por aplicações de inseticidas. Estratégias alternativas de manejo são necessárias principalmente pelo aumento da produção e demanda por produtos orgânicos. O uso de armadilhas para manejo da broca é revisado. A cor, o modelo da armadilha, os atraentes e as taxas de liberação são fatores diretamente relacionados com a eficiência das armadilhas. Metanol e etanol são os compostos utilizados como atraentes. Ocorrem interações entre fatores na atração da broca. As condições ambientais nas quais o cafeeiro é cultivado também devem influenciar as capturas. Estes aspectos podem explicar algumas diferenças em resultados de alguns estudos. Resultados conflitantes também são verificados no que se refere à eficiência das armadilhas quando utilizadas como estratégia única de controle no campo. Pesquisas adicionais devem ser incentivadas para entender com mais profundidade as interações entre a broca e a planta de café. Da mesma forma, deve-se estudar as interações dos vários fatores intrínsecos das armadilhas e destes fatores com o ambiente no qual a armadilha será instalada. O uso das armadilhas, associadas a outras estratégias de redução populacional da praga, é prática recomendável para manejo da broca
The Coffee berry borer (CBB) is the most important pest in the coffee plantings. Losses are due to quality andquantity reductions. In most plantings, CBB is controlled using insecticides. Alternative management strategiesare strongly demanded due to increasing production and demand for organic products. This paper revises theuse of traps for CBB management. Color and trap designs, attractants and release rates are the factors directlyrelated to trap efficiency. Methanol and ethanol mixture is used as attractant. Interactions among these factorsin the CBB attraction are reported. Environment conditions under which the coffee plantings are conductedinfluence trap captures. These aspects may explain some differences in results for different studies. Conflictingresults are also found in relation to traps efficiency when they are used as a unique control strategy in thefield. Additional research may be encouraged to understand more deeply the interactions between the CBBand coffee plant. In the same way, we must study the interactions of the several intrinsic factors of the trapsand the environment. The use of the trap, associated with other strategies to reduce pest population, is arecommended strategy for CBB management
Asunto(s)
Café/crecimiento & desarrolloRESUMEN
Octenol (1-octen-3-ol) é um cairomônio utilizado por vários grupos de insetos hematófagos para a localização de hospedeiros vertebrados. No entanto, o seu efeito sobre Lutzomyia (Lutzomyia) longipalpis (Lutz & Neiva) nunca foi estudado. O presente trabalho avaliou as respostas eletroantenográficas (EAG) de fêmeas de L. longipalpis. Como estímulo controle utilizou-se corrente de ar, pulsos de ar e pulsos de solvente (hexano). As concentrações logarítmicas de 1-octen-3-ol testadas foram de 10 a 10(6) etag/50mil de solvente. Observaram-se respostas olfativas significativas de 1-octen-3-ol a partir de 10³etag/50mil, tendo a maior amplitude na concentração 10(6)etag/50mil (-3,33mV). Foi observada dose-dependência, ou seja, quanto maior a concentração, maior foi a resposta eletrofisiológica. Estes resultados demonstram, pela primeira vez que L. longipalpis pode detectar a presença do 1-octen-3-ol em corrente de ar. O possível uso de 1-octen-3-ol como cairomônio é discutido para a espécie.
Octenol (1-octen-3-ol) is a kairomone used by haematophagous insects to locate their vertebrate hosts. However, effect of 1-octen-3-ol on Lutzomyia (Lutzomyia) longipalpis (Lutz & Neiva) has never been studied. The present work evaluated the electrophysiological (EAG) responses of female L. (Lutzomyia) longipalpis. Air current, air pulse and solvent (hexane) pulse were used as control stimuli. The logarithmic concentrations of 1-octen-3-ol 10 a 10(6) etag/50æl of solvent were tested. Significant olfactory responses were observed in the concentration of 1-octen-3-ol from 10³ etag/50ul with the greatest response at concentration of 10(6) etag/50ul (-3,33mV). Dose-dependency was observed, as the concentration increased, so did the electrophysiological response. These results demonstrated, for the first time, that L. longipalpis, can detect the presence of 1-octen-3-ol in air current. The possible use of 1-octen-3-ol as kairomone for this species is discussed.