Objetive: To explore the potential insecticidal, ovipositor deterrent and antifeedant effects of ethyl acetate extract of the seeds of Senna tora(Syn. Cassia tora) against cowpea weevil(Callosobruchus maculatus).Metho...Objetive: To explore the potential insecticidal, ovipositor deterrent and antifeedant effects of ethyl acetate extract of the seeds of Senna tora(Syn. Cassia tora) against cowpea weevil(Callosobruchus maculatus).Method: The activities were evaluated using standard protocols.In these bioassays, the cowpea seeds were used directly as an insect feed. The activity of the extract and isolated compounds were tested at concentrations of 100, 200 and 300 μg/mL and compared to neem oil and cinnamaldehyde(as standard positive controls). Phytochemical analysis of the ethyl acetate extract was done through a number of chromatographic techniques and the structures of the isolated compounds were established through comprehensive spectroscopic analysis including 2 D-NMR and ESI-MS studies.Results: Fractionation of the active ethyl acetate extract resulted in the isolation of one known anthraquinone,aurantio-obtusin(1) and a novel compound that was named as cassiatorin(2). Compounds1 and 2 showed comparable insect antifeedant properties with the positive controls while their insecticidal and ovipositor deterrent effects were far superior to the standard controls.Conclusions: It is thus concluded that Senna tora extracts and the isolated compounds(1 and2) may be employed in the postharvest management of stored cowpea seeds and as other crop protectants.展开更多
The Central Bank of Nigeria Anchored Borrowers Programme efforts geared towards massive production of cowpea and sustainable food security is challenged with post-harvest losses especially due to insect pest infestati...The Central Bank of Nigeria Anchored Borrowers Programme efforts geared towards massive production of cowpea and sustainable food security is challenged with post-harvest losses especially due to insect pest infestation in storage. So also, chemical method of pest control posed more health and ecological challenges than food insecurity. This work investigated the effect of Piper guineense on cowpea storage weevil at the agronomy laboratory of the Lagos State Polytechnic, Ikorodu. Contact toxicity of P. guineense at 0.2, 0.4, 0.6, 0.8 and 1 g per 20 g of cowpea seeds in test tubes including a control was observed. The treatment materials exhibited significant efficacy from 24 hours after infestation. P. guineense at 1 g concentration significantly reduced the oviposition potential, egg hatching rate, holes and emergence of adult Callosobruchus maculatus on treated seeds. The powders caused chronic toxicity and inhibit development. All the responses were found to be concentration dependent. Increasing rates of P. guineense increased performance. The implication of these results is discussed and recommendations proffered.展开更多
Callosobruchus maculatus(Fabricius,1775)(Coleoptera:Bruchinae)is a destructive agricultural pest that is harmful to beans worldwide and an important quarantine pest in China.It was divided into two phenotypes based on...Callosobruchus maculatus(Fabricius,1775)(Coleoptera:Bruchinae)is a destructive agricultural pest that is harmful to beans worldwide and an important quarantine pest in China.It was divided into two phenotypes based on polyphenism:normal and flight forms.In this study,we first compared the morphological structures of the compound eyes of the two forms.According to the results of scanning electron microscopy(SEM),transmission electron microscopy(TEM),microcomputed tomography(micro-CT),and computer three-dimensional reconstruction,there are no differences in the structures of the compound eyes between the normal and flight forms except for the number of ommatidia.From the internal structure,the compound eyes have a biconvex cornea with open rhabdom and acone eye,crystalline cone directly connected with rhabdom,and no clear zone.It is a kind of apposition eye.Ommatidia facets range in shape from quadrilateral to hexagonal and some irregular shapes.On electroretinograms(ERGs),the normal and flight forms showed different spectral sensitivities:the normal form had the strongest response to ultraviolet light,whereas the flight form had the strongest response to white light.Behavioral assays revealed that the normal and flight forms showed completely opposite phototaxis behaviors;the flight form exhibited positive phototaxis,whereas the normal form exhibited negative phototaxis.This study not only enriches our knowledge on coleopteran compound eyes but also provides a foundation for in-depth research on the photoreceptor mechanisms of compound eyes,which may be useful in pest control management.展开更多
基金The financial assistance from the Swedish International Development Agency for some of the study (travel grant for Valantine Mbatchou)
文摘Objetive: To explore the potential insecticidal, ovipositor deterrent and antifeedant effects of ethyl acetate extract of the seeds of Senna tora(Syn. Cassia tora) against cowpea weevil(Callosobruchus maculatus).Method: The activities were evaluated using standard protocols.In these bioassays, the cowpea seeds were used directly as an insect feed. The activity of the extract and isolated compounds were tested at concentrations of 100, 200 and 300 μg/mL and compared to neem oil and cinnamaldehyde(as standard positive controls). Phytochemical analysis of the ethyl acetate extract was done through a number of chromatographic techniques and the structures of the isolated compounds were established through comprehensive spectroscopic analysis including 2 D-NMR and ESI-MS studies.Results: Fractionation of the active ethyl acetate extract resulted in the isolation of one known anthraquinone,aurantio-obtusin(1) and a novel compound that was named as cassiatorin(2). Compounds1 and 2 showed comparable insect antifeedant properties with the positive controls while their insecticidal and ovipositor deterrent effects were far superior to the standard controls.Conclusions: It is thus concluded that Senna tora extracts and the isolated compounds(1 and2) may be employed in the postharvest management of stored cowpea seeds and as other crop protectants.
文摘The Central Bank of Nigeria Anchored Borrowers Programme efforts geared towards massive production of cowpea and sustainable food security is challenged with post-harvest losses especially due to insect pest infestation in storage. So also, chemical method of pest control posed more health and ecological challenges than food insecurity. This work investigated the effect of Piper guineense on cowpea storage weevil at the agronomy laboratory of the Lagos State Polytechnic, Ikorodu. Contact toxicity of P. guineense at 0.2, 0.4, 0.6, 0.8 and 1 g per 20 g of cowpea seeds in test tubes including a control was observed. The treatment materials exhibited significant efficacy from 24 hours after infestation. P. guineense at 1 g concentration significantly reduced the oviposition potential, egg hatching rate, holes and emergence of adult Callosobruchus maculatus on treated seeds. The powders caused chronic toxicity and inhibit development. All the responses were found to be concentration dependent. Increasing rates of P. guineense increased performance. The implication of these results is discussed and recommendations proffered.
基金funded by the China Postdoctoral Science Foundation(E290D51135)。
文摘Callosobruchus maculatus(Fabricius,1775)(Coleoptera:Bruchinae)is a destructive agricultural pest that is harmful to beans worldwide and an important quarantine pest in China.It was divided into two phenotypes based on polyphenism:normal and flight forms.In this study,we first compared the morphological structures of the compound eyes of the two forms.According to the results of scanning electron microscopy(SEM),transmission electron microscopy(TEM),microcomputed tomography(micro-CT),and computer three-dimensional reconstruction,there are no differences in the structures of the compound eyes between the normal and flight forms except for the number of ommatidia.From the internal structure,the compound eyes have a biconvex cornea with open rhabdom and acone eye,crystalline cone directly connected with rhabdom,and no clear zone.It is a kind of apposition eye.Ommatidia facets range in shape from quadrilateral to hexagonal and some irregular shapes.On electroretinograms(ERGs),the normal and flight forms showed different spectral sensitivities:the normal form had the strongest response to ultraviolet light,whereas the flight form had the strongest response to white light.Behavioral assays revealed that the normal and flight forms showed completely opposite phototaxis behaviors;the flight form exhibited positive phototaxis,whereas the normal form exhibited negative phototaxis.This study not only enriches our knowledge on coleopteran compound eyes but also provides a foundation for in-depth research on the photoreceptor mechanisms of compound eyes,which may be useful in pest control management.
