Kamran Yousaf | China Agricultural University (original) (raw)
Papers by Kamran Yousaf
Scientific Reports, 2019
Buprofezin, a chitin synthesis inhibitor that can be used for the control of hemipteran pests, es... more Buprofezin, a chitin synthesis inhibitor that can be used for the control of hemipteran pests, especially melon aphid, Aphis gossypii. the impact of low lethal concentrations of buprofezin on the biological parameters and expression profile of CHS1 gene were estimated for two successive generations of A. gossypii. the present result shows that the Lc 15 and Lc 30 of buprofezin significantly decreased the fecundity and longevity of both generations. exposure of f 0 individuals to both concentrations delay the developmental period in f 1. Furthermore, the survival rate, intrinsic rate of increase (r), finite rate of increase (λ), and net reproductive rate (R 0) were reduced significantly in progeny generation at both concentrations. However, the reduction in gross reproductive rate (GRR) was observed only at Lc 30. Although, the mean generation time (T) prolonged substantially at Lc 30. Additionally, expression of the CHS1 gene was significantly increased in F 0 adults. Significant in...
Scientific Reports, 2018
Cucurbitacin B is a natural triterpene present in plants of Cucurbitaceae family, which are among... more Cucurbitacin B is a natural triterpene present in plants of Cucurbitaceae family, which are among the host plants for melon aphid, Aphis gossypii. In present study we characterized the effects of two cucurbitacin B concentrations on the biological parameters of adults (F 0) and of juveniles and adults of their progeny (F 1). The results showed that cucurbitacin B at 25 ppm significantly reduced the adult longevity and fecundity of both F 0 and F 1 generation. Exposure of F 0 generation to 25 ppm though reduced the demographic traits of F 1 including the intrinsic rate of increase r (day −1), generation time T (day), finite rate of increase λ (day −1), however, only net reproductive rate R 0 (offspring/individual) decreased significantly. While 100 ppm reduced not only the longevity and fecundity of F 0 generation but also the longevity of F 1 generation. Fecundity of F 1 was not affected by 100 ppm of cucurbitacin B, however, R 0 (offspring/individual) and T (day) of F 1 generation were lower than the control population. These results support the hypothesis that high contents of cucurbitacin B caused negative impact on melon aphid and could be used as a lead for classical selection of resistant varieties of plants that are main hosts for the melon aphid. Plant secondary metabolites can serve as defensive compounds against herbivores (allelochemicals), though they are usually considered insignificant for regular plant growth processes, where primary metabolites play a crucial role 1. Some plant materials categorizing as phenols, alkaloids, terpenes, flavonoids and other associated compounds , have repellent and/or antifeedant effects for phytophagous insects 2. For example, alkaloids are feeding deterrents against Leptinotarsa decemlineata and Empoasca fabae 3. Phenolic compounds in wheat act as deterrent for the cereal aphid, Rhopalosiphum padi 4. High concentration of phenols in willow plant deterred the feeding of leaf beetle, Galerucella lineola 5. Phenols together with flavonols are related to resistance to whitefly in black gram 6. High level of gossypol in cotton plant prolonged the immature duration and reduced the survival and fecundity of Aphis gossypii 7. Triterpenes, as major plant terpenoids, have remarkable properties, such as antibacterial 8 , analgesic 9 , neuroprotective 10 , antioxidant 11 , etc. In addition, some of the triterpenes, such as azadirachtin, exhibited clear repellent, antifeedant, growth and reproduction inhibiting effects, and even acute toxicity towards many insect species 12-15. Plant species belonging to the cucurbitaceae family contain several naturally related triterpenes, collectively known as cucurbitacins, such as cucurbitacin A, B, C, D, E, I, J, K and L 16,17. Cucurbitacins are natural tetra-cyclic triterpene compounds in the plant of Cucurbitaceae family 18. These are constitutive or insect-induced allelochemicals and have been shown to have exert acute and sublethal toxicity, as well as deterrents effects for feeding and oviposition in insects 19,20. Ethanol extracts from the fruit of Citrullus colocynthis contained cucur-bitacin E glycoside and caused mortality of the cowpea aphid, Aphis craccivora 21. High level of cucurbitacin C in cucumber (Cucumis sativus) decreased the survival rate and population growth of spider mite (Tetranychus urti-cae) in cucumber plants 19,22. Cucurbitacin D inhibited the reproduction of spider mites when applied on cotton
Mango mealybug (Drosicha mangiferae) is a polyphagous insect, which has been recorded to feed on ... more Mango mealybug (Drosicha mangiferae) is a polyphagous insect, which has been recorded to feed on large number of plant species. Insecticides are considered to be the rapid method for the control of insect pests to overcome losses. In the current study, five different insecticides i-e Chlorpyriphos, Lambda cyalothrin, bifenthrin, deltamethrin and profenophos were evaluated against adult female of mango mealy bug using a leaf dip method. The data were recorded after 24, 48, 72, 96 and 120h. The Results indicated that profenophos was the most effective insecticide against adult female mealybug. Chloropyrifos was least effective among all the tested insecticides in the laboratory.
Most crops face pest situations where more than one insect pest become economic pest and require ... more Most crops face pest situations where more than one insect pest become economic pest and require mixture of insecticide application for management. Presently two pyrethroids and three new chemistry insecticides in mixtures at their lethal concentrations were tested against second instar larvae of Spodoptera litura, under laboratory conditions using leaf dip method. LC 50 of deltamethrin, bifenthrin, emamectin benzoate, chlorfluazuron and flubendamide were 619 and 100, 74.2 and 65.8, 0.08 and 0.06, 73.4 and 52.5, and 0.37 and 0.31 ul/ml, respectively after 48 and 72 hour exposure. Pyrethroids were least effective due to their high LC 50 values as compared to new chemistry insecticides. Emamectin and flubendamide were more toxic with less LC 50 values than chlorfluazuron at observed time periods. Mixtures of deltamethrin with chlorfluazuron, emamectin-benzoate and flubendamide were antagonistic. However, bifenthrin showed potentiation with emamectin and flubendamide which revealed that some pyrethroids can result in potentiating mixtures with new chemistry insecticides for S. litura control under multiple pest problem scenarios.
Scientific Reports, 2019
Buprofezin, a chitin synthesis inhibitor that can be used for the control of hemipteran pests, es... more Buprofezin, a chitin synthesis inhibitor that can be used for the control of hemipteran pests, especially melon aphid, Aphis gossypii. the impact of low lethal concentrations of buprofezin on the biological parameters and expression profile of CHS1 gene were estimated for two successive generations of A. gossypii. the present result shows that the Lc 15 and Lc 30 of buprofezin significantly decreased the fecundity and longevity of both generations. exposure of f 0 individuals to both concentrations delay the developmental period in f 1. Furthermore, the survival rate, intrinsic rate of increase (r), finite rate of increase (λ), and net reproductive rate (R 0) were reduced significantly in progeny generation at both concentrations. However, the reduction in gross reproductive rate (GRR) was observed only at Lc 30. Although, the mean generation time (T) prolonged substantially at Lc 30. Additionally, expression of the CHS1 gene was significantly increased in F 0 adults. Significant in...
Scientific Reports, 2018
Cucurbitacin B is a natural triterpene present in plants of Cucurbitaceae family, which are among... more Cucurbitacin B is a natural triterpene present in plants of Cucurbitaceae family, which are among the host plants for melon aphid, Aphis gossypii. In present study we characterized the effects of two cucurbitacin B concentrations on the biological parameters of adults (F 0) and of juveniles and adults of their progeny (F 1). The results showed that cucurbitacin B at 25 ppm significantly reduced the adult longevity and fecundity of both F 0 and F 1 generation. Exposure of F 0 generation to 25 ppm though reduced the demographic traits of F 1 including the intrinsic rate of increase r (day −1), generation time T (day), finite rate of increase λ (day −1), however, only net reproductive rate R 0 (offspring/individual) decreased significantly. While 100 ppm reduced not only the longevity and fecundity of F 0 generation but also the longevity of F 1 generation. Fecundity of F 1 was not affected by 100 ppm of cucurbitacin B, however, R 0 (offspring/individual) and T (day) of F 1 generation were lower than the control population. These results support the hypothesis that high contents of cucurbitacin B caused negative impact on melon aphid and could be used as a lead for classical selection of resistant varieties of plants that are main hosts for the melon aphid. Plant secondary metabolites can serve as defensive compounds against herbivores (allelochemicals), though they are usually considered insignificant for regular plant growth processes, where primary metabolites play a crucial role 1. Some plant materials categorizing as phenols, alkaloids, terpenes, flavonoids and other associated compounds , have repellent and/or antifeedant effects for phytophagous insects 2. For example, alkaloids are feeding deterrents against Leptinotarsa decemlineata and Empoasca fabae 3. Phenolic compounds in wheat act as deterrent for the cereal aphid, Rhopalosiphum padi 4. High concentration of phenols in willow plant deterred the feeding of leaf beetle, Galerucella lineola 5. Phenols together with flavonols are related to resistance to whitefly in black gram 6. High level of gossypol in cotton plant prolonged the immature duration and reduced the survival and fecundity of Aphis gossypii 7. Triterpenes, as major plant terpenoids, have remarkable properties, such as antibacterial 8 , analgesic 9 , neuroprotective 10 , antioxidant 11 , etc. In addition, some of the triterpenes, such as azadirachtin, exhibited clear repellent, antifeedant, growth and reproduction inhibiting effects, and even acute toxicity towards many insect species 12-15. Plant species belonging to the cucurbitaceae family contain several naturally related triterpenes, collectively known as cucurbitacins, such as cucurbitacin A, B, C, D, E, I, J, K and L 16,17. Cucurbitacins are natural tetra-cyclic triterpene compounds in the plant of Cucurbitaceae family 18. These are constitutive or insect-induced allelochemicals and have been shown to have exert acute and sublethal toxicity, as well as deterrents effects for feeding and oviposition in insects 19,20. Ethanol extracts from the fruit of Citrullus colocynthis contained cucur-bitacin E glycoside and caused mortality of the cowpea aphid, Aphis craccivora 21. High level of cucurbitacin C in cucumber (Cucumis sativus) decreased the survival rate and population growth of spider mite (Tetranychus urti-cae) in cucumber plants 19,22. Cucurbitacin D inhibited the reproduction of spider mites when applied on cotton
Mango mealybug (Drosicha mangiferae) is a polyphagous insect, which has been recorded to feed on ... more Mango mealybug (Drosicha mangiferae) is a polyphagous insect, which has been recorded to feed on large number of plant species. Insecticides are considered to be the rapid method for the control of insect pests to overcome losses. In the current study, five different insecticides i-e Chlorpyriphos, Lambda cyalothrin, bifenthrin, deltamethrin and profenophos were evaluated against adult female of mango mealy bug using a leaf dip method. The data were recorded after 24, 48, 72, 96 and 120h. The Results indicated that profenophos was the most effective insecticide against adult female mealybug. Chloropyrifos was least effective among all the tested insecticides in the laboratory.
Most crops face pest situations where more than one insect pest become economic pest and require ... more Most crops face pest situations where more than one insect pest become economic pest and require mixture of insecticide application for management. Presently two pyrethroids and three new chemistry insecticides in mixtures at their lethal concentrations were tested against second instar larvae of Spodoptera litura, under laboratory conditions using leaf dip method. LC 50 of deltamethrin, bifenthrin, emamectin benzoate, chlorfluazuron and flubendamide were 619 and 100, 74.2 and 65.8, 0.08 and 0.06, 73.4 and 52.5, and 0.37 and 0.31 ul/ml, respectively after 48 and 72 hour exposure. Pyrethroids were least effective due to their high LC 50 values as compared to new chemistry insecticides. Emamectin and flubendamide were more toxic with less LC 50 values than chlorfluazuron at observed time periods. Mixtures of deltamethrin with chlorfluazuron, emamectin-benzoate and flubendamide were antagonistic. However, bifenthrin showed potentiation with emamectin and flubendamide which revealed that some pyrethroids can result in potentiating mixtures with new chemistry insecticides for S. litura control under multiple pest problem scenarios.