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Aphid Fecundity (aphid + fecundity)
Selected AbstractsImpact of chemical elicitor applications on greenhouse tomato plants and population growth of the green peach aphid, Myzus persicaeENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2006Anthony J. Boughton Abstract Recent advances in the understanding of plant signaling pathways have opened the way for using elicitor-induced plant resistance as a tactic for protecting plants against arthropod pests. Four common elicitors of induced responses in tomato, Lycopersicon esculentum Mill. (Solanaceae), were evaluated with regard to phytotoxicity, induction of plant defensive proteins, and effects on population growth and fecundity of a common pest, the green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae). Ethephon and methyl jasmonate (MJ) treatments caused varying degrees of phytotoxicity. Ethephon caused pronounced changes in plant growth form and severe, dose-dependent negative impacts on plant growth and flowering. Effects with MJ were milder, but still caused temporary inhibition of development, leading to smaller plants and delayed flowering. The commercial elicitors benzothiadiazole (BTH) and harpin did not cause detectable phytotoxicity. The highest doses of ethephon and MJ significantly increased leaf peroxidase (POD) levels but only MJ treatments significantly increased polyphenol oxidase (PPO) levels. BTH and harpin had no detectable effects on POD and PPO. Populations of green peach aphids grew significantly more slowly on plants treated with BTH or MJ than on control plants or plants treated with harpin or ethephon. Slowed aphid population growth on BTH-treated plants was due to significant reductions in aphid fecundity, although this was independent of changes in time to onset of reproduction or time to death. Aphid fecundity was also reduced on MJ-treated plants relative to controls, but this difference was not statistically significant, suggesting that other mechanisms are involved in slowing aphid population growth on MJ-treated plants. Growth of aphid populations on plants treated with a MJ,BTH mixture was reduced almost as much as with treatments of MJ alone, suggesting that antagonism between JA-dependant and SA-dependent plant signaling pathways is only mild with regard to induced defenses against aphids. [source] Life history of the bird cherry-oat aphid, Rhopalosiphum padi, on transgenic and non-transformed wheat challenged with Wheat streak mosaic virusENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2009Edgardo S. Jiménez-Martínez Abstract The life history of the bird cherry-oat aphid, Rhopalosiphum padi (L.) (Hemiptera: Aphididae), was studied via laboratory assays on Wheat streak mosaic virus (WSMV)-infected and non-infected transgenic and non-transformed wheat [Triticum aestivum L. (Poaceae)]. Although R. padi is not a WSMV vector, it is known to colonize WSMV-infected wheat plants. Two transgenic soft white winter wheat genotypes, 366-D03 and 366-D8, that express the WSMV coat protein gene, and the WSMV-susceptible non-transformed cultivar Daws were tested. All genotypes showed disease symptoms when infected with WSMV. Whereas plant height was significantly reduced on virus-infected compared to non-infected plants of all genotypes, virus-infected transgenic plants exhibited lower virus titer and lower disease rating scores than Daws. No significant effects of WSMV infection or genotypes were observed on the length of R. padi nymphal development period, nor on their pre-, and post-reproductive periods. Rhopalosiphum padi reproductive period was significantly longer on Daws infected with WSMV than on non-infected plants of this cultivar. In contrast, there were no significant differences in length of R. padi reproductive period between virus-infected and non-infected transgenic plants within a genotype. Rhopalosiphum padi daily fecundity was significantly lower and adult longevity significantly longer on virus-infected than on non-infected plants of all genotypes. Total aphid fecundity and intrinsic rate of increase were not significantly different among treatments. The percentage of winged aphids that developed was greater on WSMV-infected compared to non-infected plants within a genotype. Results indicate that both virus infection status of plants and wheat genotype influence the life history of R. padi. [source] Impact of chemical elicitor applications on greenhouse tomato plants and population growth of the green peach aphid, Myzus persicaeENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2006Anthony J. Boughton Abstract Recent advances in the understanding of plant signaling pathways have opened the way for using elicitor-induced plant resistance as a tactic for protecting plants against arthropod pests. Four common elicitors of induced responses in tomato, Lycopersicon esculentum Mill. (Solanaceae), were evaluated with regard to phytotoxicity, induction of plant defensive proteins, and effects on population growth and fecundity of a common pest, the green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae). Ethephon and methyl jasmonate (MJ) treatments caused varying degrees of phytotoxicity. Ethephon caused pronounced changes in plant growth form and severe, dose-dependent negative impacts on plant growth and flowering. Effects with MJ were milder, but still caused temporary inhibition of development, leading to smaller plants and delayed flowering. The commercial elicitors benzothiadiazole (BTH) and harpin did not cause detectable phytotoxicity. The highest doses of ethephon and MJ significantly increased leaf peroxidase (POD) levels but only MJ treatments significantly increased polyphenol oxidase (PPO) levels. BTH and harpin had no detectable effects on POD and PPO. Populations of green peach aphids grew significantly more slowly on plants treated with BTH or MJ than on control plants or plants treated with harpin or ethephon. Slowed aphid population growth on BTH-treated plants was due to significant reductions in aphid fecundity, although this was independent of changes in time to onset of reproduction or time to death. Aphid fecundity was also reduced on MJ-treated plants relative to controls, but this difference was not statistically significant, suggesting that other mechanisms are involved in slowing aphid population growth on MJ-treated plants. Growth of aphid populations on plants treated with a MJ,BTH mixture was reduced almost as much as with treatments of MJ alone, suggesting that antagonism between JA-dependant and SA-dependent plant signaling pathways is only mild with regard to induced defenses against aphids. [source] Sublethal effects of selected insecticides on fecundity and wing dimorphism of green peach aphid (Hom., Aphididae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 2 2008X.-Y. Wang Abstract Effects of sublethal concentrations (LC25) of six insecticides (imidacloprid, rotenone, fenvalerate, abamectin, pirimicarb and azadirachtin) on fecundity and wing dimorphism of the green peach aphid, Myzus persicae (Sulzer), were studied both under laboratory and greenhouse conditions. In the laboratory, aphid reproduction reduced by 44.29% and 54.01% when rotenone and abamectin treatments were applied at sublethal dose, respectively, and sublethal fenvalerate application resulted in markedly lower average reproduction per female per day compared with control. Reproductive duration of aphid treated with abamectin significantly decreased by 44.19%. But in the greenhouse, there were no evident differences in the aphid fecundity and reproductive duration between treatments and control. Life-table parameters also demonstrated that the six insecticides at sublethal doses did not stimulate the aphid reproductive potential. In the laboratory, after being exposed to sublethal doses of imidacloprid and fenvalerate, the proportions of alate progeny in aphid progeny were significantly higher than that of the control. In the greenhouse, percentages of alate offspring from the mother aphids treated with imidacloprid, fenvalerate and abamectin increased pronouncedly compared with control. Mortality rates of offspring in the nymphal stages from adults treated with insecticides revealed no significant changes between laboratory and greenhouse. The developmental time in days of the offspring varied in all treatments. Mechanisms of insecticide-induced resurgence are discussed. [source] | ||||||||||