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Pre-reproductive Period (pre-reproductive + period)
Selected AbstractsSurvival rates in a natural population of the damselfly Ceriagrion tenellum: effects of sex and female phenotypeECOLOGICAL ENTOMOLOGY, Issue 4 2001Jose A. Andrés Summary 1. Ceriagrion tenellum females show genetic colour polymorphism. Androchrome (erythrogastrum) females are brightly (male-like) coloured while gynochrome females (typica and melanogastrum) show cryptic colouration. 2. Several hypotheses have been proposed to explain the existence of more than one female morph in damselfly populations. The reproductive isolation and intraspecific mimicry hypotheses predict greater survival of gynochrome females, while the density dependent hypothesis predicts no differential survival between morphs. 3. Mature males had greater recapture probability than females while the survival probability was similar for both sexes. Survival and recapture rates were similar for androchrome and gynochrome females. 4. Gynochrome females showed greater mortality or migration rate than androchrome females during the pre-reproductive period. This result is not predicted by the above hypotheses or by the null hypothesis that colour polymorphism is only maintained by random factors: founder effects, genetic drift, and migration. [source] Temperature-dependent ovariole and testis maturation in the yellow dung flyENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2005Wolf U. Blanckenhorn Abstract Temperature is one of the abiotic environmental factors most strongly affecting animal behaviour, physiology, and life history. In insects, lower temperatures generally slow down most physiological processes, reducing growth rate and prolonging the juvenile period. Here, we investigate temperature-dependent ovariole and testis maturation in the anautogenous yellow dung fly, Scathophaga stercoraria L. (Diptera: Scathophagidae), and relate it to corresponding temperature effects on pre-adult development time and the adult pre-reproductive period. Flies were reared in the laboratory at three constant temperatures (18, 22, and 26 °C), and the size of the developing ovarioles and testes (reflecting sperm production) was measured over time (i.e., age). Ovariole size increased asymptotically over the first 12 days of adult life, while the testes continued to fill after day 10. In accordance with the temperature-size rule, warmer temperatures resulted in smaller ovarioles (eggs) and smaller testes, independent of body size. Warmer temperatures also greatly reduced pre-adult development time by more than half, from 12 to 25 °C, the larger males always taking 1,3 days longer than the females. Corresponding temperature effects on the adult pre-reproductive period were small (<1 day between 15 and 25 °C), with males taking 5,6 days and females 10,13 days to first reproduction. Time lost by males during the pre-adult stage, when ovaries and testes are produced, can thus be more than compensated-for by time gained during the pre-reproductive period, when eggs and sperm are produced, so males can nevertheless start reproducing sooner than females. [source] Effects of systemic potato response to wounding and jasmonate on the aphid Macrosiphum euphorbiae (Sternorryncha: Aphididae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 7 2010L. Brunissen Abstract Plant induced responses are activated by multiple biotic and abiotic stresses, and may affect the interactions between a plant and phytophagous insects. The objective of this work was to evaluate the effects of different stresses inflicted to potato plants (Solanum tuberosum) on the potato aphid (Macrosiphum euphorbiae). Abiotic wounding, biotic wounding by Leptinotarsa decemlineata and treatment with volatile methyl jasmonate (MeJA) were evaluated with regard to the orientation behaviour, the feeding behaviour and the development of the potato aphids. Dual-choice olfactometry showed that plants treated with MeJA lost their attractiveness for the potato aphids, while both abiotic and biotic wounding did not alter the orientation of aphids. Electropenetrography revealed that the feeding behaviour of aphids was only slightly disturbed by a previous L. decemlineata wounding, while it was highly disturbed by mechanical wounding and MeJA treatment. Aphid nymph survival was reduced on mechanically wounded plants, the pre-reproductive period was lengthened and the fecundity reduced on plants treated with MeJA. Our results bring new information about the effects of various stresses inflicted to S. tuberosum on M. euphorbiae. We showed that wounding and MeJA treatment induced an antixenosis resistance in potato plants against M. euphorbiae, which may influence aphid colonization processes. [source] Protected raspberry production accelerates onset of oviposition by vine weevils (Otiorhynchus sulcatus)AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2010Scott N. Johnson 1Soft fruit production is increasingly reliant on crops that are grown under the protection of plastic tunnels, which may also affect insect communities as a result of localized climate change and changes to host plant physiology and chemistry. In particular, insect development rates may differ from field populations, making it more difficult to target control measures. 2The present study investigated how protected environments affected adult vine weevil (Otiorhynchus sulcatus) feeding and reproduction on red raspberry (Rubus idaeus). We focused on the period between adult emergence and the onset of oviposition (i.e. the pre-reproductive period), which represents the optimal period for control. 3Tunnels were up to 4 °C warmer than field plantations in 2008, with plants growing significantly faster (50% increase in height and 16% increase in leaf area) than field grown plants. The carbon/nitrogen ratio in leaves was higher in tunnels (12.07) than the field (10.89) as a result of a significant decrease in nitrogen concentrations (3.40 and 3.90 mg g,1, respectively). 4Over 4 weeks, weevils consumed significantly more foliage in tunnels (370.89 mg) than weevils in the field (166.68 mg), suggesting compensatory feeding to counteract lower leaf nitrogen concentrations. Weevils in tunnels achieved sexual maturity 8 days earlier than those in the field and produced 20-fold more eggs by the time they were 5 weeks old. 5Applying a degree-day model showed good agreement between predicted and observed pre-reproductive periods for weevils in tunnels (36 and 30 days, respectively) and in field plots (41 and 38 days, respectively). [source] Factors affecting the invasion success of Senecio inaequidens and S. pterophorus in Mediterranean plant communitiesJOURNAL OF VEGETATION SCIENCE, Issue 2 2007L. Caño Abstract Question: Plant invasions result from complex interactions between species traits, community characteristics and environmental variations. We examined the effect of these interactions on the invasion potential of two invasive Senecio species, S. inaequidens and S. pterophorus, across three Mediterranean plant communities in a natural park. Location: Catalonia, NE Spain. Methods: We carried out two series of experimental seedling transplantations, in the spring and fall of 2003, in grassland, shrubland and Quercus ilex forest. Competition with neighbouring plants and water availability were manipulated. We evaluated the survival, growth and reproduction with respect to each treatment combination. Results: Any habitat can be colonised if disturbance occurs. In the absence of disturbance, shrubland enhanced the survival of seedlings. Competition with resident vegetation dramatically reduced survival in grassland and forest when establishment occurred in the spring. However, establishment in the fall promoted invasion in grassland and shrubland, even in the undisturbed treatment. Grassland allowed the highest growth and reproductive performance of both species while forest was the most resistant habitat to invasion. S. inaequidens had a higher growth rate and a shorter pre-reproductive period than S. pterophorus. S. pterophorus produced more biomass and was more dependent on water availability than S. inaequidens. Conclusions: In the light of our results, we recommend surveying open shrublands and grasslands after periods of rainfall. Special attention should be paid to S. pterophorus, which is currently spreading. A preliminary assessment of the invasive-ness of this plant is given in this study. [source] Protected raspberry production accelerates onset of oviposition by vine weevils (Otiorhynchus sulcatus)AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2010Scott N. Johnson 1Soft fruit production is increasingly reliant on crops that are grown under the protection of plastic tunnels, which may also affect insect communities as a result of localized climate change and changes to host plant physiology and chemistry. In particular, insect development rates may differ from field populations, making it more difficult to target control measures. 2The present study investigated how protected environments affected adult vine weevil (Otiorhynchus sulcatus) feeding and reproduction on red raspberry (Rubus idaeus). We focused on the period between adult emergence and the onset of oviposition (i.e. the pre-reproductive period), which represents the optimal period for control. 3Tunnels were up to 4 °C warmer than field plantations in 2008, with plants growing significantly faster (50% increase in height and 16% increase in leaf area) than field grown plants. The carbon/nitrogen ratio in leaves was higher in tunnels (12.07) than the field (10.89) as a result of a significant decrease in nitrogen concentrations (3.40 and 3.90 mg g,1, respectively). 4Over 4 weeks, weevils consumed significantly more foliage in tunnels (370.89 mg) than weevils in the field (166.68 mg), suggesting compensatory feeding to counteract lower leaf nitrogen concentrations. Weevils in tunnels achieved sexual maturity 8 days earlier than those in the field and produced 20-fold more eggs by the time they were 5 weeks old. 5Applying a degree-day model showed good agreement between predicted and observed pre-reproductive periods for weevils in tunnels (36 and 30 days, respectively) and in field plots (41 and 38 days, respectively). [source] | |||||||||||||