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Dietary Mixing (dietary + mixing)
Selected AbstractsBeing a generalist herbivore in a diverse world: how do diets from different grasslands influence food plant selection and fitness of the grasshopper Chorthippus parallelus?ECOLOGICAL ENTOMOLOGY, Issue 2 2010ALEXANDRA FRANZKE 1. Generalist insect herbivores occupy a variety of habitats that differ in food plant composition. Dietary mixing has been proposed as a possibility for generalists to overcome nutritional deficiencies of single plant species, but only a few studies have investigated herbivore feeding and fitness for diets that resemble natural scenarios. We studied feeding behaviour, survival, and reproduction of the generalist grasshopper Chorthippus parallelus raised on food plants of four typical habitats. 2. Grasshopper diet consisted of grasses (92.5%), legumes (6.7%) and, in small quantities, other forbs (0.8%). Diet selection differed between the four food plant mixtures, and depended on grasshopper sex and developmental stage. There was no correlation between the relative abundance of plant species in the field and the fraction of these species in the grasshopper diet. 3. Grasshoppers survived on average for 40.4 ± 1.0 days before maturity, grew 106.8 mg until maturity moult, and females laid 4.1 ± 0.4 egg pods, each of which contained 8.5 ± 0.4 eggs. However, despite the differences in feeding behaviour, grasshopper fitness was the same in all of the four food plant mixtures. While the digestibility of ingested food was similar in the four different treatments, indices indicated differences in the conversion efficiency to body mass. 4. Our results show that C. parallelus is a plastic feeder with no fixed preferences in diet composition. The results emphasise that generalist herbivores can counteract putative quality deficiencies of single food plants by selective dietary mixing. [source] Host preference and performance of lichenivorous Eilema spp. larvae in relation to lichen secondary metabolitesJOURNAL OF ANIMAL ECOLOGY, Issue 3 2003Heikki Pöykkö Summary 1We compared the larval host preference of four lichenivorous Eilema (Lepidoptera, Arctiidae) species on four common epiphytic lichen species including Hypogymnia physodes, Melanelia exasperata, Vulpicida pinastri and Xanthoria parietina. Survival and growth of larvae on different species were monitored and correlation to qualitative and quantitative variation in lichen secondary compounds was analysed. 2All moth species preferred M. exasperata, which does not contain polyphenolic substances, over other lichens, but also foraged on other lichens in the food preference experiment. All larvae reared on V. pinastri and H. physodes died during the growth and survival experiment. Survival of larvae on X. parietina and M. exasperata were equal. Larvae grew faster and and bigger on M. exasperata than on other lichens. 3Consumption and utilization measurements also revealed that M. exasperata was of the highest quality, although the relative consumption rate was highest on X. parietina. Our results indicate that different secondary chemicals have different effect against lichenivores or that larvae are either well adapted to certain chemicals or that these chemicals may have other roles than antiherbivore function for lichens. 4It is suggested that lichenivorous lepidopteran species may have different adaptations, such as dietary mixing to receive nutrients in optimal proportions or compensatory feeding ability to ensure the maximal growth efficiency on a suboptimal host. [source] Food preferences and the value of animal food for the carabid beetle Amara similata (Gyll.) (Col., Carabidae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2005S. Fawki Abstract:, Several studies have shown that the mainly granivorous carabid beetles, e.g. Amara spp., include animal food in their diet to a considerable extent. We therefore hypothesized that the performance of these beetles would be enhanced by dietary mixing including both seeds and animal food. In order to test this, we conducted laboratory feeding experiments with adults and larvae of Amara similata. Both adults and larvae were subjected to different diet treatments including: seeds, houseflies, grasshoppers, earthworms, slugs and snails in pure and mixed diets. Larval survival, development time, pupal and teneral weights were used as indicators of food quality for the larvae. For the adult beetles, mass change was used as an indicator of food quality. We found seeds to be high-quality food, while all pure animal diets were of low quality for both adults and larvae. Animal foods added to the seed diet had both positive and negative effects. A mixed diet of all foods enhanced the mass gain of adults compared with the seed diet, but reduced larval performance dramatically. Earthworms and grasshoppers added to seeds increased the pupal and teneral weights, while reduced larval survival. Thus, A. similata is omnivorous with a mainly granivorous feeding habit. It may gain benefits on some fitness parameters and incur costs on others from preying or scavenging on animal food. Therefore, the overall fitness consequences of a mixed seed-animal diet are uncertain. [source] | ||||||||||