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Trichome Density (trichome + density)
Selected AbstractsFunctional response of Neoseiulus californicus (Acari: Phytoseiidae) to Tetranychus urticae (Acari: Tetranychidae) on strawberry leavesJOURNAL OF APPLIED ENTOMOLOGY, Issue 2 2010J. J. Ahn Abstract Neoseiulus californicus (McGregor) is a predatory mite employed for biological control of the agricultural pest Tetranychus urticae (Koch). We explored whether environmental differences, in this case the trichome densities of abaxial leaf surfaces of strawberry cultivars (,Maehyang' and ,Sulhyang' varieties) affect the functional response of adult female N. californicus preying on immature stages (egg, larva and nymph) of T. urticae. We also evaluated the functional response of N. californicus to eggs of T. urticae at different temperatures (15, 20, 25, 30 and 35°C). We conducted a logistic regression of the proportion of prey consumed as a function of initial prey density to identify functional response types, and used nonlinear least-squares regression and the random predator equation to estimate attack rates and handling times. The functional response of adult female N. californicus to T. urticae was not influenced by non-glandular trichomes on abaxial leaves but was affected by temperature. Overall, adult female N. californicus exhibited a type 2 functional response to T. urticae. The handling time of N. californicus was highest (1.9970 h) against T. urticae nymphs. The attack rate did not change much at 15,30°C, but was significantly higher at 35°C. The handling time decreased significantly with increasing temperature at 15,35°C. At 35°C, the attack rate was highest (0.2087) and the handling time was lowest (0.9511 h). [source] Comparative development of fiber in wild and cultivated cottonEVOLUTION AND DEVELOPMENT, Issue 1 2001Wendy L. Applequist SUMMARY One of the most striking examples of plant hairs is the single-celled epidermal seed trichome of cultivated cotton. The developmental morphology of these commercial "fibers" has been well-characterized in Gossypium hirsutum, but little is known about the pattern and tempo of fiber development in wild Gossypium species, all of which have short, agronomically inferior fiber. To identify developmental differences that account for variation in fiber length, and to place these differences in a phylogenetic context, we conducted SEM studies of ovules at and near the time of flowering, and generated growth curves for cultivated and wild diploid and tetraploid species. Trichome initiation was found to be similar in all taxa, with few notable differences in trichome density or early growth. Developmental profiles of the fibers of most wild species are similar, with fiber elongation terminating at about two weeks post-anthesis. In contrast, growth is extended to three weeks in the A- and F-genome diploids. This prolonged elongation period is diagnosed as a key evolutionary event in the origin of long fiber. A second evolutionary innovation is that absolute growth rate is higher in species with long fibers. Domestication of species is associated with a further prolongation of elongation at both the diploid and allopolyploid levels, suggesting the effects of parallel artificial selection. Comparative analysis of fiber growth curves lends developmental support to previous quantitative genetic suggestions that genes for fiber "improvement" in tetraploid cotton were contributed by the agronomically inferior D-genome diploid parent. [source] The role of plant trichomes and caterpillar group size on growth and defence of the pipevine swallowtail Battus philenorJOURNAL OF ANIMAL ECOLOGY, Issue 6 2001James A. Fordyce Summary 1The California population of the pipevine swallowtail Battus philenor is a specialist on the Dutchman's pipe Aristolochia californica, an endemic vine that is densely covered with trichomes. Populations of B. philenor outside California use other Aristolochia species that are largely glabrous. The average clutch size of the pipevine swallowtail is larger in California compared with populations elsewhere and larvae feed gregariously until late in the third instar. 2In the field, caterpillars consumed more leaf material and showed preference for portions of leaves with trichomes removed. However, large groups of caterpillars were consistently observed feeding on the apical portion of the plant, where trichome density was highest. Smaller groups of caterpillars were observed feeding more often on mature leaves on the lower portions of the plant, where trichome density was lower. 3Laboratory experiments showed that the walking speed of a commonly observed predator, larvae of the green lacewing Chrysopa carnea, was reduced as trichome density increased. Furthermore, lacewing search efficiency and capture rate of a model prey item were compromised by high trichome density. 4In an additional field experiment, no difference was found in the percentage mortality of groups of four and 12 caterpillars. However, growth rate of the larger group was accelerated by 25% compared with smaller groups. In an experiment using a ladybird beetle larva Hippodamia convergens as the predator, no difference was observed in absolute mortality of caterpillars, suggesting that group size does not function directly as a defence against predators. 5First instar caterpillars are most vulnerable to predators, thus feeding in larger groups may benefit caterpillars by accelerating growth. Feeding in large groups may also be an effective strategy for B. philenor to overcome plant trichomes and feed on portions of the plant conducive to faster development. However, feeding on areas with dense trichomes does not appear to provide larvae with a refuge from predators. [source] Within and between generation phenotypic plasticity in trichome density of Mimulus guttatusJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2007L. M. HOLESKI Abstract Mimulus guttatus (yellow monkeyflower) frequently produce glandular trichomes, a trait that may resist herbivory. Constitutive production of trichomes is variable both within and among populations of M. guttatus and most of this variation is genetic. This study demonstrates that damage on early leaves can induce increased trichome production on later leaves, a plastic response that is likely adaptive. Moreover, this study shows that this induction can be maternally transmitted, increasing trichome density in progeny before they experience herbivory. This transgenerational response must involve a yet undescribed epigenetic mechanism. These experiments also show genetic variation among plants in the capacity for both within and between plant generation induction. Despite the clear evolutionary importance of variation in constitutive and induced herbivory-resistance traits, few other studies have noted genetic variation in both within a plant species. [source] Leaf beetle grazing does not induce willow trichome defence in the coppicing willow Salix viminalisAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2004Peter Dalin Abstract 1,Willows are frequently attacked and defoliated by adult leaf beetles (Phratora vulgatissima L.) early in the season and the plants are then attacked again when new larvae emerge. The native willow Salix cinerea has previously been shown to respond to adult grazing by producing new leaves with an increased trichome density. Subsequent larval feeding was reduced on new leaves. This type of induced plant response may reduce insect damage and could potentially be utilized for plant protection in agricultural systems. 2,Here, we investigated if the willow species most commonly used for biomass production in short rotation coppice, Salix viminalis, also responds to adult beetle grazing by increasing trichome density. Larval performance and feeding behaviour on plants previously exposed to adult beetles was compared with that on undefoliated control plants in a greenhouse. 3,We found an overall decrease in trichome density within all the plants (i.e. trichome density was lower on new leaves compared to that for older basal leaves on S. viminalis). However, leaves of beetle defoliated plants had a higher trichome density compared to control plants. Larval growth and feeding was not affected by this difference between treatments. Larvae appeared to remove trichomes when feeding on S. viminalis, a behaviour that might explain the lack of difference between treatments. [source] | ||||||||||