Trap-Nest Design for Small Trap-nesting Hymenoptera

(excerpt) Many solitary bees and wasps construct brood cells in pre-existing natural cavities such as beetle borings or in excavations of pithy stems and twigs like Sambucus and Juglans. Artificial nesting materials are also acceptable and provide a convenient approach to study nest architecture, nesting activity, provisions and parasites. Arti- ficial nesting materials have included bamboo, glass tubes, plastic straws, cuttings of twigs and stems, and trap-nests. However, use of many of these materials have significant drawbacks

Twig selection on mountain birch Betula pubescens by winter-feeding willow grouse Lagopus lagopus in a subarctic forest

In a subarctic forest at Kvaløya, northern Norway, willow grouse Lagopus lagopus fed at snow level by clipping bits of twigs from mountain birch Betula pubescens during winter. Birch has two types of twigs ending in a terminal bud: long twigs with a smooth bark, and short twigs with rings of thicker bark. The grouse selected ringed twigs above smooth twigs despite a surplus of smooth twigs in the forest. Ringed twigs had more bark cm−1 of twig length and a higher relative bark/wood ratio than smooth twigs. Smooth twigs had growth nodes that increased in diameter inwards from the tip. Because of the non-linear relation between the area and the circumference of a circle, the bark/wood ratio decreased for each node. Although being able to clip much thicker twigs, 90% of smooth twigs clipped by grouse were ≤ 2 mm in diameter. It is concluded that willow grouse fed optimally on birch in winter by selecting twigs to minimize fibrous wood intake

Host choice and host leaving in Rhopalosiphum padi (Hemiptera: Aphididae) emigrants and repellency of aphid colonies on the winter host

Host choice and winter-host leaving in emigrants of bird cherry–oat aphid, Rhopalosiphum padi (Linnaeus), were investigated in the laboratory. In settling choice tests, emigrants collected from the winter host, Prunus padus, preferred this plant over a summer host, oats. Emigrants which had left P. padus for up to 24 h did not express a preference as a group, and those which had left for 24–48 h preferred oats. Eighty seven percent of emigrants caged as fourth-instar nymphs on P. padus leaves abandoned the host by the second day of adult life, and apparently did not subsequently return to the leaf. In an olfactometer, P. padus leaves which had supported spring generations of R. padi were repellent to emigrants. Volatiles were entrained from uninfested and R. padi-infested P. padus using cut twigs in the laboratory as well as intact twigs on a tree in the field. Entrainment extracts from uninfested P. padus had no effect on emigrants in the olfactometer, whereas those from twigs infested with nymphal emigrants were repellent. The study indicates that in R. padi, host-alternation is driven by behavioural changes which occur in individuals as well as between morphs

Ants that Frequently Colonize Twigs in the Leaf Litter of Different Vegetation Habitats

Ants often colonize twigs in the leaf litter, but some species use this resource more frequently than others. We analyzed the composition of the community and the diameter of colonized twigs to test if any species had a size preference. Samples were collected in different vegetation habitats (urban parks, eucalyptus plantations and native forests). In each site, all twigs with an ant colony in six 16-m2 plots were collected and measured, and the ants occupying them were identified. For the analyses, we only included species recorded in 10 or more twigs; these species were considered “common inhabitants” of the twigs (approximately 19.7% of the fauna analyzed). Our results indicate that the community is richer and uses a larger number of twigs of different diameters in the native forest. In addition, some species colonized twigs of similar sizes in different vegetation habitats, suggesting possible selection by ants. 

Diplodia seriata, cause of black fruit rot in organically grown apples in Holland, Belgium and Northern Germany

A fruit rot resembling Gloeosporium infections but appearing on fruits prior to harvest was noticed in organic apple orchards in Holland, Belgium and Northern Germany in 2007. Infections were most commonly observed on ‘Elstar’, but other cultivars were also affected. Fruit colonisation progressed in two steps, whereby a latent stage of sunken black lesions in immature fruits gave rise to a rapidly spreading firm brown rot upon fruit ripening. Isolation experiments from both stages consistently yielded a single species of fungus identified as Diplodia seriata, formerly known under the teleomorph name Botryosphaeria obtusa. Lesions of D. seriata were also seen on leaves as necrotic light brown spots surrounded by a purple halo, and occasionally on small twigs as cankers. Fruit mummies on apple twigs were heavily colonised by D. seriata and are thus likely to carry inoculum for fruit infections during late summer or in the following growing season

Observations on the Biology of the Oak Twig Pruner, \u3ci\u3eElaphidionoides Parallelus,\u3c/i\u3e (Coleoptera: Cerambycidae) in Michigan

(excerpt) The oak twig pruner, Elaphidionoides parallelus (Newman) (Coleoptera: Cerambycidae) is rather common in southern Michigan where it attacks living oaks and other hardwoods. The damage it inflicts is rarely serious, but it may be considered a pest insect if only for the nuisance it creates for those who must clean up the often numerous small branches pruned from street, lawn, and park trees

Some Morphological and Chemical Responses of Blackbrush (\u3cem\u3eColeogyne ramosissima\u3c/em\u3e) to Goat Browsing: Influences on Dietary Blackbrush Selection by Goats and Cattle

Domestic goats were used to modify the growth form of blackbrush, a spinescent shrub occurring in nearly monospecific stands on several million hectares of rangeland in the southwestern United States. The objective of this research was to evaluate goat browsing as a means of improving these rangelands for cattle. Winter goat browsing stimulated spring twig growth from basal and axillary buds which resulted in increased production. Twig production by heavily browsed plants (\u3e95 percent removal of current season\u27s twigs) was a function of precipitation, soil depth, branch location on the plant, and period of rest after browsing. As precipitation doubled, production increased by a factor of 1.9. Twig production by plants growing on deep soils (71 cm) was 1.9 times that by plants growing on shallow soils (39 cm). Older branches growing on the outer edges of blackbrush plants (terminal branches) produced 4.6 times more current season\u27s twigs than sprouts and young branches (basal branches) growing within the shrub canopy. Heavily browsed plants increased twig production by a factor of 3.6 relative to control plants, and production remained at this level, even after four consecutive years of browsing. Stocking intensities of 2.4 animal-unit-months·hectare-1 were required to achieve utilization levels of 80 percent in blackbrush pastures. Annual twig production declined with rest from browsing. However, plants which were browsed and subsequently rested for two years yielded an aggregate 1.6 times more available forage than plants which were browsed on a yearly basis. This was due to an accumulation of twigs ranging in age from one to three years. Browsing also improved the apparent nutritional quality of blackbrush twigs. Current season\u27s twigs contained more crude protein (6.5 versus 4.6 percent), phosphorus (0.10 versus 0.08 percent), and in vitro digestible dry matter (48 versus 38 percent) than older twigs. Current season\u27s twigs from basal branches contained more crude protein (6.1 versus 5.7 percent) and in vitro digestible dry matter (44 versus 41 percent) than those from terminal branches. The palatability of current season\u27s twigs to goats and cattle was lower, however, than that of older twigs, presumably due to their higher tannin levels. Within individual blackbrush plants, current season\u27s twigs from terminal branches were higher in tannins than those from basal branches. Rest from browsing resulted in decreased tannin levels due to a decrease in the proportion of current season\u27s to older twigs. Goats and cattle tended to prefer older twigs to current season\u27s twigs, and current season\u27s twigs from basal branches to those from terminal branches. The occurrence and allocation of tannins within blackbrush support hypotheses dealing with the elaboration and allocation of phyto-chemicals as defense mechanisms countering herbivory. Esophageally fistulated goats (does and kids) browsing in pastures where forage consisted primarily of current season\u27s twigs consumed diets with more crude protein, in vitro digestible dry matter, and tannins than goats browsing in pastures where forage consisted primarily of older twigs. They also lost less weight. Does initially consumed diets higher, but later consumed diets lower in crude protein than those consumed by kids. Kids consumed diets with more in vitro digestible dry matter, but lost more weight than does. No statistically significant differences in weight response were recorded for cattle browsing in pastures which were, and were not, previously browsed by goats. However, the average heifer in previously unbrowsed pastures consumed 1.9 times more protein supplement than her counterpart in previously browsed pastures

Taxonomic results of the Bryotrop expedition to Zaïre and Rwanda : 28., Lejeuneaceae ; a ramicolous collection

The treatment of non epiphyllous Lejeuneaceae taxa was published in the first part of the Central African BRYOTROP results (Pócs 1993b). Anyhow, a nice material collected on tiny twigs (partly from fallen canopy branches) from the W edge of Nyungwe Forest Reserve, in a wet type of montane rainforest at 2000 m altitude, remained unidentified