Neuronal connections in the ocellus of the wasp (Paravespula vulgaris L.)

Summary Studies of the dorsal ocelli of the wasp Paravespula vulgaris (L.) led to the following results: Under a biconvex corneal lens, 150 m in thickness, about 600 receptor cells are located. The rhabdomeres of two adjacent cells form a closed plate-like rhabdom (0.5–1.0 m in thickness, 6 m in width and 10–25 m in depth or length).In the lateral ocellus the receptor cells synapse up to 8 ocellar nerve fibers, and in the median ocellus they synapse up to 16 (20–30 m thick) ocellar nerve fibers.The ocellar synaptic plexus may display three types of synapses between the two types of neurons: (i) Receptor-cell axons are presynaptic to dendrites of the first-order interneurons. (ii) Dendrites of the first-order interneurons are presynaptic to receptor-cell axons. (iii) The subunits of a dendrite of first-order interneurons form synapses with each other.The present work was partially supported by the Stiftung Volkswagenwerk     

Shape discrimination by wasps (<Emphasis Type="Italic">Paravespula germanica</Emphasis>) at the food source: generalization among various types of contrast

Wasps (Paravespula germanica) were trained and tested at an artificial feeding site, using convex shapes that produced colour contrast, luminance contrast, or motion contrast against the background. With each of the three types of contrast, we tested the wasps capacity to discriminate the learned shape from novel shapes. In addition, in each experiment we tested the wasps capability to recognize the learned shape when it offered a different type of contrast than that it had during the training. With the coloured shapes, a side-glance at the colour discrimination performance of the wasps was possible in addition. Wasps are found to discriminate between a variety of convex shapes regardless of the type of contrast that they produce against the background. Mainly, they discriminate the learned shape from novel shapes even if the colour of the shapes or the type of contrast they produce against the background is altered in the test. Thus, wasps generalize the learned shape from one colour to another, as well as between colour contrast, luminance contrast, and motion contrast.     

Effect of diet quality on food consumption and body mass in Microtus pennsylvanicus

Journal of Ethology - Small herbivores, such as meadow voles (Microtus pennsylvanicus), have high metabolic requirements but small gut capacities. Therefore, they should prefer food high in...     

Effect of prey quantity and temperature on nest demography of social wasps

Abstract. 1. To determine the effect of prey quantity and temperature on nest demography of social wasps ( Polistes fuscatus ), field experiments were conducted, in which wasps were provided with a low quantity of caterpillars (approximately nest subsistence level) or high quantity (three times as much). In addition, in the third year, the nest boxes were modified to be relatively cool (white and insulated) or warm (black).
2. In 1997 and 1998, high-food nests had a high proportion of cells containing developing offspring, produced more offspring, and had disproportionately more female offspring compared with low-food nests.
3. In 1999, the cool and warm nest boxes exhibited a daily average difference of 1.3 °C and a maximum difference of 6.9 °C. The warm high-food nests produced more offspring than any other treatment. The cool high-food nests produced similar numbers of offspring as the cool low-food and warm low-food treatments.
4. As indicated by a surplus of uncapped cells, foundresses of low-food nests, which would have had the egg-laying potential to produce many offspring, apparently sacrificed eggs to provide a food supplement for the developing offspring. This pattern plus more time observed foraging suggests considerable expenditure of energy by foundresses, in response to the low supply of food.
5. Importantly, these results indicate that an interactive effect of prey quantity and temperature on offspring production occurred, which may reflect the different effects on developmental rate and growth rate at cool versus warm nest temperatures.     

Overwintering colonies of German (Vespula germanica) and common wasps (Vespula vulgaris) (Hymenoptera: Vespidae) in New Zealand

Abstract

Nests of both common (Vespula vulgaris) and German wasps (V. germanica) sometimes overwinter in New Zealand. Three overwintering common wasp colonies were found in low-altitude honeydew beech forest; about 2% of the colonies initiated there in 1988 survived the winter. Wasp traffic rates from nests in Nelson city and a nation wide survey of wasp abundance, showed that more German wasp than common wasp workers were on the wing in winter and spring. German wasp colonies in Nelson city were more likely to overwinter than were common wasp colonies. Of the active German wasp colonies recorded in Nelson in January and February 1989, only two (4%) had previously overwintered, but these two nests accounted for 38% of all German wasp workers estimated to leave nests in the area. Had other overwintering colonies not been poisoned, overwintering colonies might have accounted for up to 11 % of nests and produced up to 64% of German wasp workers on the wing in January and February 1989.

Overwintering common wasp colonies did not produce queens or drones in their first year or second spring, but all 10 overwintering German wasp colonies examined produced sexuals at both times. German wasp queens produced in winter and spring may influence the number of colonies successfully initiated and affect the population dynamics of German wasps in New Zealand.     

Variation in colour markings of German wasps Vespula germanica (F.) and common wasps Vespula vulgaris (L.) (Hymenoptera: Vespidae) in New Zealand

Abstract

German wasps (Vespula germanica F.) and common wasps (V. vulgaris L.) both show variations in colour markings in New Zealand. Overlap in the ranges of markings of the head and thorax is limited enough for ready distinction of queens and workers of the two species. Abdominal markings overlap considerably between the species. Colour markings of males were too similar to identify the species, which were completely separated by the shape of their genitalia. The frequency of occurrence of “intermediate” markings in V. germanica populations did not increase in areas where the two species overlap. This suggests there is little or no genetic exchange between the two species.     

热耐受性及温度对食物同化的影响

研究变色树蜥(Calotes versicolor)的选择体温、热耐受性、温度对食物同化的影响.结果显示:①幼体的选择体温、临界高温和临界低温的平均值分别为32.6、41.7℃和 7.7℃;成体的选择体温、临界高温和临界低温的平均值分别为33.1、42.0℃和8.2℃.②环境温度在26～34℃时,对变色树蜥食物通过时间和摄入能有显著的影响;对表观消化系数(ADC)和同化效率(AE)无显著的影响;在28～34℃时食物通过时间随温度升高而缩短;在26、28℃和30℃时,摄入能小于更高温度的对应值.     

Impacts of introduced common wasps (Vespula vulgaris) on experimentally placed mealworms in a New Zealand beech forest

An introduced social wasp Vespula vulgaris may compete with native birds for honeydew and invertebrates in New Zealand forests. Experimentally hidden mealworms (Tenebrio molitor) persisted longer at two sites following wasp poisoning that at two sites where wasps were not poisoned. Mealworms persisted longer in the morning than in the afternoon within all study sites. An unusually low mealworm removal rate during a morning trial before wasp poisoning heavily influences the results of this experiment but we have no ecological reason to ignore it. Wasps may therefore be having a heavy impact on invertebrate abundance on very short time scales (within a day following dawn emergence). They may also remove cached food items that would otherwise be retrieved by the South Island robin (Petroica australis australis) during cold or dark feeding conditions.     

Changes in body weight and intake of food by Octopus vulgaris

The changes in body weight of 12 octopuses, fed on fish or crabs, were followed under laboratory conditions for periods of 1 to 7 1/2 months. The food intake was estimated and compared with the changes in body weight of the octopuses; 25 to 55% of the total intake of food appeared to be incorporated. The range of the average increase in weight over the whole observation period of each of the animals was 1.9 to 7.7g per day (1 to 7 1/2 months); the mean value was 4.8g per day. The effect of changing the diet of small octopuses (fish or crab)was followed for four weeks but there was no evidence that alteration of the diet affected the rate of changes in body weight of animals of more than 47g initial body weight.     

Effect of body length and temperature on the crawling speed of Protophormia terraenovae larvae (Robineau-Desvoidy) (Diptera Calliphoridae)

This work investigates variation in the crawling speed of Protophormia terraenovae larvae (Robineau-Desvoidy) (Diptera Calliphoridae) as a function of body length and ambient temperature. A video-tracking system was used to follow the movement of larvae in an experimental arena, and to estimate their average crawling speed. Recordings were carried out at various temperatures using larvae of different developmental stages. As temperature increased, the larvae crawled at a faster speed. Furthermore, speed increased as a function of body length. We present a general allometric relationship to express the average crawling speed of larvae as a combined function of temperature and body length, expressed in the following equation: speed (cm/min)=5.45 x log[length (mm)]+0.66 x temperature (degrees C)-12.8. These results are particularly useful in forensic entomology for estimating the time that elapsed following the larva's departure from the corpse. This information can provide more accuracy for post-mortem interval estimations and a better comprehension of larvae behaviour and displacement.     

Carbohydrate bait preferences of wasps (Vespula vulgaris and V. germanica) (Hymenoptera: Vespidae) in New Zealand

Abstract

Carbohydrates are both a source of food and a potential bait for control of common and German wasps. Carbohydrate preferences of wasps were determined in a series of paired trials by counting the number of wasps caught in traps baited with carbohydrate‐based baits versus a standard protein‐based bait. Factors influencing wasp attraction to carbohydrate‐based baits included bait type, season, weather, and location. A 30% sucrose solution was more attractive than honey, jams, gels, or dry (solid) sugars. The sucrose solution was more attractive in spring and autumn than in summer, probably because rainfall washed away natural carbohydrate supplies. There was a significant relationship between rainfall in the previous week and the proportion of wasps caught in traps baited with sucrose solution versus sardine cat‐food. A higher proportion of German wasps than common wasps was caught in sucrose‐baited traps. This may have been related to seasonal differences in abundance and/or behavioural differences between the two species. In some locations, more wasps were caught in traps baited with sucrose solution than in those baited with sardine cat‐food. The proportion of wasps caught in sucrose‐baited traps was higher in locations without beech scale honeydew than with beech scale honey‐dew. Proportionally more non‐target species (mainly honey bees) and fewer wasps were caught in traps baited with sucrose solution than in those baited with sardine cat‐food. All five bee repellents tested also repelled wasps. These results indicate the importance of determining the bait preferences of wasps (carbohydrate or protein) and the presence of non‐target species before attempting a poison‐baiting operation. They also emphasise the need for a wasp‐specific carbohydrate‐based bait.     

Effect of oxygen on the growth (yield) of Chlorella vulgaris

The growth yield of Chlorella vulgaris, Y _kJ defined as g cells harvested per kJ of light energy absorbed by the cells, was assessed in a turbidostat culture by varying CO₂ and O₂ partial pressures ( and ). The value of Y _kJ ranged from 3.1×10^-3 to 5.0×10^-3 g cells/kJ under light-limited conditions [ = 1.02.4%, = 065%; total pressure of gas (composed of CO₂, O₂ and N₂)=1 atm]. In the light-limited environment, the algal specific growth rate deteriorated appreciably with the increase of . The deterioration accounts for the above range of Y _kJ observed. The growth inhibition due to oxygen that was defined by subtracting from 1.0 the ratio of at given values of to that at = 0% extended from 0.07–0.30 (7–30%). However, glycolate could not be detected in the turbidostat culture. Isotopic experiments on the specific rate of ¹⁴CO₂ uptake also revealed that the inhibition due to oxygen was from 22–38% when was varied from 0 to nearly 100%. These effects of oxygen were discussed, referring to the activity of ribulose-1,5-bisphosphate carboxylase that is inhibited competitively by oxygen.Non-Standard Abbreviations INH isonicotinic acid hydrazide - PPO 2,5-diphenyloxazole - DCMU 3-(-3,4-dichlorophenyl)-1,1-dimetylurea - CA carbonic anhydrase - RuP₂ ribulose-1,5-bisphosphate     

Zur Abhängigkeit des Putzens von der Konzentration der Zuckerlösung bei der Gemeinen Wespe (Paravespula vulgaris)

Several activities of foraging wasps (Paravespula vulgaris) collecting sucrose solution at an artificial food source are described. The concentration of the solution has an influence on the number of preening movements performed per unit time (= rate of preening). The rate of preening as a function of the concentration is explained in a quantitative manner using a diagram which corresponds to the disinhibition hypothesis for displacement activities.     

Effect of body fat and gender on body temperature distribution

It is well known that body composition can influence peripheral heat loss and skin temperature. That the distribution of body fat is affected by gender is well known; however, there is little information on how body composition and gender influences the measure of skin temperature. This study evaluated skin temperature distribution according to body fat percentage (BF%) and gender. A sample of 94 apparently healthy volunteers (47 women and 47 men) was assessed with Dual-Energy X-Ray Absorptiometry (DXA) and infrared thermography (mean, maximum and minimum temperatures – T_Mean, T_Max and T_Min). The sample was divided into groups, according to health risk classification, based on BF%, as proposed by the American College of Sports Medicine: Average (n = 58), Elevated (n = 16) or High (n = 20). Women had lower T_Mean in most regions of interest (ROI). In both genders, group High had lower temperature values than Average and Elevated in the trunk, upper and lower limbs. In men, palms and posterior hands had a tendency (p < 0.05) for increased temperature along with increased BF%. T_Mean, T_Max and T_Min of trunk, upper and lower limbs were negatively correlated with BF% and the fat percentage of each segment (upper limbs, lower limbs and trunk). The highest correlations found in women were between posterior trunk and BF% (rho = −0.564, p < 0.001) and, in men, between anterior trunk and BF% (rho = −0.760, p < 0.001). Overall, this study found that women have lower skin temperature than men, which was related with higher BF%. Facial temperature seems not to be influenced by body fat. With the future collection of data on the relationship between BF% and skin temperature while taking into account factors such as body morphology, gender, and ethnicity, we conclude that measurement of BF may be reliably estimated with the use of thermal imaging technology.