Evaluating Basking-Habitat Deficiency in the Threatened Eastern Massasauga Rattlesnake

ABSTRACT Woody plant succession is hypothesized to threaten many reptile populations by reducing the amount of solar energy available for thermoregulation. Mitigation via vegetation management is often recommended; however, the need for such management practices rarely has been evaluated. We examined the need for basking-site enhancement for the eastern massasauga rattlesnake (Sistrurus c. catenatus; hereafter EMR) in New York, USA, where only 2 populations remain: one at an open-canopy site and another at a closed-canopy site. Microhabitat temperatures were substantially lower at the closed-canopy site, where EMRs selected the warmest available basking sites. Eastern massasauga rattlesnakes in the open-canopy population selected basking sites that afforded greater cryptic cover. We recommend experimental reduction of shrub cover to improve EMR basking habitat at the closed-canopy site. More generally, we caution that management efforts to reduce shrub cover for basking EMRs should maintain adequate cryptic cover.     

1961—2007年海口市气候环境变化及其对城市发展的响应

基于海口市1961—2007年的气象资料以及1989—2007年的城市化水平,对海口市气候环境变化及其与城市化水平的关系进行了分析.结果表明：与1961—1990年相比,海口市1995—2007年气温呈明显的增高态势,年均增温0.93 ℃;而相对湿度则明显降低,年均湿度降低了3%;海口市年均气温、年均相对湿度与城市化水平分别呈显著和极显著相关,说明城市化较好地解释了近20年来海口市气候要素的变化.海口城市的发展,不仅改变了气候环境要素,而且影响了大气环境质量,使酸雨次数增加、年均酸雨pH值降低.     

温度和CO2浓度升高对荒漠藻结皮光合作用的影响

2007年,对腾格里沙漠东南缘沙坡头地区1956年(51龄)和1981年(26龄)人工植被区及自然植被区的藻结皮净光合速率(P_n)变化,及其与结皮含水量(>100%、40%～60%和<20%)、大气CO₂浓度(360和700 mg·L^-1)和温度(13 ℃、24 ℃ 和28 ℃)的关系进行研究.结果表明：51龄、26龄人工植被区和自然植被区的藻结皮P_n分别为3.4、4.4和3.2 μmol·m^-2·s^-1,且51龄人工植被区藻结皮的P_n显著高于26龄人工植被区和自然植被区;藻结皮含水量对其P_n影响显著,且中等含水量(40%～60%)藻结皮的P_n显著高于低含水量(<20%)和高含水量(>100%);CO₂倍增(700 mg·L^-1)后,中等和高含水量藻结皮的P_n增加了1.8～3.3倍,而低含水量时,藻结皮的P_n变化不明显;高含水量和中等含水量处理时,24 ℃和28 ℃条件下藻结皮的P_n较13 ℃时提高27%～66%,而在低含水量时,不同温度的藻结皮P_n值无显著差异.     

光照和温度对氮饥饿及饱和营养条件下石莼(Ulva lactuca)的硝态氮吸收动力学影响

为探讨海藻养分吸收能力并以高效养分过滤器筛选为目标,以N饥饿和N饱和的石莼为材料,研究了3种光照及温度因子及其交互作用对不同N素营养限制状态下石莼NO3-吸收动力学特征的影响。结果表明:N饱和条件下,随着光照的增强,石莼对NO3-的最大吸收速率也增加;30℃条件下,光照强度的增加虽然使得其最大吸收速率提高,但Vmax/Km在中等光强下最大;20℃最有利于石莼对NO3-的吸收。N饥饿条件下,石莼对NO3-的吸收速率显著大于非饥饿状态。在10℃和20℃条件下,呈现与N饱和条件下相似的规律,但在30℃条件下,中等光强石莼对NO3-的最大吸收速率最高。在10℃和20℃条件下,增加光强促进石莼对NO3-的吸收,但30℃条件下光强的增加并未起到促进作用。饥饿状态下的石莼的NO3-吸收速率较高,当石莼吸收NO3-饱和时,依然可以以较低的速率继续吸收环境中的NO3-。     

beta-Endorphin-induced hyperthermia in the cat

beta-Endorphin was injected into the third cerebral ventricle (ICV) of conscious, unrestrained cats. Hyperthermic response to 50 microgram of this peptide were reduced by 20-100 microgram naloxone given ICV 1 hr later. A dose of 40 microgram beta-endorphin increased body temperature at ambient temperature of 4, 22 and 34 degrees C, with the response being greater the warmer the environment. These results indicate that beta-endorphin acts on a central naloxone-sensitive receptor which is probably the v2 receptor that is activated by low doses of D-Ala2-Met-enkephalinamide to evoke a similar pattern of change in body temperature over a comparable range of ambient temperatures.     

Microsomal polypeptides in sunflower (Helianthus annum). Comparison between normal type before and after cold-induction, and a high oleic acid mutant

Differences in high-resolution two-dimensional gel electrophoresis patterns of micro-somal proteins from developing normal sunflower ( Helianthus annuus L.) seeds before and after cold-induction, and also from normal and a high oleic sunflower mutant have been studied in order to detect the polypeptides associated with the microsomal Δ^l2-desaturase activity and its regulation by temperature. Proteins were obtained from developing seeds of two isogenic sunflower lines HA-89 (normal) and HA-OL9 (high oleic) which greatly differed in linoleic acid content and "in vitro" oleate desaturase activity. In the high oleic mutant, four polypeptides of about 32 kDa and two of 33 kDa were found to change in position, to the same extent, toward a lower isoelectric point in the high oleic mutant. Also, two polypeptides, of 32 and 49 kDa each, appeared in the mutant. Quantitative differences between cold-induced seeds (10°C, 24 h) and their non-induced controls were found. One polypeptide of 43 kDa decreased in the cold-treated seeds and two others, of 30 and 32 kDa each, increased markedly after cold induction. Some of these polypeptides could be related to oleate desatnrase activity or its regulation by temperature.     

Activity patterns of reintroduced lion Panthera leo and spotted hyaena Crocuta crocuta in the Addo Elephant National Park, South Africa

Africa's large predator guild competes for a limited food resource base. To minimize the degree of competition, we hypothesized that the two largest members of this guild and its fiercest competitors, the lion and the spotted hyaena, would partition their activity patterns to avoid interacting. We used 96‐h continuous follows of focal animal(s) to determine when the six radio‐collared lions and eight radio‐collared spotted hyaenas, reintroduced into Addo Elephant National Park in 2003/2004, were active using a binomial measure of activity which was defined as movements >100 m during each hourly period. Contrary to our predictions, lions and hyaenas did not partition their activity times, probably because of their current low population densities. Both species exhibited a crepuscular activity pattern although hyaenas were far less active during daylight. A sub‐adult lioness minimized competitive interactions by becoming diurnal. This is likely to be a common strategy for lions that have been expelled from their natal pride to become nomadic, as it allows them to minimize kleptoparasitic and agonistic interactions from competitively dominant conspecifics and competitors. The increase in testosterone that occurs in males upon reaching sexual maturity, darkens their pelage and causes them to be more directly impacted by the heat, and thereby affords females an opportunity to escape from males during hot temperatures. Similarly, the longer pelage of young hyaenas restricts their activity to the cooler night‐time.     

Within-tree and seasonal distribution of the pine woolly aphid Pineus boerneri on Pinus kesiya trees

1 The spatial and temporal distribution of pine woolly aphids, Pineus boerneri (Homoptera: Adelgidae) a pest of exotic pine trees in Malawi, was investigated in 5‐year‐old Pinus kesiya trees. 2 Pineus boerneri was generally found to settle and reproduce on the outer shoot‐end sections of young P. kesiya trees. There was no evidence of preference for any particular levels of the tree canopy. 3 The study suggests that the biological performance and, by implication, the pest status of P. boerneri in young P. kesiya trees can be influenced by external factors, particularly by the within‐tree and seasonal fluctuations in the level of nitrogen in the host trees, total rainfall and canopy structure. 4 These findings are discussed in relation to possible management and control of P. boerneri in Malawi.     

Dose-dependent influence of Microplitis rufiventris factors on developmental rate and growth of last-instar Spodoptera littoralis larvae

The solitary endoparasitoid, Microplitis rufiventris, attacks and can develop in earlier instars of Spodoptera littoralis larvae with preference to third‐instar larvae. We used the last stadium (sixth instar), a stage which is not naturally parasitized. The newly moulted larvae (0–3 h old) of this stadium were more acceptable for parasitization by the wasp females than the older ones (24 h old). Parasitization by M. rufiventris wasp of last instar S. littoralis larvae leads to dose (no. of eggs + parasitoid factors)‐dependent effects which were more pronounced at 20°C than at 27°C. A single oviposition into a sixth instar host larva resulted in normal development of the host. However, superparasitization increased the proportions of developmentally arrested hosts and number of live wasp larvae. Development of supernumerary individuals of the parasitoid in the host larva leads to dose‐related adverse effects on host growth and development. The present study may provide interesting opportunities for studying the physiological bases of host–parasitoid interactions and parasitoid intra‐specific competition in the biological system considered.     

Control of the flexible annual/biennial life cycle of the heather psyllid Strophingia ericae

Abstract. Strophingia ericae (Curtis) (Homoptera: Psylloidea) takes one or two years to complete its life cycle. In both cases eggs hatch over a prolonged period from midsummer, possibly extending into the following spring at high altitude, and instars overlap in time. Instar III is the predominant overwintering stage in the lowland, annual cycle, whereas in the upland, biennial cycle most first-year nymphs overwinter in instars I and II and most second-year nymphs in instar V. When moved to the laboratory, instars IV and V from a predominantly annual population showed accelerated development in response to elevated temperatures and to long days in both mid-winter and early spring. In the biennial life cycle, short autumn days retard instar V development but the response to photoperiod disappears by the end of winter. Exposure to LD 18 : 6 h retarded development of early instars in the annual population, resulting in an accumulation in instar III. The proportion of overwintering instars I and II rises with increase in altitude and moult to instar III becomes progressively delayed. Nymphs that reach instar III under long daylengths in the year following hatching are channelled towards the biennial cycle. Exposure of a predominantly biennial population to 15 °C and LD 18 : 6 h after midsummer, thus avoiding autumn conditions, promoted the rapid development of overwintered nymphs, switching the cycle from biennial to annual.