Behavioral thermoregulation in a tropical gastropod: links to climate change scenarios

Tropical species are vulnerable to global warming because they live at, or near to, their upper thermal threshold limits. Therefore, the predicted increase in the frequency of warming events in the tropics is expected to be critical for the survival of local species. This study explored the major environmental variables which were thought to be correlated with body temperatures (BTs) of the tropical snail Littoraria scabra at the niche level. A correlation between BT and substrate temperature (ST) was detected from field observations which suggests a possible causal relationship between both substrate and BTs. In contrast, there was no correlation between BT and air temperature. Field observations suggest that 33.4 °C may be L. scabra upper limit of substrate surface temperature, although further experiments are needed to assess if the upper limit of physiological tolerance is actually different. As L. scabra individuals were free to choose their substrata, the observed distribution pattern at the niche level is related to L. scabra's behavior. Additionally, substrate surface temperatures were very heterogeneous at centimeter scale (i.e. from 22.5 to 53.1 °C) and L. scabra was shown to select specific STs (i.e. between 22.5 and 33.4 °C) rather than microhabitat type. Therefore, L. scabra did not seem to behaviorally thermoregulate through microhabitat selection nor aggregation. In contrast, behavioral experiments showed that L. scabra has the ability to actively select a thermally favorable site over short temporal scale (i.e. individual average speed of 1.26 cm min^?1) following exposure to high temperatures above 33.4 °C. Hence, this study supports the crucial need to integrate intertidal invertebrate behavioral responses to thermal constraints in climate change studies.     

艾草和窃衣挥发物的提取鉴定及其对烟粉虱MED隐种成虫选择性的影响

[目的]在前期研究中,我们发现艾草Artemisia argyi和窃衣Torilis scabra都有吸引或驱避昆虫的作用.然而还未见有研究报道艾草和窃衣以及它们的挥发物对烟粉虱Bemisia tabaci MED隐种成虫的作用.本研究旨在检测能否利用艾草和窃衣及其挥发物对烟粉虱MED隐种成虫实施绿色防控.[方法]通过...     

Genetic and morphological variation in two littorinid gastropods: evidence for recent population expansions along the East African coast

In marine species, population diversity and differentiation is affected by the population history and by the complex interaction between oceanographic dynamics and ecological traits. In the present study, we examined two species of marine gastropods (the mangrove periwinkle Littoraria scabra and the rocky shore Littoraria glabrata) along the East African coast, using both genetic and geometric morphometric methods. We report a greater variation of shell shape in L. scabra compared to the slightly smaller variation in L. glabrata. This variation was probably associated with variation of environmental factors along the coast, such as temperature and hydrodynamics. Despite morphological variation, we found low mitochondrial genetic differentiation among samples from different localities for both species, which is probably a consequence of the ongoing gene flow during the free‐swimming larval stage of these gastropods. Additionally, high levels of haplotype diversity, low nucleotide diversity, and ‘star‐like’ genealogies were found in both species. These observations and the results from mismatch distributions, indicate a possible signature of recent population expansions in both species, which probably started during interglacial periods of the Pleistocene and led to the colonization of the Indian Ocean coast. © 2013 The Linnean Society of London     

<i>In vitro</i> evaluation of antifungal activity of Agave (<i>Agave scabra</i>, Salm Dyck) extracts against post-harvest mushrooms

The agricultural sector, and particularly the horticultural production, has a singular importance in agriculture, considering that it ranks second on agricultural products, nationally and worldwide. Fungal diseases are one of the major causes of vegetable loss during storage, reducing their nutritional value, quality and sale price. Vegetables are usually exposed to diverse treatments with chemical products before storage; as a result, fungal populations develop an increased resistance over time becoming more difficult to control. Because of this, research efforts toward finding more suitable chemicals to control fungal diseases are needed. Natural extracts may be an alternative solve this problem. In the present investigation the fungicidal activity of aqueous and ethanol extracts of Agave scabra was evaluated on the growth of Botrytis cinerea, Mucor sp., Aspergillus niger, Fusarium sp. and Penicillium sp., whose strains were isolated from potato and tomato. To assess their effects, the agar-dilution and agar-well techniques were performed. The ethanol extract was more effective against Botrytis cinerea and Mucor sp. when the agar-well method was used. However, when using the agar-dilution method the ethanol extract of Agave scabra inhibited the growth of Botrytis cinerea, Mucor sp. and Penicillium sp.     

蔓赤车的一个新异名

根据对产自湖南的蔓赤车Pelliona scabra Benth．标本的研究,结合在头序赤车P．cephaloidea W． t. Wang模式产地湖南南岳衡山的野外调查,发现头序赤车的模式标本是采自幼雌花序时期的蔓赤车,故将头序赤车作为蔓赤车的新异名,头序赤车组作为赤车组的新异名。     

Migration and trail affinity of snails, Littoraria scabra, on mangrove trees of Nananu-i-ra, Fiji Islands

The distribution of mobile species such as grazing snails may be influenced by migration patterns, which often are excluded from ecological studies. To highlight this point, the migration patterns of Littoraria scabra on mangrove trees were investigated during incoming and outgoing tides at Nanaru-i-ra, Fiji Islands. Marked snails were used to track the position of snails, relative to the ground, during advancing and receding tides. Snails were found to move quickly upward during incoming tides, potentially to avoid immersion. During the outgoing tide, snails migrated downward, but at a slower pace than upward movement, presumably as a consequence of active feeding on the newly replenished micro-organisms on the mangrove structures (i.e., stems and roots). Aggregation behavior during migration was also recorded by measuring the distance of marked snails to two nearest neighbors. Affinity to neighboring snails was found to be maintained throughout tidal cycles, although greater affinity was observed during incoming tides compared to outgoing tides. These migratory and aggregation behaviors may be a result of increased feeding and reproductive efficiency.     

A new synonym of Pellionia scabra Benth.

Based on the study of specimens from Hunan, and field observations in Hengshan (holotype locality of Pellionia cephaloidea W. T. Wang), Nanyue, Hunan, China, Pellionia cephaloidea W. T. Wang is regarded as a new synonym of Pellionia scabra Benth., and Pellionia Gaudich. sect. Elatostematopsis W. T. Wang as a new synonym of Pellionia Gaudich. sect. Pellionia.