Coat colour variation in the banded palm civet Hemigalus derbyanus and in Owston's civet Chrotogale owstoni

1. Coat colour variation was studied in two viverrid species belonging to the subfamily Hemigalinae, on the basis of museum specimens and observations of live animals. 2. In both species, polymorphism and ontogenetic colour change occur, and in the Owston's civet, sexual dimorphism in coat colour was identified.     

Emergent body size of mayfly survivors

1. Employing field-deployed mesocosms, we examined the effects of 12-h pulse and 20-day press (continuous) exposures of the common agricultural insecticide, imidacloprid, on nymph abundance, emergence patterns and adult body size of Epeorus spp. (Heptageniidae) and Baetis spp. (Baetidae).
2. In press exposures, reduced nymph density was driven by reduced survivorship; in pulse exposures, reduced nymph density may reflect increased emergence because of stress.
3. Once exposed to imidacloprid, Epeorus and Baetis mayflies developed less and emerged smaller than their control counterparts. Concentrations as low as 0.1  μ g L⁻¹ (12-h pulse) reduced head length in Baetis and thorax length in Epeorus .
4. In all of the Baetis and Epeorus examined, effects were only found in males. Male survivorship and body size can affect population dynamics. Sublethal doses of this widely applied agricultural insecticide have the potential to reduce reproductive success of mayfly populations.     

Effects of resource availability and social parasite invasion on field colonies of Bombus terrestris

Abstract.  1. The survival, growth and fecundity of bumblebee colonies are affected by the availability of food resources and presence of natural enemies. Social parasites (cuckoo bumblebees and other bumblebees) can invade colonies and reduce or halt successful reproduction; however, little is known about the frequency of invasion or what environmental factors determine their success in the field.
2. We used 48 experimental colonies of the bumblebee Bombus terrestris , and manipulated both resource availability at the landscape scale and date of colony founding, to explore invasion rates of social parasites and their effect on the performance of host colonies.
3. Proximity to abundant forage resources (fields of flowering oilseed rape) and early colony founding significantly increased the probability of parasite invasion and thus offset the potential positive effects of these factors on bumblebee colony performance.
4. The study concludes that optimal colony location may be among intermediate levels of resources and supports schemes designed to increase the heterogeneity of forage resources for bumblebees across agricultural landscapes.     

Anatomical Features of Modellnaia siamensis (Mollusca, Bivalvia, Unionidae)

Although conchologically an etheriid mussel, M. siamensis from northeastern Thailand is, according to anatomical and larval features, an unionid. Its unique character states among the Unionidae are: relatively distant spacing of septa in all four demibranchs in both, males and females, absence of a foot in adults, and generation of subelliptical glochidial larvae. This species is seemingly a phylogenetic relic.     

A field study of the pattern of local spread of ryegrass mosaic virus in mown grassland

In a field experiment at Hurley, small areas of old ryegrass sward, known to be infected with ryegrass mosaic virus (RMV) were partially surrounded by newly-sown Italian ryegrass. The experiment was harvested by mowing on five occasions. Samples of Italian ryegrass taken when it was 11 months old showed a very marked increase in the levels of RMV close to the areas of old sward. Thus, 84% of the Italian ryegrass plants bordering the old sward to the north contained RMV, compared with 63% of plants only 2.7 m away. The corresponding values to the south were 68% and 39%. The much higher values encountered to the north are presumed to be caused by the movement of the mite vector of RMV (Abacarus hystrix) in relation to the prevailing wind. Two different mowers were used, a rotary mower and a reciprocating knife mower. We could demonstrate no increase in the level of RMV as a result of mowing from the infected sward and on to the new sowing and could demonstrate no difference in the infection levels as a result of using the different mowers. We conclude that in mown swards migration by the mite is responsible for all or nearly all of very local spread of RMV.     

Evidence for mate‐encounter Allee effect in an invasive longhorn beetle (Coleoptera: Cerambycidae)

1. Limited empirical support is available for mate‐encounter Allee effects in invasive insects due to the logistical challenges of studying demographic trends in low‐density populations. 2. Traps baited with pheromone and spruce volatiles were used to monitor the abundance of female Tetropium fuscum F. (Coleoptera: Cerambycidae) at multiple sites in Nova Scotia in 2011 and 2012. Each female was dissected to determine the presence or absence of sperm in its spermatheca (mated or virgin female, respectively). 3. Both male and total T. fuscum abundance declined with increasing distance to the focal point of T. fuscum's invasion. Female mating probability declined with male abundance and with distance from the invasion focus, and mating probabilities were very low at the most peripheral sites. Difficulty in encountering mates may thus contribute to limiting the spread of T. fuscum. 4. The approach outlined here could be integrated into existing surveys of wood borers using traps baited with semiochemicals to improve our understanding of the role of the mate‐encounter Allee effect in invasion dynamics.