Pollinator attraction in Cornus capitata (Cornaceae): the relative role of visual and olfactory cues

Aims it is generally accepted that visual displays and floral scent play important roles in communication between flowering plants and their pollinators.However,the relative role of visual and olfactory cues in pollinator attraction is largely unknown.in this study,we determined the roles of both types of cue in attracting pollinators to Cornus capitata,a medium sized tree with each capitulum sur-rounded by four large,white,petaloid bracts.Methods Pollinator observations and pollination experiments were con-ducted in a natural population;the inflorescences’visual and olfactory signals were characterized by spectral and chemical analyses;the responses of pollinators to visual and olfactory cues were tested using dual-choice behavioural bioassays;the relative roles of visual and olfactory cues in pollinator attrac-tion were tested by comparing the responses of pollinators to inflorescences subjected to three experimental treatments(intact,all bracts removed,and capitulum removed)within the natural population.Important Findings For fruit set,C.capitata is entirely dependent on pollinators,with a bee,Anthophora sp.,being the main pollinator.bracts present high colour distance and green contrast against the leaves.Twelve volatile compounds in the floral scent were detected,most of which have previously been reported to be attractive to a broad spectrum of bee species.behavioural bioassays showed that both,visual cues alone and olfactory cues alone,are attractive to pollinating bees.However,vis-ual cues alone attracted significantly more approaches than olfactory cues alone,while olfactory cues alone elicited a significantly higher landing percentage than visual cues alone.The finding suggests that,in the C.capitata-Anthophora sp.interaction,visual cues are mainly used for location from long distances,while olfactory cues mainly aid landing from short distances.our results indicate that different modalities of floral cues should be considered together to understand fully the communication between flowering plant and pollinators.

Repellent effect of synanthropic house mouse urine odor on small forest mammals

In this study,we examined the effect of synanthropic house mouse(Mus musculus)urine odor on catching probability of small mammals to live traps.We conducted a series of field experiments in August 2016 and 2017 in a natural forests of the northwestern Moscow Region(Russia).Small mammals were trapped at two 4-ha fields using capture-mark-recapture technique by setting 200 live traps(100 points,2 traps per point)within each field.One trap in each pair was odorless(control)with bait only,whereas the other one was odor-baited with 20μL of the urine of a synanthropic house mouse.Further analysis was based on the data collected from 2 rodent species(bank vole Myodes glareolus,herb field mouse Apodemus uralensis)and 3 shrew species(common shrew Sorex araneus,Laxmann’s shrew Sorex caecutiens,and Eurasian pygmy shrew Sorex minutus).As a result,only bank voles significantly avoided odor-baited live traps.Using generalized linear mixed models,we showed that the choice of a trap by bank voles depended on their age,whereas the probability of repeated capture to a certain live trap was related to their prior experience.We discuss the possible role of components of synanthropic house mouse urine in the population management of exoanthropic small mammals.

HOST PLANT PREFERENCES OF BEMISIA TABACI GENNADIUS

The preferences of Bemisia tabaci Gennadius for five host plants:poinsettia, tomato, cabbage,sweet potato and flowering Chinese cabbage, was tested using a Y-tube olfactometer and a desiccator in the labo-ratory. The results show that B. tabaci adults were attracted by the odors of the five plants. The order of prefer-ence was poinsettia > flowering Chinese cabbage > sweet potato > cabbage > tomato. Preference was extremely sig-nificant between poinsettia and the other four plants, and between flowering Chinese cabbage, cabbage and toma-to. There was no significant difference in preference for flowering Chinese cabbage and sweet potato, sweet pota-to, cabbage and tomato or between cabbage and tomato.

I smell a rat： Can New Zealand birds recognize the odor of an invasive mammalian predator？

Although it is well known that birds can assess predation risk through visual and auditory cues, there has been little research into whether similar processes occur with olfactory cues. We examined the role of odor cues in assessing nest predation risk in four species of passerine birds in New Zealand. We compared the ability of two introduced European species （common starling Sturnus vulgaris and song thrush Turdus philomelos） and two native New Zealand species （rifleman Acanthisitta chloris and South Island robin Petroica australis） to respond to the scent of rat urine placed in the nest. Rats are an introduced predator in New Zealand and we expected the native birds, which did not co-evolve with any mammalian predators, to lack behavioral adaptations to the scent of rats at their nest. As expected, both riflemen and robins failed to show any change in their behavior at their nest when rat urine was present compared to a control period in which no scent was present. However, a similar lack of re- sponse was observed in the introduced song thrush; only the common starling changed its behavior in the presence of the rat urine Starlings with rat urine at the nest box were more likely to hesitate before entering and they also approached the nest, but refused to enter more often in the presence of rat scent. Both responses suggest they detected the presence of a predator and changed their behavior to minimize risk to themselves. Although based on a small number of species, our results suggest that responses to pre- dator scent may be less common in New Zealand species, and may be a factor contributing to the vulnerability of native birds to introduced mammalian predators [Current Zoology 61 （1）： 34-41, 2015].