Role of plant sensory perception in plant-animal interactions

Plants actively gather information about their environments via a range of sensory modalities and respond in ways that profoundly influence their interactions with other organism

Olfactory Cues from Plants Infected by Powdery Mildew Guide Foraging by a Mycophagous Ladybird Beetle

Powdery mildews (Erysiphales) are economically important plant pathogens that attack many agricultural crops. Conventional management strategies involving fungicide application face challenges, including the evolution of resistance and concerns over impacts on non-target organisms, that call for investigation of more sustainable alternatives. Mycophagous ladybird beetles (Coleoptera: Coccinellidae) feed on powdery mildew and have considerable potential as biological control agents; however, the foraging ecology and behavior of these beetles is not well understood. Here we document the olfactory cues presented by squash plants (Cucurbita moschata) infected by powdery mildew (Podosphaera sp.) and the behavioral responses of twenty-spotted ladybird beetles (Psyllobora vigintimaculata) to these cues. Volatile analyses through gas chromatography revealed a number of volatile compounds characteristic of infected plants, including 3-octanol and its analogues 1-octen-3-ol and 3-octanone. These compounds are typical “moldy” odorants previously reported in volatiles collected from other fungi. In addition, infected plants exhibited elevated emissions of several compounds also observed in collections from healthy leaves, including linalool and benzyl alcohol, which are reported to have anti-fungal properties. In Y-tube choice assays, P. vigintimaculata beetles displayed a significant preference for the odors of infected plants compared to those of healthy plants. Moreover, beetles exhibited strong attraction to one individual compound, 1-octen-3-ol, which was the most abundant of the characteristic fungal compounds identified. These results enhance our understanding of the olfactory cues that guide foraging by mycophagous insects and may facilitate the development of integrated disease-management strategies informed by an understanding of underlying ecological mechanisms

Topological complexity of symplectic manifolds

Open Access via Springer Compact Agreement. The authors wish to thank Ay¸se Borat, Michael Farber, Jarek Kedra, and John Oprea for helpful comments regarding an earlier draft of this paper.Peer reviewedPreprintPublisher PD

Phéromones d'alarme

Many animals respond to the threat of predation by producing alarm signals that warn other individuals of the presence of danger or otherwise reduce the success of predators. While alarm signals may be visual or auditory as well as chemical, alarm pheromones are common, especially among insects and aquatic organisms. Plants too emit chemical signals in response to attack by insect herbivores that recruit the herbivores’ natural enemies and can induce preparations for defense in neighboring plants (or other parts of the same plant). In this chapter we discuss our current understanding of chemical alarm signaling in a variety of animal groups (including social and pre-social insects, marine invertebrates, fish, and mammals) and in plants. We also briefly discuss the exploitation of alarm pheromones as foraging cues for natural enemies. We conclude with a brief discussion of the potential exploitation of alarm signaling to achieve the applied goal of managing pest species

Distribution and Prevalence of Wolbachia Infections in Native Populations of the Fire Ant Solenopsis invicta (Hymenoptera: Formicidae)

Wolbachia are endosymbiotic bacteria that commonly infect arthropods. These bacteria induce a number of phenotypes in their hosts, including cytoplasmic incompatibility, thelytokous parthenogenesis, feminization, and male killing. We surveyed native South American populations of the fire ant Solenopsis invicta Buren for Wolbachia infections by using a diagnostic polymerase chain reaction assay. In addition, we determined the fidelity of vertical transmission of the bacteria from mother to offspring in this species by assaying daughters in 24 simple-family (monogyne) colonies. Infections were common in many parts of the extensive native range of S. invicta. However, the proportion of individuals infected varied greatly among samples, ranging from zero in several populations from the northerly parts of the range to >90% in more southerly populations. Possible explanations for this variation in the prevalence of Wolbachia infections are discussed. A survey of the two social forms of S. invicta from four geographic areas showed that the prevalence of Wolbachia infections consistently was higher in the monogyne form (single queen per colony) than the sympatric polygyne form (multiple queens per colony). One likely explanation for this trend is that the selective regimes acting on Wolbachia in the two forms differ because of the dissimilar reproductive strategies used by each form. Finally, overall transmission efficiency was found to be very high (>99%), making it unlikely that imperfect transmission prevents the spread of the microbe to near fixation in native population

Distribution of the Two Social Forms of the Fire Ant Solenopsis invicta (Hymenoptera: Formicidae) in the Native South American Range

Polygyne (multiple queen) colony social organization in the fire ant Solenopsis invicta Buren is always associated with the presence of a particular class of alleles at the gene Gp-9. We used diagnostic polymerase chain reaction assays capable of distinguishing these alleles to determine the location of polygyne populations in the native South American range of this species. We found that polygyny occurs in a mosaic pattern with respect to the more common monogyne (single queen) social form, a pattern superficially similar to that seen in the introduced range in the United States. However, polygyny appears to be relatively restricted in its geographical prevalence in the native range compared with the introduced range. This difference may stem from higher dispersal rates in the introduced range, which are associated with greater opportunities for human-mediated transport of mated queens or colony fragments. On the basis of our distributional data and results from other studies, the southern part of the native range of S. invicta, particularly northeastern Argentina, is emerging as the most likely geographic source of the founders of the U.S. populatio