Thesis (doctoral)--Christian-Albrechts-Universität zu Kiel, 2000.

Kairomones are infochemicals that benefit a heterospecific receiver. Chaoborus spp. release a kairomone from their gut when feeding on Daphnia spp. Daphnia respond to kairomone by shifting life history parameters or producing neonates with induced morphological defenses, increasing their chance of survival. When laboratory-cultured Daphnia are exposed to environmentally-relevant metal concentrations, a kairomone response is not induced, increasing predation vulnerability. Currently Daphnia live in metal-contaminated lakes in Sudbury, ON. It is possible the extant population is tolerant of relatively high copper (Cu) concentrations and can still induce a kairomone response. In comparison, it is hypothesized clones found in lakes isolated from anthropogenic sources of metal-contamination would be less tolerant as they have not been exposed to high Cu concentrations. The purpose of this study was to examine how multiple clones of D. pulicaria obtained from lakes along a Cu gradient respond to kairomone in the absence and presence of copper. Several different clones from Ontario lakes located in the Canadian Shield were exposed to environmentally-relevant Cu concentrations and Chaoborus kairomone. Neonates were collected and measured to assess predator-induced defenses. Results indicate that kairomone-mediated responses and Cu-tolerance vary among D. pulicaria clones. Clones from the Sudbury area were able to induce a response to kairomone when exposed to Cu, indicating a Cu-tolerance. However, this was not true for all Sudbury clones. In contrast, most clones from clean lakes did not respond to kairomone when exposed to Cu; while some clones exhibited a Cu-tolerance. Clones that were not tolerant of Cu were affected at concentrations much lower than those predicted by the Biotic Ligand Model (BLM) that induce acute toxicity. Predictions generated by the BLM can be conservative making them useful when creating water quality criteria; however, my results indicate these predictions can also be under-protective. Chemosensory cues mediate vital life processes that are essential for survival. Populations may be devastated if metals interfere with chemosensory cues. Overall, the results of my study suggest that genetic variation is important for population establishment and maintenance, specifically when exposed to multiple stressors, and that directional selection may result in stress tolerance. / Thesis (Master, Biology) -- Queen's University, 2009-12-23 09:50:46.152

Exploiting the chemical ecology of an insect can unveil novel strategies for its pest management. Though much has been learned about the chemical ecology of Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), a major pest of solanaceous crops in the U.S., there has been little use of this knowledge in pest management. To better understand host plant selection by CPB, field and laboratory-choice experiments were conducted in Virginia. In laboratory studies, CPB preferred potato over both tomato and eggplant foliage and eggplant over tomato foliage. However, field studies using counts of live beetles on untreated paired plants and counts of dead beetles on insecticide-treated plants revealed no significant preference for potato over eggplant. Additional studies showed that the presence of adult male CPB on foliage greatly impacted host plant selection, with significantly more adults being attracted to eggplant with male beetles than any other treatment combination. Adult CPB have been shown to be attracted to (S)-3,7-dimethyl-2-oxo-oct-6-ene-1,3-diol [(S)-CPB I], a male-produced aggregation pheromone. Field studies were conducted to determine if the opposite enantiomer of the pheromone, (R)-CPB I had an effect on CPB in the field. Results revealed no differences in counts of all CPB life stages between untreated potato plots with and without rows inundated with (R)-CPB I lures. In addition, the relative attraction of CPB adults to various racemic forms of the (S)- and (R)-enantiomers was also investigated and showed that racemic blends that were less than 97%(S) were not attractive to CPB adults. Combinations of the (S)-CPB I pheromone with synthetic plant volatiles consisting of (Z)-3-hexenyl acetate, (+)-linalool, and methyl salicylate were investigated in a trap crop strategy in potatoes, but failed to reduce CPB numbers in untreated middle rows of potatoes. Combinations of the (S)-CPB I pheromone with synthetic plant volatiles were also used in a novel CPB trap designed to catch colonizing adults in the field. Although the traps caught CPB adults, no differences were observed in traps baited with and without the attractant. Metaflumizone, a novel semicarbazone insecticide, was recently shown to be highly efficacious on CPB. Laboratory studies found the combination of metaflumizone and a low concentration (0.39 ppm) of the pyrethroid esfenvalerate was slightly synergistic on CPB adults and early (1st-2nd) instar larvae. Field trials combining a low rate of esfenvalerate and metaflumizone at one tenth the field rate controlled beetles as well as the full rate of metaflumizone. / Ph. D.

La localisation des plantes-hôtes est un processus déterminant dans la stratégie adaptative des insectes phytophages et les stimuli olfactifs, qui sont des composés volatils émis par les plantes, jouent un rôle essentiel dans ce processus. Bactrocera cucurbitae (Diptera, Tephritidae) est responsable d'importants dégâts sur maintes cultures maraîchères à l'échelle mondiale et à La Réunion. Si la bio-écologie et la structuration génétique des populations de cette espèce sont relativement bien connues, des connaissances sur la médiation chimique se produisant lors de la localisation des fruits-hôtes restent nécessaires pour améliorer la gestion des populations de cette espèce. L'objectif de la thèse est de caractériser les stimuli olfactifs impliqués dans la localisation à distance par les femelles de B.cucurbitae, d'une large gamme de fruits-hôtes de Cucurbitaceae sauvages et cultivées de La Réunion. Une approche bidisciplinaire (comportementale et chimique) a été adoptée afin d'identifier, parmi 27 fruits-hôtes, les composés volatils responsables de l'attraction des femelles vers leurs sites de ponte. Les résultats soulignent, qu'au sein de la gamme de plantes-hôtes, la réponse des femelles aux effluves de ces fruits est très hétérogène (taux d’attraction de 1 % à 74 %), variant selon l'espèce végétale, la variété et le stade de maturité des fruits. Parallèlement, l'étude de la composition chimique des effluves de ces fruits révèle une chimiodiversité inter- et intraspécifique considérable : 280 composés volatils identifiés au total, avec des profils d'émission différents d'un fruit à l'autre. Ces résultats, complétés par de l’électroantennographie couplée à la chromatographie gazeuse, ont permis de déterminer 34 composés potentiellement impliqués dans l'attraction des femelles. De plus, un mélange à deux composés volatils de synthèse, aussi attractif qu'une odeur de fruits frais, a été identifié à partir des réponses des femelles à 10 des 34 composés, présentés individuellement ou en mélange. Les rôles des composés volatils de fruits-hôtes dans le processus de localisation des sites de ponte et dans la spécialisation écologique de cette espèce de ravageurs sont discutés. Par ailleurs, l'association des résultats de préférence des femelles et de performance larvaire représente une perspective de recherche prometteuse, qui contribuerait à acquérir une connaissance plus fine du phénomène de spécialisation d'hôte. Enfin, il est désormais possible d'envisager l'utilisation du mélange simple à deux composés volatils dans un système de piégeage des femelles, à intégrer dans un schéma de gestion agroécologique des populations de B. cucurbitae. / Locating host-plants is a key process in the adaptive strategy of phytophagous insects, and olfactory stimuli, which arevolatile compounds emitted by plants, play an essential role in this process. Bactrocera cucurbitae (Diptera,Tephritidae) is responsible for significant damage to many vegetable crops in Reunion Island and worldwide. Whilethe bioecology and genetic population structure of this species are relatively well known, understanding the chemicalmediation occurring during host-fruit location is needed to improve the management of this pest. The aim of this thesis is to characterize the olfactory stimuli involved in the location by females of B. cucurbitae, of awide range of wild and cultivated host fruits of Cucurbitaceae in Reunion Island. A multidisciplinary approach (behavioural and chemical) was adopted to identify volatile compounds responsible for the attraction of females to their oviposition sites in 27 host fruits. The results highlight that within the range of host plants the female response to fruit odours is very heterogeneous(attraction rates from 1% to 74%). These levels of female response vary according to the plant species and the varietyand the stage of fruit maturity. Meanwhile, the study of the chemical composition of fruit odours reveals aconsiderable inter- and intraspecific chemodiversity: 280 volatile compounds identified in total, with differentemission profiles from one fruit to another. These results, complemented by coupled gas chromatographyelectroantennographic detection, have identified 34 compounds potentially involved in female attraction. In addition, ablend of two synthetic compounds as attractive as fresh fruit odour was identified by measuring attractiveness of 10 ofthe 34 compounds presented individually or in combination. The roles of volatiles in oviposition sites location and ecological specialization of this pest are discussed. Moreover,the association of these results with data on female preference and larval performance represents a promising researchdirection, which would contribute to a better understanding of the phenomenon of host specialization. Finally, theintegration of a simple two-component blend in a trapping system for females into an agroecological management scheme for B. cucurbitae populations is proposed.

Predator avoidance behaviors are a critical defense mechanism that can increase the chances of survival for potential prey species. We tested the avoidance behavior of the freshwater amphipod, Gammerus sp., under two different chemical predation cues. The first was the presence of kairomone, which was derived from a species of fish, Gambusia affinis, that was fed a diet exclusively of amphipods. The second predation cue was potential alarm cue derived from macerated conspecific amphipods from the same population as the test species. Response variables included time spent moving after the introduction to the signal as well as the time spent in refuge. Movement of amphipods significantly decreased and time spent in refuge significantly increased when amphipods were exposed to alarm cue as compared to control organisms that received no exposure to predation cues. Exposure to the fish kairomone treatments significantly increased time spent in the refuge but did not significantly influence time spent moving during the trials. These results suggest that amphipods exhibit predator avoidance behavior primarily when there is evidence that an attack has occurred (evidenced by the death of conspecifics within the population), but will also demonstrate avoidance behaviors to a lesser degree when a predator is detected.

Organisms living in aquatic environments are subject to a number of stressors from natural (temperature, predation, food availability) and anthropogenic origins (pesticides, metals, etc). Natural stressors may amplify the effects of contaminants and increase an organism’s sensitivity to them. Understanding the impact of these combined factors is therefore essential for the practical management of contaminants. This study sought to examine how predatory cues affect copper tolerance in the mosquitofish, Gambusia affinis. The influence of predatory cues on fish metabolic rate was also evaluated to gain insight on any interactive effects between the natural stressor and copper. Alarm cues, chemicals released into the water when prey are injured were obtained from humanely sacrificed G. affinis, and kairomones, passive cues released by predators, were obtained from adult bluegill (Lepomis macrochirus). Paired 96-h toxicity tests with copper and predatory cue and with copper alone were conducted to determine the influence of predatory cues on G. affinis sensitivity to the metal. In the presence of alarm cue neither G. affinis copper tolerance or metabolic rate was altered. At copper concentrations ranging from 0.25mg Cu/L - 0.50mg Cu/L kairomone presence had no influence on survival, while between 0.50mg Cu/L and 1.0mg Cu/L, kairomone presence increased survival. Kairomone had no significant effect on metabolic rate. The apparent antagonistic effect between kairomone and copper may have resulted from the presence of organic material from predator-derived cues or from potential changes in fish behavior. This study adds to the growing body of literature which illustrates the complexity of stressor interactions in aquatic systems.

Having means to detect and avoid potential predators is a necessity for prey species. Most mammalian prey species are able to detect odours emitted by predators and to adapt their behaviour accordingly. These odour cues are therefore considered to act as semiochemicals. Predator odours consist of several dozen different odourants. In order to assess if single odourants elicit aversive behavioural reactions, predator-naïve CD-1 mice were presented with six odourants which are part of body-borne odours of different mammalian predator species. A two-compartment chamber was used in order to assess place-preference, motor activity and faecal excretions when the animals were simultaneously presented with a predator odourant and a blank control. Further trials were performed to assess whether the odourant concentrations had an influence on the behaviours. The only odourant that elicited a significant aversion was 3-methyl-1-butanethiol, a compound found in the anal gland secretion of skunks, when presented at a factor of 100 above the olfactory detection threshold of mice. Two other concentrations of 3-methyl-1-butanethiol did not elicit significant behavioural changes. Based on the present study, only one out of six selected predator odourants elicited a significant aversive response in CD-1 mice. This suggests that more than one odour component, or perhaps even the full mixture of odourants, may be necessary for CD-1 mice to respond to a predator odour with aversive behaviour.

In the present dissertation the possibilities of aggregation of antagonists of bark beetles using allochthonous kairomones were to be analysed. The focus of the analysis was the species of European red-bellied clerids (Thanasimus spp.) in forests of Scots pine (Pinus sylvestris) and common spruce (Picea abies). Differences in trap efficiency have been analysed using the normal THEYSOHN® - slit trap and those with closed lids filled with a catching liquid. It transpired that significantly more target organisms have been locked in with the closed trap system than with the customary model. As potential attractants for European red-bellied clerids (Thanasimus spp.) standard attractants such as Pheroprax®, Sexowit®, Cembräwit®, Acuwit®, Tomowit® as well as Chalcoprax® have been tested. Furthermore the aggregate effect of individual semiochemicals, which form part of the above attractants, have been analysed in relation to European red-bellied clerids and bark beetles which appeared in the habitat. The effect of an increase of the emission rate of the attractant onto the target organisms was also part of the analysis. In addition to trials with attractants in THEYSOHN®-slit traps trials with attractants on stems of pine wood and spruce wood have also been conducted and analysed. This was to clarify whether one could aggregate that many antagonists of bark beetles that the stem does not at all or gets less populated with bark beetles. In the course of this analysis it has been attempted to identify further antagonists of bark beetles that could be aggregated with attractants. It was determined that there are important differences in levels of aggregation between the species of Thanasimus formicarius, Thanasimus rufipes and Thanasimus pectoralis with respect to the substances tested. Thanasimus formicarius has been observed in spring and early summer in pine and spruce forests. The concentration of activity of this species was higher in pine forests than in spruce forests. With respect to the tested attractants Thanasimus formicarius showed a stronger preference for Ipsdienol and Ipsenol as for (S)-cis-Verbenol in each case in connection with 2-3-2-Methylbutenol. It is also possible to replace 2-3-2-Methylbutenol with other substances. The substances of Sexowit® and Acuwit® ((+)-Ipsdienol, (-)-Ipsenol, α- and β-Pinen, 2-Phenylethanol or rather Ethanol) also seem to have a strong attraction for the Thanasimus formicarius. Thanasimus rufipes and Thanasimus pectoralis mainly appeared from early summer into the late summer and were respectively recorded in the traps. Both species, in comparison to the Thanasimus formicarius, showed a much stronger preference to (S)-cis- Verbenol, respectively attractant mixtures which contained (S)-cis-Verbenol. Thanasimus rufipes has mainly been detected in pine forests and Thanasimus pectoralis in spruce forests. In pine forests Pheroprax® could be confirmed as an effective allochthonous kairomone. In spruce forests, until the completion of this analysis, no definitive attractant could be identified which aggregats European red-bellied clerids (Thanasimus spp.) on the object to be protected without attracting bark beetles (namely Ips typographus).

Until recently, it was assumed that African mole-rats search for food randomly, as it is in concordance with Aridity food distribution hypothesis. However, recent studies indicate that some subterranean rodent species including mole-rats could be able to use plant chemicals (kairomones) for food localization. In my master thesis I conducted a battery of experiments on four mole-rat species to prove, that these species also posses the ability of kairomone guided foraging independently of their social organization.

Many organisms utilize toxic or noxious compounds as a means of deterring predation. Eastern newts (Notopthalmus viridescens), along with other species in the family Salamandridae, possess a potent neurotoxin called tetrodotoxin (TTX). Although TTX can serve as an effective antipredator mechanism in species of newts with high concentrations (e.g., Taricha), eastern newts have relatively low levels of toxicity in comparison to those species, and it may not serve as an effective antipredator mechanism against all threats. In this case, they may benefit rather by utilizing behavioral changes to avoid initial contact with predators. We tested for predator-avoidance behavior in newts by exposing individuals to kairomones from various predators. We recorded activity patterns of newts when they were exposed to cues from potential predators including bullfrogs (Lithobates catesbeiana), water snakes (Nerodia sipedon) and snapping turtles (Chelydra serpentina), as well as a non-predator (bullfrog tadpoles), and a control (deionized water). Newts reduced activity when exposed to snapping turtle stimuli, but did not change activity when exposed to any other chemical cues. We verified that newts interact with this predator by trapping snapping turtles found in ponds from which newts were collected. Finally, we used turtles caught during this sampling to test whether they are an actual predator of newts and whether newts shift microhabitat use when exposed to this predator. In each replicate, turtles consumed newts, and newts spatially avoided the snapping turtle, relative to a control. The results of these experiments indicate newts rely on predator-avoidance behavior to reduce the probability of being consumed by snapping turtles, but do not reduce activity in response to other potential predators that may only consume them rarely.