Measuring Ucrit and endurance: equipment choice influences estimates of fish swimming performance

This study compared the critical swimming speed (U_crit) and endurance performance of three Australian freshwater fish species in different swim‐test apparatus. Estimates of U_crit measured in a large recirculating flume were greater for all species compared with estimates from a smaller model of the same recirculating flume. Large differences were also observed for estimates of endurance swimming performance between these recirculating flumes and a free‐surface swim tunnel. Differences in estimates of performance may be attributable to variation in flow conditions within different types of swim chambers. Variation in estimates of swimming performance between different types of flumes complicates the application of laboratory‐based measures to the design of fish passage infrastructure.     

The courtship behaviour of Yponomeuta padellus

The sequence of behavioural steps from male attraction until copulation is described and analyzed for Yponomeuta padellus L. (Yponomeutidae, Lepidoptera). Males respond to a pheromone emitting female with wing fanning followed by upwind zigzagging flight. Males will land near the females and then walk while wing fanning. The antennae drum onto the substratum and the abdominal-hair pencils are displayed. When in contact with a female the male drums with his antennae onto wings, head and antennae. Mostly a clasping attempt follows. A male has a higher chance to be accepted when he firt encounters the rear of a female instead of the head. Females refuse males by walking away or wing fanning or a combination of both.

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Résumé Les séquences du comportement depuis l'attraction du mâle jusqu'à la copulation ont été décrites et analysées chez Y. padellus (L.). Les mâles réagissent à une femelle émenttant une phéromone par un hattement d'ailes suivi d'un vol en zigzag contre le vent. Les mâles atterriront près des femelles et marcheront avec leurs ailes en battement. Les antennes tambourinent le substrat et les pinceaux abdominaux sont déplyés. Lorsqu'il est au contact de la femelle, le mâle tambourine avec ses antennes les ailes, la tête et les antennes. Généralement suit une tentative d'étreinte. Les chances de succès sont les plus élevées quand les premiers contacts du mâle sont avec la partie postérieure de la femelle plutôt qu'avec la tête. Les femelles refusent les mâles en s'écartant ou en battant des ailes ou les deux à la fois.Il semble qu'en plus des stimuli cliniques, des stimuli mécaniques fournis par les écailles sont nécessaires pour que les mâles localisent la femelle et s'orientent pour une tentative d'étreinte.

     

Sex-linked control of sex pheromone behavioral responses in European corn-borer moths (Ostrinia nubilalis) confirmed with TPI marker gene

In two races of European corn-borer moths (ECB), the E-race females emit and males respond to 99:1 sex pheromone blend of (E)/(Z)-11-tetradecenyl acetates, whereas the Z-race females and males produce and respond to the opposite 3:97 pheromone blend of (E)/(Z)-11-tetradecenyl acetates, respectively. We previously have shown that female production of the final blend ratio is under control of a major autosomal locus but that the sequence of male upwind flight responses to the blend is controlled by a sex-linked (Z-linked) locus. This sex-linked control of behavioral responses in crosses of E and Z ECB now is confirmed by use of sex-linked TPI (triose phosphate isomerase) allozyme phenotypes to determine the origin of the sex chromosomes in F₂ populations. F₁ males from reciprocal E × Z crosses generate similar behavioral-response profiles in wind-tunnel studies, with moderate numbers responding to the Z pheromone and intermediate blends (35%–65% Z), but very few responding to the E pheromone. The F₂ behavioral-response profiles indicate that they are composed of 1:1 mixtures of hybrids and paternal profiles. Analysis of TPI allozyme differences allowed us to separate male F₂ populations into individuals whose Z chromosomes both originated from their grandfathers, and individuals who had one Z chromosome originating from each grandparent. With these partitioned F₂s, the TPI homozygotes exhibited behavioral-response profiles very much like their grandfathers, whereas the TPI hybrids produced response profiles similar to their heterozygous F₁ fathers. These results demonstrate incontrovertibly that the response to sex pheromone in male ECB is controlled by a sex-linked gene that is tightly linked to the TPI locus and therefore is independent of the locus controlling pheromone blend production in females.     

Chemical ‘generalists’ and behavioral ‘specialists’: a comparison of host finding by Stelidota geminata and Stelidota octomaculata

Host orientation by two nitidulid beetles was compared: Stelidota geminata (Say), which is very broad in its' host range, and Stelidota octomaculata (Say), a species whose feeding is restricted primarily to acorns. In a no-choice assay, both species responded to all food substrates offered and neither showed a significant preference among substrates (except banana versus wood fungi for S. octomaculata), or between aseptic and inoculated treatments; however, S. geminata readily displayed both phototactic flights and host-orienting flights, whereas S. octomaculata never exhibited phototactic flight and never responded to food odors by flying to the source. Furthermore, when upwind-walking response was compared, S. octomaculata walked to the source at a rate of 0.16±0.01 cm/s, which was significantly lower than that of S. geminata, with a rate of 0.54±0.02 cm/s. Turning frequency on the way to the source also differed between the two species, whereas distance traveled, number of pauses, and duration of pauses did not differ significantly. We submit that both species represent olfactory generalists, and that the restricted host range of S. octomaculata compared to S. geminata is not mediated by differences in long-range response to host odors, but rather is due to differences in other behaviors such as a reduced rate of locomotion, post-landing behavior, and possibly ecological factors.     

Specificity of olfactory responses in the tephritid fruit fly, Rhagoletis pomonella

Electroantennograms (EAG) were recorded from, and behavior observed of female apple maggot flies, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), in response to over 60 individual esters. For acetates through decanoates, 2 methylbutyrates, and isobutyrates, we tested homologous series of systematically altered chain lengths. Most of the compounds had been isolated from behaviorally active fractions derived from extracts of volatiles produced by host fruits of R. pomonella. For the acetates through hexanoates, maximum EAG amplitudes were elicited by esters with chain lengths of 9 carbons and for the heptanoates through nonanoates, by 10 carbon esters. Recovery time, or the rate at which the EAG trace returned to the baseline following maximum depolarization, was slowest for straight chain esters that were 9–11 carbons long. Branching of the chain by addition of a methyl group to either side of the ester resulted in a decline in amplitude and a faster recovery time. Compared to EAG results, only 5 esters (butyl and pentyl hexanoate; propyl and butyl heptanoate; propyl octanoate) were highly active in wind tunnel bioassays, demonstrating (1) the hazard of assigning significance to EAG-active compounds without accompanying behavioral data, but more importantly; (2) a high degree of olfactory specificity. Maximum behavioral response was contingent upon the following rules regarding size and structure of the molecule. The ester must (1) be a straight chain; (2) be 10–11 carbons in length; (3) have an acid portion of 6–8 carbons and an alcohol portion of 3–5 carbons. One of the active esters, butyl hexanoate, appears in significant concentrations in the headspace of host fruit and, because this ester elicits such a pronounced behavioral response, our results suggest that R. pomonella is adapted to perception of a compound that is typical of its hosts.

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Résumé Les réactions de R. pomonella à plus de 60 esters différents ont été enregistreées par électroantennogrammes (EAG) et par ovservation du comportement. Pour les acétates, avec les décanoates, les 2-méthylbutyrates et les iso butyrates, nous avons examiné des séries homologues de chaînes aux longueurs systématiquement altérées. La plupart de ces composés ont été isolés à partir des fractions actives sur le comportement, issues des extraits des substances volatiles des fruits des plantes hôtes de cette téphritidae. Pour les acétates, avec les hexanoates, les EAG aux plus grandes amplitudes ont été obtenus avec des esters dont la longueur des chaînes est de 9 carbones, et avec les heptanoates et les nonanoates pour les esters à 10 carbones. Le temps de récupération ou temps mis par l'EAG pour revenir à l'ordonnée de départ après dépolarisation maximum, a été plus lent pour les esters à chaînes droites avec 9 à 11 carbones. La ramification de la chaîne par addition d'un groupe méthyl de chaque côté de l'ester a provoqué une réduction de l'amplitude et une accélération de la récupération. 5 esters seuls provoquent une forte réaction dans le tunnel à vent (hexanoates butilique et pentylique, heptanoates propylique et butylique, octanoate propylique). Ceci montre (1) le risque qu'il y a à attribuer une signification aux substances provoquant une réaction en EAG, lorsqu'il n'y a pas d'observations comportementales parallèles, et, surtout; (2) le degré élevé de spécificité olfactive.La résponse comportementale optimale obéit aux règles suivantes concernant la taille et la structure de la molécule. L'ester doit avoir: (1) une chaîne linéaire; (2) 10–11 carbone de longueur; (3) une portion acide de 6 à 8 C et une portion alcool de 3 à 5 C. Le butyl hexanoate, l'un des esters actifs, présent en concentration suffisante près de fruits utilisés, provoque pour cette raison une réponse comportementale tellement marquée, que nos résultats suggèrent que R. pomonella est adapté à la perception des substances caractéristiques de leurs hôtes.

     

The visual responses of free-flying summer and autumn forms of the black bean aphid, Aphis fabae, in an automated flight chamber

ABSTRACT Summer (virginoparae) and autumn (gynoparae) winged forms of Aphis fabae were flown in an automated flight chamber for up to 100 min, while being exposed to a small green target at their own level for 5 s of each minute. Virginoparae climbed more slowly than gynoparae and responded to the target by turning towards it throughout experimental flights. Gynoparae, on the other hand, were almost completely unresponsive to the target, although some individuals began to respond after an hour or more of flight. The differences between the two migratory forms are discussed with reference to previous work on aphid flight behaviour in the field and the laboratory.     

Interaction Effects of Wrist and Forearm Posture on the Prediction of Carpal Tunnel Syndrome Cases Within a Fish-Processing Facility

Deviated wrist posture has been implicated as a risk factor for carpal tunnel syndrome (CTS), although alone it has not been found to have a causal relationship with CTS. Studies investigating deviated wrist posture have quantified posture in a single plane of motion and not interactions of wrist postures in multiple planes. The objective of this cross-sectional study was to investigate the ability of wrist and forearm posture interaction effects to predict CTS among a population of fish processing operators. A total of 53 participants performing five job tasks were evaluated using electrogoniometers. Due to task asymmetry, each hand was evaluated separately and treated independently, providing 106 hands as data observations. Using logistic regression analysis it was found that a model including flexed (F); extended (E), the interaction of length of employment (LE) by FE, and the interaction of LE by FE by pronation/supination (PS) accurately classified 78% of all hands as cases or non-cases. The sensitivity of the final model was approximately 48%. The developed model was found to have superior predictive ability when compared to models not considering interaction terms, indicating that posture interactions may in fact have a significant effect on CTS alone.     

Activation of Anopheles gambiae mosquitoes by carbon dioxide and human breath

Abstract. Female Anopheles gambiae Giles mosquitoes were observed individually in a cage within a wind tunnel and their responses to pulses of carbon dioxide recorded on video tape. The range of concentrations tested revealed an 'activation' threshold concentration of carbon dioxide in the region of 0.01% above background. At this concentration, approximately 60% of the mosquitoes took off and flew upwind. Pulses of human breath, diluted with wind tunnel air to reproduce equivalent concentrations of carbon dioxide, elicited similar levels of response and the same 'activation' threshold concentration. These findings are discussed in relation to the activation of host-seeking mosquitoes.     

Response of the melon fly parasitoidPysttalia fletcheri (Hymenoptera: Braconidae) to host-habitat stimuli

Cohorts of mass-reared adult femalePysttalia fletcheri, parasitoids of the melon fly (Bactrocera cucurbitae), were exposed to host-plant stimuli in a laminar airflow wind tunnel to analyze the cues used in host-habitat finding. Parasitoids hovered twice as frequently around plastic zucchini models emitting fresh cucumber odor as around models emitting clean air. The odor of decaying pumpkin was even more attractive, resulting in over a 10-fold increase in hovering, a 50-fold increase in landing, and a 150-fold increase in host-searching and probing behaviors compared to clean air. Fresh cucumber leaf odors were not attractive to the parasitoids, but decomposing leaves elicited a strong increase in hovering, landing, and searching behaviors. Plastic leaves which visually simulated cucurbit foliage did not in themselves significantly alter orientation behaviors, but the combination of leaf visual stimuli plus decaying leaf odors caused strong increases in hovering, landing, and searching. Fresh pumpkin odor and the odor of yeast-inoculated pumpkin were not as attractive to parasitoids as decaying leaf odors. Yeast isolated from decaying pumpkin and cultured on various sterile media were not substantially more attractive than clean air.