Stage-Specific Behavioral Responses of Ageneotettix deorum (Orthoptera: Acrididae) in the Presence of Lycosid Spider Predators

Grasshoppers must gather food while avoiding size-selective predation from other arthropods, especially spiders, potentially leading to a trade-off between foraging and defensive behaviors. This trade-off becomes less intense as prey grow larger and are less susceptible to arthropod predation. Activity budgets were constructed for three nymphal (third- to fifth- instar) and adult life cycle stages of Ageneotettix deorum, a common rangeland grasshopper, for three conditions of predation risk by lycosid spiders (spider absence, spider presence, and presence of a nonlethal, chelicerae-modified spider). In third and fourth instars, exposure to predators resulted in reduced feeding activity, increased time spent in antipredator and defensive behaviors, and reduced general activity compared to individuals not exposed to spiders. No significant shifts in behaviors were observed for fifth-instar nymphs and adult A. deorum in response to spider presence. Activity levels in functional spiders and chelicerae-modified spiders were statistically indistinguishable.     

Network analysis as a tool to understand social development in spider monkeys

The emerging field of network science has demonstrated that an individual's connectedness within their social network has cascading effects to other dimensions of life. Like humans, spider monkeys live in societies with high fission–fusion dynamics, and are remarkably social. Social network analysis (SNA) is a powerful tool for quantifying connections that may vary as a function of initiating or receiving social behaviors, which has been described as shifting social roles. In primatology, the SNA literature is dominated by work in catarrhines, and has yet to be applied to the study of development in a platyrrhine model. Here, SNA was utilized in combination with R-Index social role calculation to characterize social interaction patterns in juvenile and adult Colombian spider monkeys (Ateles fusciceps rufiventris). Connections were examined across five behaviors: embrace, face-embrace, grooming, agonism, and tail-wrapping from 186 hr of observation and four network metrics. Mann–Whitney U tests were utilized to determine differences between adult and juvenile social network patterns for each behavior. Face-embrace emerged as the behavior with different network patterns for adults and juveniles for every network metric. With regard to social role, juveniles were receivers, not initiators, for embrace, face-embrace, and grooming (ps < .05). Network and social role differences are discussed in light of social development and aspects of the different behaviors.     

Female preference for complex/novel signals in a spider

Identifying the various factors that influence complex signalevolution is a difficult task, yet it is fundamental to understandingthe evolution of animal communication. Here we explore the evolutionof complex courtship signaling by taking advantage of a systemin which sexual selection on male courtship traits has driventhe diversification of geographically isolated populations ofthe jumping spider Habronattus pugillis Griswold. Using 2 populations(Santa Rita [SR] and Atascosa [AT]) in which SR females showxenophilic mating preferences for foreign (AT) over local males(SR), we examine the mechanisms driving this preference. BothAT and SR males produce multimodal signals (visual + seismic),and while SR and AT signals share certain seismic components,AT seismic signals are more complex and contain novel components.We conducted mate choice trials where SR females were presentedwith AT or SR males that were either muted or nonmuted. SR femalespreferred to mate and mated more quickly with foreign AT malesover local SR males only if AT males could produce seismic signals(nonmuted treatment). In addition, we found that SR femalesspent a higher proportion of time attentive to foreign AT malesonly if they could produce seismic signals. This evidence suggeststhat SR females have a bias for complex and/or novel forms ofseismic signals.     

Factors affecting the feeding of northern fowl mites, Ornithonyssus sylvarium, through a membrane

Northern fowl mites, Ornithonyssus sylviarum (Canestrini & Fanzago) (Acari: Macronyssidae), were fed artificially through chick skin membranes to investigate several factors that affected the degree of mite feeding. More mites fed after starving 24 h than unstarved mites or mites starved 48 or 72 h. Protonymphs fed as well as adults. More mites fed on refrigerated blood than on fresh blood and on frozen blood than on refrigated blood. However, mites fed well on newly drawn blood that had been lysed. They fed as well on plasma and serum as on whole blood but less well on washed erythrocytes. They also fed well on citrated blood, but fewer mites fed on oxalated blood or freshly defibrinated blood.

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Résumé O. sylviarum Canestri & Fanzago a été alimenté artificiellement pour étudier plusieurs facteurs qui affectent l'intensité de la prise de nourriture. Le dispositif d'alimentation consistait en un cylindre de verre de 24 mm de long, dont les ouvertures étaient fermées, à une extrémité par une membrane en peau de volaille, et à l'autre extrémité avec du polyéthylène.Après un jeûne de 24 h, le nombre de pucerons qui s'étaient alimentés était plus élevé (87%) qu'après un jeûne de 48 ou 72 h (respectivement 71 et 73%) ou en absence de jeûne (11%). Les protonymphes se sont aussi bien alimentées que les adultes; elles ont été significativement plus nombreuses à le faire aprés 2 h (84%) qu'après 1 h (71%). Le sang refroidi pendant une nuit, ou pendant une ou 2 semaines a été consommé par un plus grand nombre d'acariens (59%, 70% et 78%) que le sang frais (46%); les différences entre durées voisines ne sont pas significatives, mais elles le sont entre une nuit et deux semaines. Le sang congelé pendant 1, 2 ou 4 semaines a été consommé par un plus grand nombre d'acariens (87%, 90% et 82%) que le sang refroid: la consommation était aussi bonne pour les différentes durées de congélation. Puisque les acariens se sont bien alimentés sur sang lysé (75%), les matériaux propres au sang frais devaient être tombés hors d'atteinte des pièces bucales des acariens. Autant se sont alimentés sur plasma (87%), sérum (79%) que sur sang complet (85%), mais ils ont été moins nombreux à le faire sur érythrocytes lavés (69%); ils ont été nombreux à le faire sur sang citraté (87%), mais en plus faible nombre sur sang oxalaté (66%) ou défibriné depuis peu (32%). Le taux de mortalité des acariens qui avaient consommé du sang oxalaté était élevée (25%), à l'opposé de celui observé après alimentation sur sang citraté (6%) ou sang héparinisé (9%). Le sang défibriné n'était pas lysé, et ales érythrocytes étaient probablement hors d'atteinte, et ainsi, non ingérés par les acariens.

     

Egg production and survival of the citrus red mite on an artificial feeding system

An artificial feeding system was developed for the citrus red mite, Panonychus citri McGregor (Acari: Tetranychidae) to determine egg production and survival of adult female mites in response to various nutrient solutions. Egg production increased with increasing sugar concentration up to 20%, then declined. Autoclaved sodium caseinate was the most suitable nitrogen source examined, and egg production was highest on diet fractions containing 8% sodium caseinate, the highest concentration examined. Fecundity was higher when dietary nitrogen was provided entirely by protein than in whole or in part by free amino acids. Results are qualitatively similar to studies with Tetranychus urticae Koch, however optimal concentrations of major nutrients were ca. 4 to 10 times higher for P. citri than for T. urticae.

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Résumé Une méthode d'alimentation sur diète artificielle a été mise au point pour l'acarien du citrus, Panonychus citri Mc Gregor (Acari: Tetranychidae) et a été utilisée pour déterminer l'influence de différentes solutions nutritives sur la fécondité et la survie des femelles adultes. La fécondité augmente avec la teneur en sucre jusqu'à une concentration maximale de 30%, et décline ensuite pour des concentrations supérieures. Du caséinate de sodium autoclavé s'est révélé être la meilleure source d'azote et la fécondité a été la plus forte sur des milieux contenant 8% de caséinate de sodium, concentration la plus élevée testée. La fécondité est plus grande lorsque l'azote alimentaire est fourni entièrement sous forme de protéine plutôt que sous forme d'acides aminés libres, en tout ou en partie. Les résultats sont qualitativement semblables à ceux obtenus précédemment chez Tetranychus urticae Koch, cependant les concentrations optimales des nutriments majeurs sont environ 4 à 10 fois plus élevées pour P. citri que pour T. urticae.