The male mate search: an optimal foraging issue?

5 pagesInternational audienceMale insects must find and mate females to have some descendants; male fitness therefore depends on the number of females they inseminate. Males are for this reason expected to optimize the behaviors related to mate location, orientation and copulation. Although optimization of the reproductive behavior of males has long been neglected in the literature, recent studies suggest a renewed interest for this idea. Here we discuss the parallel between male mate-finding and mating strategies in insects and optimal foraging theory (OFT), a class of models which formalize the behavior of organisms seeking and exploiting resources, generally food. We highlight the different facets of male mating systems allowing such a parallel, and claim for a unifying approach of foraging behavior. Finally, we discuss novel research perspective emerging from the application of OFT to male reproductive behavior

Humans and Insects Decide in Similar Ways

Behavioral ecologists assume that animals use a motivational mechanism for decisions such as action selection and time allocation, allowing the maximization of their fitness. They consider both the proximate and ultimate causes of behavior in order to understand this type of decision-making in animals. Experimental psychologists and neuroeconomists also study how agents make decisions but they consider the proximate causes of the behavior. In the case of patch-leaving, motivation-based decision-making remains simple speculation. In contrast to other animals, human beings can assess and evaluate their own motivation by an introspection process. It is then possible to study the declared motivation of humans during decision-making and discuss the mechanism used as well as its evolutionary significance. In this study, we combine both the proximate and ultimate causes of behavior for a better understanding of the human decision-making process. We show for the first time ever that human subjects use a motivational mechanism similar to small insects such as parasitoids [1] and bumblebees [2] to decide when to leave a patch. This result is relevant for behavioral ecologists as it supports the biological realism of this mechanism. Humans seem to use a motivational mechanism of decision making known to be adaptive to a heterogeneously distributed resource. As hypothesized by Hutchinson et al. [3] and Wilke and Todd [4], our results are consistent with the evolutionary shaping of decision making because hominoids were hunters and gatherers on food patches for more than two million years. We discuss the plausibility of a neural basis for the motivation mechanism highlighted here, bridging the gap between behavioral ecology and neuroeconomy. Thus, both the motivational mechanism observed here and the neuroeconomy findings are most likely adaptations that were selected for during ancestral times

Comment valoriser l’oral des élèves en difficulté scolaire ?

Professorat des collèges et lycéesLes élèves de nos classes de sixième de consolidation présentent de nombreux points communs, en particulier une difficulté d’expression écrite. Or, parmi ces élèves, certains prennent la parole avec un certain enthousiasme mais de façon souvent non réfléchie. Ces situations aboutissent à un certain désordre dans la classe. Nous avons donc entrepris de canaliser cette énergie. Cet oral spontané et non structuré doit devenir plus construit et doit mettre en évidence une élaboration de démarches intellectuelles. Le professeur doit alors faire de ce défaut une qualité afin que l’oral permette aux élèves de verbaliser leurs idées et de confronter leurs conceptions pour construire les savoirs. Nous avons cherché à valoriser cet oral en espérant que cette action ait des répercutions sur la qualité de l’écrit

Data from: Pair-bonding influences affective state in a monogamous fish species

In humans, affective states are a key component in pair-bonding, particularly in the early stage of a relationship. Pairing with a high-quality partner elicits positive affective states which, in turn, validate and reinforce the mate choice. Affective states thus strongly affect pair stability and future reproductive success. We propose generalizing the link between affective states and pair-bonding to encompass other monogamous species exhibiting biparental care, chiefly where the reproductive success of the pair critically depends on the coordination between partners. The convict cichlid Amatitlania siquia is a monogamous fish species that forms long-lasting pairs with strong cooperation between parents for parental care. In this species, we showed that females paired with their non-preferred male had lower reproductive success than those paired with their preferred male. We then transposed the judgement bias paradigm, previously used in other animal species, to assess objectively affective states in fish. Females that were assigned their non-preferred partner exhibited pessimistic bias, which indicates a negative affective state. By contrast, females that were assigned their preferred partner did not exhibit changes in their affective state. Our results highlight that the influence of pair-bonding on affective states is not human-specific and can also be observed in non-human species

Measuring the evolutionary potential of a winter-active parasitic wasp to climate change

10 pagesInternational audienceIn temperate climates, as a consequence of warming winters, an increasing number of ectothermic species are remaining active throughout winter months instead of diapausing, rendering them increasingly vulnerable to unpredictable cold events. One species displaying a shift in overwintering strategy is the parasitoid wasp and biological control agent Aphidius avenae. The current study aimed to better understand the consequence of a changing overwintering strategy on the evolutionary potential of an insect population to adapt to the cold stress events, set to increase in frequency, even during milder winters. Using a parental half-sibling breeding design, narrow-sense heritability of the cold tolerance, morphology and longevity of A. avenae was estimated. The heritability of cold tolerance was estimated at 0.07 (CI = [0.00; 0.25]) for the Critical Thermal Minima (CT) and 0.11 (CI = [0.00; 0.34]) for chill coma temperature; estimates much lower than those obtained for morphological traits (tibia length 0.20 (CI = [0.03; 0.37]); head width 0.23 (CI = [0.09; 0.39]); wing surface area 0.28 (CI = [0.11; 0.47])), although comparable with the heritability estimate of 0.12 obtained for longevity (CI = [0.00; 0.25]). The heritability estimates obtained thus suggest that A. avenae possesses low adaptive potential against cold stress. If such estimates are indicative of the evolutionary potential of A. avenae cold tolerance, more emphasis may be placed on adaptive phenotypic plasticity at the individual level to persist in a changing climate, with potential implications for the biological control function they provide

Pair-bonding influences affective state in a monogamous fish species.

8 pagesInternational audienceIn humans, affective states are a key component in pair-bonding, particularly in the early stage of a relationship. Pairing with a high-quality partner elicits positive affective states which, in turn, validate and reinforce the mate choice. Affective states thus strongly affect pair stability and future reproductive success. We propose generalizing the link between affective states and pair-bonding to encompass other monogamous species exhibiting biparental care, chiefly where the reproductive success of the pair critically depends on the coordination between partners. The convict cichlid Amatitlania siquia is a monogamous fish species that forms long-lasting pairs with strong cooperation between parents for parental care. In this species, we showed that females paired with their non-preferred male had lower reproductive success than those paired with their preferred male. We then transposed the judgement bias paradigm, previously used in other animal species, to assess objectively affective states in fishes. Females that were assigned their non-preferred partner exhibited pessimistic bias, which indicates a negative affective state. By contrast, females that were assigned their preferred partner did not exhibit changes in their affective state. Our results highlight that the influence of pair-bonding on affective states is not human-specific and can also be observed in non-human species

laubu_original_datasets

The three original datasets from Laubu et al. in txt format. The attached 'readme' file explains the meaining of each variable name and value

A perspective on insect–microbe holobionts facing thermal fluctuations in a climate‐change context

Temperature influences the ecology and evolution of insects and their symbionts by impacting each partner independently and their interactions, considering the holobiont as a primary unit of selection. There are sound data about the responses of these partnerships to constant temperatures and sporadic thermal stress (mostly heat shock). However, the current understanding of the thermal ecology of insect–microbe holobionts remains patchy because the complex thermal fluctuations (at different spatial and temporal scales) experienced by these organisms in nature have often been overlooked experimentally. This may drastically constrain our ability to predict the fate of mutualistic interactions under climate change, which will alter both mean temperatures and thermal variability. Here, we tackle down these issues by focusing on the effects of temperature fluctuations on the evolutionary ecology of insect–microbe holobionts. We propose potentially worth-investigating research avenues to (i) evaluate the relevance of theoretical concepts used to predict the biological impacts of temperature fluctuations when applied to holobionts; (ii) acknowledge the plastic (behavioural thermoregulation, physiological acclimation) and genetic responses (evolution) expressed by holobionts in fluctuating thermal environments; and (iii) explore the potential impacts of previously unconsidered patterns of temperature fluctuations on the outcomes and the dynamic of these insect–microbe associations

Warming increases tolerance of an insect pest to fungicide exposure through temperature-mediated hormesis

Pest management strategies relying on agrochemicals could be altered by climate change, because of the temperature-dependent toxicity of the compound involved. Many studies have explored the response of targeted pests to pesticide and temperature. Pesticides are seldom strictly selective and also affect nontarget pests. Surprisingly, the way temperature may shape these side effects of pesticides remains overlooked, limiting our understanding of the net impacts of future chemical treatments on the overall damage induced by different pests. We investigated how temperature modulates the response of a major grape insect pest (the tortricid moth Lobesia botrana) to a copper-based fungicide. We examined the lethal (larval survival) and sublethal (larval development, pupal mass, immune parameters) effects of exposure to different concentrations of copper in larval food. We found that copper concentration had negative linear effects on larval development and pupal mass. In addition, copper concentration had biphasic curvilinear effects on total phenoloxidase activity, which is indicative of hormesis (stimulation and inhibition of insect performance at low and high copper concentrations, respectively). Temperature stimulated development, while compromising immunity (total phenoloxidase activity). Significant interaction between copper concentration and temperature was detected for larval survival and phenoloxidase activity: warmer conditions improved pest tolerance to copper through temperature-driven hormesis (larval survival) or by shifting the hormesis-related peak of performance toward higher copper concentrations (phenoloxidase activity). This combination of simple and interactive effects could propagate to populations, communities and agroecosystem, with implications for future management of viticultural pests

Reproductive performance of the European grapevine moth Lobesia botrana (Tortricidae) is adversely affected by warming scenario

The European grapevine moth, Lobesia botrana (Denis and Schiffermüller), is an important grape pest worldwide. To forecast how this species might respond to climate change has emerged as one major challenge in recent viticultural research. Predictions about L. botrana population dynamics under global warming scenario are usually derived from physiologically based demographic models (PBDMs). Despite their ecological realism, PBDMs are based on physiological equations derived from constant, unrealistic thermal regimes, and they exclude the effects of temperature on male’s reproductive traits, which importantly mediates population dynamics in this species. Focused on Burgundy (a viticultural region of France), we compared the adult performance of L. botrana between the Current Fluctuating Regime (CFR) based on in situ meteorological data and the Future Fluctuating Regime (FFR) based on the outputs of climate models. Under controlled conditions complying to the scenario of local warming termed FFR, L. botrana individuals incurred reduced adult lifespan, while their body amounts of four major energetic components (proteins, lipids, glycogen, soluble carbohydrates) remained unchanged compared to individuals exposed to the CFR. Furthermore, each sex endured reproductive costs associated with local warming scenario: females incurred reduced mating success, and males bore decreased fertility (lower number of eupyrene sperms within spermatophore). Our results indicate that global warming should adversely impact the reproductive success of L. botrana and the local abundance of this pest. In terms of pest management, our findings might contribute to the increase in the ecological realism of PBDMs and improve the reliability of their predictions about the population dynamics of L. botrana