The lack of plasticity and interspecific variability in thermal limits produce a highly heat-tolerant tropical host-parasitoid system.

Thermal limits are often used as proxies to assess the vulnerability of ectotherms to environmental change. While meta-analyses point out a relatively low plasticity of heat limits and a large interspecific variability, only few studies have compared the heat tolerance of interacting species. The present study focuses on the thermal limits, and their plasticity (heat hardening), of three species co-occurring in Western Africa: two ectoparasitoid species, Dinarmus basalis (Rondani) (Hymenoptera: Pteromalidae) and Eupelmus vuilleti (Crawford) (Hymenoptera: Eupelmidae), and their common host, Callosobruchus maculatus (F.

Adverse effects of the Bordeaux mixture copper-based fungicide on the non-target vineyard pest Lobesia botrana.

Background: Bordeaux mixture is a copper-based fungicide commonly used in vineyards to prevent fungal and bacterial infections in grapevines. However, this fungicide may adversely affect the entomological component, including insect pests. Understanding the impacts of Bordeaux mixture on the vineyard pest Lobesia botrana is an increasing concern in the viticultural production.

Sublethal doses of pyriproxyfen stimulate reproduction and aggressive behavior in a non-target parasitoid wasp.

Insecticides are commonly used to control populations of pests and disease vectors. However, they can have multiple unintended effects on non-target species. Assessing their impacts on the physiology and behavior of beneficial insects, such as biological control agents, is thus necessary to gain insight into the diversity and nature of such side effects.

Ecdysteroids affect female reproductive status and outcome of contest over hosts in the parasitoid wasp Eupelmus vuilleti.

Ecdysteroids are a family of insect hormones that may play a role in modulating aggressive behavior in reproductive contexts. In Hymenoptera, the few studies investigating the link between ecdysteroid titers, reproduction and aggressiveness during contests concern solely eusocial species. Here, we explored whether ecdysteroid titers influenced female reproductive status as well as aggressiveness and resolution of conflict in a solitary ectoparasitoid, Eupelmus vuilleti (Hymenoptera: Eupelmidae).

The challenge hypothesis in insects.

The 'challenge hypothesis' provides a predictive framework for how the social environment influences within-species variation in hormone titers. High testosterone levels are beneficial during reproduction and competition, but they also impose costs because they may suppress traits like parental care and immunity. As a result, the challenge hypothesis predicts that individuals will change their testosterone levels to match the current social environment.

Juvenile hormone manipulation affects female reproductive status and aggressiveness in a non-social parasitoid wasp.

In vertebrates, titers of androgens such as testosterone are known to upregulate aggressive behaviors associated with reproduction. In insects, juvenile hormone (JH) is a good candidate for studying the flexibility of insect endocrine responses because it has important effects on both reproductive processes and behavior. JH has a gonadotropic effect across a broad range of insect species, increasing ovarian development in females, and may have a role in the regulation of aggressive behavior during competition.

Sperm limitation affects sex allocation in a parasitoid wasp Nasonia vitripennis.

Insect reproduction is influenced by various external factors including temperature, a well-studied constraint. We investigated to what extent different levels of sperm limitation of males exposed to different heat stresses (34 and 36 °C) affect females' offspring production and sex allocation in Nasonia vitripennis. In this haplodiploid parasitoid wasp attacking different species of pest flies, we investigated the effect of the quantity of sperm females received and stored in their spermatheca on their sperm use decisions, hence sex allocation, over successive ovipositions.

The metabolic costs of fighting and host exploitation in a seed-drilling parasitic wasp.

Oviposition sites may be challenging and energetically costly to access for females in the presence of competitors contesting that resource. Additionally, oviposition sites may be difficult to reach, and penetrating a hard substrate can raise energy costs. In the seed-drilling parasitic wasp , females actively fight with conspecific competitors over access to hosts.

Volatile Chemical Emission as a Weapon of Rearguard Action: A Game-Theoretic Model of Contest Behavior.

We use a game-theoretic model to explore whether volatile chemical (spiroacetal) emissions can serve as a weapon of rearguard action. Our basic model explores whether such emissions serve as a means of temporary withdrawal, preventing the winner of the current round of a contest from translating its victory into permanent possession of a contested resource. A variant of this model explores an alternative possibility, namely, that such emissions serve as a means of permanent retreat, attempting to prevent a winner from inflicting costs on a fleeing loser.

Do males choose their mates in the lekking moth Achroia grisella? Influence of female body mass and male reproductive status on male mate choice.

Lekking males aggregate to attract females and contribute solely to egg fertilization, without any further parental care. Evolutionary theory therefore predicts them to be nonchoosy toward their mates, because any lost mating opportunities would outweigh the benefits associated with such preferences. Nevertheless, due to time costs, the production of energetically costly sexual displays, and potential sperm limitation, the mating effort of lekking males is often considerable.

Modeling the evolution of winner and loser effects: A survey and prospectus.

The evolution of winner or loser effects-higher probabilities of winning after winning or of losing after losing-has received remarkably little attention from theoreticians, even though such effects are widespread across the animal kingdom. We review game-theoretic models that regard such winner and loser effects as outcomes of a strategic response. We show that these models have been well supported by the empirical literature in the past, but are not designed to address some recent observations.

Amino acid composition of the bushcricket spermatophore and the function of courtship feeding: Variable composition suggests a dynamic role of the nuptial gift.

Nuptial gifts are packages of non-gametic material transferred by males to females at mating. These gifts are common in bushcrickets, where males produce a complex spermatophore consisting in a sperm-containing ampulla and an edible sperm-free spermatophylax. Two non-mutually exclusive hypotheses have been suggested to explain the function of the spermatophylax: the paternal investment hypothesis proposes that it represents a male nutritional investment in offspring; the mating effort hypothesis proposes that the spermatophylax maximizes the male's sperm transfer.

A combined approach to heat stress effect on male fertility in Nasonia vitripennis: from the physiological consequences on spermatogenesis to the reproductive adjustment of females mated with stressed males.

In recent years, several studies have shown a decline in reproductive success in males in both humans and wildlife. Research on male fertility has largely focused on vertebrates, although invertebrates constitute the vast majority of terrestrial biodiversity. The reduction of their reproductive capacities due to environmental stresses can have strong negative ecological impacts, and also dramatic consequences on world food production if it affects the reproductive success of biological control agents, such as parasitic wasps used to control crop pests.

The effect of direct interspecific competition on patch exploitation strategies in parasitoid wasps.

The presence of competitors may affect the pay-off of individuals' foraging strategies. They should therefore modify their resource exploitation decisions accordingly. In such a direct competition situation, theory predicts that individuals should stay longer on a resource patch than when foraging alone.

Previous experience and contest outcome: winner effects persist in absence of evident loser effects in a parasitoid wasp.

The experience of a previous conflict can affect animals' performance during a later contest: a victory usually increases and a defeat usually decreases the probability of winning a subsequent conflict. These winner and loser effects could result from a reassessment by contestants of their perceived fighting abilities. Game-theoretic models based on this assumption predict that a loser effect can exist alone or in the presence of a winner effect, but a winner effect cannot persist alone, at least when contestants are young and without experience of contest.

Abdominal sensory equipment involved in external host discrimination in a solitary parasitoid wasp.

Already parasitized hosts are often of poorer quality than healthy hosts. It is therefore usually advantageous for parasitoid females to recognize and reject them. Parasitized hosts can be identified on the basis of various physical or chemical marks present on the surface or inside the hosts or their surroundings in the case of concealed host.

Encountering competitors reduces clutch size and increases offspring size in a parasitoid with female-female fighting.

Understanding the size of clutches produced by only one parent may require a game-theoretic approach: clutch size may affect offspring fitness in terms of future competitive ability. If larger clutches generate smaller offspring and larger adults are more successful in acquiring and retaining resources, clutch size optima should be reduced when the probability of future competitive encounters is higher. We test this using Goniozus nephantidis, a gregarious parasitoid wasp in which the assumption of size-dependent resource acquisition is met via female-female contests for hosts.

Volatile emission by contest losers revealed by real-time chemical analysis.

Animal interactions often involve chemical exchange but simultaneous evaluation of chemistry and behaviour has been problematical. Here we report findings from a novel method, atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) coupled with manipulation of molecular-mass achieved by rearing organisms on deuterium-enhanced nutrients. This allows real-time monitoring of the occurrence and quantity of volatile chemicals released by each of two interacting individuals, in tandem with behavioural observations.