Adult beetles compensate for poor larval food conditions

Adult Feeding Experience Determines the Fecundity and Preference of the Henosepilachna vigintioctopunctata (F.) (Coleoptera: Coccinellidae)

Both larvae and adults of the Henosepilachna vigintioctopunctata feed on leaves of potatoes, tomatoes, and eggplants. Given the variation in planting times of host plants in the Jianghan Plain, host switching between larvae and adults of H. vigintioctopunctata is inevitable to ensure continuous food availability. We evaluated the effect of consistent versus diverse larval and adult host plant feeding experience on growth performance, fecundity, longevity, and feeding preferences of H. vigintioctopunctata through match-mismatch experiments. Host plant quality significantly influences larval development and adult reproduction. Potatoes are identified as the optimal host plant for H. vigintioctopunctata, whereas eggplants significantly negatively affect the adult fecundity. Adult stage host feeding experience determines the fecundity of H. vigintioctopunctata, irrespective of the larval feeding experience. The fecundity of H. vigintioctopunctata adults on eggplant leaves remains significantly lower than that observed on potato leaves. Similarly, adult H. vigintioctopunctata demonstrate a preference for consuming potato leaves, irrespective of the larval feeding experience. Although host switching between larval and adult stages offers lesser benefits for the performance of herbivorous insects compared to a consistent diet with potato leaves, it maintains H. vigintioctopunctata population continuity amidst shortages of high-quality potato hosts.

Wood trait preferences of Neotropical xylophagous beetles (Coleoptera: Cerambycidae)

Tree life history strategies are correlated with functional plant traits, such as wood density, moisture content, bark thickness, and nitrogen content; these traits affect the nutrients available to xylophagous insects. Cerambycid beetles feed on substrates that vary in these traits, but little is known about how they affect community composition. The goal of this project is to explore the community composition of two cerambycid subfamilies (Cerambycinae and Lamiinae) according to the wood traits in the wood they eat. In a salvage project conducted adjacent to the Panama Canal, trees were felled and exposed to Cerambycidae for oviposition. Disks from branches of differing thickness from the same plant individuals were used to calculate wood density, moisture content, and bark thickness in the field; nitrogen data were acquired offsite. Thick and thin branches tended to differ in wood trait values; therefore, data were analyzed separately in subsequent analyses. In thin branches, cerambycid abundance and species richness were higher in samples with less dense, moister wood, and thicker bark. Thick branches showed similar trends, but the wood traits accounted for little variability in beetle abundance or species richness. There were no significant regressions between beetle data and nitrogen. Cerambycines emerged more slowly, and from denser, drier wood, than lamiines. Cerambycines might be more drought-tolerant than lamiines, and therefore more resistant to the longer, more severe dry seasons that are predicted to occur due to climate change.

Larval and adult diet affect phenotypic plasticity in thermal tolerance of the marula fly, Ceratitis cosyra (Walker) (Diptera: Tephritidae)

Introduction

Temperature fluctuations are important for the distribution and survival of insects. Rapid hardening, a type of phenotypic plasticity, is an adaptation that can help individuals better tolerate lethal temperatures because of earlier exposure to a sublethal but stressful temperature. Nutrition and sex are also known to influence a species ability to tolerate thermal stress. This study determined the effects of larval diet, adult diet, sex and hardening on the thermal tolerance of Ceratitis cosyra (Walker) (Diptera: Tephritidae) at lower and upper lethal temperatures.

Methods

Larvae were raised on either an 8% torula yeast (high) or a 1% torula yeast (low) larval diet and then introduced to one of three dietary regimes as adults for thermal tolerance and hardening assays: no adult diet, sugar only, or sugar and hydrolysed yeast diet. Flies of known weight were then either heat- or cold-hardened for 2 hours before being exposed to a potentially lethal high or low temperature, respectively.

Results

Both nutrition and hardening as well as their interaction affected C. cosyra tolerance of stressful temperatures. However, this interaction was dependent on the type of stress, with nutrient restriction and possible adult dietary compensation resulting in improved cold temperature resistance only.

Discussion

The ability of the insect to both compensate for a low protein larval diet and undergo rapid cold hardening after a brief exposure to sublethal cold temperatures even when both the larva and the subsequent adult fed on low protein diets indicates that C. cosyra have a better chance of survival in environments with extreme temperature variability, particularly at low temperatures. However, there appears to be limitations to the ability of C. cosyra to cold harden and the species may be more at risk from long term chronic effects than from any exposure to acute thermal stress.

Evolution of immune function in response to dietary macronutrients in male and female decorated crickets

Although dietary macronutrients are known to regulate insect immunity, few studies have examined their evolutionary effects. Here, we evaluate this relationship in the cricket Gryllodes sigillatus by maintaining replicate populations on four diets differing in protein (P) to carbohydrate (C) ratio (P- or C-biased) and nutritional content (low- or high-nutrition) for >37 generations. We split each population into two; one maintained on their evolution diet and the other switched to their ancestral diet. We also maintained populations exclusively on the ancestral diet (baseline). After three generations, we measured three immune parameters in males and females from each population. Immunity was higher on P-biased than C-biased diets and on low- versus high-nutrition diets, although the latter was most likely driven by compensatory feeding. These patterns persisted in populations switched to their ancestral diet, indicating genetic divergence. Crickets evolving on C-biased diets had lower immunity than the baseline, whereas their P-biased counterparts had similar or higher immunity than the baseline, indicating that populations evolved with dietary manipulation. Although females exhibited superior immunity for all assays, the sexes showed similar immune changes across diets. Our work highlights the important role that macronutrient intake plays in the evolution of immunity in the sexes.

Fluctuating Starvation Conditions Modify Host-Symbiont Relationship Between a Leaf Beetle and Its Newly Identified Gregarine Species

Gregarines are ubiquitous endosymbionts in invertebrates, including terrestrial insects. However, the biodiversity of gregarines is probably vastly underestimated and the knowledge about their role in shaping fitness-related traits of their host in dependence of fluctuating environmental conditions is limited. Using morphological and molecular analyses, we identified a new gregarine species, Gregarina cochlearium sp. n., in the mustard leaf beetle, Phaedon cochleariae. Applying a full-factorial design, we investigated the effects of a gregarine infection in combination with fluctuating starvation conditions during the larval stage on the development time and fitness-related traits of adult beetles. Under benign environmental conditions, the relationship between gregarines and the host seemed neutral, as host development, body mass, reproduction and survival were not altered by a gregarine infection. However, when additionally exposed to starvation, the combination of gregarine infection and this stress resulted in the lowest reproduction and survival of the host, which points to a parasitic relationship. Furthermore, when the host experienced starvation, the development time was prolonged and the adult females were lighter compared to non-starved individuals, independent of the presence of gregarines. Counting of gregarines in the guts of larvae revealed a lower gregarine load with increasing host body mass under stable food conditions, which indicates a regulation of the gregarine burden in dependence of the host condition. Contrary, in starved individuals the number of gregarines was the highest, hence the already weakened host suffered additionally from a higher gregarine burden. This interactive effect between gregarine infection and fluctuating starvation conditions led to an overall reduced fitness of P. cochleariae. Our study emphasizes the need to study endosymbionts as important components of the natural environment and to investigate the role of host-symbiont relationships under fluctuating environmental conditions in an evolutionary and ecological context.

Realism in Immune Ecology Studies: Artificial Diet Enhances a Caterpillar's Immune Defense but Does Not Mask the Effects of a Plastic Immune Strategy

The immune system is considered a functional trait in life-history theory and its modulation is predicted to be costly and highly dependent on the host's nutrition. Therefore, the nutritional status of an individual has a great impact on an animal's immune ecology. Herbivorous insects are commonly used as model organisms in eco-immunology studies and the use of an artificial diet is the predominant rearing procedure to test them. However, this diet differs from what herbivores experience in nature and it is unclear to what degree this distinction might impact on the relevance of these studies for the real world. Here, we compared plant-based vs. artificial diet in a set of three experiments to investigate the interaction of both diets with a plastic immune strategy known as Density-Dependent Prophylaxis (DDP). We used as a model organism the velvetbean caterpillar Anticarsia gemmatalis, which is known to adjust its immune defense in line with the DDP hypothesis. Our main results showed that larvae fed with artificial diet had 20.5% more hemocytes circulating in the hemolymph and died 20% more slowly when infected with an obligate (viral) pathogen. Crucially, however, we did not find any indication of fitness costs related to DDP. The use of artificial diet did not interact with that of DDP except in the case of host survival after infection, where the DDP effect was only observable in this diet. Our findings suggest the use of an artificial diet does not mask resource allocation conflicts between immune investment and fitness related traits, but to some extent it might lead to an overestimation of immune parameters and host survival time after infection. We believe that this is the first study to compare an artificial diet and a host plant covering all these aspects: immune parameters, life-history traits, and host survival after infection. Here we provide evidence that, besides the quantitative effects in immune parameters and host survival time, the use of artificial diet interacts only marginally with a density-dependent immune response. This provides support for the use of artificial diets in eco-immunology studies with insects.

A meta-analysis of sex differences in animal personality: no evidence for the greater male variability hypothesis

The notion that men are more variable than women has become embedded into scientific thinking. For mental traits like personality, greater male variability has been partly attributed to biology, underpinned by claims that there is generally greater variation among males than females in non-human animals due to stronger sexual selection on males. However, evidence for greater male variability is limited to morphological traits, and there is little information regarding sex differences in personality-like behaviours for non-human animals. Here, we meta-analysed sex differences in means and variances for over 2100 effects (204 studies) from 220 species (covering five broad taxonomic groups) across five personality traits: boldness, aggression, activity, sociality and exploration. We also tested if sexual size dimorphism, a proxy for sex-specific sexual selection, explains variation in the magnitude of sex differences in personality. We found no significant differences in personality between the sexes. In addition, sexual size dimorphism did not explain variation in the magnitude of the observed sex differences in the mean or variance in personality for any taxonomic group. In sum, we find no evidence for widespread sex differences in variability in non-human animal personality.

Gregarines modulate insect responses to sublethal insecticide residues

Throughout their lifetime, insects face multiple environmental challenges that influence their performance. Gregarines are prevalent endoparasites in most invertebrates that affect the fitness of their hosts, but are often overlooked in ecological studies. Next to such biotic factors, a current common challenge is anthropogenic pollution with pesticides, which causes a major threat to non-target organisms that are readily exposed to lethal or sublethal concentrations. In a laboratory study, we investigated whether the presence of gregarines modulates the food consumption and life history traits of a (non-target) leaf beetle species, Phaedon cochleariae, in response to sublethal insecticide exposure. We show that the larval food consumption of the herbivore was neither affected by gregarine infection nor sublethal insecticide exposure. Nevertheless, infection with gregarines led to a delayed development, while insecticide exposure resulted in a lower body mass of adult males and a reduced reproduction of females. Individuals exposed to both challenges suffered most, as they had the lowest survival probability. This indicates detrimental effects on the population dynamics of non-target insects infected with naturally occurring gregarines that face additional stress from agrochemical pollution. Moreover, we found that the infection load with gregarines was higher in individuals exposed to sublethal insecticide concentrations compared to unexposed individuals. To counteract the global decline of insects, the potential of natural parasite infections in modulating insect responses to anthropogenic and non-anthropogenic environmental factors should be considered in ecological risk assessment.

Direct and delayed effects of exposure to a sublethal concentration of the insecticide λ-cyhalothrin on food consumption and reproduction of a leaf beetle

Anthropogenic pollution such as the application of pesticides poses a major threat to many (non-target) organisms. However, little is known about the persistence of harmful effects or potential recovery in response to a period of exposure to a sublethal insecticide dose. Adults of the mustard leaf beetle, Phaedon cochleariae (Coleoptera: Chrysomelidae), were either exposed to a sublethal concentration of the pyrethroid λ-cyhalothrin for two weeks or kept unexposed as control. During, immediately after and at a delayed time after the exposure, consumption and reproduction, i.e., number of eggs laid and hatching success, were assessed. In addition, long-term effects on unexposed offspring were investigated. Exposure to λ-cyhalothrin reduced the consumption during the insecticide exposure, but led to compensatory feeding in females at a delayed time after exposure. The reproductive output of females was impaired during and directly after λ-cyhalothrin exposure. At the delayed time point there was no clear evidence for a recovery, as the reproduction of heavier females was still negatively affected, while lighter females showed an enhanced reproduction. Persistent negative effects on unexposed offspring had been found when collected from parents directly after a λ-cyhalothrin exposure period. In contrast, in the present experiment neither negative effects on life-history traits nor on consumption were observed in unexposed offspring derived from parents at the delayed time after λ-cyhalothrin exposure. Moreover, eggs of offspring from insecticide-exposed parents showed a higher hatching success than those of offspring of unexposed parents, which may indicate transgenerational hormesis. Our results highlight that λ-cyhalothrin exposure has persistent negative effects on fitness parameters of the exposed generation. However, offspring may not be harmed if their parents had sufficient time to recover after such an insecticide exposure. Taken together, our study emphasises that the time-course of exposure to this anthropogenic pollution is crucial when determining the consequences on life-history.

Direct evidence for a new mode of plant defense against insects via a novel polygalacturonase-inhibiting protein expression strategy

Plant cell wall-associated polygalacturonase-inhibiting proteins (PGIPs) are widely distributed in the plant kingdom. They play a crucial role in plant defense against phytopathogens by inhibiting microbial polygalacturonases (PGs). PGs hydrolyze the cell wall polysaccharide pectin and are among the first enzymes to be secreted during plant infection. Recent studies demonstrated that herbivorous insects express their own PG multi-gene families, raising the question whether PGIPs also inhibit insect PGs and protect plants from herbivores. Preliminary evidence suggested that PGIPs may negatively influence larval growth of the leaf beetle Phaedon cochleariae (Coleoptera: Chrysomelidae) and identified BrPGIP3 from Chinese cabbage (Brassica rapa ssp. pekinensis) as a candidate. PGIPs are predominantly studied in planta because their heterologous expression in microbial systems is problematic and instability and aggregation of recombinant PGIPs has complicated in vitro inhibition assays. To minimize aggregate formation, we heterologously expressed BrPGIP3 fused to a glycosylphosphatidylinositol (GPI) membrane anchor, immobilizing it on the extracellular surface of insect cells. We demonstrated that BrPGIP3_GPI inhibited several P. cochleariae PGs in vitro, providing the first direct evidence of an interaction between a plant PGIP and an animal PG. Thus, plant PGIPs not only confer resistance against phytopathogens, but may also aid in defense against herbivorous beetles.

Plants use identical inhibitors to protect their cell wall pectin against microbes and insects

As fundamentally different as phytopathogenic microbes and herbivorous insects are, they enjoy plant-based diets. Hence, they encounter similar challenges to acquire nutrients. Both microbes and beetles possess polygalacturonases (PGs) that hydrolyze the plant cell wall polysaccharide pectin. Countering these threats, plant proteins inhibit PGs of microbes, thereby lowering their infection rate. Whether PG-inhibiting proteins (PGIPs) play a role in defense against herbivorous beetles is unknown. To investigate the significance of PGIPs in insect-plant interactions, feeding assays with the leaf beetle Phaedon cochleariae on Arabidopsis thaliana pgip mutants were performed. Fitness was increased when larvae were fed on mutant plants compared to wild-type plants. Moreover, PG activity was higher, although PG genes were downregulated in larvae fed on PGIP-deficient plants, strongly suggesting that PGIPs impair PG activity. As low PG activity resulted in delayed larval growth, our data provide the first in vivo correlative evidence that PGIPs act as defense against insects.

Effects of carbohydrate types on larval development and adult traits in a polyphagous fruit fly

Nutrition is a major mediator of insect life-history trait expression. While the role of macronutrient (carbohydrate and protein) balance on trait expression has received substantial attention, the implications of different classes of specific macronutrients remains virtually unexplored. Here, we addressed this gap by varying the type of carbohydrate in larval diets of the polyphagous fruit fly Bactrocera tryoni (aka 'Queensland fruit fly'). Sourcing insects from a colony maintained using larval diets that contain sucrose, we assessed the effects of sucrose, maltose, and lactose on larval development and adult traits. Replacement of sucrose with lactose resulted in slow larval growth, as well as decreases in pupation, adult emergence and adult body weight for both sexes, although adult lipid reserves were unaffected. Sucrose and maltose were equivalent in terms of larval growth, pupation, adult emergence and adult weight of both sexes. Surprisingly, adults from larvae reared on diets containing maltose had lower lipid reserves than adults from larvae reared on diets containing either lactose or sucrose. The sex ratio of adults at emergence from larvae reared on diets containing lactose and maltose was balanced, but was female-biased in adults from larvae reared on diets containing sucrose. Our results show that carbohydrate sources are not equivalent for development of the Queensland fruit fly, affecting both larval development and adult traits. These findings have implications for understanding the ecology of this highly polyphagous species which infests fruits with highly diverse carbohydrate contents, as well as for the rearing and management of this pest species.

Life Table Parameters of the Zoophytophagous Predator Brontocoris tabidus (Heteroptera: Pentatomidae) on Introduced and Native Plants

Brontocoris tabidus Signoret (Heteroptera: Pentatomidae) is a zoophytophagous predator of lepidopteran defoliators of eucalyptus in Brazil. This predator complements its diet with plants, which is fundamental for its population maintenance. The objective was to evaluate the B. tabidus development, reproduction, and life table parameters in the field on Eucalyptus cloeziana F. Muell. (T1), Psidium guajava Linn (Myrtales: Myrtaceae) (T2), or without plants (T3). The parameters estimated were: net reproductive rate (Ro); generation duration (DG); time for the population to double in size (TD); intrinsic population growth rate (rm), survival rate (lX), specific fertility (mx), life expectancy (ex), and mortality risk (qx). Ro, DG, TD, and rm were higher in the T1 and T2 than in T3. Plant presence favored the lx, mx, and qx. Ex values were 36.1 and 56.9 in the T3 and T1, respectively. The B. tabidus fertility, longevity, and life table parameters improvement on E. cloeziana and P. guajava plants are due to the water and nutrients obtained from them. B. tabidus can be reared with Tenebrio molitor Linnaeus (Coleoptara: Tenebrionidae) pupae on E. cloeziana or P. guajava plants in the field.

Pectin Digestion in Herbivorous Beetles: Impact of Pseudoenzymes Exceeds That of Their Active Counterparts

Many protein families harbor pseudoenzymes that have lost the catalytic function of their enzymatically active counterparts. Assigning alternative function and importance to these proteins is challenging. Because the evolution toward pseudoenzymes is driven by gene duplication, they often accumulate in multigene families. Plant cell wall-degrading enzymes (PCWDEs) are prominent examples of expanded gene families. The pectolytic glycoside hydrolase family 28 (GH28) allows herbivorous insects to break down the PCW polysaccharide pectin. GH28 in the Phytophaga clade of beetles contains many active enzymes but also many inactive counterparts. Using functional characterization, gene silencing, global transcriptome analyses, and recordings of life history traits, we found that not only catalytically active but also inactive GH28 proteins are part of the same pectin-digesting pathway. The robustness and plasticity of this pathway and thus its importance for the beetle is supported by extremely high steady-state expression levels and counter-regulatory mechanisms. Unexpectedly, the impact of pseudoenzymes on the pectin-digesting pathway in Phytophaga beetles exceeds even the influence of their active counterparts, such as a lowered efficiency of food-to-energy conversion and a prolongation of the developmental period.

Sublethal insecticide exposure of an herbivore alters the response of its predator

Sublethal insecticide exposure poses risks for many non-target organisms and is a challenge for successful implementation of integrated pest management (IPM) programs. Next to detrimental effects of short-term insecticide exposure on fitness-related traits of organisms, also properties such as chemical signaling traits can be altered, which mediate intra- and interspecific communication. We investigated the effects of different durations of larval sublethal exposure to the pyrethroid lambda-cyhalothrin on performance traits of larvae and adults of the herbivorous mustard leaf beetle, Phaedon cochleariae. Moreover, by applying a direct contact and olfactometer bioassays, we determined the reaction of a generalist predator, the ant Myrmica rubra, towards insecticide-exposed and unexposed herbivore larvae and their secretions. Already short-term sublethal insecticide exposure of a few days caused a prolonged larval development and a reduced adult body mass of males. These effects may result from an insecticide-induced reduction in energy reserves. Furthermore, ants responded more frequently to insecticide-exposed than to unexposed larvae of P. cochleariae and their secretions. This increased responsiveness of ants towards insecticide-exposed larvae may be due to an insecticide-induced change in synthesis of chrysomelidial and epichrysomelidial, the dominant compounds of the larval secretion, which act defensive against various generalist predators. In conclusion, the results highlight that short-term insecticide exposure can impair the fitness of an herbivorous species due to both direct toxic effects and an increased responsiveness of predators. Consequently, exposure of single non-target species can have consequences for ecological communities in both natural habitats and IPM programs.

Adult diet does not compensate for impact of a poor larval diet on stress resistance in a tephritid fruit fly

Adult holometabolous insects may derive metabolic resources from either larval or adult feeding, but little is known of whether adult diets can compensate for deficiencies in the larval diet in terms of stress resistance. We investigated how stress resistance is affected and compensated for by diet across life stages in the marula fruit fly Ceratitis cosyra (Diptera: Tephritidae). Larvae were fed diets containing either 8% torula yeast, the standard diet used to rear this species, or 1% yeast (low protein content similar to known host fruit). At emergence, adults from each larval diet were tested for initial mass, water content, body composition, and desiccation and starvation resistance or they were allocated to one of two adult diet treatments: sucrose only, or sucrose and yeast hydrolysate. The same assays were then repeated after 10 days of adult feeding. Development on a low protein larval diet led to lower body mass and improved desiccation and starvation resistance in newly emerged adults, even though adults from the high protein larval diet had the highest water content. Adult feeding decreased desiccation or starvation resistance, regardless of the diet provided. Irrespective of larval diet history, newly emerged, unfed adults had significantly higher dehydration tolerance than those that were fed. Lipid reserves played a role in starvation resistance. There was no evidence for metabolic water from stored nutrients extending desiccation resistance. Our findings show the possibility of a nutrient-poor larval environment leading to correlated improvement in adult performance, at least in the short term.

Developmental diet irreversibly shapes male post-copulatory traits in the neriid fly Telostylinus angusticollis

Nutrient availability has been shown to influence investment in many fitness-related traits, including male reproductive success. Many studies have demonstrated that a reduction in nutrient availability alters male post-copulatory trait expression, with some studies demonstrating an effect of developmental nutrients and others, an effect of adult nutrients. However, few studies have manipulated both developmental and adult nutrients in the same experiment. Therefore, it is not clear what life-stage has the greatest effect on post-copulatory trait expression, and if the effects of developmental and adult nutrients can interact. Here, we investigate effects of developmental and adult nutrition on male testes and accessory gland size, sperm movement within the female reproductive tract and sperm length in the neriid fly, Telostylinus angusticollis. We found that males fed a nutrient-poor developmental diet produced sperm with a reduced tail beat frequency and had smaller testes and accessory glands compared to males fed a nutrient-rich developmental diet. In contrast, we found no effects of adult nutrition on any traits measured, although sperm length was correlated with body size and male age but unaffected by nutrition at any stage. Therefore, investment in adult post-copulatory traits is determined early on by developmental nutrients in male neriid flies, and this effect is not altered by adult nutrient availability.

Phenotype of a leaf beetle larva depends on host plant quality and previous test experience

Phenotypic expressions of insects are strongly dependent on various external and internal factors, like diet or density and age or sex. However, environmental effects on the behavioural phenotype and repeatability are rather unexplored for holometabolous insects in their larval stage. We examined the effects of the food environment (young versus old cabbage leaves) and previous test experience on growth and behaviour of Phaedon cochleariae larvae. A more nutritious diet, i.e., young leaves, had beneficial consequences on larval growth. Contrary to findings on adults, the behaviour of larvae was neither consistent over time nor across contexts, thus larvae did not show personality. Furthermore, larval behaviour was shaped independent of the diet, pointing to a stage-dependent receptivity towards diet conditions in this species. Besides, larval activity was significantly influenced by former test experience, with naïve larvae being more active than previously tested larvae. In general, in insects memories in an olfactory or sexual behaviour context can lead to behavioural responses later in life. Mechanisms of memory-learning should be further explored in different contexts in insects. Overall, the present study reveals that growth-related traits are diet-dependent and that the activity of a holometabolous larva is shaped in dependence of its previous test experience.

Resource allocation and compensation during development in holometabolous insects

We provide an extensive review on current knowledge and future research paths on the topic of resource allocation and compensation during development in holometabolous insects, emphasizing the role of resource management during development, and how compensatory mechanisms may be acting to remediate nutritional deficiencies carried over from earlier stages of development. We first review resource allocation in "open" and "closed" developmental stages and then move on to the topic of modelling resource allocation and its trade-offs. In doing so, we review novel methodological developments such as response-surface methods and mixture experiments as well as nutritional geometry. We also dwell on the fascinating topic of compensatory physiology and behavior. We finish by discussing future research paths, among them the emerging field of nutrigenomics and gut microbiome, which will shed light into the yet poorly understood role of the symbiotic microbiota in nutrient compensation or assimilation.

Consequences of mating with siblings and nonsiblings on the reproductive success in a leaf beetle

Choosing a suitable mating partner is crucial for the fitness of an individual, whereby mating with siblings often results in inbreeding depression. We studied consequences of mating with siblings versus nonsiblings in the mustard leaf beetle, Phaedon cochleariae (Coleoptera: Chrysomelidae), on lifetime reproductive traits. Furthermore, we analyzed whether cuticular hydrocarbon (CHC) profiles are family specific and could potentially influence the mating behavior of young adults. We hypothesized a reduced reproductive success of females mated with siblings and a more rapid mating of males with nonsiblings. The hatching rate from eggs of sibling pairs was lower compared to that of nonsibling pairs, pointing to inbreeding depression. Furthermore, the number of eggs laid by females decreased over time in both sibling and nonsibling pairs. Interestingly, the CHC profiles and the body mass differed between families. However, the beetles did not avoid siblings and accepted them as readily as nonsiblings for mating in no‐choice tests. In summary, although it had negative consequences to mate a sibling and although siblings could potentially be recognized by their CHC profiles, the beetles did not show a delayed mating with siblings. Our results indicate that P. cochleariae beetles have not developed a precopulatory mechanism to avoid inbreeding, at least under the test conditions applied here. We predict that instead a polyandrous mating system and/or postcopulatory mechanisms might have evolved in this species by which inbreeding costs can be reduced.