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We studied the potential of a recently introduced species, the Asian brush-clawed crab ( Hemigrapsus takanoi ), to expand its distribution range further into the Baltic Sea. H. takanoi has been documented in the southwestern Baltic Sea since 2014. The ability to persist and further expand into the Baltic Proper will depend on their potential to sustain all stages of their complex life cycle, including pelagic larvae, under the Baltic Sea's conditions. Range limits may be established by the tolerance to low salinity, which in addition may be affected by water temperature. A key question is whether local populations at the distribution limit (within the Baltic Sea) show increased tolerance to low salinities and hence promote further expansion. We quantified the combined effects of salinity (10–33 PSU) and temperature (15–24 °C) on larval development in four populations of H. takanoi (two from the Baltic and two from the North Sea). We found substantial differences in larval performance between the populations from the Baltic and North Seas. Larvae from the North Sea populations always showed higher survival and faster development compared with those from the Baltic Sea. Only weak evidence of elevated tolerance towards low salinity was found in the larvae from the Baltic Sea populations. In addition, larvae from the population located near the range limit showed very low survival under all tested salinity-temperature combinations and no evidence of increased tolerance to low salinity. There was no apparent genetic differentiation among the studied populations in the mitochondrial cytochrome c oxidase subunit one gene (COI) implying high connectivity among the populations. In conclusion, the weak evidence of low salinity tolerance in Baltic Sea populations, and poor larval performance for the population located near the range limit, coupled with limited genetic differentiation suggest that subsidies are needed for populations to persist near the range limit. Alternatively, ontogenetic migrations would be required to sustain those populations. Monitoring efforts are needed to elucidate the underlaying mechanisms and document potential future range expansions.

Hermetia illucens is an efficient bioconverter able to grow on various different organic materials, producing larvae, which are a good source of protein and fat with applications in the animal feed and biochemical industries. This fly’s capacity to reduce huge amounts of waste presents an interesting opportunity to establish a circular food economy. In this study, we assessed the suitability of using organic wastes from cricket and locust farming to rear H. illucens. Larvae developed until adult emergence on all the wastes, with a mean survival of over 94%. Cricket waste allowed faster development of heavier larvae than locust waste. Substrate reduction was particularly interesting on cricket waste (<72%), while locust waste was only reduced by 33%. The nutritional composition of the larvae reflected that of the growing substrates with a high protein and fat content. These results demonstrate the potential of using H. illucens to reduce and valorise waste generated when farming various insects through the production of a larval biomass for use as a protein meal in animal feeds or industrial applications.

Induced defense in trees refers to the increased production of specific substances in response to herbivore attacks, which negatively affects the herbivore. This type of resistance can contribute to the sustainable management of herbivorous insect problems in forest ecosystems. The Aleppo pine, a drought-resistant forest tree species, holds great ecological and socioeconomic importance. One of its predators is the Pine Processionary Moth (PPM) Thaumetopoea pityocampa. This study explores the impact of new foliage that emerges following severe defoliation caused by the PPM on the subsequent year’s larval performance. Moreover, we investigate whether there is a difference in the chemical composition of the foliage of defoliated and undefoliated trees in terms of terpenes (monoterpenes, sesquiterpenes, and diterpenes), total phenols, nitrogen (N), carbon (C), and the C/N ratio. The aim is to determine whether these components act as an induced defense mechanism. The results indicate that the performance of L1 larvae was negatively affected by new foliage after defoliation. Larvae feeding on new foliage experienced high mortality rates and were significantly shorter than those that fed on the foliage of undefoliated trees. The chemical composition analysis revealed that only the new foliage after defoliation contained bornyl acetate (monoterpene), and the concentration of p-cymene (another monoterpene) was higher in this new foliage compared to that of undefoliated trees. Furthermore, two diterpenes, methyl dehydroabietate and dehydroabietal, showed a stronger correlation with defoliation. These compounds have demonstrated insecticidal activity against other insects and could potentially serve as starting components for a bio-insecticide against the PPM. These findings suggest the presence of an induced defense in Aleppo pine, as the tree produces foliage containing specific terpenes that are unfavorable to larvae. This is one of the factors contributing to the reduction of the PPM population. However, due to the current climate change situation, further research is necessary to better understand how these conditions impact the susceptibility of trees to defoliation.

The preference-performance hypothesis suggests that female insects prefer to oviposit on the host plant that provides the highest fitness for offspring. However, introduced plants can cause ecological traps, wherein animals lay eggs on low quality (often introduced) species instead of higher quality (usually native) species. Pürerehua kahukura | New Zealand red admiral butterfly (Vanessa gonerilla gonerilla) lay eggs on native and introduced nettles (Urtica spp.). We tested both host preference for female oviposition and host performance for development of larvae. To test preference, we used oviposition cages in which we provided adult kahukura with native Urtica ferox, native/introduced U. australis hybrid, and introduced U. urens. To test performance, we collected the eggs and, after hatching, provided them with one of the three nettles for their development to adulthood. Kahukura only laid on U. ferox (п = 8) and U. australis hybrid (п = 2). No butterflies laid eggs on more than one Urtica species, even though some individuals laid >10 eggs while in the oviposition cages. Pupal weights were significantly higher for larvae reared on U. ferox compared to those reared on U. australis hybrid and U. urens. Although larvae were significantly heavier when fed U. ferox, larvae raised on U. australis hybrid had higher probability of survival to adulthood and faster development rates. Kahukura oviposition preference ranking (U. ferox > U. australis > U. urens) qualitatively matched larval development ranking (U. ferox > U. australis = U. urens), supporting the preference-performance hypothesis for this population. If kahukura have the option to oviposit on native Urtica spp., our results suggest that they are unlikely to be duped into ovipositing on a lower quality host plant. While U. urens may act as a trap in some areas, kahukura may be able to escape that fate if native plant species are made more readily available.

In marine ecosystems, crustaceans face an alarming threat from the increasing frequency and intensity of marine heatwaves as their early planktonic stages are particularly temperature sensitive. While the impact of heatwaves on adult crustaceans is well-studied, their effects on larvae remain underexplored. This study focuses on heatwave effects on larvae of the European shore crab, Carcinus maenas . Through a factorial experiment, larvae were exposed to different heatwaves of varying onset timings, durations, and intensities. Survival, development duration, and dry mass decreased under intense heatwaves, with more severe effects observed when heatwaves occurred later in development, highlighting a stage-specific sensitivity to heatwave. We also identified a “region of existence” beyond which larval performance was compromised compared to baseline temperatures. This region defines the heatwave components considered “extreme” for the organism, as well as those inducing neutral or positive effects on performance. Additionally, we distinguished heatwave effects (characterised by their components) from those attributed to the average temperature experienced during the experiments. Our findings demonstrated that larval performance was lower during intense heatwaves compared to the performance expected under a constant average temperature. These findings emphasize the importance of considering heatwave timing relative to the life cycle for predicting marine population responses to climate change.

Current understanding of species capacities to respond to climate change is limited by the amount of information available about intraspecific variation in the responses. Therefore, we quantified between- and within- population variation in larval performance (survival, development, and growth to metamorphosis) of the shore crab Carcinus maenas in response to key environmental drivers (temperature, salinity) in 2 populations from regions with contrasting salinities (32–33 PSU: Helgoland, North Sea; 16–20 PSU: Kerteminde, Baltic Sea). We also accounted for the effect(s) of salinity experienced during embryogenesis, which differs between populations. We found contrasting patterns between populations and embryonic salinity conditions. In the Helgoland population, we observed a strong thermal mitigation of low salinity stress (TMLS) for all performance indicators, when embryos were kept in seawater. The negative effects of low salinity on survival were mitigated at increased temperatures; only at high temperatures were larvae exposed to low salinity able to sustain high growth rates and reduced developmental time, thereby metamorphosing with comparable levels of carbon and nitrogen to those reared in seawater. By contrast, larvae from the Kerteminde population showed a detrimental effect of low salinity, consistent with a maladaptive response and a weak TMLS. Low salinity experienced during embryogenesis pre-empted the development of TMLS in both populations, and reduced survival for the Kerteminde population, which is exposed to low salinity. Our study emphasises the importance of evaluating species responses to variation in temperature and salinity across populations; the existence of maladaptive responses and the importance of the maternal habitat should not be underestimated.

Economic losses from insect herbivory in agroecosystems has driven the development of integrated pest management strategies that reduce pest incidence and damage; however, traditional chemicals-based control is either being complemented or substituted with sustainable and integrated methods. Major sustainable pest management strategies revolve around improving host plant resistance, and one of these traits of interest is Brown midrib (BMR). Originally developed to increase nutritional value and ease of digestion for animal agriculture, BMR is a recessive plant gene usually found in annual grasses, including sorghum and sorghum-sudangrass hybrids. In sorghum-sudangrass, BMR expressed plants have lower amounts of lignin, which produces a less fibrous, more digestible crop, with possible implications for plant defense against herbivores- an area currently unexplored. Fall Armyworm (FAW; Spodoptera frugiperda ) is a ruinous pest posing immense threat for sorghum producers by severely defoliating crops and being present in every plant stage. Using FAW, we tested the effect of seed treatment, BMR, and plant age on FAW growth, development, and plant defense responses in sorghum-sudangrass. Our results show that seed treatment did not affect growth or development, or herbivory. However, presence of BMR significantly reduced pupal mass relative to its non-BMR counterpart, alongside a significant reduction in adult mass. We also found that plant age was a major factor as FAW gained significantly less mass, had longer pupation times, and had lower pupal mass on the oldest plant stage explored, 60-days, compared to younger plants. These findings collectively show that pest management strategies should consider plant age, and that the effects of BMR on plant defenses should also be studied.

Flowering plants use volatiles to attract pollinators while deterring herbivores. Vegetative and floral traits may interact to affect insect behavior. Pollinator behavior is most likely influenced by leaf traits when larval stages interact with plants in different ways than adult stages, such as when larvae are leaf herbivores but adult moths visit flowers as pollinators. Here, we determine how leaf induction and corresponding volatile differences in induced plants influence behavior in adult moths and whether these preferences align with larval performance. We manipulated vegetative induction in four Nicotiana species. Using paired induced and control plants of the same species with standardized artificial flowers, we measured foraging and oviposition choices by their ecologically and economically important herbivore/pollinator, Manduca sexta . In parallel, we measured growth rates of M. sexta larvae fed leaves from control or induced plants to determine if this was consistent with female oviposition preference. Lastly, we used plant headspace collections and gas chromatography to quantify volatile compounds from both induced and control leaves to link changes in plant chemistry with moth behavior. In the absence of floral chemical cues, vegetative defensive status influenced adult moth foraging preference from artificial flowers in one species ( N. excelsior ), where females nectared from induced plants more often than control plants. Plant vegetative resistance consistently influenced oviposition choice such that moths deposited more eggs on control plants than on induced plants of all four species. This oviposition preference for control plants aligned with higher larval growth rates on control leaves compared with induced leaves. Control and induced plants of each species had similar leaf volatile profiles, but induced plants had higher emission levels. Leaves of N. excelsior produced the most volatile compounds, including some inducible compounds typically associated with floral scent. We demonstrate that vegetative plant defensive volatiles play a role in host plant selection and that insects assess information from leaves differently when choosing between nectaring and oviposition locations. These results underscore the complex interactions between plants, their pollinators, and herbivores.

Abstract The potential of enriched live feeds, such as Artemia nauplii, to enhance the growth performance of Thai mahseer (Tor tambroides) larvae during the larviculture phase is not yet fully understood. This study evaluated the effects of Artemia enriched with squid oil (FSO) and Pangasius catfish oil (FCO) emulsions- on proximate and fatty acid composition of Artemia salina nauplii and larval, larval survival, growth, and tolerance to air exposure stress. Six enrichment treatments with varying FSO and FCO proportions were prepared: P0 (control), P1, P2, P3, P4, and P5. Feeding trials were conducted for 21 days using standardized larval densities, and fatty acid profiles were analyzed via gas chromatography. Results showed that Artemia salina nauplii enriched with P2 had the highest eicosapentaenoic acid (EPA, C20:5n-3), P1 had the highest docosahexaenoic acid (DHA, C22:6n-3), and P5 contained the highest oleic acid (C18:1n-9) and linoleic acid (C18:2n-6). Among all treatments, P1 enrichment most effectively improved larval survival, growth, and stress tolerance. Larvae fed P1 Artemia salina nauplii also exhibited higher DHA and highly unsaturated fatty acids (HUFA) levels compared to other treatments. Under these experimental conditions, P1 produced a DHA to EPA ratio of 2.89 in Artemia salina nauplii, making it the most suitable option for early feeding of Thai mahseer larvae. Resumo O potencial de alimentos vivos enriquecidos, como náuplios de Artemia, para melhorar o desempenho de crescimento das larvas de mahseer tailandês (Tor tambroides) durante a fase de larvicultura ainda não é totalmente compreendido. Este estudo avaliou os efeitos dos náuplios de Artemia salina enriquecidos com emulsões de óleo de lula (FSO) e óleo de bagre Pangasius (FCO) sobre a composição de proximate e ácidos graxos dos náuplios de Artemia salina e das larvas, bem como sobre a sobrevivência, o crescimento e a tolerância ao estresse por exposição ao ar. Foram preparadas seis formulações de enriquecimento com proporções variadas de FSO e FCO: P0 (controle), P1, P2, P3, P4 e P5. Ensaios de alimentação foram conduzidos por 21 dias utilizando densidades larvais padronizadas, e os perfis de ácidos graxos foram analisados por cromatografia gasosa. Os resultados mostraram que os náuplios de Artemia salina enriquecidos com P2 apresentaram o maior teor de ácido eicosapentaenoico (EPA, C20:5n-3); com a formulação P1, apresentaram o maior teor de ácido docosahexaenoico (DHA, C22:6n-3), e na P5, continham os maiores teores de ácido oleico (C18:1n-9) e ácido linoleico (C18:2n-6). Entre todos os tratamentos, o enriquecimento P1 foi o mais eficaz para melhorar a sobrevivência das larvas, o seu crescimento e a sua tolerância ao estresse. Larvas alimentadas com náuplios de Artemia salina P1 também apresentaram níveis mais elevados de DHA e ácidos graxos altamente insaturados (HUFA) em comparação com os outros tratamentos. Nestas condições experimentais, a proporção P1 produziu uma razão DHA/EPA de 2,89 nos náuplios de Artemia salina, tornando-a a opção mais adequada para a alimentação inicial das larvas de mahseer tailandês.

Species’ responses to climate change may vary considerably among populations. Various response patterns define the portfolio available for a species to cope with and mitigate effects of climate change. Here, we quantified variation in larval survival and physiological rates of Carcinus maenas among populations occurring in distant or contrasting habitats (Cádiz: Spain, Helgoland: North Sea, Kerteminde: Baltic Sea). During the reproductive season, we reared larvae of these populations, in the laboratory, under a combination of several temperatures (15–24 °C) and salinities (25 and 32.5 PSU). In survival, all three populations showed a mitigating effect of high temperatures at lower salinity, with the strongest pattern for Helgoland. However, Cádiz and Kerteminde differed from Helgoland in that a strong thermal mitigation did not occur for growth and developmental rates. For all populations, oxygen consumption rates were driven only by temperature; hence, these could not explain the growth rate depression found at lower salinity. Larvae from Cádiz, reared in seawater, showed increased survival at the highest temperature, which differs from Helgoland (no clear survival pattern), and especially Kerteminde (decreased survival at high temperature). These responses from the Cádiz population correspond with the larval and parental habitat (i.e., high salinity and temperature) and may reflect local adaptation. Overall, along the European coast, C. maenas larvae showed a diversity of responses, which may enable specific populations to tolerate warming and subsidise more vulnerable populations. In such case, C. maenas would be able to cope with climate change through a spatial portfolio effect.