Environmental rearrangements by ecosystem engineers influence food‐web characteristics by altering resource accessibility/availability in the newly created habitat. However, the paucity of empirical ...studies on this indirect interaction has hindered the integration of ecosystem engineering and food‐web theory. Here, we investigated the effect of the Canadian beaver Castor canadensis on the activity, realized fecundity and ecosystem functions provided by saproxylic beetles by quantifying beetle emergence holes on woody debris within the Kouchibouguac National Park, New Brunswick, Canada. We tested the hypothesis that perturbation induced by beaver activity enhances the activity and realized fecundity of saproxylic beetles by modifying their habitat and resource accessibility. We used 16 sites identified as beaver modified, each paired with a control site <500 m away. At each site, we quantified insect emergence holes on snags at increasing distances from the watercourse. Our results suggest that engineered habitat patches enhance the activity and reproduction of saproxylic beetle species, small emergence holes from Scolytinae being only observed in abundance on small trees located close to the watercourse and large emergence holes from Cerambycidae being one third more abundant throughout beaver‐modified sites. The complementary relationship between the Canadian beaver and saproxylic beetles demonstrates the potential for conservation measures encapsulating all of these organisms.
Environmental rearrangements by ecosystem engineers can influence food‐web characteristics by altering resource accessibility/availability in the newly created habitat. We tested the hypothesis that perturbation induced by beaver activity enhances the activity and realized fecundity of saproxylic beetles by modifying their habitat and resource accessibility, by quantifying insect emergence holes on snags around beaver‐engineered sites. Results suggest that engineered habitat patches enhance the activity and reproduction of saproxylic beetle species, demonstrating the complementary relationship between the Canadian beaver and saproxylic beetles and the potential for conservation measures encapsulating all of these organisms.
In migratory insects, increasing evidence has demonstrated juvenile hormone (JH) is involved in regulating adult reproduction and flight. Our previous study demonstrated that the switch from migrants ...to residents in Mythimna separata could be induced by adverse environmental conditions during a sensitive period in adulthood (the first day post-emergence), but the role of JH in this switch is not clear. Here, we found a significantly different pattern of JH titers between migrants and residents, with migrants showing a slower release of JH during adulthood than residents. Application of JH analogue (JHA) in the 1-day-old adults, significantly accelerated adult reproduction and suppressed flight capacity. The pre-oviposition period and period of first oviposition of migrants treated with JHA were significantly shorter, while the total lifetime fecundity and mating percentage increased. The flight capacity and dorso-longitudinal muscle size of the migrants were decreased significantly when treated with JHA. The effect of JHA on reproduction and flight capacity indicate that JH titers during the sensitive period (first day post-emergence) regulates the shift from migrants to residents in M. separata.
Summary
Bursaphelenchus xylophilus, the causative agent of pine wilt disease, and B. mucronatus are transmitted by Monochamus adults to host trees. Feeding and oviposition wounds made by vectors are ...the primary transmission pathways to trees. Monochamus saltuarius female adults carrying B. mucronatus were reared singly and allowed to mate with nematode-free males at 5-day intervals, to determine the ratio of nematodes transmitted via the two different pathways. The survival time, lifetime fecundity and other reproductive traits decreased with increasing initial nematode load (number of nematodes carried by a newly-emerged adult). Model selection indicated that numbers of B. mucronatus departing from M. saltuarius and of those transmitted to pine via oviposition and feeding wounds were closely related to the initial nematode load, which was affected by survival time and number of oviposition wounds constructed. Most temporal patterns of nematode departure and transmission via oviposition or feeding wounds from individual vectors had a peak in the medium and heavy initial nematode loads. The nematode departure curve was significantly similar in shape to each of the nematode transmission curves via oviposition and feeding wounds, which were not significantly similar to each other, for individual vectors. After M. saltuarius females began to construct the oviposition wounds, it was estimated that B. mucronatus was transmitted via the oviposition wounds at a probability of 0.767. If B. xylophilus is transmitted in the same way as B. mucronatus, the incidence of pine wilt disease by mature vectors would be much lower than in the case of no oviposition-related transmission.
Pesticide resistance arises rapidly in arthropod herbivores, as can host plant adaptation, and both are significant problems in agriculture. These traits have been challenging to study as both are ...often polygenic and many arthropods are genetically intractable. Here, we examined the genetic architecture of pesticide resistance and host plant adaptation in the two-spotted spider mite,
, a global agricultural pest. We show that the short generation time and high fecundity of
can be readily exploited in experimental evolution designs for high-resolution mapping of quantitative traits. As revealed by selection with spirodiclofen, an acetyl-CoA carboxylase inhibitor, in populations from a cross between a spirodiclofen-resistant and a spirodiclofen-susceptible strain, and which also differed in performance on tomato, we found that a limited number of loci could explain quantitative resistance to this compound. These were resolved to narrow genomic intervals, suggesting specific candidate genes, including
itself, clustered and copy variable cytochrome P450 genes, and
, which encodes a redox partner for cytochrome P450s. For performance on tomato, candidate genomic regions for response to selection were distinct from those responding to the synthetic compound and were consistent with a more polygenic architecture. In accomplishing this work, we exploited the continuous nature of allele frequency changes across experimental populations to resolve the existing fragmented
draft genome to pseudochromosomes. This improved assembly was indispensable for our analyses, as it will be for future research with this model herbivore that is exceptionally amenable to genetic studies.
Abstract
Many organisms display changes in behaviour and life-history traits when facing variabilities in environmental conditions. A subset of these changes comprises reversible within-individual ...variations, known as phenotypic flexibility. Using red squat lobster (Pleuroncodes monodon) individuals harvested at the Humboldt Current Ecosystem (HCE), we evaluated how changes in habitat temperatures associated with warm El Niño (EN) conditions and cold La Niña conditions induce phenotypic flexibility in reproductive traits and how this flexibility affects recruitment success. The biological data were obtained from swept area surveys conducted between 2015 and 2020. Remotely sensed sea surface temperature (SST) data were used to compute anomalies (SSTA). Our results showed that females facing warmer environmental conditions carried more eggs with smaller sizes, and under cold conditions, females carried fewer eggs with larger sizes. The recruitments lagged by 1 year correlated positively with the egg density and negatively with the egg size. Our evidence shows that for phenotypic flexibility to be expressed in recruitment success, the warm conditions experienced by females should match good food availability for the planktonic stages. We discussed how climate change predictions for HCE will amplify responses of the reproductive traits of red squat lobster with strong impacts on recruitment likely.
Gravid (i.e., with fully developed eggs), mated
females typically lay their eggs directly on water ∼48-72 h after a blood meal. Unlike some other mosquito species,
eggs cannot be desiccated and ...stored for long durations, and, hence, colonies must be reared continuously. In this protocol, we discuss methods for egg collection, including individual and
oviposition; egg disinfection to avoid the transmission of infectious agents to the next generation; and egg hatching for colony maintenance or experimentation. We also include optional methods for estimating life history traits such as fecundity, fertility, and larval mortality rates from egg counts.
Some corals may become more resistant to bleaching by shuffling their Symbiodiniaceae communities toward thermally tolerant species, and manipulations to boost the abundance of these symbionts in ...corals may increase resilience in warming oceans. However, the thermotolerant symbiont Durusdinium trenchii may reduce growth and fecundity in Caribbean corals, and these tradeoffs need to be better understood as this symbiont spreads through the region. We sought to understand how D. trenchii modulates coral gene expression by manipulating symbiont communities in Montastraea cavernosa to produce replicate ramets containing D. trenchii together with paired ramets of these same genets (n = 3) containing Cladocopium C3 symbionts. We then examined differences in global gene expression between corals hosting Durusdinium and Cladocopium under control temperatures, and in response to short‐term heat stress. We identified numerous transcriptional differences associated with symbiont identity, which explained 2%–14% of the transcriptional variance. Corals with D. trenchii upregulated genes related to translation, ribosomal structure and biogenesis, and downregulated genes related to extracellular structures, and carbohydrate and lipid transport and metabolism, relative to corals with Cladocopium. Unexpectedly, these changes were similar to those observed in Cladocopium‐dominated corals in response to heat stress, suggesting that thermotolerant D. trenchii may cause corals to increase expression of heat stress‐responsive genes, explaining both the increased heat tolerance and the associated energetic tradeoffs in corals containing D. trenchii. These findings provide insight into the ecological changes occurring on contemporary coral reefs in response to climate change, and the diverse ways in which different symbionts modulate emergent phenotypes of their hosts.
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