Do parasitoids diversify in response to host‐plant shifts by herbivorous insects?

1. For herbivorous insects, the incorporation of a novel host into the diet, and subsequent formation of distinct host associations (races), is thought to be a significant early step in the speciation process. While many studies have addressed this issue, virtually nothing is known about the evolutionary response of natural enemies to herbivore host‐race formation. 2. The hypothesis that the parasitoid wasp Eurytoma gigantea (Hymenoptera: Eurytomidae) has formed host races in direct response to the host shift and subsequent host‐race formation by its host, the gallmaker Eurosta solidaginis (Diptera: Tephritidae) was tested. Emergence time, mating preference, and female oviposition preference were determined for parasitoids derived from galls of each Eurosta host race. 3. Male and female E. gigantea overlap broadly in their emergence times from each Eurosta host race, suggesting that there is no phenological barrier to gene flow. 4. In choice experiments, female parasitoids did not mate assortatively: females that emerged from one Eurosta host race were equally likely to mate with males from either Eurosta host race. 5. Oviposition behaviour experiments revealed that female parasitoids do not prefer to oviposit on their host race of origin and that there is no overall preference for one host race, even though fitness is higher when parasitoids are reared from Eurosta galls of the Solidago gigantea host race than when reared from Eurosta galls of the Solidago altissima host race. 6. These results suggest that E. gigantea has not diverged in parallel with its host in response to the herbivore host‐plant shift. Further studies are needed before the ubiquity of this diversification mechanism can be evaluated fully.     

Animal board invited review: Risks of zoonotic disease emergence at the interface of wildlife and livestock systems

The ongoing coronavirus disease 19s pandemic has yet again demonstrated the importance of the human-animal interface in the emergence of zoonotic diseases, and in particular the role of wildlife and livestock species as potential hosts and virus reservoirs. As most diseases emerge out of the human-animal interface, a better understanding of the specific drivers and mechanisms involved is crucial to prepare for future disease outbreaks. Interactions between wildlife and livestock systems contribute to the emergence of zoonotic diseases, especially in the face of globalization, habitat fragmentation and destruction and climate change. As several groups of viruses and bacteria are more likely to emerge, we focus on pathogenic viruses of the Bunyavirales, Coronaviridae, Flaviviridae, Orthomyxoviridae, and Paramyxoviridae, as well as bacterial species including Mycobacterium sp., Brucella sp., Bacillus anthracis and Coxiella burnetii. Noteworthy, it was difficult to predict the drivers of disease emergence in the past, even for well-known pathogens. Thus, an improved surveillance in hotspot areas and the availability of fast, effective, and adaptable control measures would definitely contribute to preparedness. We here propose strategies to mitigate the risk of emergence and/or re-emergence of prioritized pathogens to prevent future epidemics.     

不同剂量右美托咪定辅助麻醉对老年结肠癌根治术患者麻醉效果和术后谵妄的影响及谵妄的相关因素分析

摘要 目的：探讨不同剂量右美托咪定辅助麻醉对老年结肠癌根治术患者麻醉效果,并分析术后谵妄的影响因素。方法：选取2019年4月~2021年1月期间我院收治的160例老年结肠癌根治术患者,根据随机数字表法将患者分为A组（53例）、B组（53例）和C组（54例）。A组和B组均于麻醉诱导前给予0.5 μg/kg右美托咪定,以0.2 μg/kg?h速率静脉输注至手术结束前30 min,A组术后镇痛时再给予右美托咪定0.05 μg/kg?h。C组给予等容量和等速率的生理盐水。观察三组的应激反应、麻醉效果、不良反应发生率、谵妄发生率。根据是否发生谵妄分为谵妄组（n=28）和无谵妄组（n=132）。采用Logistic回归分析术后谵妄的影响因素。结果：三组术后第3 d C反应蛋白（CRP）、白介素-6（IL-6）、多巴胺、肾上腺素均较手术结束升高（P<0.05）。A组、B组术后第3 d CRP、IL-6、多巴胺、肾上腺素低于C组（P<0.05）。A组、B组术后第3dCRP、IL-6、多巴胺、肾上腺素组间对比,无明显差异（P>0.05）。A组、B组、C组的不良反应总发生率组间的对比无明显差异（P>0.05）。B组的谵妄发生率明显低于A组、C组（P<0.05）。A组、C组谵妄发生率组间对比无明显差异（P>0.05）。单因素分析结果显示,术后谵妄的发生与年龄、术前抑郁、术前合并基础疾病数量、术中低氧血症、气腹后PaCO₂、白蛋白有关（P<0.05）。多因素Logistic回归分析结果显示：术前抑郁、年龄≥70岁、术前合并基础疾病数量≥3、术中低氧血症、气腹后PaCO₂偏高、白蛋白偏低是导致老年结肠癌根治术患者术后谵妄的危险因素（P<0.05）。结论：小剂量右美托咪定辅助麻醉可提高老年结肠癌根治术患者的麻醉效果,减少谵妄的发生率,同时术前抑郁、年龄≥70岁、术前合并基础疾病数量≥3、术中低氧血症、气腹后PaCO₂偏高、白蛋白偏低是引起谵妄发生的危险因素。     

Evolving learning rules and emergence of cooperation in spatial prisoner's dilemma

In the evolutionary Prisoner's dilemma (PD) game, agents play with each other and update their strategies in every generation according to some microscopic dynamical rule. In its spatial version, agents do not play with every other but, instead, interact only with their neighbours, thus mimicking the existing of a social or contact network that defines who interacts with whom. In this work, we explore evolutionary, spatial PD systems consisting of two types of agents, each with a certain update (reproduction, learning) rule. We investigate two different scenarios: in the first case, update rules remain fixed for the entire evolution of the system; in the second case, agents update both strategy and update rule in every generation. We show that in a well-mixed population the evolutionary outcome is always full defection. We subsequently focus on two-strategy competition with nearest-neighbour interactions on the contact network and synchronised update of strategies. Our results show that, for an important range of the parameters of the game, the final state of the system is largely different from that arising from the usual setup of a single, fixed dynamical rule. Furthermore, the results are also very different if update rules are fixed or evolve with the strategies. In these respect, we have studied representative update rules, finding that some of them may become extinct while others prevail. We describe the new and rich variety of final outcomes that arise from this co-evolutionary dynamics. We include examples of other neighbourhoods and asynchronous updating that confirm the robustness of our conclusions. Our results pave the way to an evolutionary rationale for modelling social interactions through game theory with a preferred set of update rules.     

Viewing brain processes as Critical State Transitions across levels of organization: Neural events in Cognition and Consciousness,and general principles

In this theoretical and speculative essay, I propose that insights into certain aspects of neural system functions can be gained from viewing brain function in terms of the branch of Statistical Mechanics currently referred to as “Modern Critical Theory” [Stanley, H.E., 1987. Introduction to Phase Transitions and Critical Phenomena. Oxford University Press; Marro, J., Dickman, R., 1999. Nonequilibrium Phase Transitions in Lattice Models. Cambridge University Press, Cambridge, UK]. The application of this framework is here explored in two stages: in the first place, its principles are applied to state transitions in global brain dynamics, with benchmarks of Cognitive Neuroscience providing the relevant empirical reference points. The second stage generalizes to suggest in more detail how the same principles could also apply to the relation between other levels of the structural-functional hierarchy of the nervous system and between neural assemblies. In this view, state transitions resulting from the processing at one level are the input to the next, in the image of a ‘bucket brigade’, with the content of each bucket being passed on along the chain, after having undergone a state transition. The unique features of a process of this kind will be discussed and illustrated.     

The Poetics of Purpose

Hackles have been raised in biosemiotic circles by T. L. Short’s assertion that semiosis, as defined by Peirce, entails “acting for purposes” and therefore is not found below the level of the organism (2007a:174–177). This paper examines Short’s teleology and theory of purposeful behavior and offers a remedy to the disagreement. Remediation becomes possible when the issue is reframed in the terms of the complexity sciences, which allows intentionality to be understood as the interplay between local and global aspects of a system within a system. What is called “acting for purposes” is not itself a type of behavior so much as a relationship between a dynamic system that “exists for a purpose” and its microprocesses that “serve purposes.” The “intentional object” of philosophy is recast here as the holistic self-organized dynamics of a system, which exists for the purpose of self-maintenance, and that constrains the parts’ behaviors, which serve the purpose of forming the system. (A “system” can be any emergent, e.g. an abiotic form, an adapted species, a self, a conditioned response, thought, or a set of ideas.) The self-organized whole, which is represented to the parts in their own constrained behaviors, assumes the guiding function so long attributed to the mysterious “intentional object.” If emergent self-causation is not disallowed, creative originality, as well as directionality, becomes part of the definition of purposeful behavior. Thus, key tools used here, required for understanding emergence, come from poetics rather than semoitics. In the microprocesses of self-organization, I find what I call “accidental” indices and icons — which are poetic in the sense that they involve mere metonymic contiguity and metaphoric similarity — and which are preferentially selected under constrained conditions allowing radically new connections to habituate into an “intentional” self-organized system that, not coincidentally, has some of the emergent characteristics of a conventional symbolic system.

Inhibition of the larval ecdysis and emergence behavior of the parasitoid Cotesia congregata by methoprene

Parasitism of the tobacco hornworm, Manducasexta, by the braconid wasp Cotesiacongregata, induces developmental arrest of the host in the larval stage. During the final instar of the host, its juvenile hormone (JH) titer is elevated, preventing host metamorphosis. This study investigated the effects of hormonal manipulation of the host on the parasitoid’s emergence behavior. The second larval ecdysis of the wasps coincides with their emergence from the host, and application of the juvenile hormone analogue methoprene to day 4 fifth instar hosts either delayed or totally suppressed the subsequent emergence of the wasps. Effects of methoprene were dose-dependent and no parasitoids emerged following treatment of host larvae with doses >50 μg. Parasitoids which failed to emerge eventually succumbed as unecydsed pharate third instar larvae in the hemocoel of the host. Effects of host methoprene treatment on parasitoid metamorphosis were also assessed, and metamorphic disruption occurred at much lower dosages compared with doses necessary to suppress parasitoid emergence behavior. The inhibitory effect of methoprene on parasitoid emergence behavior appears to be mediated by effects of this hormone on the synthesis or release of ecdysis-triggering hormone (ETH) in the parasitoid, the proximate endocrine cue which triggers ecdysis behavior in free-living insects. ETH accumulated in the epitracheal Inka cells of parasitoids developing in methoprene-treated hosts, suggestive of a lack of hormone release. Thus, the hormonal modulation of parasitoid emergence behavior appears to be complex, involving a suite of hormones including JH, ecdysteroid, and peptide hormones.     

Strategies of emergence in the chestnut weevil Curculio elephas (Coleoptera: Curculionidae)

In the chestnut weevil Curculio elephas, adult emergences spread over 3 or 4 years due to prolonged larval diapause in some individuals. Weevils with an extended diapause emerge, on the average, 1–10 days before those with simple diapause, but whatever the age of insects, emergences occur always from mid-August to early October. When the summer is dry, some adults cannot emerge because of the hardness of the soil. Emergence sucess of adults is smaller in females than in males. The result is that the sex ratio is female-biased before emergence and male-biased after. Summer drought cannot be predicted by the chestnut weevil, and when the soil is dry 27–78% of females cannot emerge and do not reproduce. The year after a summer drought, many reproducing females may emerge from larvae with prolonged diapause. These results suggest an evolutionary influence on the variability in diapause duration. Computer simulations and observations do not support the hypothesis that the main cause of variation in diapause length is the existence of several distinct genotypes within populations. On the contrary, our data strengthen the hypothesis for coin-flipping plasticity discussed in a previous paper.     

An atypical brook charr (Salvelinus fontinalis) spawning area

Synopsis Brook charr (Salvelinus fontinalis) spawned successfully on a 0.3 m thick aggregation of waterlogged sticks, woodchips and debris overlying the soft ooze bottom of a small Precambrian Shield lake. Brook charr were apparently attracted to groundwater seeping up through the aggregation and utilized the tangle of various sized sticks as a spawning substrate. Eggs were deposited in late October and alevins emerged from the area in late March, periods that coincide with the conventional spawning of native brook charr on gravel areas in nearby lakes. Our observations support the contention that upwellin, water is more important than bottom type in stimulating brook charr to select a spawning site.