Floral scents: their roles in nursery pollination mutualisms

Mutualisms are interspecies interactions in which each participant gains net benefits from interacting with its partner. In nursery pollination mutualisms, pollinators reproduce within the inflorescence they pollinate. In these systems, each partner depends directly on the other for its reproduction. Therefore, the signal responsible for partner encounter is crucial in these horizontally transmitted mutualisms, in which the association between specific partners must be renewed at each generation. As in many other interspecies interactions, chemical signals are suspected to be important in the functioning of these mutualisms. We synthesized and compared the published data available on the role of floral scents in the functioning of the 16 known independently evolved nursery pollination mutualisms. So far, attraction of pollinators to their specific hosts has been investigated in only seven of these systems, and the majority of the studies have been conducted on one of them, fig/fig wasp interactions. While such unevenness of the information limits the potential for meta-analysis, some patterns emerge from this review concerning the role of flower volatiles in maintaining the specificity of pollinator attraction, in signaling the appropriate phenological stage for pollinator visit, in attracting the pollinator toward the rewardless sex in dioecious plant species and in aiding the location and exploitation of resources by parasites and predators associated with these mutualisms. Finally, we highlight new perspectives on the evolution of signals in these diversified systems depending on the age and the degree of specificity of the interaction, and on the effect of phylogenetic inertia on the evolutionary dynamics of plant signals.     

Characterizing source-sink dynamics with genetic parentage assignments

Source-sink dynamics have been suggested to characterize the population structure of many species, but the prevalence of source-sink systems in nature is uncertain because of inherent challenges in estimating migration rates among populations. Migration rates are often difficult to estimate directly with demographic methods, and indirect genetic methods are subject to a variety of assumptions that are difficult to meet or to apply to evolutionary timescales. Furthermore, such methods cannot be rigorously applied to high-gene-flow species. Here, we employ genetic parentage assignments in conjunction with demographic simulations to infer the level of immigration into a putative sink population. We use individual-based demographic models to estimate expected distributions of parent-offspring dyads under competing sink and closed-population models. By comparing the actual number of parent-offspring dyads (identified from multilocus genetic profiles) in a random sample of individuals taken from a population to expectations under these two contrasting demographic models, it is possible to estimate the rate of immigration and test hypotheses related to the role of immigration on population processes on an ecological timescale. The difference in the expected number of parent-offspring dyads between the two population models was greatest when immigration into the sink population was high, indicating that unlike traditional population genetic inference models, the highest degree of statistical power is achieved for the approach presented here when migration rates are high. We used the proposed genetic parentage approach to demonstrate that a threatened population of Marbled Murrelets (Braclhyrarmphus marmotus) appears to be supplemented by a low level of immigration (approximately 2-6% annually) from other populations.     

Fragrant legs in Paysandisia archon males (Lepidoptera, Castniidae)

Paysandisia archon was accidentally introduced into Europe where it damages endemic and ornamental palms, also threatening the date palm from North Africa. Little was known about sex pheromones in the Castniidae day-flying moth before a recent paper that concluded on the absence of female sex pheromone in P. archon. A putative identification of a short-range male pheromone, present on fore- and hindwings, was reported. In this paper, we describe the original structure of the male androconia located on the tarsi of the mid-legs. The extracts of mid-legs were analysed by GC/MS and the chemical structure of the male androconia component was identified as E2,Z13-18:OH. After extraction in solvent, biological activity of the extracts was assessed by EAG. The chemistry and the morphology of the androconia reinforce the current classification of the Castniidae in the Cossoid/Sesioid assemblage and provide new information on the chemical ecology in day-flying Lepidoptera and suit the recent paper describing the courtship behaviour     

Unexpected effects of sublethal doses of insecticide on the peripheral olfactory response and sexual behavior in a pest insect

Pesticides have long been used as the main solution to limit agricultural pests, but their widespread use resulted in chronic or diffuse environmental pollutions, development of insect resistances, and biodiversity reduction. The effects of low residual doses of these chemical products on organisms that affect both targeted species (crop pests) but also beneficial insects became a major concern, particularly because low doses of pesticides can induce unexpected positive—also called hormetic—effects on insects, leading to surges in pest population growth at greater rate than what would have been observed without pesticide application. The present study aimed to examine the effects of sublethal doses of deltamethrin, one of the most used synthetic pyrethroids, known to present a residual activity and persistence in the environment, on the peripheral olfactory system and sexual behavior of a major pest insect, the cotton leafworm Spodoptera littoralis. We highlighted here a hormetic effect of sublethal dose of deltamethrin on the male responses to sex pheromone, without any modification of their response to host-plant odorants. We also identified several antennal actors potentially involved in this hormetic effect and in the antennal detoxification or antennal stress response of/to deltamethrin exposure.     

Atrazine biodegradation modulated by clays and clay/humic acid complexes

The fate of pesticides in the environment is strongly related to the soil sorption processes that control not only their transfer but also their bioavailability. Cationic (Ca-bentonite) and anionic (Layered Double Hydroxide) clays behave towards the ionisable pesticide atrazine (AT) sorption with opposite tendencies: a noticeable sorption capacity for the first whereas the highly hydrophilic LDH showed no interactions with AT. These clays were modified with different humic acid (HA) contents. HA sorbed on the clay surface and increased AT interactions. The sorption effect on AT biodegradation and on its metabolite formation was studied with Pseudomonas sp. ADP. The biodegradation rate was greatly modulated by the material's sorption capacity and was clearly limited by the desorption rate. More surprisingly, it increased dramatically with LDH. Adsorption of bacterial cells on clay particles facilitates the degradation of non-sorbed chemical, and should be considered for predicting pesticide fate in the environment.     

Bioaccumulation and public health implications of trace metals in edible tissues of the crustaceans <Emphasis Type="Italic">Scylla serrata</Emphasis> and <Emphasis Type="Italic">Penaeus monodon</Emphasis> from the Tanzanian coast

The coastal population in East Africa is growing rapidly but sewage treatment and recycling facilities in major cities and towns are poorly developed. Since estuarine mangroves are the main hotspots for pollutants, there is a potential for contaminants to accumulate in edible fauna and threaten public health. This study analysed trace metals in muscle tissues of the giant mud crabs (Scylla serrata) and the giant tiger prawns (Penaeus monodon) from the Tanzanian coast, in order to determine the extent of bioaccumulation and public health risks. A total of 180 samples of muscle tissues of S. serrata and 80 of P. monodon were collected from nine sites along the coast. Both species showed high levels of trace metals in the wet season and significant bioaccumulation of As, Cu and Zn. Due to their burrowing and feeding habits, mud crabs were more contaminated compared to tiger prawns sampled from the same sites. Apart from that, the measured levels of Cd, Cr and Pb did not exceed maximum limits for human consumption. Based on the current trend of fish consumption in Tanzania (7.7 kg/person/year), the measured elements (As, Cd, Co, Cu, Mn, Pb and Zn) are not likely to present health risks to shellfish consumers. Nevertheless, potential risks of As and Cu cannot be ruled out if the average per capita consumption is exceeded. This calls for strengthened waste management systems and pollution control measures.     

Cost shifting and other perverse incentives in biodiversity offsetting in India

Biodiversity offsetting aims to compensate for development‐induced biodiversity loss through commensurate conservation gains and is gaining traction among governments and businesses. However, cost shifting (i.e., diversion of offset funds to other conservation programs) and other perverse incentives can undermine the effectiveness of biodiversity offsetting. Additionality—the requirement that biodiversity offsets result in conservation outcomes that would not have been achieved otherwise—is fundamental to biodiversity offsetting. Cost shifting and violation of additionality can go hand in hand. India's national offsetting program is a case in point. Recent legislation allows the diversion of offset funds to meet the country's preexisting commitments under the United Nations Framework Convention on Climate Change (UNFCCC) and United Nations Convention on Biological Diversity (CBD). With such diversions, no additional conservation takes place and development impacts remain uncompensated. Temporary additionality cannot be conceded in light of paucity of funds for preexisting commitments unless there is open acknowledgement that fulfillment of such commitments is contingent on offset funds. Two other examples of perverse incentives related to offsetting in India are the touting of inherently neutral offsetting outcomes as conservation gains, a tactic that breeds false complacency and results in reduced incentive for additional conservation efforts, and the clearing of native vegetation for commercial plantations in the name of compensatory afforestation, a practice that leads to biodiversity decline. The risks accompanying cost shifting and other perverse incentives, if not preempted and addressed, will result in net loss of forest cover in India. We recommend accurate baselines, transparent accounting, and open reporting of offset outcomes to ensure biodiversity offsetting achieves adequate and additional compensation for impacts of development.     

Quantifying the connections—linkages between land-use and water in the Kathmandu Valley,Nepal

Land development without thoughtful water supply planning can lead to unsustainability. In practice, management of our lands and waters is often unintegrated. We present new land-use, ecological stream health, water quality, and streamflow data from nine perennial watersheds in the Kathmandu Valley, Nepal, in the 2016 monsoon (i.e., August and September) and 2017 pre-monsoon (i.e., April and May) periods. Our goal was to improve understanding of the longitudinal linkages between land-use and water. At a total of 38 locations, the Rapid Stream Assessment (RSA) protocol was used to characterize stream ecology, basic water quality parameters were collected with a handheld WTW multi-parameter meter, and stream flow was measured with a SonTek FlowTracker Acoustic Doppler Velocimeter. A pixel-based supervised classification method was used to create a 30-m gridded land use coverage from a Landsat 8 image scene captured in the fall of 2015. Our results indicated that land-use had a statistically significant impact on water quality, with built land-uses (high and low) having the greatest influence. Upstream locations of six of the nine watersheds investigated had near natural status (i.e., river quality class (RQC) 1) and water could be used for all purposes (after standard treatments as required). However, downstream RSA measurements for all nine watersheds had RQC 5 (i.e., most highly impaired). Generally, water quality deteriorated from monsoon 2016 to pre-monsoon 2017. Our findings reinforce the importance of integrated land and water management and highlight the urgency of addressing waste management issues in the Kathmandu Valley.     

Understanding and actioning BRE environmental assessment method: a socio-technical approach

The following research applies a socio-technical approach to an original study of the role of BRE environmental assessment method (BREEAM) in sustainable building practice. The primary objective is to gain insight into what facilitates and what weakens professional associations to implement a sustainability agenda in a building project. It focuses on understanding different sets of meaning which underlie engagement with BREEAM and how BREEAM is actioned. To do this, the research framework draws on social network analysis. However, this research does not consider that sustainable building is merely an outcome of planned action. Instead, sustainable building is seen to involve processes of engagement amongst different groups, technologies, materials and methods. Therefore, the conceptual framework adopted incorporates consideration of the materiality of sustainable building engagements, highlighting the relations between actors. Interviews with project professionals involved in a case study of a BREEAM Outstanding development provide the empirical basis for this work. This research will be of interest to scholars interested in socio-technical approaches to building development, environmental building assessment methods and sustainable building.