Pollinator-attracting semiochemicals of the wasp-flower Epipactis helleborine

The orchid genus Epipactis is represented by 25 species in Europe (Richards 1982). Epipactis helleborine (L.) Crantz is the most common and widely distributed species of the genus (Wiefelspütz 1970), and is a prime example for wasp-flowers, because it is mainly pollinated by social wasps (Hymenoptera: Vespidae), like Vespula vulgaris and V. germanica (Müller 1873). Darwin (1888) already noticed that E. helleborine is almost exclusively ignored by bees and bumblebees, an observation that was confirmed in recent investigations (Keppert 2001). The flowers of E. helleborine show morphological, physiological and phenological adaptations to the visit and the pollination by Vespidae (Keppert 2001). They possess a reddish-brown or dirty purple coloration of the inflorescence (Keppert 2001), have relatively small, mostly bulbous blossoms with a broad entrance and bulbous widened, nectar-rich juice holders (Müller 1873, 1881; Schremmer 1962). Although there is much reported about wasp-pollinated flowers there is little known about the signals that are responsible for the attraction of wasps. Wiefelspütz (1970) proclaimed the statement that only the visual stimulus is responsible for the wasp attraction. Recently studies, however, assumed that odour is involved in the wasp attraction (Keppert 2001). Hölzler (2003) showed that the main attraction of the wasp-flower Epipactis for pollinators is its olfactory stimulus. It remains an unanswered question why E. helleborine flowers almost exclusively attracts social wasps, as opposed to bees and bumblebees. In this study we analysed the role of floral volatiles which are responsible for the specific attraction of social wasps. We supposed a mimicry-system in E. helleborine for the specific attraction of pollinators for the following reasons. So-called “green leaf volatiles” (GLVs) are emitted by plants while herbivorous insects, for example caterpillars, feed on them. GLVs thereby attract predators or parasitoids of the herbivorous insects (Dicke & Sabelis 1988; Turlings & al. 1990, 1995; Dicke & Vet 1999). Among the GLVs so far identified in former studies there are aldehydes, compounds that were also found in flower extracts of E. helleborine (Hölzler 2003). Therefore, we postulated that E. helleborine flowers produce GLVs in order to attract prey hunting social wasps for pollination. We performed bioassays and analysed flower odour gained to headspace-sampling using gas chromatography (GC), mass spectrometry (GC-MS) and gas chromatography coupled with electrophysiological analysis (GC-EAD) to investigate the hypothesis that E. helleborine flowers mimic “green leaf volatiles” (GLVs) to attract their pollinators.Die Orchideenart Epipactis helleborine gilt als typische Wespenblume. Die Blüten weisen Anpassungen an den Besuch und die Bestäubung durch soziale Faltenwespen (Hymenoptera: Vespidae) auf und werden häufig durch Vespula vulgaris und V. germanica bestäubt. In früheren Untersuchungen konnte gezeigt werden, dass olfaktorische Reize bei der Bestäuberanlockung eine übergeordnete Bedeutung vor optischen Reizen haben (Hölzler 2003). Die Frage, warum E. helleborine fast ausschließlich ihren optimalen Bestäuber, die soziale Faltenwespe, zur Bestäubung anlockt, und nicht auch auf andere Blütenbesucher attraktiv wirkt, ist noch unbeantwortet. Wir untersuchten die Hypothese, dass E. helleborine Blüten GLVs, die von Herbivoren befallenen Pflanzen abgegeben werden, nachahmen, um Beute jagende Wespen zur Bestäubung anzulocken. Dazu sammelten und analysierten wir Duftstoffe von Epipactis Blüten und mit Pieris-Raupen befallenen Kohl und identifizierten vier gemeinsam vorkommende GLVs. In Y-Rohrtests konnte die wespenanlockende Wirkung dieser Verbindungen nachgewiesen werden

Pollinator attraction in wasp-flowers

Because little was known about the pollinator attracting floral signals that are used by flowers pollinated by social wasps, in my thesis I investigated in a comparative approach the floral cues, which are responsible for the specific attraction of social wasps to the flowers. I wanted to answer the question, if there is a wasp specific attractant that can be found in all wasp-flowers or if various wasp-flowers use different strategies to attract wasps. Furthermore I explored if there is a difference between orchids and non-orchids and between rewarding and deceptive wasp-flowers concerning the attractants used for the specific wasp attraction

Diario de Córdoba de comercio, industria, administración, noticias y avisos: Año XXXVI Número 10788 - 31 Octubre 1885

Copia digital. Madrid : Ministerio de Cultura. Subdirección General de Coordinación Bibliotecaria, 200

The value added by private equity in mergers and acquisitions by financial institutions

We compare and contrast (i) mergers and acquisitions (M&amp;As) by financial institutions (FIs) that had the involvement of one or more private equity firms (PE) with (ii) acquisitions with no private equity involvement. We find that the M&amp;A announcement abnormal stock returns are higher for acquisitions with- than without private equity involvement. Likewise, the post-announcement long-term annual stock returns are higher for deals with PE involvement. These deals also produce higher operating performance, and their stocks exhibit less volatility in the months following the announcement after controlling for a host of confounding variables. Our results are robust to year fixed effects, industry (i.e. business line) effects, and self-selection bias.</p

Asset vs. equity acquisitions by financial institutions

We examine the impact of asset vs. equity acquisitions in generating firm value for financial institutions. We find that acquirers experience statistically and economically significant higher CARs in asset acquisitions compared to equity acquisitions. We analyze the announcement period returns and find that investors' reaction to asset acquisitions by financial institutions is met more favorably than equity acquisitions. When employing the differences-in-differences approach, we find that asset acquisitions entail improved operating performance

Does the interest tax shield align with maqasid al Shariah in finance?

The debt-equity distinction is critical in modern corporate finance. We assess the compliance of the interest tax shield with the maqasid al Shariah in finance. For our analysis, we use the ends of maqasid al Shariah as proposed by Akram Laldin & Furqani, 2013. We develop a survey questionnaire to survey an international sample of well-informed individuals in the field of Islamic economics and finance. We use mean comparison, exploratory factor analysis (EFA), and structured equation modeling (SEM) to evaluate 176 responses. Our results reveal that experts consider the interest tax shield as anathema to the ends of maqasid al Shariah in Islamic finance. We find that the interest tax shield discourages equity financing and hinders the objective of overall human well-being. We recommend reframing the tax shield in favor of equity financing to promote profit and loss sharing. Keywords: Maqasid al Shariah, Islamic finance, Interest tax shield, JEL classification: K22, J88, Z12, G32, G0

Customer Satisfaction in Microfinance Institutions: Insights from Ghana

With increased competition in the microfinance industry in most African markets, customer satisfaction and retention are important issues for most microfinance institutions (MFIs) in the region. We rely on survey data from customers of MFIs in Ghana to examine the potential determinants of customer satisfaction in the microfinance sector. We find customer satisfaction to be significantly related to customers’ experiences and motivations such as the primary reason for associating with MFIs, and the size of credit they seek. We further find customers’ demographic factors such as educational attainment and household income levels to be related to customer satisfaction in the microfinance sector. Our results are largely consistent with the view that MFIs offer a valuable service by expanding access to small credits to poor households and microenterprises who are either denied credit by the formal banking sector or who are exploited by informal moneylenders. Further, our interviews with top managers of MFIs highlight various tactics utilised by MFIs in Ghana to manage their credit risks

Environmental performance and financial constraints in emerging markets

We examine how corporate environmental performance relates to financial constraints in an environment likely to face high global pressure to address climate change. Using multivariate regressions and a large dataset of over 8,500 firm-years from 24 emerging market countries during a period of 18 years from 2003 to 2020, we find superior environmental performance (especially relating to carbon emissions) to be associated with significantly lower levels of financial constraints. This finding is robust to an alternative measure of financial constraints, different sample compositions, and to endogeneity concerns. Further analyses reveal that the reductions in financial constraints are significantly higher for firms: (i) in high carbon-emitting countries; (ii) in countries that adopted the 2015 Paris Climate Agreement early; and (iii) that cross-list onto foreign stock exchanges. Finally, we provide evidence to suggest that the environmental aspects of a firm’s CSR efforts mitigate its financial constraints more than can be attained by the other major CSR dimensions. Overall, the findings imply that stakeholders of emerging market firms prioritise environmental concerns and, therefore, reward environmentally responsible firms with cheaper and easier access to financing, especially when global environmental concerns are high

Customer satisfaction in microfinance institutions: insights from Ghana

With increased competition in the microfinance industry in most African markets, customer satisfaction and retention are important issues for most microfinance institutions (MFIs) in the region. We rely on survey data from customers of MFIs in Ghana to examine the potential determinants of customer satisfaction in the microfinance sector. We find customer satisfaction to be significantly related to customers’ experiences and motivations such as the primary reason for associating with MFIs, and the size of credit they seek. We further find customers’ demographic factors such as educational attainment and household income levels to be related to customer satisfaction in the microfinance sector. Our results are largely consistent with the view that MFIs offer a valuable service by expanding access to small credits to poor households and microenterprises who are either denied credit by the formal banking sector or who are exploited by informal moneylenders. Further, our interviews with top managers of MFIs highlight various tactics utilised by MFIs in Ghana to manage their credit risks