Amino acid content and nectar choice by forager honeybees (Apis mellifera L.)

Dual choice feeding tests were performed to determine a preference of forager honeybees for specific amino acids. Artificial nectar containing proline was preferred over those containing only sugars. Nectar containing alanine was preferred on the first day, but preference was no longer significant thereafter. On the contrary, a negative response was found for serine. When the bees were given the choice between two nectars enriched with different compounds, proline was preferred above both alanine and serine, and alanine above serine

The long-term impact of Italian colonial roads in the Horn of Africa, 1935-2000

Between 1935 and 1940 the Italians built an extensive road network to facilitate the occupation of Ethiopia and secure control over the Horn of Africa, but were expelled in 1941. This provides a unique case study to examine the long-run effect of cheap transport networks on the concentration of economic activity in developing countries. The results show that cells located next to Italian paved roads are significantly richer today and that the relationship is causal. Persistence is explained by a combination of direct and indirect mechanisms: colonial roads attracted economic activity through lower transport costs until 1960. After that date, the advantage of treated locations persisted only indirectly through increasing returns to scale

The economic impact of Italian colonial investments in Libya and in the Horn of Africa, 1920-2000

This dissertation examines the micro-level effects of Italian colonial investments in Libya, Somalia, Eritrea, and Ethiopia, and sheds light on both their short and long-term impact. It focuses on two flagship projects, launched by the dictator Benito Mussolini during the 1930s, namely the construction of a modern road network in the Horn of Africa and the settlement of Italian farmers in Libya. The contributions are twofold. First, this thesis focuses on types of colonial investment that have not been studied before, while looking at a group of colonies that have previously been neglected by the cliometrics revolution in African economic history. Thus, it enhances our understanding of the effect of colonialism in general and, on Africa, in particular. Second, by exploiting a set of quasi-natural experiments from the history of Italian colonialism to explore the micro-effect of specific policies, this thesis also contributes to the economic geography and development literatures that have looked at the determinants of agglomeration and productivity in developing countries. It is structured around three substantive chapters. The first one studies the effect of Italian road construction in the Horn of Africa on economic development and shows how locations that enjoyed a first-mover advantage in transportation thanks to the Italian road network are significantly wealthier today. The second substantive chapter assesses the effect of Italian agricultural settlement on indigenous agriculture in Libya at the end of the colonial period and pinpoints an adverse effect of Italian presence on Libyan productivity. Finally, the third substantive chapter studies the effect of the expulsion of Italian farmers from Libya after World War II and finds a reduction in agricultural commercialization in affected districts following the shock

Role and Regulation of Osmolytes and ABA Interaction in Salt and Drought Stress Tolerance

Abiotic stress conditions lead to the defects in plant growth and development and also reduction in flowering and fertility. Under prolonged stresses, imminent death of the plants has been observed. To cope with such stress conditions, plants accumulate a wide variety of organic solutes called osmolytes. Osmolytes are accumulated in bacteria, lower, and higher plants as a response primarily to abiotic stress. They encompass amino acids such as proline, tertiary sulfonium, and quaternary ammonium compounds like beatines, sugars (trehalose), and polyhydric alcohols (mannitol, sorbitol, pinitol, etc.). Osmolytes are accumulated in the cytoplasm as well as in chloroplasts in certain cases for osmotic adjustment under stress conditions. This enables the plants to absorb water and survive under stress. Out of the many phytohormones that play diverse roles during abiotic stress, abscisic acid (ABA) is an important one and perceived by plants by a core signaling module. As an integral part of signal transduction during stress conditions, ABA and other hormones regulate not only stomatal closure, but also a wide array of gene expressions including osmolyte biosynthetic pathway genes. Many signal molecules like nitric oxide, carbon monoxide, and hydrogen sulfide also play a vital role in osmolyte biosynthesis. Osmolytes appear to have multiple functions during stress such as osmotic adjustment and scavenging of reactive oxygen species (ROS). Thus, generation of ROS and osmolyte accumulation are linked together. This review summarizes the role played by ABA in signal transduction, the role of hormones to regulate osmolyte biosynthesis, and various functions carried out by them

Stress-driven increase in proline levels, and not proline levels themselves, correlates with the ability to withstand excess salt in a group of 17 Italian rice genotypes

In most plant species, a rapid increase in free proline content occurs following exposure to hyperosmotic stress conditions. However, inconsistent results were reported concerning the role of such an increase on the plant response to water shortage or excess salt. Therefore, the possibility that proline accumulation may help the cell to withstand stress conditions, or that it simply represents a stress marker, is still a matter of debate. A possible relationship between proline accumulation and salt tolerance was investigated in a set of 17 Italian rice varieties. Rice seedlings were exposed to increasing salt concentrations during germination and early growth. The resulting levels of free proline were measured separately in shoots and roots and compared to those in untreated controls. Results were related to the corresponding ability of a given genotype to tolerate stress conditions. Neither absolute proline levels in untreated or in salt-stressed seedlings showed a straightforward relationship to the relative tolerance to salt, estimated as conductivity values able to reduce growth by 10 or 50%. Conversely, a highly significant correlation was found between the increase in proline levels in shoots and the ability to withstand stress. The results strengthen a recent hypothesis suggesting than an increase in proline metabolic rates, more than the resulting proline content, may help the cell to counteract the effects of abiotic stress conditions

The long-term impact of Italian colonial roads in the Horn of Africa, 1935-2015

This article exploits the quasi-natural experiment provided by the extensive road network that was built across the Horn of Africa during the Italian occupation of Ethiopia (1936–1941), to examine how a first-mover advantage in transportation can affect the spatial distribution of economic activity in developing countries over the long run. The results show that Italian paved roads rendered areas located within 10 km of them significantly more populated, urbanized and luminous around 2010, relative to comparable, more distant locations. Early roadbuilding lifted first-mover locations out of isolation and allowed for net welfare gains, thanks to a reduction in transport costs and specialization. To this day, first-mover locations continue to diverge from the control group, due to a coordination mechanism that led to an oversupply of governmental facilities in the post-colonial period

The long-term impact of Italian colonial roads in the Horn of Africa, 1935-2000

Between 1935 and 1940 the Italians built an extensive road network to facilitate the occupation of Ethiopia and secure control over the Horn of Africa, but were expelled in 1941. This provides a unique case study to examine the long-run effect of cheap transport networks on the concentration of economic activity in developing countries. The results show that cells located next to Italian paved roads are significantly richer today and that the relationship is causal. Persistence is explained by a combination of direct and indirect mechanisms: colonial roads attracted economic activity through lower transport costs until 1960. After that date, the advantage of treated locations persisted only indirectly through increasing returns to scale

The effect of settler farming on indigenous agriculture: Evidence from Italian Libya

What effect did the settlement of European farmers have on the indigenous agricultural sector during the colonial period? On the one hand, European immigrants imported skills and capital but, on the other, they took control of local resources. By looking at the short-term effect of Italian farming in colonial Libya, I shed new light on this question. Through regression analysis on a novel village dataset covering the entire country, I show that, in 1939, proximity to Italian farms was associated with significantly lower land productivity relative to distant locations. Lower yields can be explained by the adoption of land-extensive cultivation techniques, implemented by indigenous farmers to counteract a labour drain operated by Italian farms through factor markets. The combined mitigating effect of monetary wages and land-extensive farming only partially compensated for the fall in income linked to reduced land productivity

The effect of settler farming on indigenous agriculture: Evidence from Italian Libya

What effect did the settlement of European farmers have on the indigenous agricultural sector during the colonial period? On the one hand, European immigrants imported skills and capital but, on the other, they took control of local resources. By looking at the short-term effect of Italian farming in colonial Libya, I shed new light on this question. Through regression analysis on a novel village dataset covering the entire country, I show that, in 1939, proximity to Italian farms was associated with significantly lower land productivity relative to distant locations. Lower yields can be explained by the adoption of land-extensive cultivation techniques, implemented by indigenous farmers to counteract a labour drain operated by Italian farms through factor markets. The combined mitigating effect of monetary wages and land-extensive farming only partially compensated for the fall in income linked to reduced land productivity