Chitin is a linear polysaccharide of N-acetylglucosamine, which is highly abundant in nature and mainly produced by marine crustaceans. Chitosan is obtained by hydrolytic deacetylation. Both polysaccharides are renewable resources, simply and cost-effectively extracted from waste material of fish industry, mainly crab and shrimp shells. Research over the past five decades has revealed that chitosan, in particular, possesses unique and useful characteristics such as chemical versatility, polyelectrolyte properties, gel- and film-forming ability, high adsorption capacity, antimicrobial and antioxidative properties, low toxicity, and biocompatibility and biodegradability features. A plethora of chemical chitosan derivatives have been synthesized yielding improved materials with suggested or effective applications in water treatment, biosensor engineering, agriculture, food processing and storage, textile additives, cosmetics fabrication, and in veterinary and human medicine. The number of studies in this research field has exploded particularly during the last two decades. Here, we review recent advances in utilizing chitosan and chitosan derivatives in different technical, agricultural, and biomedical fields.

Summary For thousands of years, farmers have protected their crops by combating one pest at a time, using a single control method with very little consideration of the surrounding environment. In its early form, Integrated Pest Management (IPM) was intended to provide a more holistic approach to pest management than the ‘supervised control’ that was commonplace at the time. However, when public support later declined, agro-chemical companies were quick to step in and take on a major role in directing pest management back towards supervised control. To reduce yield losses to pests and produce more food in sustainable and environmentally compatible ways, major long-term governmental commitments are needed. We argue that governmental inputs acting to promote sustainable agricultural practices and nature conservation should have four main thrusts that are currently missing in most legislation: (1) establishing goal-oriented agro-environmental schemes, (2) externalizing the true costs of pesticide use, (3) strengthening the public extension service, and (4) soliciting goal-specific research.

Summary Increasing awareness and concerns regarding the adverse effects of pest management activities on human health and the environment have led researchers and, to a lesser extent non-governmental activists and policymakers, to seek ways to restrain harmful pest control practices. Conservation biologists, in their efforts to protect biodiversity, have begun to document the importance of the environment in pest management. At the same time, the Integrated Pest Management (IPM) approach, formulated more than 55 years ago, has for the most part failed to fulfil its mission developing effective, safe and sustainable plant protection systems. To this end, a new pest management paradigm is needed: a top-down, system-centric approach should replace the historical bottom-up, pest-centric viewpoint. This change is particularly important if we are to harness pest control activities to a global effort to increase food security and environmental protection.

Successful reproduction requires interactions between males and females at many levels: the organisms, their cells (the gametes), and their molecules. Among the latter, secreted products of male and female reproductive glands are especially important. These molecules are particularly well understood in Drosophila melanogaster, because of this insect's excellent molecular genetic tools. Here, we discuss the biology of Drosophila reproductive glands, including their development, structure, and secreted products. These glands include important secretory centers, tissues that play roles in gamete maintenance and perhaps in modification, and organs that mediate dynamic transfer of gametes and molecules, and gamete support and/or discharge. Components of seminal fluid produced by male reproductive glands enter the female during mating. There, they interact with female proteins, neurons, and pathways to convert the female from a ``poised'' pre-mated state to an active post-mating state. This mated state is characterized by high levels of egg production, by sperm storage, and by post-mating behaviors related to re-mating, activity, and feeding. Female reproductive gland secretions include additional molecules important for sperm survival or egg transit. The interplay and coordination between male- and female-derived molecules is an area of intense study. Its conclusions are relevant to understanding reproduction in insects and, more broadly, in all animals, and as well as to questions about chemical communication, hormone biology and evolution.