Linda Abenaim

In recent years, edible insects have gained significant attention as a sustainable and innovative source of feed for animal nutrition due to their excellent content of protein, fats, vitamins, and chitin. Among these, chitin is the least studied nutritional component, despite its promising properties and potential benefits. Chitin, an important polysaccharide found in the exoskeleton of arthropods, including insects, presents both negative and positive aspects in animal nutrition. As is known, the main drawback is its digestibility, which varies among livestock animal species depending on their ability to produce chitinase. However, chitin also exhibits benefits, including the enhancement of gut microbiota and immune response, together with the reduction in cholesterol and pathogen levels in animals. This review aims to summarise the current knowledge on the effects of chitin derived from edible insects on animal nutrition by analysing both the negative aspects and benefits for the different farmed animals for which insect feeding is legally permitted (fish, poultry, and pigs), while proposing future research directions.

The interest in edible insects’ mass rearing has grown considerably in recent years, thereby highlighting the challenges of domesticating new animal species. Insects are being considered for use in the management of organic by-products from the agro-industry, synthetic by-products from the plastics industry including particular detoxification processes. The processes depend on the insect’s digestive system which is based on two components: an enzymatic intrinsic cargo to the insect species and another extrinsic cargo provided by the microbial community colonizing—associated with the insect host. Advances have been made in the identification of the origin of the digestive functions observed in the midgut. It is now evident that the community of microorganisms can adapt, improve, and extend the insect’s ability to digest and detoxify its food. Nevertheless, edible insect species such as Hermetia illucens and Tenebrio molitor are surprisingly autonomous, and no obligatory symbiosis with a microorganism has yet been uncovered for digestion. Conversely, the intestinal microbiota of a given species can take on different forms, which are largely influenced by the host’s environment and diet. This flexibility offers the potential for the development of novel associations between insects and microorganisms, which could result in the creation of synergies that would optimize or expand value chains for agro-industrial by-products, as well as for contaminants.

Hermetia illucens is a species of great interest for numerous industrial applications. A high-quality reference genome is already available for H. illucens. However, the worldwide maintenance of numerous captive populations of H. illucens, each with its own genotypic and phenotypic characteristics, made it of interest to perform a de novo genome assembly on one population of H. illucens to define a chromosome-scale genome assembly. By combining the PacBio and the Omni-C proximity ligation technologies, a new H. illucens chromosome-scale genome of 888.59 Mb, with a scaffold N50 value of 162.19 Mb, was assembled. The final chromosome-scale assembly obtained a BUSCO completeness of 89.1%. By exploiting the Omni-C proximity ligation technology, topologically associated domains and other topological features that play a key role in the regulation of gene expression were identified. Further, 65.62% of genomic sequences were masked as repeated sequences, and 32,516 genes were annotated using the MAKER pipeline. The H. illucens Lsp-2 genes that were annotated were further characterized, and the three-dimensional organization of the encoded proteins was predicted. A new chromosome-scale genome assembly of good quality for H. illucens was assembled, and the genomic annotation phase was initiated. The availability of this new chromosome-scale genome assembly enables the further characterization, both genotypically and phenotypically, of a species of interest for several biotechnological applications.

The use of food waste as a rearing substrate to grow insects is an ecofriendly and sustainable alternative to food waste disposal. In the present research, Hermetia illucens prepupae were reared with a standard diet, different food waste-based diets based on vegetables, fruits, and meat, and a mixed one, where the previous three components were present equally. The demineralization and deproteination of the prepupae allowed for the obtainment of chitin that was then deacetylated to produce chitosan. Also, the bleaching of chitosan was attempted for further purification. The yield of the different reactions was investigated, and the infrared spectra of the obtained materials were analyzed to obtain information on the quantity and acetylation degree trend of the chitin and chitosan as a function of the diet. The possibility to slightly modulate the yield and acetylation degree of both biopolymers thanks to the specific diet was enlightened. Interestingly, the standard diet resulted in the highest fraction of chitin having the highest acetylation degree, and in the highest fraction of chitosan having the lowest acetylation degree.

Chitosan, a polysaccharide derived from the deacetylation of chitin, is a versatile and eco-friendly biopolymer with several applications. Chitosan is recognized for its biodegradability, biocompatibility, and non-toxicity, beyond its antimicrobial, antioxidant, and antitumoral activities. Thanks to its properties, chitosan is used in many fields including medicine, pharmacy, cosmetics, textile, nutrition, and agriculture. This review focuses on chitosan’s role as a tool in insect pest control, particularly for agriculture, foodstuff, and public health pests. Different formulations, including plain chitosan, chitosan coating, chitosan with nematodes, chitosan’s modifications, and chitosan nanoparticles, are explored. Biological assays using these formulations highlighted the use of chitosan–essential oil nanoparticles as an effective tool for pest control, due to their enhanced mobility and essential oils’ prolonged release over time. Chitosan’s derivatives with alkyl, benzyl, and acyl groups showed good activity against insect pests due to improved solubility and enhanced activity compared to plain chitosan. Thus, the purpose of this review is to provide the reader with updated information concerning the use and potential applications of chitosan formulations as pest control tools.

The onion thrips, Thrips tabaci, is a main insect pest for many field crops worldwide, with a particular preference for the species of the genus Allium. Aeolothrips intermedius is a banded thrips, whose larvae are considered the primary native predator of T. tabaci. Due of their predatory behaviour, A. intermedius larvae are considered a good candidate for biological control against thrips pests. However, limited information is available on the specific predation rate of A. intermedius against T. tabaci. The aim of our study was to evaluate the predatory efficiency of A. intermedius larvae against T. tabaci adults. Predation assays, performed under laboratory conditions, indicated that A. intermedius larvae begin to prey after an average of about 23 min, and the time taken by an A. intermedius larva to capture and subdue the prey until its death is about 26 min. Furthermore, the maximum number of prey that the A. intermedius larvae are able to kill in 12 h is up to eight adults of T. tabaci/A. intermedius larva.

The first report of Stephanitis lauri Rietschel, 2014 (Heteroptera, Tingidae) in Tuscany and Liguria (Italy). The species has been observed in Pisa (Pisa, Tuscany) and Piano di Vezzano (La Spezia, Liguria) on bay laurel plants. S. lauri has been firstly described in Greece and it was recorded in Cote d’Azur (France) in 2017.