The effect of temperature on resistive ZnO layers and the performance of thin film CdTe solar cells

The use of a highly resistive transparent (HRT) layer has been shown to increase the efficiency of thin film CdTe heterostructure solar cells incorporating a thin CdS layer. In this study ZnO HRT layers were deposited at different substrate temperatures on soda lime glass and on fluorine-doped tin oxide-coated glass to enable structural, optical and electrical characterization. The performance of equivalent films was tested within CdS/CdTe solar cells. The ZnO thickness was limited to 150 nm, whilst the substrate temperature was varied from 20 °C to 400 °C during deposition. X-ray diffraction patterns and transmission electron microscopy of the cross-sectional microstructure of completed devices showed that the growth of the ZnO is improved when the films are deposited at higher temperatures. Film resistivity was lowest at 100 °C and highest at 400 °C, ranging from 10− 2 Ω·cm to 0.33 Ω·cm. The high temperature deposited ZnO exhibits improved micro-structural growth and an improvement in device efficiency

Implementing mass rearing of trissolcus japonicus (Hymenoptera: Scelionidae) on cold-stored host eggs

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), a pest of Asian origin, has been causing severe damage to Italian agriculture. The application of classical biological control by the release of Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae), an exotic egg parasitoid, appears to be one promising solution. In Italy, releases of T. japonicus in the field were authorized in 2020. In this study, some parameters that could influence the rearing of T. japonicus in insectaries were investigated. A significantly higher production of progeny was observed on host eggs stored at 6◦C (86.5%) compared to −24◦C (48.8%) for up to two months prior to exposure to parasitism. There were no significant differences in progeny production from single females in a vial provided with only one egg mass (83.2%) or 10 females inside a cage with 6 egg masses (83.9%). The exposure of parasitoids to refrigerated (6◦C) egg masses of H. halys for 72 h led to a significantly higher production of progeny (62.1%) compared to shorter exposures for 48 (44.0%) or 24 h (37.1%). A decline in production of progeny by the same female was detected between the first (62.1%) and the second parasitization (41.3%). Adult parasitoids stored at 16◦C for up to 90 days had an 87.1% survival rate, but a significant decrease in progeny production was detected. These parameters could be adjusted when rearing T. japonicus for specific aims such as the production of individuals for field release or colony maintenance

Cetaceans in the Mediterranean Sea. Encounter rate, dominant species, and diversity hotspots

We investigated the presence and diversity of cetaceans in the Mediterranean Sea, analysing the data collected by 32 different research units, over a period of 15 years (2004–2018), and shared on the common web-GIS platform named Intercet. We used the encounter rate, the species prevalence, and the Shannon diversity index as parameters for data analysis. The results show that cetacean diversity, in the context of the Mediterranean basin, is generally quite low when compared with the eastern Atlantic, as few species, namely the striped dolphin, the bottlenose dolphin, the fin whale, and the sperm whale, dominate over all the others. However, some areas, such as the Alboran Sea or the north-western Mediterranean Sea, which includes the Pelagos Sanctuary (the Specially Protected Area of Mediterranean Interest located in the northern portion of the western basin), show higher levels of diversity and should be considered hotspots to be preserved. Primary production and seabed profile seem to be the two main drivers influencing the presence and distribution of cetaceans, with the highest levels of diversity observed in areas characterized by high levels of primary production and high bathymetric variability and gradient. This collective work underlines the importance of data sharing to deepen our knowledge on marine fauna at the scale of the whole Mediterranean Sea and encourages greater efforts in the networking process, also to accomplish the requirements of the Marine Strategy Framework Directive, with particular reference to Descriptor 1: biological diversity is maintained

Degradation of Mg-doped zinc oxide buffer layers in thin film CdTe solar cells

Cadmium Sulphide is the conventional n-type buffer layer used in thin film Cadmium Telluride solar cells. It is well known that Cadmium Sulphide causes optical losses and sulphur diffuses into the absorber during high temperature activation. Sputter-deposited Mg-doped ZnO (MZO) has been shown to be an attractive buffer layer for Cadmium Telluride solar cells due to its transparency and tuneable band gap. It is also stable to high temperature processing and avoids diffusion of elements into the cadmium telluride absorber during the cadmium chloride activation treatment. However, degradation is observed in solar cells incorporating MZO buffer layers. Analysis of the MZO film surface potential has revealed significant fluctuations in the thin film work function once the layer is exposed to the atmosphere following deposition. These fluctuations are attributed to the high reactivity to water vapour of the MgO contained in the MZO films. This has been analysed using X-ray Photoelectron Spectroscopy to determine corresponding changes in the surface chemistry. The Zinc Oxide component is relatively stable, but the analysis shows that MgO forms a Mg(OH)2 layer on the MZO surface which forms a secondary barrier at the MZO/CdTe interface and/or at the interface between MZO and the Fluorine-doped SnO2. This affects the Fill Factor and as a consequence it degrades the conversion efficiency

Indagini sulla parassitizzazione di Halyomorpha halys in Emilia Romagna nell’ambito del progetto “Haly.Bio"

Because of the extensive damage caused by the invasive Halyomorpha halys on the fruit system of northern Italy, it is urgent to identify effective management strategies with a low environmental impact. The PSR "HALY.BIO" project is focused on the implementation of biological control of H. halys in Emilia Romagna, and was developed by pursuing the following objectives: a) verifying the presence, distribution and impact of egg parasitoids capable to parasitize H. halys eggs; b) investigating the settlement and diffusion capacity of exotic parasitoids, considering in particular the effect of the releases of Trissolcus japonicus. The partial results of the project (still in progress) are presented, in terms of distribution maps for the different parasitoid species and their parasitization efficacy on H. halys and non-target species in different contests

Current status of Drosophila suzukii classical biological control in Italy

For over a decade, the invasive pest Drosophila suzukii (Matsumura) has threatened the soft-skinned fruit production worldwide, causing increased management costs and yield losses. Current integrated pest management (IPM) exploits different control tools but relies mainly on insecticides. The local natural enemy community mostly consists of generalist species, mainly parasitoids attacking the puparia of the fruit fly. These antagonists resulted unable to control the pest efficiently, regardless the adoption of conservative or augmentative approaches. By contrast, in the native area of D. suzukii, sympatric larval parasitoids have co-evolved with the pest and provide a stable control of its population. Foreign explorations and quarantine risk assessment studies for classical biological control programs have identified different species of parasitoids characterized by a variable level of specificity. The Japanese G1 lineage of the larval endoparasitoid Ganaspis brasiliensis (Ihering) has proved to be much more selective and efficient than other larval parasitoids, including Leptopilina japonica Novković & Kimura recently reported in Europe. In this context, a voluntary partnership of Italian researchers imported a colony of the G1 lineage of G. brasiliensis into Italian quarantine facilities and proposed its release in Italian fields. A three-year working program has been set up in several locations of nine Italian regions/provinces. Field releases of laboratory-reared parasitoids have been planned. Pre- and post-release samplings of fresh and fallen fruits around the release points will be undertaken to assess the impact of the exotic G. brasiliensis on D. suzukii and its potential interactions with other non-target insects in the field. The possible establishment of this efficient and specific biological control agent would promote a long-lasting control of this invasive species less dependent on the use of chemicals, reducing the negative effects associated with the