Marco Porporato

Design of an harmonic radar for the tracking of the Asian yellow‐legged hornet

Abstract The yellow‐legged Asian hornet is an invasive species of wasps, indigenous to the Southeast Asia but recently spreading in Southern Europe. Because of its exponential diffusion and its serious threat to the local honeybee colonies (and to humans as well), restraint measures are currently under investigation. We developed and tested an harmonic radar capable of tracking the flying trajectory of these insects, once equipped with a small transponder, in their natural environment. Several hornets were captured close to a small cluster of honeybee hives, tagged with different transponders and then released in order to follow the flight toward their nest. On‐field testing proved an initial maximum detection range of about 125 m in a hilly and woody area. A number of detections were clearly recorded, and preferential directions of flight were identified. The system herein described is intended as a first low‐cost harmonic radar; it proved the capability to track the hornets while flying and it permitted to test the tagging techniques. Several upgrades of the system have been identified during this work and are extensively described in the last chapter. The designed system has three major advantages over conventional harmonic radars. First and most importantly, it adopts advanced processing techniques to suppress clutter and to improve target detection. Second, it allows radar operations in complex environments, generally hilly and rich in vegetation. Finally, it can continuously track tagged insects (24/7) and in any meteorological condition, providing an effective tool in order to locate the nests of the yellow‐legged Asian hornet.

Nosema ceranae has been infecting honey bees Apis mellifera in Italy since at least 1993

(2013). Nosema ceranae has been infecting honey bees Apis mellifera in Italy since at least 1993. Journal of Apicultural Research: Vol. 52, No. 2, pp. 60-61.

Recent upgrades of the harmonic radar for the tracking of the Asian yellow-legged hornet

Abstract The yellow‐legged Asian hornet is an invasive species of wasps, indigenous of the South‐East Asia but quickly spreading in Southern Europe. Because of its exponential diffusion and its serious threat to the local honey bee colonies and to humans as well, restraint measures are under investigation. Among them, the harmonic radar described in (Ecology and Evolution, 6, 2016 and 2170) already proved to be a quite effective way to follow the hornets to their nests; it is in fact capable of tracking the flying trajectory of these insects, once equipped with a small transponder, in their natural environment. The aforementioned harmonic radar was upgraded after a period of intense experimentation; the capture of the hornets was enhanced as well, and other improvements were adopted in the mounting procedure of the transponder. Thanks to these upgrades, the flying capabilities of the hornets were not reduced and a huge collection of data was recorded. The main upgrade to the radar was the adoption of the vertical polarization of the radiated field, with the consequent redesign and manufacturing of the antennas and the different mounting of the transceiver on the insect. The installation of the radar on a telescopic tower drastically improved the maneuverability of the system and the capability to follow the insects’ preferential flying directions. Eventually, the system was able to produce much more continuous traces with a clear indication of the most probable position of the nest. The maximum range of detection was also increased to 150 m.

Research on the rearing of bumblebees in artificial nests

Rearing trials on several Bombus species were carried out in 1990 and 1991. The purpose was to improve techniques of colony management and to observe colony growth and the behaviour of foraging workers. A total of 5 queens of Bombus hortorum (L.), 32 of B. humilis Ill., 93 of B. lapidarius (L.), 77 of B. pratorum (L.), 5 of B. ruderatus (F.), and 177 of B. terrestris (L.) were collected in spring on flowering plants. No queen of B. hortorum, but 1 of B. humilis, 1 of B. lapidarius, 11 of B. pratorum, 3 of B. ruderatus, and 33 of B. terrestris started to rear larvae, however, workers emerged only in 1 colony of B. lapidarius, 5 of B. pratorum, 2 of B. ruderatus, and 29 of B. terrestris. In 1990, virgin queens and males coming from B. terrestris artificial nests were placed in mating cages; these queens were then used to found new colonies, that were reared throughout the winter until the completion of their cycle.

Survey of the Health Status of Some Honey Bee Queens in Italy

Abstract While observing: non-acceptance, frequent replacements, and reduced performance in honey bee (Apis mellifera ligustica) queens, we were induced to analyse a certain number of queens to detect the causes. For this purpose, 99 newly mated queens were bought from 20 Italian queen breeders. In addition, 109 older or at-the-end-of-their-career queens, that showed poor productivity, were collected from honey production hives throughout Italy. All the queens were dissected to check the status of their reproductive system and/or the presence of various anomalies and diseases. Anatomical and functional anomalies, pertaining to ovaries and spermatheca, also in association with tissue alterations and microorganisms like Nosema spp. and protozoa, were common in both newly mated and older queens, but they were more prevalent in the latter. Observed differences permitted us to highlight the causes of the reduced performance of the queens and of the colonies they originated from. The obtained information could prove useful when it comes to improving queen breeding techniques.