Describing the pollen content in the gastrointestinal tract of Vespa velutina larvae

Vespa velutina is an invasive species that exhibits flexible social behavior, which may have contributed to its introduction in several European countries. It is important to understand its behavior in order to combat the effects of its introduction in different areas. This implies knowing the resources that it uses during its biological cycle. Hornets require protein resources taken from insects and organic matter as well as carbohydrates as an energy source to fly and also to forage for food and nest-building materials. The gastrointestinal tract of adults and larvae contains a wide variety of pollen types. The identification of this pollen in larvae collected from nests could offer information about the plant species that V. velutina visits as a foraging place. The main objective of this research was to study the pollen content in the gastrointestinal tract of larvae. Patterns of pollen content and pollen diversity were established according to the nest type, altitude, season, and location in the nest comb. The abundance of pollen types such as Eucalyptus, Castanea, Foeniculum vulgare, Hedera helix, Taraxacum officinale, Echium, or Cytisus pollen type stands out in many of the samples.Simple Summary: The yellow-legged hornet is an invasive species from southeast Asia that has turned the European beekeeping sector upside down. The spread of this species has been advancing in recent years, and today, several European countries are threatened by Vespa velutina. The need to study its behavior is urgent given the increasingly evident economic and environmental impacts. In this regard, there is little information about the feeding habits and the resources it uses during the life cycle. Like other Hymenoptera, hornets require carbohydrates and proteins as their primary nutrients. Sugary secretions such as floral nectar, honeydew, or fruit juices are the main sources of carbohydrates but the protein intake is provided by the consumption of a diverse diet of insects such as the honey bee. There is scarce information on the presence of pollen grains in the gastrointestinal content of larvae other than secondary contamination from hunting. This content could represent the surrounding flora of its habitat that is used as a resource. Therefore, the objective of this study was to describe the main pollen types present in the gastrointestinal system of larvae taken from V. velutina nests.Fundación Centro de Estudos Eurorrexionais Galicia - Norte de Portugal | Ref. EAPA_800/2018-Atlantic-POSitiveXunta de Galicia | Ref. ED481D-2022-02

Study of the behavior of the invasive species Vespa velutina nigrithorax and the pressure exerted on the species Apis mellifera iberiensis in Galician hives

Se estudiará el comportamiento, ciclo biológico, alimentación, morfología y biología de la especie invasora Vespa velutina nigrithorax y la presión que ejerce sobre Apis mellifera iberiensis en los colmenares gallegos. Se hará una evaluación sanitaria de los colmenares estudiados con el fin de conocer qué otros factores, junto con la avispa asiática, pueden provocar la pérdida de colmenas y, así, proponer técnicas de manejo que disminuyan estas pérdidas.Estudarase o comportamento, ciclo biolóxico, alimentación, morfoloxía e bioloxía da especie invasora Vespa velutina nigrithorax e a presión que exerce sobre Apis mellifera iberiensis nos colmenares galegos. Farase unha avaliación sanitaria dos colmeares estudados co fin de coñecer que outros factores, xunto coa avespa asiática, poden provocar a perda de colmeas e, así, propoñer técnicas de manexo que diminúan estas perdas.The behaviour, life cycle, feeding, morphology and biology of the invasive species Vespa velutina nigrithorax and the pressure it exerts on Apis mellifera iberiensis in Galician apiaries will be studied. A health evaluation of the studied apiaries will be made in order to know which other factors, together with the asian yellow hornet, can cause the loss of colonies and, thus, to propose management techniques to reduce these losses

Monitoring study in honeybee colonies stressed by the invasive hornet vespa velutina

Vespa velutina is an invasive species that is currently the main concern for beekeeping in some areas of northern Spain. The hornet hunts honeybees to feed its larvae, stressing and weakening the honeybee colonies. To avoid losses of honeybee colonies, it is essential to investigate the pressure that is exerted by the yellow-legged hornet on apiaries and its consequences. In the present study, hives were monitored in an apiary that was situated in a high-pressure area of V. velutina during the years 2020 and 2021. The monitoring of environmental conditions of the apiary, the internal conditions of the colonies, and a hunting camera were used to relate the presence of hornets in front of the hives to the weather conditions in the apiary and the consequences caused on the colonies. The relationships between weather conditions and the hornet’s activity showed two types of hornet behavior. In the months of July and August, the maximum number of hornets appeared in non-central hours of the day. Meanwhile, in the months of September and October, the highest pressure in the apiary occurred in the central hours of the day, coinciding with temperatures between 15 °C and 25 °C and a relative humidity that was higher than 60%. The honeybee colony with the highest thermoregulatory capacity was the strongest and it was the key factor for the colony survival even when the hornet pressure was high too. Therefore, strengthening the hives and improving beehive health status is essential to avoid colonies decline.INTERREG ATLANTIC AREA PROGRAM | Ref. EAPA_800/2018—Atlantic-POSitiveXunta de Galicia | Ref. ED481B-2018/05