Embryo, Relocation and Secondary Nests of the Invasive Species Vespa velutina in Galicia (NW Spain)

Abstract

Invasive species become established in non-native areas due to their intrinsic characteristics and the ability to adapt to new environments. This work describes the characteristics of the nesting behavior of the invasive yellow-legged hornet (Vespa velutina nigrithorax) in Galicia (Northwest Spain). The first nest was detected in the area in 2012 and after that, the distribution pattern shows a species-invasion curve with slow progress at first but followed by rapid expansion. The nesting places for this hornet differ between the kinds of nests, while embryo nests are mainly found in buildings in spring, secondary nests are observed in vegetation in summer, autumn, and winter. The annual life cycle starts when the queen builds the embryo nests and starts to lay eggs. This leads to the emergence of the first workers, usually small in size, and sometimes a few males. After this stage, large nests called secondary nests are normally observed in most exposed sites. Relocation nests can also be observed; these are nests in the first stage of development presenting adults insects but without brood or meconium. The period of decline is characterized by the emergence of new queens and males, that are distinguishable even in the pupal stage, the appearance of two eggs per cell, and an irregular brood pattern.

Host Range Expansion of Nest-Parasitic Moths Pyralis regalis and Hypsopygia mauritialis in Social Wasp Nests: New Findings and Implications for Biological Control

“…However, when the nests were discovered in August, during periods of rapid expansion, such as Nests 11 and 38 (Table 1), few combs were almost entirely infested (Figure 6C), and there were limited numbers of hornet larvae, pupae, and adults remaining (Figure 6A). As this is the time when V. velutina nigrithorax relocates from the primary to the secondary nest [56], it seems that the nest gradually emptied due to the movement of V. velutina nigrithorax, rather than the colony collapsing, allowing the moths to occupy the entire nest. Therefore, these nest-feeding moths do not appear to significantly affect the maintenance of V. velutina nigrithorax colonies.…”

Describing the Pollen Content in the Gastrointestinal Tract of Vespa velutina Larvae

“…The smaller cell size and probably poorer nutrition compared to later-born workers account for these differences. As the cycle progresses, the embryo nest becomes larger; it may continue to grow in the same location or the colony may move to another location with the construction of a new nest [8]. Large colonies require large amounts of food.…”

“…Sugary secretions are important for energy but protein resources are taken by predation on other insects or by cutting up pieces of organic matter from animals. When the colony reaches its maximum size and population, the time for larval development and metamorphosis is reduced to 29 days and this is the time when the most damage occurs in apiaries [4,7,8]. The period of nest decline begins when the colony produces mostly males and future queens (mainly in autumn) which will be the new foundresses.…”

“…For this reason, this study analyzed the content and diversity of pollen grains found in larvae of Asian hornets collected from nests located in different points of Galicia. Even though the coastal areas continue to be the ones with the highest number of nests [8], the latest data from the Xunta de Galicia, through the Vespa velutina Hornet Surveillance and Control Program, have registered nests throughout the Galician territory. Therefore, this species is currently invading any area regardless of altitude.…”

Investigating the Architecture and Characteristics of Asian Hornet Nests: A Biomimetics Examination of Structure and Materials

“…Expansion refers to the space between the combs, which also allows for the expansion of the colony. As the colony grows, hornets can construct additional combs and add them to the existing space between the combs, ensuring that the colony can accommodate more members as needed [40]. The hexagonal shape of Asian hornet comb cells allows for a regular, gap-f division of a plane surface.…”