Environmental factors influencing daily foraging activity of Vespula germanica (Hymenoptera, Vespidae) in Mediterranean Australia

Abstract

In social insects, workers forego reproduction in favour of foraging and other tasks to promote growth of the whole colony. Maximising individual work effort is limited by the physical constraints on foraging outside the nest. Previous studies of factors influencing activity in social insects suggest that light intensity, ground and air temperature, relative humidity, solar radiation, wind speed and/or rainfall may be important. This study aimed to determine which environmental factors influence foraging in an invasive social insect, Vespula germanica, which has been introduced to Australia, where it experiences a hotter and drier climate than in its native range. Activity was measured in terms of foraging traffic, with nests from a range of locations being monitored. Results indicate that the onset of rain reduces activity by approximately 30 %, but foraging returns to previous levels immediately after rain stops. Foraging time is correlated with duration of daylight, with wasp daily activity being on average 22 min longer than the time between sunrise and sunset. Low light was found to restrict wasp activity, as were low and high temperatures. A linear mixed-effects model developed to explain the influence of these variables on numbers of foragers was highly significant. Under hot conditions, V. germanica individuals thermoregulate their body temperature by regurgitating water. They also use water in evaporative cooling to keep nests at optimum temperatures. Thus, in this species, hot temperatures increase the need for water, and so populations may be severely impacted in seasonally hot regions where water is limited.

Activity rhythm and action range of workers of the invasive hornet predator of honeybees Vespa velutina, measured by radio frequency identification tags

“…V. crabro is also active with low light intensity but in a higher propensity (Kelber et al., 2011). Second, the worker activity is driven by weather conditions that is quite classical in Vespidae (Canevazzi & Noll, 2011; de Castro, Guimaraes, & Prezoto, 2011; Cruz, Giannotti, Santos, Bichara Filho, & Resende, 2006; Kasper, Reeson, Mackay, & Austin, 2008; da Rocha & Giannotti, 2007). The observed enhancement of the hornet activity during the day with a maximum around noon, already observed by video analysis (Monceau et al., 2017), can be either attributed to an increase in temperature or in UVB solar irradiation.…”

Influência dos Fatores Ambientais e da Quantidade de Néctar na Atividade de Forrageio de Abelhas em Flores de Adenocalymma bracteatum (Cham.) DC. (Bignoniaceae)

“…A maioria das espécies de abelhas aumenta a atividade de forrageio nos períodos em que a temperatura e a intensidade luminosa estejam elevadas, e tanto a umidade relativa do ar, quanto a velocidade do vento estejam baixas (soMMeijeR et al 1983;hiLáRio et al 2000;kasPeR et al 2008). Contudo, cada espécie está adaptada a condições climáticas específicas (CoRbet et al 1993), que muitas vezes resulta no uso dos mesmos recursos florais de forma partilhada (WiLMs et al 1996).…”

Environmental Factors Influencing Foraging Activity in the Social WaspPolybia paulista(Hymenoptera: Vespidae: Epiponini)

“…A variety of studies has demonstrated the influence of weather conditions on social wasp foraging and nearly all of them point to temperature as the key factor influencing foraging [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]38]. We found a great influence of temperature on foraging, since there was an increase in the number of foragers simultaneously to the increase of temperature (Figure 3).…”

“…Many studies have been done with the purpose of verifying several aspects related to the flight and foraging activity of social wasps, such as daily and seasonal activity of searching for resources, items collected, influence of colony and environment factors on the foraging, and foraging activity behavior patterns [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. The foraging activity of these wasps varies throughout a day and throughout the seasons, but also according to the place where the study is carried out [26].…”