Nesting behaviour consists of various behavioural components such as nest and cell founding and closing as well as building, provisioning, and protection. This pattern is essential in the reproductive process of every species of bee, and thus, nesting behavior should be a well–studied scientific branch.

Andrena vaga is a gregarious early spring solitary bee that nests on sandy soils. We individually marked all the females on the nesting site (Čelákovice, 20km NE from Prague) and observed them daily.

Dye-marked female of Andrena vaga

This observation enabled us to construct detailed etogram, to determine  a sequence of behavioral elements within the provisioning cycle (from one provisioning flyght to another one, Fig.1) and estimate their length and to compute the transition probability between the subsequent behavioural elements. One provisioning cycle generaly consist of two different parts: the repeat cycle (R–cycle) and the long cycle (L–cycle). The L–cycle represents the key part of the provisioning cycle, and it is the entire interval between two following returns with provisions [R(p)l–R(p)r/l]. The R-cycle [R(p)r–R(p)r/l] is a subsection of the provisioning cycle, which may precede the long cycle. It is characterized by a fast departure shortly after the return with provision on the nesting site without entering the nest (see ethogram, R–cycle). There may be a variable number of R–cycles before the long cycle. All of the parts of the provisioning cycle are separated by single key activities (pointed bold in Fig.1) that are present on both pollen and nectar days.We also computed average daily activity scheme, which illustrates average daily foraging pattern (Fig. 2). We confirmed the existence of distinctive pollen and nectar days in A. vaga, which has been mentioned by previous studies (Andrena vaga tend to collect either pollen or nectar in one day, but only very rarely both). We showed apparent differences in the overall daily provisioning pattern in pollen and nectar days as well as in the probability of transition between some behavioral elements in these days.

Figure 1: Activity scheme. Behavioral elements of Andrena vaga in sequential scheme; activities connected by arrows show the known direction of transitions between elements and show that behavioral patterns are context dependent. R(p) return with nectar (pollen), G digging into the nest, B/W basking/waiting, E entering the nest, SE sitting in the nest entrance, S nest servicing, C covering of the nest entrance, D departure, F fake entrance digging, I imprinting flight. Indexes r and l show the incidence to the repeat (R)- or long (L)-cycle. The key activities of the provisioning cycle are in black frames; the bold arrows show the most important transitions between activities. Gray arrows represent the transitions not found in real data, but expected. Sequence R(p)l−R(p)l represents the long cycle, R(p)r−R(p)r/l represents R cycle (from Rezkova, K., Žáková M., Žáková Z. & Straka J. 2012: Analysis of nesting behavior based on daily observation of Andrena vaga (Hymenoptera: Andrenidae). Journal of Insect Behavior 25: 24-47).

Figure 2: Average daily activity scheme: R - return without pollen, Rp - return with pollen, D - departure from the nest, N - number of activities/intervals used for time calculation (from Rezkova, K., Žáková M., Žáková Z. & Straka J. 2012: Analysis of nesting behavior based on daily observation of Andrena vaga (Hymenoptera: Andrenidae). Journal of Insect Behavior 25: 24-47).

Bees typically performed one provisioning trip and carried no pollen on nectar days, but they performed up to four pollen-provisioning trips on pollen days. The duration of one pollen trip depended on the number and sequence of the trip in a given day, with the shortest trip usually occurring last in the day.

Andrena vaga is further interesting model as it hosts the parasite Stylops mellitae. The presence of this parasite influences not only the overall body morhology but most interestingly also the behaviour of parasitised animals, which we pursuied further projects (see section Bee parasites).

For further reading:

Rezkova K., Žáková M., Žáková Z. & Straka J. (2012): Analysis of Nesting Behavior Based on Daily Observation of Andrena vaga (Hymenoptera: Andrenidae). Journal of Insect Behavior 25: 24-47.