Optical identification of bumblebee species: Effect of morphology on wingbeat frequency

• A photovoltaic sensor was developed for analyzing wingbeat characteristics of bumblebees.
• Morphological characteristics of the wings had a significant influence on the wingbeat.
• The area of the forewings was the most determining factor for wingbeat, not the wing loading.
• Wingbeat characteristics allowed to discriminate between two bumblebee species with an accuracy of 88%.

Insects play a very important role in agriculture: while pests have a negative influence on the yield, beneficial insects are indispensable for pollinating purposes. Because of this importance, several systems are developed to monitor insect activity. These are mainly based on manual counting procedures which are very time consuming and labour intensive. In order to automate this procedure, the possibility to detect and classify insects based on their optical signatures has been investigated using two bumblebee species (Bombus terrestris and Bombus ignitus) as case study. Also the influence of morphological parameters of the bumblebee wings on the wingbeat is investigated. It is shown that the wingbeat frequencies of the two species are significantly different, and that bumblebees with larger wings had a lower wingbeat frequency. Based on the differences found, a simple classifier was built to discriminate between both species with an accuracy of 88%.