flagflag

The blowfly (Protophormia terraenovae) and its characteristic behavior


Sakiko Shiga (Graduate School of Science, Osaka City University)




Protophormia terraenovae (Robineau-Desvoidy)
Left photograph, male (left) and female (right) adults; right photograph, aerial view of the brain of the fly with the dorsal cuticula removed from the head


The blowfly Protophormia terraenovae is a deepblue colored fly with a body length of approximately 1 cm, which is distributed widely in Holarctic regions and dominant in the Arctic and Subarctic. In Japan, it is maily found in Hokkaido. Development in molecular and developmental biology have substantially benefitted from Drosophila flies. However, experiments that require a relatively large body size are difficult to conduct on Drosophila. P. terraenovae, which belongs to the order Diptera, same as Drosophila, is characterized by a larger body size and readiness in rearing, which make it suitable for experiments, involving microsurgeries on the nervous system and extraction of substances from specific tissues or organs collected. It is also advantageous that genetic information from Drosophila ia available to some extent to P. terraenovae.


Characteristic responses and behavior

Photoperiodism

How do living organisms respond to annually occurred seasonal change? Because physical changes such as temperature, humidity, and light occurs annually biological changes such as available food sourcesalso occur. To produce offspring responding to these physical and biological seasonal changes, many animals know the season using the length of daylight or dark period in a day (photoperiod) as a clue. The response to photoperiod to change a physiological phenomenon is called photoperiodism.

P. terraenovae regulates its reproductive diapause depending on the photoperiod. Adult flies reproduce when raised under long-day conditions, whereas they enter diapause under short-day conditions, where they stop reproduction. When the flies receive information of short days (and low temperature) for a certain period, they predict the forthcoming unfavorable seasons like winter and suppress their reproductive activities to avoid larvae developing during severe seasons, when there is lack of food. Ovarian development is suppressed in females, and copulatory behavior is inhibited in males. Through this response, they ensure that they reproduce only during the short period of summer in the Arctic and Subarctic, and when autumn comes, they enter diapause and overwinter as adults.



Fig.1. Life cycle in P. terraenovae



Fig. 2. Ovaries in the adult female P. terraenovae


Circadian activity rhythms

Adults of P. terraenovae show typical diurnal behavior. They are active during the day and inactive in the night period after sunset. This change in the activity is repeated every day. The periodicity of an active and non-active cycle is synchronized with the day–night cycle (entrainability) and maintained even under constant conditions (free running). In addition, the free-running period is constant at a various given temperature (temperature compensation). Thus, it is considered that the activity rhythm is driven by an intrinsic circadian clock.



Fig. 3. Locomotor activity recording device
ショ糖溶液(sugar water), ハエ(fly), 赤外線投光器・センサー(infrared beam projector and sensor)
The activity is recorded by counting the number of crossings past the infrared line per unit time. This allows observation of the circadian activity rhythms synchronized with the light–dark cycle.




Fig. 4. Locomotor activity rhythms in P. terraenovae


updating of the site
Copyright (C) 2018 Neuroinformatics Unit, RIKEN Center for Brain Science