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 Swarming
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| Nikita Vikhrev |
Posted on 01-05-2008 19:46
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 Member Location: Moscow, Russia Posts: 9220 Joined: 24.05.05 |
What do you think (know), what is the reason of male swarming in Diptera?
Nikita Vikhrev - Zool Museum of Moscow University |
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| jorgemotalmeida |
Posted on 01-05-2008 23:35
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 Member Location: Viseu - PORTUGAL Posts: 9296 Joined: 05.06.06 |
Discussing ways of run away from humans!    One possible hypothesis: (?) Maybe a marking of territorial zone. I don't know, but I'm interesting to hear opinions about this interesting observation. Another reason: http://www.cartoo..._flies.asp  |
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| jorgemotalmeida |
Posted on 02-05-2008 08:26
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Member Location: Viseu - PORTUGAL Posts: 9296 Joined: 05.06.06 |
I remembered another reason: maybe orientation. I will try to observe this event more times. And noting the position where the flies are facing. This event could easy their orientation in a particular object, for example, I suppose. It could enable the copulation too... |
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| jorgemotalmeida |
Posted on 02-05-2008 08:58
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Member Location: Viseu - PORTUGAL Posts: 9296 Joined: 05.06.06 |
Nikita I found a bunch of VERY interesting papers!! # Insect Swarming and Mating # Robert T. Sullivan # The Florida Entomologist, Vol. 64, No. 1 (Mar., 1981), pp. 44-65 (article consists of 22 pages) >> here an extract: http://www.jstor....ss/3494600 Annual Review of Entomology Vol. 14: 271-298 (Volume publication date January 1969) (doi:10.1146/annurev.en.14.010169.001415) The Swarming and Mating Flight of Diptera J A Downes here an extract: http://arjournals...169.001415 This is very interesting: http://www.spring...4m5281848/ in "Sexual dimorphism in the visual system of flies: The free flight behaviour of male bibionidae (Diptera)" by Jochen Zeil. I will copy here the contents. We never know if the site could be off... ". The free flight behaviour of swarming male Bibionidae (Diptera) has been filmed in the field with two cameras simultaneously at 50 frames/s. A method is described which allows the reconstruction of the three-dimensional trajectories of flies from the two films. 2. Males track other flies and dummy targets from below and from downwind (Figs. 5?8; 10a). They keep pointing into the wind and control flight direction and their position relative to the target by way of translational movements (forward, side-ways and vertical movements) (Fig. 9; Fig. 16b?d). Angular tracking is minimal, there is evidence, however, that the flies roll and pitch. 3. When interacting with a target, the flies keep the target's image close to and within the zone of binocular vision of their dorsal compound eyes (Figs. 3; 10c). There is some evidence that the flies' sideways acceleration is determined by the error angle velocity with a delay of 90 ms (Fig. 12). Underneath the target the flies perform sideways oscillations at 3?5 Hz (Fig. 13). 4. The flies repeatedly home in on and retreat from a target. At close range (0?20 cm) their vertical and forward velocity is linearily related to the target distance (Figs. 14a, 15a). Switches from ascending to descending flight occur whenever the target is lost from the visual field of the dorsal eyes. 5. Both forward and vertical velocity are to some extent dependent on the altitude of the target above the horizon of the fly (Figs. 14b, 15 .6. Rotational body movements in response to rotating striped patterns can only be elicited by stimulating the ventral eyes, the dorsal eyes do not mediate the optomotor response (Fig. 17). 7. In bibionids, male-specific visually guided behaviour is mediated through the dorsal eyes only. The visual tasks of swarming males are discussed. The complex behaviour seen in males interacting with a dummy target might reflect their need to distinguish other males in a swarm from females and to keep the surrounding airspace clear of unwanted targets." FONT: http://www.spring...4m5281848/ by Jochen Zeil If anyone has full access to these articles let me know. MORE articles on swarming: "Energy budget of swarming male mosquitoes" here >> http://www.blackw....tb00392.x I'll copy the resum? here for the same reasons pointed above: ". The objective of this study was to determine, in the field, the energetic costs of swarming for male Anopheles freeborni (Diptera: Culicidae). By comparing the caloric contents of resting males to marked males captured after swarming, we established when sugar feeding takes place, what energy source is used to fuel swarming flight, and how much energy is invested in this activity. 2. Sugar-feeding takes place sometime during the night after swarming is concluded. Nectar sugars are therefore not immediately available to fuel flight. Stored sugars (trehalose and glucose) and glycogen are the primary sources of energy for flight. Lipids are not used to fuel flight but may be used in resting metabolism. 3. Male size is not related to feeding success. For males of all sizes, swarming consumes more than 50% of available calories. Accordingly, the ability of an individual to find and exploit nectar sources will greatly affect reproductive success." Is this helps, Nikita? |
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| jorgemotalmeida |
Posted on 02-05-2008 09:02
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Member Location: Viseu - PORTUGAL Posts: 9296 Joined: 05.06.06 |
I found more one article about " Why insects swarm: testing the models for lek mating systems on swarming Empis borealis females" http://www.spring...713728355/ SUMMARY: "Female dance-flies, Empis borealis L., gather to swarm, and males carrying nuptial gifts visit swarms for mating. Field observations and experiments were performed on this behaviorally sex-role reversed species to test models of lekking behavior. The key predictions were: (1) female preference model: male visiting rate and mating rate should increase with the number of females in swarm (swarm size), (2) hotspot model: male visiting rate should be independent of swarm size, and (3) hotshot model: swarm size should be positively correlated with the body size of the largest female in swarm. We found that male visiting rate and mating rate increased with swarm size, and that mating rate per female increased with swarm size. Males also mated more often in larger swarms than in smaller ones. Both males and females visited swarm sites even in the absence of other individuals. When females were successively removed from swarm sites more males than females on average arrived at these sites: 2.25 males per female. When no individuals were present at the swarm site, arriving males moved on to another site, whereas arriving females generally stayed. Larger experimental swarm-markers attracted both more males and more females and even more males when swarming females were present. There was no correlation between mean or median female size in swarms and the number of females in swarms. Thus, the female preference model and the hotspot model were corroborated, while other models were judged unlikely to explain swarming behavior in E. borealis." BY Bo. G. Svensson1 and Erik Petersson Edited by jorgemotalmeida on 02-05-2008 09:02 |
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| Nikita Vikhrev |
Posted on 02-05-2008 17:26
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Member Location: Moscow, Russia Posts: 9220 Joined: 24.05.05 |
Thank you Jorge. It helps. Nikita Nikita Vikhrev - Zool Museum of Moscow University |
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but don't see the image in the post.