4
Flight Morphology and Flight Muscles
53
Table 4.5 Comparision ofa Flight Parameters of Various Insects
Parameter
Units
Primitive insects
Advanced insects
Dragon fly
Chalcid wasp
C.purpureusa
T.javanicaa
Beff (Chord)
cm
1
0.65
1.15
l
cm
4
0.5 – 0.7
1.2
2.2
L
cm
3.16
6.0
ϑh
Hz
40
400
90
50
Forward velocity (V)
m/s
1.8–2
3–4
Re
–
103
25
1000
4000
Mass
gm
0.17
0.86
Angle of attack(∝)
deg
25–45
25–45
25–45
25–45
aThis work is carried out at SNIST, Hyderabad, others from various sources
Insect Flight Muscles
The arrangement of direct and indirect flight muscles in the thorax and their contribu-
tion to up and down movements of the wings in both primitive and advanced insects
have been discussed. However, the wingbeat frequency is an important parameter
that helps in classifying the insects as Neurogenic (Synchronous) and Myogenic
(Asynchronous) fliers. The differences between these two types of fliers have been
listed below in Table 4.6.
Table 4.6 Differences between neurogenic and myogenic fliers
S. No
Neurogenic fliers (Synchronous)
Myogenic fliers (Asynchronous)
1
Frequency of wingbeat (ϑh): 2–200cps
Frequency of wingbeat (ϑh): 200–1000cps
2
Primitive insects such as dragonflies,
cockroaches and locust
Advanced insects such as houseflies,
mosquitoes and drosophila
3
Metabolism of flight muscles—oxidative
type
Metabolism of flight muscles—highly
oxidative and depends on fat metabolism
4
Number of mitochondria (cristae)—more
(++)
Number of mitochondria (cristae)—more
(++++)
5
Wing tip mutilation frequency does not
increase
Wing tip mutilation frequency increases by
50% or more
6
Resilin elastomer at wingbase is
moderately developed
Resilin elastomer at wingbase is more
efficiently developed
7
Flight muscle contraction—Twitch-like
(Direct muscles)
Flight muscle contraction—Tetanus-like
oscillations (Indirect muscles)
8
Sarcoplasmic Reticulum (SR)—Highly
developed for storing calcium
Sarcoplasmic Reticulum (SR)—developed
for storing calcium
9
Small myofibrils
Large myofibrils