Chemical Defense of Aquatic Firefly Larave, Luciola ficta Olivier (Coleoptera: Lampyridae)
Date Issued
2010
Date
2010
Author(s)
Chen, Chun-Tai
Abstract
Aquatic firefly larvae, Luciola ficta Olivier will curl body and stretch forked-shape eversible organs after simulating. In the meantime, “pine oil” smell will be spread. Ten pairs of eversible organs distribute on meso- and metathorax, as well as the abdomen 1-8, above the tracheal gills on the pleural. The external structure of eversible organs of the fifth instar larvae is densely covered with flower-shaped protuberances. There are 3-6 petals on the protuberances, and no additional structure within protuberances. There are several hemi-spheres with hollow surrounding on the inner surface of eversible organs, which have mitochondrion inside. It should be the secretion gland that for defense. The protuberance and secretion gland connected with tube structure, should be the channel of secretion.
There are several conditions between different predators attack L. ficta larvae. It shows 16％ possibility that Coenagrionidae nymph prey on L. ficta larvae, and make firefly larvae injure or die. In that situation, Coenagrionidae nymph do not consume whole body of L. ficta larvae. In Loach (Misgurnus anguillicaudatus) experiment, they will attack L. ficta larvae several times within the experimental time, and then spit it out immediately. In the meantime, the firefly larvae will not be hurt. On the contrary, shrimp (Palaemonidae) will rotate L. ficta larvae and push aside their internal body part, then consume the larvae. There are different deterrent effects on different kinds of predators, the defense mechanism of L. ficta larvae should be the sense of taste, rather than the visual defense.
Using gas chromatography-Mass spectrometry (GC - MS) detect the secretion chemicals of larvae, and get 82 peaks. Ignore impurities and the peaks less than 0.05％, only get 12 peaks, possess about 85％ area. There are well known chemicals on 9 peaks within the analysis results. The peaks of results are simple and stable, the main components of secretion should play an important role in the chemical defense of L. ficta larvae.
The main components of eversible organs ranked from high to low are Terpinolene (relative area = 20.87％, RT = 17.35 min), L - (-) - Verbenone (relative area = 12.23％, RT = 21.13 min), (-) - Sabinene (relative area = 9.31％, RT = 11.07 min), Limonene (relative area = 1.28％, RT = 14.20 min), and γ - Terpinene (relative area = 1.22％, RT = 15.82 min), and so on.
Most of the secretions of L. ficta are monoterpene derivatives. These derivatives are confirmed that have deterrent effects, resistance of insects, and antibacterial properties. It can be produce by artificial synthesis in great quantity.
Add terpinolene concentration in 3 concentration, 0.0425％、0.425％、4.25％, into commercial fish food and mix with 2% agar. The control food without terpinolene, then feed predators with different concentration. There are obviously deterrent efficiency in Misgurnus anguillicaudatus and palaemonidae in different concentration.
3 terpinolene concentration ranked from low to high have 30％- 95％ deterrent efficiency of loach, and 20％- 80％ deterrent efficiency of shrimp. From the results, the tolerance of shrimp is higher than loach, fit in with the results of deterrent experiment of L. ficta.
Subjects
Luciola gicta
eversible organs
chemical defense
GC-MS
terpinolene
Type
thesis
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