BP 2 Linda Morehead

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Contents

Location of collection:

Beaver Pond on Georgia Gwinnett College campus

Date of Collection:

August 2012

Pictures

Caption Overview from above Caption Close up of Tail

Caption Close up of Head Caption Extended Jaw or Scoop

Distinguishing morphological features of Order:

When identifying nymphs, the important features to look for are (1):

  • short, stiff pointed valves at the tip of the abdomen
  • when extended, the jaw or "prementum and palpal lobes" form a scoop-shaped structure
  • the scoop has even sized "teeth" near the v-shaped opening at its end
  • the spikes at the very back and bottom of the nymph are nearly the same size when compared to each other
  • there is no "horn" between its antennae

Classification:

Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Odonata
Family: Libelluloidea
Genus: Unknown
Species:unknown

Our specimen is not an adult but rather is a nymph. Without DNA information or advanced taxonomic skills we are not able to classify it beyond its family. It is most likely one of the 23 species shown in the list below, that have been identified to be in Gwinnett County, Ga (2):

Common Name Latin Name
Red-veined Pennant (Celithemis bertha)
Calico Pennant (Celithemis elisa)
Halloween Pennant (Celithemis eponina)
Banded Pennant (Celithemis fasciata)
Swift Setwing (Dythemis velox)
Eastern Pondhawk (Erythemis simplicicollis)
Little Blue Dragonlet (Erythrodiplax miniscula)
Blue Corporal (Ladona deplanata)
Golden-winged Skimmer (Libellula auripennis)
Spangled Skimmer (Libellula cyanea)
Slaty Skimmer (Libellula incesta)
Widow Skimmer (Libellula luctuosa)
Great Blue Skimmer (Libellula vibrans)
Roseate Skimmer (Orthemis ferruginea)
Blue Dasher (Pachydiplax longipennis)
Wandering Glider (Pantala flavescens)
Spot-winged Glider (Pantala hymenaea)
Eastern Amberwing (Perithemis tenera)
Widow Skimmer (Plathemis lydia)
Blue-faced Meadowhawk (Sympetrum ambiguum)
Autumn Meadowhawk (Sympetrum vicinum)
Carolina Saddlebags (Tramea carolina)
Black Saddlebags (Tramea lacerata)

Geographical Distribution:

Dragonflies are found all over the world. The nymphs are normally found in freshwater - most often in slow-moving streams or ponds. Adult dragonflies usually stay near water as well but hunt in open areas that are free of thick trees or other dense vegetation. (3)

Life cycle:

Eggs are laid in freshwater in late summer or fall and hatch in spring. Depending on the species they may spend several months to several years as aquatic predators. During this nymph stage, they molt several times. The final molt happens in late spring or summer and involves the nymph crawling out of the water and emerging as a winged adult. Some adult dragonflies migrate to warmer climates in the winter, however the adult stage is usually short lived and lasts only a few months until reproduction is complete and eggs are laid. (3)

Sexual dimorphism:

When mature, female dragonflies are almost always bigger and heavier than males. During the immature nymph stage, there is no discernible differences between the sexes. (4)

Ecological and Economic Importance:

In fishless ponds, dragonfly nymphs are sometimes at the top of the food chain. The nymphs eat other aquatic insects, tadpoles and invertebrates. In ponds with fish, dragonfly nymphs may eat the smaller fish but are preyed upon by larger fish. Adult dragonflies eat just about any flying insect they can grab but especially mosquitoes. Their main economic impact is mosquito control. (3)


PCR Gel:

We extracted DNA from our specimen and used PCR to amplify the mitochondrial gene Cytochrome c oxidase, subunit 1 (CO1). The image below shows a DNA fragment corresponding to the correct size for the gene of interest, indicating our PCR was successful. This DNA was sent out for sequencing but did not return any usable data.

Bp2gel.jpg

References

1. Sarah, Nelson. "Dragonfly Larvae Identification Key." Dragonfly Larvae Identification Key. Acadia Learning, n.d. Web. 30 Nov. 2012. <http://www.parkcitizenscience.org/dragonfly/>.

2. Dobbs, Marion. "Dragonflies and Damselflies (Odonata) of Georgia." Dragonflies and Damselflies (Odonata) of Georgia. N.p., n.d. Web. 30 Nov. 2012.

3. George, Hammond. "Dragonflies." BioKIDS - Kids Inquiry of Diverse Species. University of Michigan, n.d. Web. 30 Nov. 2012. <http://www.biokids.umich.edu/critters/Anisoptera/>.

4. Anholt, B. R.; Marden, J. H.; Jenkins, D. M.. "Patterns of mass gain and sexual dimorphism in adult dragonflies (Insecta: Odonata") Canadian Journal of Zoology, 1991, 69:1156-1163, 10.1139/z91-164. <http://www.nrcresearchpress.com/doi/abs/10.1139/z91-164#.ULixn-TAeSo>.

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