Notonecta undulata: Difference between revisions - Wikipedia

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== ''Notonecta undulata'' ==

''Notonecta undulata'' also known by the common name Grousewinged backswimmer are from the family [[[Notonectidae]]| Notonectidae]]and the insect suborder [[[Heteroptera]]| Heteroptera]]. They are a type of hemipteran or [[[True bug]]| true bug]]. These aquatic insects typically spend their time at the water's surface, using their abdomen and legs to cling to the underside of the [[[Surface tension]]| surface tension]]. The Grousewinged backswimmer can be found in both lotic and [[[Lentic]]| lentic]] environments, however they typically prefer small ponds and lakes where the water is slow moving with less current. They swim upside down looking for prey. Once they stop swimming they float back up to the surface. These insects can be distinguished from water boatman or [[[Corixidae]]| Corixidae]] by their segmented beak and front legs. Water boatman have highly modified front legs where as back swimmers do not.<ref name="Brooks and Kelton, 1972">Arthur R. Brooks and Leonard A. Kelton. Aquatic and Semiaquatic Heteroptera of Alberta, Saskatchewan and Manitoba (Hemiptera). 1972. Memoirs of the Entomological Society of Canada 51:38-41</ref>. Backswimmers are distributed across a broad range throughout [[[North america]]| North America]]. However, the species ''Notonecta undulata'' has only been documented and studied in southern [[[Manitoba]]| Manitoba]],[[[Saskatchewan]]| Saskatchewan]], [[[Alberta]]| Alberta]] and the western [[[United states]]| United States]]. N. undulata differs from other back swimmers by their antennae and size. They are approximately 10-12 mm long and their [[[Antenna (biology)]]| antennae]] are 4 segmented <ref name="Brooks and Kelton, 1972" />

==== Taxonomy and Morphology ====

''Notonecta undulata'' is the linnaean name for Grousewinged backswimmer. This species is classified as a true bug under the suborder heteroptera. They are located under the family Notonectidae which is divided into two subfamilies: Notonectinae and Anisopinae. Individuals that are in the subfamily Notonectinae are distinguishable from their Anisopinae relatives by their 4 segmented beak and antennae. Insects from the subfamily Notonectinae are also larger, approximately 10-16 mm in length. ''N. undulata measure'' 10-12 mm.<ref name="Brooks and Kelton, 1972" />. Grousewinged back swimmers can range from a dull greenish yellow to black. The head of back is convex and the antennae are short and concealed beneath the eye.The [[[Scutellum (insect anatomy)]]| scutellum]] is usually black with pale spots on the sides and at the apex. The hind [[[Tibia]]| tibiae]] and [[[Arthropod leg]]| tarsus]] have dense bristle like hairs that make them appear oar like. This allows them to be efficient swimmers, however, it has been documented that members of the genus ''Notonecta'' are not as good at swimming as ''Buenoa sp.'' The front and middle tarsi have apical claws; however, the hind tarsi are claw less. There are 5 points on the backswimmer that allow it to attach to the surface film of the water.<ref name="Murphey and Mendenhall, 1973">R.K Murphey and Barbara Mendenhall. Localization of Receptors Controlling Orientation to the Prey by Backswimmer ''Notonecta undulata''Journal of Comparative Physiology 84: 19-30</ref>. These 5 points include the anterior legs and the abdomen of the insect. There are receptors associated with each of these points that help the insect in locomotion and capturing prey. Grousewinged backswimmers also lack [[[Ocellus#Ocelli]]| ocelli]]. The need to detect light was mostly likely lost through natural selection due to a variety of environmental pressures. Their beak is stout and the [[[Ventral#Dorsal and ventral]]| ventral]] surface of the abdomen has a prominent hairy keel. The front and middle legs are approximately one half shorter then the hind legs and the [[[Femur]]| femur]] is enlarged basally.The wing membrane also has a large black spot on the median line and the hemelytra are pale <ref name="Brooks and Kelton, 1972" />

Prior to 1917, there had been no complete description of the ''Notonecta'' [[[Genus]]| genus]] until H.B Hungerford described the species ''N.undulata'' under the Kansas University Science Bulletin. Today, the species ''N.undulata'' is not well documented. Scientific literature and taxonomy referenced range between the 1920's and 1970's, with only a few articles published after the 1990's. Taxonomic classification of the species remains similar today as it did 40 years ago.

==== Habitat and Ecology ====

''N. undulata'' typically inhabit ponds and lakes but have been known to occupy small streams or rivers when resources become limited or competition in lentic environments is too high <ref name="(Streams, 1982)">Frederick A. Streams.Diel Foraging and Reproductive Periodicity in ''Notonecta undulata'' Say (Heteroptera).1982. Aquatic Insects 4:111-119</ref>. Back swimmers will maximize conditions by flying and seeking out areas to settle. It is has also been tested that the Grousewinged backswimmer will have a higher dispersal rate when predation levels increase in the environment <ref name="McCauley and Rowe, 2010"> Shannon J. McCauley and Locke Rowe. ''Notonecta exhibit threat-sensitive, predator induced dispersal.2010. Biology Letters 4: 448-452</ref>. Ponds have a greater surface area to volume ratio of vegetation than lakes which increases the amount of hiding places and food for the insect. This makes ponds one of the best locations for the back swimmer. These insects may prefer ponds because the distribution of ''N. undualata'' depends on food supply. It has been found that ponds and [[[Wetlands]]| wetlands]] have a higher diversity of organisms which is often related to nutrient and food resources <ref name="Dodds and Whiles, 2010">Walter Dodds and Matt Whiles. Fresh Water Ecology: concepts and environmental factors of limnology. 2nd ed. Depatment of Ecology and Evolutionary Biology. 2010</ref>. Temperature can also effect the distribution of Grousewinged backswimmers. Scientific study has shown that ''N.undulata'' is capable of surviving over a wide range of temperatures and conditions. They have been known to withstand temperatures ranging from 4-32°C and water hardness between 28-220 ppm <ref name="Ellis and Borden, 1969)">R.A Ellis and J.H Borden. Effects of Temperature and other Environmental Factors on ''Notonecta undulata'' (Hemiptera:Notonectidae)1969.Annals of the Entomological Society of America 45:20-29</ref>. In nature, they will avoid temperatures higher than 32°C by flying and searching out new locations; however, they can withstand them for short periods of time through the use of their cuticular [[[Lipid]]| lipid]] [[[Monolayer]]| monolayer]]. This physiological adaptation allows them to uptake water and avoid dehydration when temperatures get too high <ref name="Ellis and Borden, 1969)" />. The pH level of water can also affect the back swimmer's choice of habitat or [[[Ecological niche]]| niche]]. N.undulata has been documented to prefer pH levels between 6.0 and 7.1, a relatively normal water acidity.Environmental factors such as pH, temperature and trophic interactions effect the ecology of the Grousewinged backswimmer.

Predator prey interactions are another factor effecting back swimmer ecology. ''Notonecta'' are generalist predators that attack and consume many types of aquatic inverebrates and terrestrial prey that fall on the surface of the water <ref name="Streams, 1994">F.A Streams.Effect of Prey Size on attack Components of the Functional Response by ''Notonecta undulata''.1994.Oecologia 98: 57-63</ref>. They are known to prey on small [[[Crustacea]]| crustacea]], nymphs and adults of corixids, dragonfly nymphs, [[[Caddisfly]]| caddisflies]] and fish eggs<ref name=" Clark, 1928 ">L.B, Clark. Seasonal Distribution and Life History of ''Notonecta undulata in the Winnipeg Region of Canada. 1928. Ecology 9: 383-403</ref>. Specifically, ''N.undulata'' prefers to eat mosquito larvae over any other type of invertebrate. Studies have been conducted between the Grousewinged back swimmer and ''[[[Aedes aegypti]]| Aedes aegypti]]'', a type of mosquito that has been known to act as a vector for [[[Malaria]]| malaria]] and [[[Yellow fever]]| yellow fever]]. As a consequence, ''N. undulata'' has been suggested as a prudent [[[Biological pest control]]| biological control]] <ref name="Toth and Chew, 1972">Robert S. Toth and Robert M. Chew. Development and Energetics of ''Notonecta undulata'' during predation on ''Culex tarsalis''. 1972. Annals of the Entomological Society of America 63: 1270-1281</ref>. `

==== Reproduction ====

The Grousewinged back swimmer is [[[Bivoltine]]| bivoltine]].<ref name="Cummins and Berg, 2008">K.W. Cummins and M.B. Berg. An Introduction to the Aquatic Insects of North America. Fourth Ed.Kendall Hunt Publishing Company. 2008</ref>. Females of the first generation become adults and reproductively mature in July producing a second generation. The adults that become mature after July enter reproductive diapause which ends by late October. All ''N.undulata'' will overwinter in the adult stage and begin depositing eggs in the early spring. Eggs develop through 5 nymphal [[[Instars]]| instars]] during the spring and summer <ref name="Vanderlin and Streams, 1977">Robert L. Vanderlin and Frederick A. Streams. Photoperiodic Control of Reproductive Diapause in ''Notonecta undulata''. 1977. Environmental Entomology6:258-262</ref>. The preoviposition period lasts 16 days and eggs tend to be laid in ponds or calmer lakes rather than fast flowing streams. The eggs are attached to plants or other suspended objects within the water column. They are elongate ovals, usually 1.7 mm x 0.6 mm. The incubation period lasts 5-14 days and oviposition is continuous in summer <ref name="Cummins and Berg, 2008" />

== References ==