Weed Science Vol. 51(3): pp. 449-455.
The purple loosestrife is the cause of a lot of destruction to the habitat around it, and it has been shown that two particular species of beetles, Galerucella calmariensis and G. puscilla, are very effective at controlling the loosestrife. But with any biocontrol method, they have their downsides, and one of the big ones is their effect on several species of native plants, one of which is the crepe myrtle. To help assess whether it is more beneficial ecologically to release the beetles to control the loosestrife, Schooler et al. preformed a test to see the relationship between distance from the released beetle colony and damage done to the crepe myrtle. They found that as you get further away from the colony of beetles, the damage to the crepe myrtle also decreases, and at 50 meters away, the damage is basically zero to the plants. The plants were actually not too severely damaged, because the beetles couldn’t complete development on the crepe myrtle, so these results suggest that though there was damage, that the beetle’s introduction to control the purple loosestrife would still be more beneficial overall.
Marine Pollution Bulletin 54, 1170-1178 (2007)
Aquatic invasive species detrimentally affect the ecosystems they invade. Many invasive species are transported very long distances to environments in which they are nonindigenous in ship ballast water. An experiment on the deoxygenation of ballast water suggests that the control method could cause high mortality rates of aquatic life in ballast tanks.
Tracy McCollin of the Fisheries Research Services Marine Laboratory and his colleagues tested the efficacy of deoxygenating water as a treatment method for eradicating aquatic life in the ballast tanks. The researchers conducted a full scale experiment in actual ballast tanks. They found that the method was effective on zooplankton, however, their phytoplankton results were inconclusive. The deoxygenation method may provide a simple and relatively cheap way to prevent aquatic invasive species from spreading for foreign environments.
Journal of Great Lakes Research 35 (2009) 608-612
The spawning and nesting behaviors of the invasive round goby (Neogobius melanostomus) were observed in laboratory conditions in a recent study. Meunier and his colleagues, working with the University of Windsor, collected round gobies and placed them in tanks in their laboratory which contained nests. They did not observe any spawning activities until they lowered the temperature and available food to simulate winter conditions, then increased the temperature and food supply to simulate the arrival of spring. Male round gobies excavated nests and guarded them until a female that they deemed suitable arrived. The female was allowed to enter the nest and deposit eggs, which the male then fertilized. After the female departed, males continued to guard the nest against intruders using vocalizations or even chasing them away. In the study, the males eventually ate the eggs in their nest, though it was concluded that this cannibalism was only a result of the laboratory conditions and small brood size.
Entomophaga 30(3): 279-286
Biological control using the Cyrtobagous salviniae weevil is a popular control method for giant salvinia. Both the effectiveness of biocontrol and the growth rate of the plant are reliant on environmental conditions such as nitrogen levels and temperature.
Forno and Bourne (1985) examined how temperature, nitrogen content of the plant, and density of weevils altered the effectiveness of the weevil. The results showed that high-density populations of weevils (4 adults/bud) at high temperatures had significant damage to the plant. However, plants with low-density populations (1 adult/bud) developed buds faster than control plants with no insects. Varying nitrogen levels in plant tissue, however, did not influence plant development. The study suggested that high temperatures and high population density is the weevil are more important for reducing giant salvinia growth than a high nitrogen content.
In their study, Longcore et. al. (2007), from the Patuxent Wildlife Research Center, wanted to determine whether B. dendrobatidis is infecting amphibians from the Northeast. B. dendrobatidis is a chytrid fungus that is known to kill amphibians and even cause species to go extinct. There is a specific temperature and weather range B. dendrobatidis can thrive in, so Longcore et. al. (2007) also wanted to determine whether temperature and whether effected infection rates in the amphibians. In addition, researchers hoped to find out whether or not gender, species and age correlate with higher infection rates. Finally, Longcore et. al. (2007) also wanted to determine if detection rates differ between fresh and fixed tissue examinations.
Longcore et. al. (2007) collected data from areas throughout New England. They employed citizen science to collect road kill amphibians, and, when these were not enough, researchers also collected amphibians from select sites throughout New England. Most amphibians came from Maine, and many were from wild life refuges and National parks. Upon gathering the amphibians, researchers cut skin samples primarily from the animals’ toe webbing and between their hind legs. Researchers then examined some of these samples fresh under a microscope and others after fixing and staining them. B. dendrobatidis can be detected with relative accuracy under a microscope at 100-400x and 1000x magnification in both sample types.
Longcore et. al. (2007) found that infection rates varied between the nine species studied and among locations. Most all areas and species were infected with B. dendrobatidis. Generally aquatic habitat hibernators had higher infection rates than terrestrial habitat hibernators, presumably because B. dendrobatidis zoospores are typically present only in water. Infections rates did not vary significantly between young and adult amphibians. Neither fresh sample analysis nor fixed sample analysis was completely accurate, but they were accurate an equally high percentage of the time.
Longcore, Jerry R., J.E. Longcore, A.P. Pessier, and W.A. Halteman. 2007. Chytridiomycosis Widespread in Anurans of Northeastern United States. Journal of Wildlife Management 71: 435-444.