Methods Of The Gypsy Moth Control - Research Paper Example

Methods Of The Gypsy Moth Control Natural History of the Gypsy Moth The Gypsy Moth (Lymantria dispar dispar) is a native species from Europe and Asia regions; nevertheless, the species has currently spread in Europe Africa and the North America regions. It was first introduced into North America region in 1869; however, it was first discovered in British Columbia province in 1912, Canada after the country imported cedar seedlings from Japan, which contained the eggs. This insect is polyphagous as it injures plants growth by chewing up leaves becoming the most significant defoliators of hardwoods in North America, a characterized that made it to be categorized as a pest. The initial invasion took place in 1924 close to the United States borders in the Quebec province of Canada while the second invasion by the moth took place in 1936 in the maritime province of New Brunswick. Etienne Leopold Trouvelot, a French biologist introduced it in 1890 so as to commercially exploit them for silk production. Unfortunately, hundreds of the species escaped and rapidly increased in numbers causing a devastating effect on the foliage coverage in the state of Massachusetts. The Asian strain was introduced into the country in the Northwestern region of the United States and on the Canadian borders by US military equipment from Russia and Germany (Baskin 167). Consequently, in the United States the European strain of the moth is more common while in Canada it is the Asian strain; for sustenance, the insect feeds and lives on over hundreds of species of hardwood trees, conifer and shrubs but they depend on the oak trees. It has been observed that in the eastern United States the invasive species prefer oaks, apple, black hawthorn, basswood, aspens, sugar maple, cottonwoods and a host of other plant species. Problems Associated with the Plant Species The damage by gypsy moth is entirely caused by the caterpillars and this happen episodically in May as they the larvae emerges from the eggs laid by the moth in the winter season. Several researches focusing on the economic and environmental effect of the pest revealed that it has devastating effect on aesthetic, recreational and home values in infested regions. The larva begins feeding on the host species in response to sunlight and ravenously chews the plant leaves as they go through their growth life cycles. They grow in size and this increases their appetite for more foliage critically hampering plants growth. The caterpillars achieve maturity stage in mid June and there after seek new hosts to and pupate- this the stage when they finally develop into moths. In the regions where the species has invaded, they end becoming a nuisance to area residents as they gather in immense numbers on lawns, vehicles, sidewalks and in building. In regions where they are low in density, caterpillars populate in cracks of rocks and plants, under the branches of some trees or on moist grounds covered by leaves. In regions with where the caterpillars have a high population density the destructive species pupate everywhere. Gypsy moth appetite for foliage is a threat to the ecosystem of those regions and this implies that they would affect the natural balance that exists amongst plant and animal species living in these regions. This results in both environmental damage and the economic loss when trying to eradicate the species from the infested region. During the 1988 outbreak in Pennsylvania the species defoliated more than 16 million acres of a variety of hardwood, the state estimate than during the outbreak more than $72 million dollars in timber losses was actualized( Wallner). In the year 2006, up to 700, 000 acres of woodlands in the same Pennsylvania were victims to the defoliating species, this resulted in mortality of up to half of the oak trees defoliated, and subsequently others crumbled in the next year (Napsha). It is estimated that more than $219 million were spent on efforts to eradicate the species in the years between 1968 and 1985 and $17 million were spent in the year 2006 to 2009 in a similar endeavor in the State of Pennsylvania alone. It is estimated that more than a million acreages of trees have been defoliated by the species in the North Eastern region of the United States alone excluding Canada. In the United States, the species contributes to an annual loss of up to $868 million and it emerged as the most destructive inspect species. Currently three quarters of hardwood regions in the United States are not in the regions infested by the species, further poking fear into the threat of its spread either southwards or westwards. This means that such annual loss incurred in the eradication of the destructive moth could ultimately spiral much higher if sufficient intervention programs are not employed. Control mechanism of the Gypsy Moth Bt (Bacillus thuringiensis) a bacterial insecticide can be used to contain and eradicate the spread and infestation of the gypsy moth, available as either Dipel or Thuricide. The bacterial insecticide can be sprayed using the familiar backpack or alternatively in a huge area aerial spraying would be effective. The most effective date to spray the insects is during mid may when the eggs have just hatched and the larva begins crawling out. This is the second and that instars when the larvae are approximately three quarters inch in length. Bt is a naturally occurring bacterium and many consider it as the safest insecticide, this is because it does not affect human beings and other plant and animal species and only fatal to caterpillars of the moths. This bacterium unlike other insecticides does not kill the moths through contact but rather after ingestion. This means that the insecticide is sprayed on the branches, thereafter the moths feed on the leaves, which ultimately leads to their deaths. The most crucial strategy to be considered when attempting to control the moths is time, this is very crucial as the importance of the period in which the moths go through their life cycle aids in the eradication process. Additionally, weather patterns must be considered, during the rainy season spraying the leaves with the Bt insecticides might run up to a loss as the rains might wash away such an investment. Similarly, a careful appraisal of the area must be efficiently carried out to determine whether the area is actually infested by the insects. This presents the most obvious disadvantage of using Bt as to control the pest, weather patterns and life cycle of the caterpillar of the moth. Other alternative and widely used methods of controlling this pest include chemical, predatory and parasitic intervention strategies. However, parasitic, predatory and pathogenic interventions by reptiles such lizards and geckos, and mammals especially mice, rats and other insects naturally occur in the ecosystems without interference by human roles. There are other commercially available parasitic insects that can be used to control the moths, this is the Trichogramma and they have been advertised aggressively as control agents. Chemicals used to control the moths are Diflubenzuron and Tebufenozide kill the pest when they are exposed to the caterpillars of the moths. However, use of these chemicals is disadvantageous since they have very drastic harmful effects to mammals. The other two chemicals used include DDVP and disparlure they also exhibit toxological effects on humans though different from the effects on the other two, though the later has not been conclusively studied to determine its effects on mammals. In the laboratories polyhedrois (NPV) virus has been used to kill caterpillars of the gypsy moth, they do this by infecting caterpillars. They can prove effective over period of about 2 to 3 year as they normally collapse the outbreak of these moths within the period. This control mechanism may be very effective but supply may be limited because they can only be generated from live caterpillars and this hampers efforts to fully use them. A certain type fungus Entomophaga maimaiga infects the moth by causing a disease and can immensely affect the low population of the gypsy moth. In favorable and proper weather conditions, the fungus multiplies at a very high rate in the given region thereby killing the moths during the caterpillar stage. Summary The use of the parasitic wasp, which belongs to the genus Trichogramma attacks indigenous species of butterflies and moths and not the gypsy’s eggs. The use of this control method can be disastrous to the naturally occurring ecosystem that is if the wasp invades such native species. NPV is said to be achieve good results when applied in regions where the moth is said to be densely populated. The fungus mentioned above is highly dependent on the weather patterns and are only effective during the spring period; moreover, the fungus may prove unsuccessful during a severe outbreak of the moth in a particular area. Bt can be applied aerially this is because they are very harmless to plants and animals, the only drawback is that they can only be used during the larvae stage of the moth life cycle and that the aerial applicability of the insecticide is usually ineffective when applied aerially. However, given the correct timing they can prove to be the most effective of the other methods. Just like the NPV Bt method can have a negative impact on the environment; this is because they can also harm other native moth and butterfly species. Additionally, both the two methods can harmfully affect endangered and sensitive species of butterflies and moths. Application of other chemical methods such as using Diflubenzuron can have harmful consequences and effects on non-target plants and animal species (Simser and Moran). Gypsy outbreaks usually threaten to occur despite aggressive and consistent control mechanisms and other natural control mechanisms. However the effectiveness of most of these control mechanisms is highly dependent on climatic conditions for instance, natural control mechanisms such as the Entomophaga rely on weather patterns to expose their potential means. Other mechanisms such as Bt and the NPV virus are also effective on certain life cycle of the moth and Bt in particular is very effective given that there is no rain to wash away the insecticide (Shetlar, Mary and Herms). The moth has led to serious shocking effects in the United States and Canada and overseas native land of the species; therefore, eradication of the species has proved futile and the only available option for policy makers is the application of correct control measures. Works Cited Baskin, Yvonne. A Plague of Rats and Rubbervines: The Growing Threat of Species Invasions. Washington, DC: Island Press/Shearwater Books, 2002. Print. Napsha, Joe. W.Pa. trees get reprieve from gypsy moth attacks; other regions not so lucky. Trib Total Media. 2013. Web. 13 June 2013 Wallner, W. E. “Global Gypsy -The Moth That Gets Around”. Invasive.org. 2002. Web. 13 June 2013 Simser, Dave and Moran Pam. “Gypsy Moth Control”. New Alchemy Institute. n.d. Web. 13 June 2013 Shetlar, David, J , Mary, Donell and Herms, Daniel, A. “Controlling the Gypsy Moth with BT”. Ohio State University n.d. Web. 13 June 2013 Read More