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Introduction:
Glyptapanteles
is a genus consisting of hundreds of species of
endoparasitic wasps that parasitize caterpillars of several moth species such
as Thyrinteina leucocerae and Lymantria
dispar, which are common pest found throughout the world [1]. Glyptapanteles species are used to
control populations of gypsy moths in Europe, Asia and the Americas. Glyptapanteles sp. female wasps
parasitize the gypsy moth larvae by laying eggs in the host [1]. The
wasp larvae then continue to exploit the hosts for nutrients and protection;
this involves complete takeover of the caterpillar and eventually its demise.
Symbiont
Description:
Glyptapanteles
sp. female wasps parasitize the Lymantria dispar and Thyrinteina leucocerae caterpillars by laying eggs in the host
during the early instars, phases between larva molting stages[1]. The
female wasp has an organ called an ovipositor that it used to insert eggs into
the host [1]. The wasp larvae exploit the host’s body fluids for nutrients
and continue to grow until they are prepared to pupate. The Glyptapanteles pupae exit the host and immediately
begin to spin their cocoon. After the parasitoid exits from the host the
caterpillar’s behavior begins to change, it positions itself near the cocoons, and
stops eating and moving, therefore becoming the bodyguard of the Glyptapanteles sp. [3]. The
most astounding behavioral change observed is the violent head trusting that
the caterpillar engages in as to ward off predators that may eat the Glyptapanteles pupae [3]. These
behavior changes are thought to be due to a virion found in the genome of the
female wasp that is transferred to the gypsy moth along with the Glyptapanteles eggs [2]. The
viral genes disrupt the host immune response and development, ensuring the
survival of the Glyptapanteles larvae
[2]. After the Glyptapanteles pupae
become adult wasps the host caterpillar dies.
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Host
Description:
Glyptapanteles species are holoxenous because they only infect one host, the
caterpillar larvae stage of various species of moths including Lymantria
dispar, Chrysodeixis chalcites
and
Life Cycle:
Glyptapanteles species have four life stages: egg, larva, pupa, and adult. Their life cycle beings when a female wasp lays its eggs on a caterpillar host. The eggs become larvae inside the caterpillar and then pupate outside of the host. After some time, the pupae become adult wasps. There is only one host required for the life cycle of Glyptapanteles species. Glyptapanteles species can use venom to paralyze their host temporarily to enable the female wasps to lay their eggs. Furthermore, the phenotypic effects of the virions transmitted along with the eggs promote the completion of the Glyptapanteles life cycle.
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Ecology:
This parasitic relationship is important to the management of gypsy moths
throughout Europe, Asia and the Americas. Glyptapanteles
species are often introduced in non-native environments for the purpose of controlling
moth populations. Some of the hosts of Glyptapanteles
species include gypsy moths or noctuidae that feed on foliage making them common
agricultural and domestic pests. These pests were estimated to cause
approximately $410 million decrease per year in property value in the United
States [4].
An Example
of Extended Phenotype:
The behavioral modifications observed in the host caterpillars are
an example of extended phenotype in a durable interaction. The virions that are
present in the female wasp are translated in the host caterpillar and induce
the discontinuation of eating and moving, and the head thrust that are crucial
for the survival of the Glyptapanteles pupae.
References:
1. Schopr, A, and Steinberger P. (2001) The influence of the endoparasitic
wasp Glyptapanteles liparidis
(Hymenoptera: Braconidae) on the growth, food consumption, and food utilization
of its host larva, Lymantria dispar
(Lepidoptera: Lymantriidae. Journal of Invertebrate Pathology. 77(1): 37-43. doi.org/10.1006/jipa.2000.4987
2. Desjardins
CA, Gundersen-Rindal DE, Hostetler JB, Tallon LJ, Fuester RW, et al. (2007) Structure
and Evolution of a Proviral Locus of Glyptapnateles
indiensis bracovirus. BMC Microbiology, 7(61): doi:10.1186/1471-2180-7-61 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1919376/
3. Grosman
AH, Janssen A, de Brito EF, Cordeiro EG, Colares F, et al. (2008) Parasitoid
Increases Survival of Its Pupae by Inducing Hosts to Fight Predators. PLoS ONE
3(6): e2276. doi:10.1371/journal.pone.0002276 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0002276
4. Aukema JE,
Leung B, Kovacs K, Chivers C, Britton KO, et al. (2011) Economic Impacts of
Non-Native Forest Insects in the Continental United States. PLoS ONE 6(9):
e24587. doi:10.1371/journal.pone.0024587 http://journalistsresource.org/studies/environment/sustainability/invasive-forest-insects/
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