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Asynchrony between Host Plant and Insects-Defoliator within a Tritrophic System: The Role of Herbivore Innate Immunity.

Martemyanov VV, Pavlushin SV, Dubovskiy IM, Yushkova YV, Morosov SV, Chernyak EI, Efimov VM, Ruuhola T, Glupov VV - PLoS ONE (2015)

Bottom Line: The effects of asynchrony in the phenology of spring-feeding insect-defoliators and their host plants on insects' fitness, as well as the importance of this effect for the population dynamics of outbreaking species of insects, is a widespread and well-documented phenomenon.We show that a phenological mismatch induced by the delay in the emergence of gypsy moth larvae and following feeding on mature leaves has negative effects on the female pupal weight, on the rate of larval development and on the activity of phenoloxidase in the plasma of haemolymph.This study also reveals some indirect mechanisms of effect related to host plant quality, which operate through the insect innate immune status and affect resistance to both exogenous and endogenous virus.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Insect Pathology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia; Biological Institute, National Research Tomsk State University, Tomsk, Russia.

ABSTRACT
The effects of asynchrony in the phenology of spring-feeding insect-defoliators and their host plants on insects' fitness, as well as the importance of this effect for the population dynamics of outbreaking species of insects, is a widespread and well-documented phenomenon. However, the spreading of this phenomenon through the food chain, and especially those mechanisms operating this spreading, are still unclear. In this paper, we study the effect of seasonally declined leafquality (estimated in terms of phenolics and nitrogen content) on herbivore fitness, immune parameters and resistance against pathogen by using the silver birch Betula pendula--gypsy moth Lymantria dispar--nucleopolyhedrovirus as the tritrophic system. We show that a phenological mismatch induced by the delay in the emergence of gypsy moth larvae and following feeding on mature leaves has negative effects on the female pupal weight, on the rate of larval development and on the activity of phenoloxidase in the plasma of haemolymph. In addition, the larval susceptibility to exogenous nucleopolyhydrovirus infection as well as covert virus activation were both enhanced due to the phenological mismatch. The observed effects of phenological mismatch on insect-baculovirus interaction may partially explain the strong and fast fluctuations in the population dynamics of the gypsy moth that is often observed in the studied part of the defoliator area. This study also reveals some indirect mechanisms of effect related to host plant quality, which operate through the insect innate immune status and affect resistance to both exogenous and endogenous virus.

No MeSH data available.


Related in: MedlinePlus

Effect of mismatch in egg hatch of L. dispar (a) on general mortality rate of insects until adults (mean±SE), and (b) on mortality rate induced by covert LdMNPV (mean±SE).The black line shows the percentage of viral DNA-positive eggs. The ANOVA statistics is presented within the figure. The letters above the bar mean the significant differences (at P<0.05) to be compared with the bars abbreviated by the same letters within the bar compared in detail by the Fisher LSD-method.
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pone.0130988.g004: Effect of mismatch in egg hatch of L. dispar (a) on general mortality rate of insects until adults (mean±SE), and (b) on mortality rate induced by covert LdMNPV (mean±SE).The black line shows the percentage of viral DNA-positive eggs. The ANOVA statistics is presented within the figure. The letters above the bar mean the significant differences (at P<0.05) to be compared with the bars abbreviated by the same letters within the bar compared in detail by the Fisher LSD-method.

Mentions: The total mortality rate of insects was not significantly affected by mismatch but there was a noticeable trend of the mortality rate increasing at 10 days of mismatch (Fig 4A). However, the etiology of mortality reveals the effect of mismatch on the mortality rate induced by covert LdMNPV with the maximal value at 20-days' mismatch (Fig 4B). PCR analysis revealed that 16% of the eggs of the stock of the L. dispar cohort contained the cover virus above the detection limit (Fig 4B, the black line). Thus, the maximal mismatch in the hatching induced viral pathogenesis in more than half of the larvae that carried a covert viral infection (the mortality rate in Fig 4B to compare with the black line).


Asynchrony between Host Plant and Insects-Defoliator within a Tritrophic System: The Role of Herbivore Innate Immunity.

Martemyanov VV, Pavlushin SV, Dubovskiy IM, Yushkova YV, Morosov SV, Chernyak EI, Efimov VM, Ruuhola T, Glupov VV - PLoS ONE (2015)

Effect of mismatch in egg hatch of L. dispar (a) on general mortality rate of insects until adults (mean±SE), and (b) on mortality rate induced by covert LdMNPV (mean±SE).The black line shows the percentage of viral DNA-positive eggs. The ANOVA statistics is presented within the figure. The letters above the bar mean the significant differences (at P<0.05) to be compared with the bars abbreviated by the same letters within the bar compared in detail by the Fisher LSD-method.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482610&req=5

pone.0130988.g004: Effect of mismatch in egg hatch of L. dispar (a) on general mortality rate of insects until adults (mean±SE), and (b) on mortality rate induced by covert LdMNPV (mean±SE).The black line shows the percentage of viral DNA-positive eggs. The ANOVA statistics is presented within the figure. The letters above the bar mean the significant differences (at P<0.05) to be compared with the bars abbreviated by the same letters within the bar compared in detail by the Fisher LSD-method.
Mentions: The total mortality rate of insects was not significantly affected by mismatch but there was a noticeable trend of the mortality rate increasing at 10 days of mismatch (Fig 4A). However, the etiology of mortality reveals the effect of mismatch on the mortality rate induced by covert LdMNPV with the maximal value at 20-days' mismatch (Fig 4B). PCR analysis revealed that 16% of the eggs of the stock of the L. dispar cohort contained the cover virus above the detection limit (Fig 4B, the black line). Thus, the maximal mismatch in the hatching induced viral pathogenesis in more than half of the larvae that carried a covert viral infection (the mortality rate in Fig 4B to compare with the black line).

Bottom Line: The effects of asynchrony in the phenology of spring-feeding insect-defoliators and their host plants on insects' fitness, as well as the importance of this effect for the population dynamics of outbreaking species of insects, is a widespread and well-documented phenomenon.We show that a phenological mismatch induced by the delay in the emergence of gypsy moth larvae and following feeding on mature leaves has negative effects on the female pupal weight, on the rate of larval development and on the activity of phenoloxidase in the plasma of haemolymph.This study also reveals some indirect mechanisms of effect related to host plant quality, which operate through the insect innate immune status and affect resistance to both exogenous and endogenous virus.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Insect Pathology, Institute of Systematics and Ecology of Animals SB RAS, Novosibirsk, Russia; Biological Institute, National Research Tomsk State University, Tomsk, Russia.

ABSTRACT
The effects of asynchrony in the phenology of spring-feeding insect-defoliators and their host plants on insects' fitness, as well as the importance of this effect for the population dynamics of outbreaking species of insects, is a widespread and well-documented phenomenon. However, the spreading of this phenomenon through the food chain, and especially those mechanisms operating this spreading, are still unclear. In this paper, we study the effect of seasonally declined leafquality (estimated in terms of phenolics and nitrogen content) on herbivore fitness, immune parameters and resistance against pathogen by using the silver birch Betula pendula--gypsy moth Lymantria dispar--nucleopolyhedrovirus as the tritrophic system. We show that a phenological mismatch induced by the delay in the emergence of gypsy moth larvae and following feeding on mature leaves has negative effects on the female pupal weight, on the rate of larval development and on the activity of phenoloxidase in the plasma of haemolymph. In addition, the larval susceptibility to exogenous nucleopolyhydrovirus infection as well as covert virus activation were both enhanced due to the phenological mismatch. The observed effects of phenological mismatch on insect-baculovirus interaction may partially explain the strong and fast fluctuations in the population dynamics of the gypsy moth that is often observed in the studied part of the defoliator area. This study also reveals some indirect mechanisms of effect related to host plant quality, which operate through the insect innate immune status and affect resistance to both exogenous and endogenous virus.

No MeSH data available.


Related in: MedlinePlus