Intrastadial developmental resistance of third instar gypsy moths (Lymantria dispar L.) to L. dispar nucleopolyhedrovirus

Grove, Michael; Hoover, Kelli

doi:10.1016/j.biocontrol.2006.12.003

Cited by 37 publications

(32 citation statements)

References 25 publications

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“…Within an instar, developmental resistance of the gypsy moth to LdMNPV has been found to be unrelated to larval weight (Hoover et al 2002;Grove and Hoover 2007). In our study, no evidence was found of a relationship between larval size and disease resistance in the absence of crowding.…”

Section: Discussioncontrasting

confidence: 76%

Density-dependent resistance of the gypsy moth Lymantria dispar to its nucleopolyhedrovirus, and the consequences for population dynamics

Reilly

Hajek

2007

Oecologia

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The processes controlling disease resistance can strongly influence the population dynamics of insect outbreaks. Evidence that disease resistance is density-dependent is accumulating, but the exact form of this relationship is highly variable from species to species. It has been hypothesized that insects experiencing high population densities might allocate more energy to disease resistance than those at lower densities, because they are more likely to encounter density-dependent pathogens. In contrast, the increased stress of high-density conditions might leave insects more vulnerable to disease. Both scenarios have been reported for various outbreak Lepidoptera in the literature. We tested the relationship between larval density and disease resistance with the gypsy moth (Lymantria dispar) and one of its most important density-dependent mortality factors, the nucleopolyhedrovirus (NPV) LdMNPV, in a series of bioassays. Larvae were reared in groups at different densities, fed the virus individually, and then reared individually to evaluate response to infection. In this system, resistance to the virus decreased with increasing larval density. Similarly, time to death was faster at high densities than at lower densities. Implications of density-resistance relationships for insect-pathogen population dynamics were explored in a mathematical model. In general, an inverse relationship between rearing density and disease resistance has a stabilizing effect on population dynamics.

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Section: Discussioncontrasting

confidence: 76%

Density-dependent resistance of the gypsy moth Lymantria dispar to its nucleopolyhedrovirus, and the consequences for population dynamics

Reilly

Hajek

2007

Oecologia

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“…Although these results may explain why infection levels in the field are generally low, the factors that promote occasional spikes of MdSGHV infection in field populations remain unknown. Age-or development-related changes in susceptibility or resistance to viral infection are a well-established phenomenon and have been documented in various insects (4,9,11,20). Differences in susceptibility may occur among life stages (i.e., egg, larva, pupa, and adult), among larval instars, or within a given instar (19).…”

Section: Resultsmentioning

confidence: 99%

Musca domestica Salivary Gland Hypertrophy Virus, a Globally Distributed Insect Virus That Infects and Sterilizes Female Houseflies

Prompiboon

Lietze

Denton

et al. 2010

Appl Environ Microbiol

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The housefly, Musca domestica, is a cosmopolitan pest of livestock and poultry and is of economic, veterinary, and public health importance. Populations of M. domestica are naturally infected with M. domestica salivary gland hypertrophy virus (MdSGHV), a nonoccluded double-stranded DNA virus that inhibits egg production in infected females and is characterized by salivary gland hypertrophy (SGH) symptoms. MdSGHV has been detected in housefly samples from North America, Europe, Asia, the Caribbean, and the southwestern Pacific. In this study, houseflies were collected from various locations and dissected to observe SGH symptoms, and infected gland pairs were collected for MdSGHV isolation and amplification in laboratory-reared houseflies. Differences among the MdSGHV isolates were examined by using molecular and bioassay approaches. Approximately 600-bp nucleotide sequences from each of five open reading frames having homology to genes encoding DNA polymerase and partial homology to the genes encoding four per os infectivity factor proteins (p74, pif-1, pif-2, and pif-3) were selected for phylogenetic analyses. Nucleotide sequences from 16 different geographic isolates were highly homologous, and the polymorphism detected was correlated with geographic source. The virulence of the geographic MdSGHV isolates was evaluated by per os treatment of newly emerged and 24-h-old houseflies with homogenates of infected salivary glands. In all cases, 24-h-old flies displayed a resistance to oral infection that was significantly greater than that displayed by newly eclosed adults. Regardless of the MdSGHV isolate tested, all susceptible insects displayed similar degrees of SGH and complete suppression of oogenesis. Salivary gland hypertrophy virus (SGHV) ofMusca domestica L. (Diptera: Muscidae) (MdSGHV) was originally detected in adult houseflies collected from dairies located in north Florida (2). Since the original description of this virus, a series of studies have detailed its molecular and biological properties. The circular double-stranded DNA (dsDNA) genome of MdSGHV consists of 124,279 bp and contains over 100 open reading frames (ORFs) (6,16). The virus, which replicates in the salivary glands of adult flies, is readily transmitted per os to healthy conspecific animals (15). During feeding, high numbers of infectious virus particles are deposited on the solid food substrate that is fed upon by healthy houseflies. The development of viremia in female houseflies leads to a shutdown of egg production (7,14). Associated with female sterility is the downregulation of egg protein gene transcription in the fat body (14). In feral housefly populations, the incidence of infection may peak at 34% at selected sites (7), although at any given sampling time the incidence typically ranges from 1 to 10%. As expected with an orally transmitted virus, infection frequency is positively correlated with housefly density.Recently, we initiated a program directed at expanding the current collection of SGHVs associated with M. domestica. ...

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“…It is likely that developmental resistance to LdMNPV, both among and within instars, is responsible for much of the reduced potency in feeding larvae (mid-instars) (Hoover et al, 2002). Developmental resistance of L. dispar to LdMNPV is also distinct among lepidopteran/NPV systems in that it involves both midgut-and systemic-based barriers (Grove & Hoover, 2007;Hoover et al, 2002). Hoover et al (2002) hypothesized that immune responses play a role in systemic resistance in L. dispar.…”

Section: Introductionmentioning

confidence: 99%

Pathogenesis of Lymantria dispar multiple nucleopolyhedrovirus in L. dispar and mechanisms of developmental resistance

McNeil

Cox-Foster

Gardner

et al. 2010

Journal of General Virology

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Lymantria dispar has a long historical association with the baculovirus Lymantria dispar multiple nucleopolyhedrovirus (LdMNPV), which is one of the primary population regulators of L. dispar in the field. However, host larvae exhibit strong developmental resistance to fatal infection by LdMNPV; the LD 50 in newly moulted fourth instars is 18-fold lower than in the middle of the instar (48-72 h post-moult). Using a recombinant of LdMNPV expressing lacZ, we examined the key steps of pathogenesis in the host to explore mechanisms of developmental resistance. At the midgut level, we observed reduced primary midgut infections in mid-fourth instars, indicating increased sloughing of infected cells. Additional barriers were observed as the virus escaped the midgut. Mid-fourth instars had higher numbers of melanized foci of infection associated with the midgut, apoptotic tracheal epidermal cells and haemocytes, and reduced numbers of infected haemocytes later in infection. Our results show that the co-evolutionary relationship between L. dispar and LdMNPV has resulted in both midgut-based and systemic antiviral defences and that these defences are age-dependent within the instar. This age-related susceptibility may contribute to how the virus is maintained in nature and could influence management of L. dispar by using the virus.

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Intrastadial developmental resistance of third instar gypsy moths (Lymantria dispar L.) to L. dispar nucleopolyhedrovirus

Cited by 37 publications

References 25 publications

Density-dependent resistance of the gypsy moth Lymantria dispar to its nucleopolyhedrovirus, and the consequences for population dynamics

Density-dependent resistance of the gypsy moth Lymantria dispar to its nucleopolyhedrovirus, and the consequences for population dynamics

Musca domestica Salivary Gland Hypertrophy Virus, a Globally Distributed Insect Virus That Infects and Sterilizes Female Houseflies

Pathogenesis of Lymantria dispar multiple nucleopolyhedrovirus in L. dispar and mechanisms of developmental resistance

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