Overcrowding of false codling moth, Thaumatotibia leucotreta (Meyrick) leads to the isolation of five new Cryptophlebia leucotreta granulovirus (CrleGV-SA) isolates

Opoku-Debrah, John Kwadwo; Hill, Martin; Knox, Caroline; Moore, S.D.

doi:10.1016/j.jip.2012.12.008

Cited by 34 publications

(32 citation statements)

References 39 publications

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“…Early studies concluded that physiological stress was a major contributor to virus activation (Podgawaite and Mazzone, 1986). Specifically, overcrowded rearing conditions (Fuxa et al, 1999; Opoku-Debrah et al, 2013), marked changes in temperature or relative humidity (Fuxa et al, 1999; Kouassi et al, 2009), the ingestion of mildly toxic chemical compounds (Ilyinykh et al, 2004; Virto et al, 2017a), parasitism (Stoltz and Makkay, 2003), or changes in nutrient availability (David and Gardiner, 1965, 1966), have all been reported as potential activators of overt disease, although insect responses are often unpredictable. One report on granulovirus infection in Pieris rapae indicated that dehydration-induced activation of lethal disease could be atenuated to a non-lethal covert infection by switching larvae from a dessicated diet to a diet with a high water content (Biever and Wilkinson, 1978).…”

Section: Factors That Favor Virus Activationmentioning

confidence: 99%

Covert Infection of Insects by Baculoviruses

et al. 2017

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Baculoviruses (Baculoviridae) are occluded DNA viruses that are lethal pathogens of the larval stages of some lepidopterans, mosquitoes, and sawflies (phytophagous Hymenoptera). These viruses have been developed as biological insecticides for control of insect pests and as expression vectors in biotechnological applications. Natural and laboratory populations frequently harbor covert infections by baculoviruses, often at a prevalence exceeding 50%. Covert infection can comprise either non-productive latency or sublethal infection involving low level production of virus progeny. Latency in cell culture systems involves the expression of a small subset of viral genes. In contrast, covert infection in lepidopterans is associated with differential infection of cell types, modulation of virus gene expression and avoidance of immune system clearance. The molecular basis for covert infection may reside in the regulation of host–virus interactions through the action of microRNAs (miRNA). Initial findings suggest that insect nudiviruses and vertebrate herpesviruses may provide useful analogous models for exploring the mechanisms of covert infection by baculoviruses. These pathogens adopt mixed-mode transmission strategies that depend on the relative fitness gains that accrue through vertical and horizontal transmission. This facilitates virus persistence when opportunities for horizontal transmission are limited and ensures virus dispersal in migratory host species. However, when host survival is threatened by environmental or physiological stressors, latent or persistent infections can be activated to produce lethal disease, followed by horizontal transmission. Covert infection has also been implicated in population level effects on host–pathogen dynamics due to the reduced reproductive capacity of infected females. We conclude that covert infections provide many opportunities to examine the complexity of insect–virus pathosystems at the organismal level and to explore the evolutionary and ecological relationships of these pathogens with major crop and forest pests.

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Section: Factors That Favor Virus Activationmentioning

confidence: 99%

Covert Infection of Insects by Baculoviruses

et al. 2017

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“…A piece of sterilised tightly fitting cotton wool was immediately inserted into the opening of each vial as a pupation medium for both T. leucotreta and parasitoid larvae as well as a barrier to microbial contamination (particularly fungi). Vials were then transferred into a controlled environment room and maintained at 25°C ± 2, 30 % ±10 RH, 12D: 12 L photoperiod (Opoku-Debrah et al 2013;Zimba et al 2016). After pupation, the cotton wool plugs were carefully removed from the vials and placed into 2 l ventilated emergence glass jars to facilitate easy and safe eclosion of A. bishopi parasitoids.…”

Section: Insectsmentioning

confidence: 99%

“…Considerable research has been recently undertaken to develop more robust management options for T. leucotreta such as screening for resistant cultivars (Love et al 2014), and improved preharvest (Li and Bouwer 2012;Coombes et al 2013;Opoku-Debrah et al 2013) and postharvest (Johnson and Neven 2010;Boardman et al 2012) control measures. Although considerable success has been recorded in the preharvest and postharvest control of T. leucotreta, limited research has focused on developing improved technology for postharvest detection of infested fruit, particularly in the packhouse where fruit is sorted and packed for export.…”

Section: Introductionmentioning

confidence: 99%

Agathis bishopi (Hymenoptera: Braconidae) as a Potential Tool for Detecting Oranges Infested with Thaumatotibia leucotreta (Lepidoptera: Tortricidae)

et al. 2015

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In South Africa, Thaumatotibia leucotreta is a key pest of citrus impacting its production and trade. Detection of newly infested fruit by visual inspection is challenging and poses a risk of packing infested with healthy fruit for export. Agathis bishopi is a larval endoparasitoid of T. leucotreta, attacking early larval instars. Understanding how A. bishopi parasitoids locate fruit infested with their host is of interest for developing an efficient detector for T. leucotreta infested fruit. The response of female adult A. bishopi parasitoids to olfactory and visual cues associated with T. leucotreta infested fruit were evaluated using a Y-tube olfactometer and flight tunnel. Agathis bishopi parasitoids were strongly attracted to infested fruit over healthy fruit, either when only olfactory or combinations of visual and olfactory cues were offered. Among the four synthetic compounds tested, D-limonene and ocimene elicited a strong attraction to parasitoids with response rates of 92 % and 72 % respectively. A blend of four synthetic compounds simulating T. leucotreta infested fruit odour equally elicited strong attraction to parasitoids (84 % response rate). Attraction of parasitoids to infested fruit cues was heightened by prior experience, suggesting the occurrence of associative learning. Results from this study indicate that A. bishopi parasitoids mainly rely on olfactory cues in host habitat location and that D-limonene and ocimene are the major attractants in infested fruit volatiles. These findings and the potential for manipulating A. bishopi for detection of infested fruit in the packhouse are discussed.

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“…; Opoku‐Debrah et al. ), high relative humidity (Fuxa et al. ) or ingestion of chemical compounds (Il'inykh et al.…”

Section: Introductionmentioning

confidence: 99%

Chemical and biological stress factors on the activation of nucleopolyhedrovirus infections in covertly infected Spodoptera exigua

Virto

Navarro

Tellez

et al. 2016

J Applied Entomology

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Following the consumption of baculovirus occlusion bodies (OBs), insects may succumb to lethal disease, but the survivors can harbour sublethal covert infections and may develop, reproduce and transmit the infection to their offspring. The use of different chemical and biological stressors was examined to determine whether they could be used to activate covert infections in populations of Spodoptera exigua larvae infected by the homologous nucleopolyhedrovirus (SeMNPV). Treatment of covertly infected S. exigua second instars with Tinopal UNPA‐GX, hydroxylamine, paraquat, Bacillus thuringiensis var. kurstaki crystals, spores or mixtures of crystals + spores, or a heterologous nucleopolyhedrovirus (Chrysodeixis chalcites SNPV) did not result in the activation of SeMNPV covert infections. Similarly, virus treatments involving permissive NPVs did not result in greater mortality in covertly infected insects compared with the virus‐free controls. In contrast, 0.1% copper sulphate, 1% iron (II) sulphate and 1 mg/l sodium selenite treatments resulted in 12–41% lethal polyhedrosis disease in covertly infected larvae. A greenhouse trial using copper sulphate and sodium selenite as activation factors applied to covertly infected S. exigua larvae on sweet pepper plants resulted in very low levels of SeMNPV activation (<3%). These results highlight the important roles of copper, iron and selenium in insect immunity and baculovirus‐induced disease. However, these substances seem unlikely to prove useful for the activation of covert SeMNPV infections in S. exigua larvae under greenhouse conditions.

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Overcrowding of false codling moth, Thaumatotibia leucotreta (Meyrick) leads to the isolation of five new Cryptophlebia leucotreta granulovirus (CrleGV-SA) isolates

Cited by 34 publications

References 39 publications

Covert Infection of Insects by Baculoviruses

Covert Infection of Insects by Baculoviruses

Agathis bishopi (Hymenoptera: Braconidae) as a Potential Tool for Detecting Oranges Infested with Thaumatotibia leucotreta (Lepidoptera: Tortricidae)

Chemical and biological stress factors on the activation of nucleopolyhedrovirus infections in covertly infected Spodoptera exigua

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