Monos Medium sized, ochraceous, thickly and darkly punctate, punctures bronze, head with a central pale band, antennae ochraceous, apical halves of third, fourth and fifth joints reddish brown, pronotum with a broken transverse bronze band, scutellum black at base, with a large furcellta at each basal angle, ventrally body and legs ochraceous, black marginal spots on abdomen, black rings on all femora near apices. Male face color Odonata. Male hindwing size Odonata mm. Please send me product announcements, helpful advice, and special promotions.

Author:Kigazragore Kiktilar
Language:English (Spanish)
Published (Last):28 November 2004
PDF File Size:16.18 Mb
ePub File Size:12.3 Mb
Price:Free* [*Free Regsitration Required]

Copyright This is an open access paper. We use the Creative Commons Attribution 3. Abstract Infectivity of polyhedra of Spodoptera litura multiple nucleopolyhedrovirus before and after passage through the gut of the predatory stink bug, Eocanthecona furcellata Wolff Hemiptera: Pentatomidae was compared through field bioassay studies.

Three sets of E. The predators were subsequently released on cabbage plants that were infested with healthy S. The median lethal dose LD 50 and survival time ST 50 values before and after passage through the gut were not significantly different. It was concluded that E. They are well known due to their potential as agents of biological control of pests in agriculture and forestry. The predatory bug Eocanthecona furcellata Wolff Hemiptera: Pentatomidae is regarded as potential predator of pest insects at both the nymphal and adult stages.

Predator-mediated baculovirus dispersal has been demonstrated to be an important mechanism for virus dissemination in diverse crop and forest habitats Entwistle et al. This dispersal occurs through the excretion of viable viral polyhedra in their feces for periods of several days following ingestion of baculovirus-infected meal Beekman ; Young and Yearian ; Vasconcelos et al.

Natural enemies may become superficially contaminated during the consumption of infected prey, and may physically disperse the virus over plant surfaces Sait et al. Although the consumption of infected larvae and subsequent release of viable virus by predatory bugs are likely to occur in nature, the ecological implication of this phenomenon is poorly understood. The importance of predaceous arthropods in the dissemination of insect viruses depends on three factors: the acceptance of virus-infected insects as food, the effect of passage through the predator gut on virus infectivity, and the interactive behavior of predator and prey in relation to virus acquisition.

However, effective integration of baculoviruses into existing pest management systems depends on their compatibility with other components of the systems. A full understanding of the spread of baculovirus by predators is therefore necessary for the successful application of biopesticides and also to predict the environmental fate of natural and genetically modified microorganisms Fuxa and Ritcher For instance, some parasitoids and predators could be affected detrimentally by the pathogens infecting their prey Cossentine and Lewis ; Ruberson et al.

Insect predators that feed on virus-infected larvae can acquire moderate to high levels of infection Young and Yearian , , and the release of viable virus in the predator feces occurs for at least four days after feeding on infected larvae Beekman It is not known, however, whether infectivity of the virus is altered after passage through the gut of insect predators.

In this study, we used a bioassay method to observe the infectivity of Spodoptera litura multiple nucleopolyhedrovirus SpltMNPV before and after passage through the gut of E.

Materials and Methods Host insect Spodoptera litura The Spodoptera litura Fabricius Lepidoptera: Noctuidae insects used in this study were from the offspring of 34 th generation female moths obtained from the Indian Agriculture Research Institute, New Delhi.

Egg masses were collected and surface-sterilized with 0. The diet and the paper were changed on alternate days. Predator Eocanthecona furcellata The predator used in this study was from the offspring of 20 th generation female bugs that emerged from field-collected eggs laid on Parthenium leaves Gupta et al.

The virus was propagated in S. Viral polyhedra were extracted by homogenizing virus-killed larvae in 0. Feces were collected up to 48 hours after feeding on infected prey, as no significant loss of infectivity of polyhedra occurred during passage through the gut within 24—48 hours.

For feces collection, predators were used only once throughout the experiment. Circular discs measuring 1. One larva was then placed in each compartment. A total of larvae were used for each concentration.

Larvae, having eaten the entire diet disc within 24 hours, were transferred to fresh uncontaminated diet. Mortality was recorded daily until pupation. The experiment was replicated five times.

The plants were randomly selected and allocated to three different treatments. Each experimental cabbage plant was at an average distance of cm or seven cabbage plants away from any other experimental plant, such that each plant represented a single independent replicate. One day prior to the trial, pre-starved adult predators three days old were fed a single meal of five healthy or SpltMNPV-infected before passage and after passage third instars of S.

Only those predators that consumed all the larvae within 24 hours were used in the experiment. Treatments involved placing one adult and healthy third instar S. Each treatment was replicated five times. After six days, the bags were opened, the predators were removed, and remaining S. All virus deaths were confirmed by microscopic examination through Giemsa staining. Data on cumulative mortality percentage of S.

The data on recovery and viral mortality of S. A gradual increase in the cumulative mortality was observed as the dose increased from However, when the cumulative mortality percentage of S. Table 1. Open in a separate window It was also found that higher doses led to faster mortality.

The ST 50 values for the respective doses , , , , and Table 2. However, when the viral mortality was compared on plants that hosted predators that were fed with two kinds of polyhedra the original PIBs that were not passed through the gut and the PIBs that were subsequently passed through the gut of E. Table 3. Discussion The results suggest that PIBs of SpltMNPV were still infectious and the infectivity of the virus was not altered after passage through the gut of the predator.

Further, at similar virus doses, ST 50 values of SpltMNPV before and after passage through the gut of the insect predator were not significantly different from each other.

It is well established that after feeding on infected larvae, predators excrete viable baculovirus in their feces Boucias et al. These predators apparently do not suffer significant deleterious effects from consuming virus-infected lepidopteran larvae Heinz et al.

This is likely because the gut of most insect predators is acidic, in contrast to the highly alkaline guts of phytophagous lepidoptera that degrade the proteinaceous matrix of the viral polyhedra, resulting in the release of virions and the subsequent infection of host midgut cells Granados and Lawler However, Castillejos et al. Similarly, Vasconcellos et al. However, Cooper suggested that infectivity of the virus is reduced during prolonged retention in the alimentary tract of the predator, presumably as a result of enzymatic activity.

These studies established that there is a loss of infectivity over time, but did not focus on the infectivity of virus before and after passage through the gut of the predator. A loss of infectivity was attributed to a reduction of the number of polyhedra in feces over time following ingestion of baculovirus-infected meal. However, when the viral mortality was compared among these two sets of predators, the observed differences were nonsignificant.

As no significant variation in larval recovery up to six days was observed, we assume that there was nearly equal predation by virus-fed and non-virus-fed bugs. Mortality in the field, although not high, showed that predators released infective virus in a form that could be acquired by susceptible lepidopteran hosts. This is because in comparison to carabids, pentatomids are quite mobile, exhibiting frequent contact between predator and prey with a mean searching time of 3. This higher infectivity was due to higher mobility of the predator as compared to host larvae, which may increase the speed of inoculum dispersal Vasconcellos et al.

In field conditions, virus disseminated in the feces of insect predators is sufficient to initiate epizootics in larval populations. This has been reported in predators such as Sycanus leucomesus Walk. Sajap et al. In our previous studies, we found that the survival of predators that fed on infected hosts was not affected by the ingestion of NPV. The present study suggests that E. Acknowledgments The authors are grateful to an anonymous reviewer for comments on the manuscript and Dr.

Rabindra for guidance during the course of investigation.





Eocanthecona furcellata


Related Articles