Nuclear Polyhedrosis Virus and Resistant Corn Silks Enhance Mortality of Corn Earworm (Lepidoptera: Noctuidae) Larvae

1993 ◽  
Vol 3 (4) ◽  
pp. 337-342 ◽  
Author(s):  
B.R. Wiseman ◽  
J.J. Hamm
1997 ◽  
Vol 32 (2) ◽  
pp. 148-153 ◽  
Author(s):  
J. J. Hamm ◽  
J. E. Carpenter

Inherited sterility has been proposed as a means of suppressing the populations of the corn earworm, Helicoverpa zea (Boddie), and the fall armyworm, Spodoptera frugiperda (J. E. Smith). If nuclear polyhedrosis viruses could be used to kill larvae, thereby reducing the number of moths in the field populations, fewer moths treated with substerilizing doses of irradiation would need to be released. However, for these two methods to be compatible, the progeny of substerile moths should be no more susceptible to the virus than the progeny of the field populations. The corn earworm nuclear polyhedrosis virus (Elcar™) was bioassayed against corn earworm larvae from untreated moths and larvae from male, female, and male and female moths treated with 100 Gy of irradiation and larvae from male moths treated with 150 Gy of irradiation. The fall armyworm nuclear polyhedrosis virus was bioassayed against fall armyworm larvae from untreated moths and larvae from male moths treated with 100 to 150 Gy of irradiation. There was no significant difference between susceptibility of larvae from untreated moths and larvae from irradiated moths. Thus, the use of nuclear polyhedrosis viruses for control of larvae should be compatible with the release of substerilized moths as part of an integrated pest management approach for area-wide management of the corn earworm and fall armyworm.


1992 ◽  
Vol 27 (2) ◽  
pp. 126-134 ◽  
Author(s):  
S. Y. Young ◽  
W. C. Yearian

Nabis roseipennis Reuter nymphs that preyed on larvae of the nuclear polyhedrosis virus (NPV) infected velvetbean caterpillar, Anticarsia gemmatalis (Hübner), excreted the virus (AgNPV) for several days thereafter. Based on bioassays, fifth instar and second instar nymphs excreted 84.7 × 105 and 9.7 × 105 polyhedral inclusion bodies (PIB) per nymph, respectively. The AgNPV-contaminated nymphs effectively disseminated the virus via the feces over soybean plants where it served as inoculum to initiate disease in larval populations of A. gemmatalis caged in the field. Larval mortality from AgNPV ranged from 11.4 to 48.5% over treatments in two tests. Larval mortality in treatments where the source of virus inoculum was AgNPV-contaminated fifth instar nymphs was similar to that in treatments where the source of viral inoculum was diseased larvae. Larval mortality resulting from AgNPV dissemination by the nymphs was usually higher in treatments containing fifth instar nymphs than in those with second instar nymphs. Dissemination of NPV by fifth instar nymphs was higher in mixed-age than in uniformed-age A. gemmatalis larval populations. This was not the case with the smaller second instar nymphs.


1989 ◽  
Vol 24 (4) ◽  
pp. 500-506 ◽  
Author(s):  
S. Y. Young ◽  
W. C. Yearian

Heliothis nuclear polyhedrosis virus (HNPV) transmission by Microplitis croceipes (Cresson) [Hymenoptera: Braconidae] that emerged from HNPV-infected Heliothis virescens (F.) (Lepidoptera: Noctuidae) larvae was investigated in the laboratory and in single plant cage tests on field grown soybean. In the laboratory a small percentage of the M croceipes adults (13.3%) from infected larvae transmitted Heliothis HNPV. The mortality from HNPV in larvae exposed as late second instars to female parasitoids was 20.0%. In a single plant cage test on soybean conducted in the field, however, the percentage of mortality from HNPV in larvae did not differ significantly from that in the control group. When larvae were caged with females that had been artificially contaminated with HNPV up to 79.2% of the H. virescens larvae died of HNPV.


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