Frugiperda Resistance Research Articles

Bt cotton and the predator Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) in the management of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) resistance to lambda-cyhalothrin

This study sought to provide relevant information for developing effective programs to manage Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) resistance to insecticides by quantifying and describing the interactions between cotton Bt and Podisus nigrispinus (Dallas) (Heteroptera; Pentatomidae) in the management of lambda-cyhalothrin resistance in S. frugiperda fed Bt cotton leaves expressing Cry1Ac (Bollgard, Monsanto, St Louis, MO, USA). These effects were assayed by studying functional responses. Third instar S. frugiperda larvae were used for the following treatments: strains resistant (1) or susceptible (2) to lambda-cyhalothrin fed Bollgard cotton leaves and strains resistant (3) or susceptible (4) to lambda-cyhalothrin fed non-Bt cotton leaves. The predatory behavior of P. nigrispinus females was best represented by a sigmoid curve. The type of P. nigrisinus functional response was not affected by the cotton cultivar or S. frugiperda strain used in the trials. P. nigrispinus females invested a greater amount of handling time (T h) in S. frugiperda larvae that were suseptible to insecticides and fed non-Bt cotton (T h = 1.72 h) compared to those from the insecticide-resistant strain fed with Bt cotton (T h = 1.23 h) or even compared to those that were lambda-cyhalothrin resistant and fed Bt (T h = 1.17 h) or non-Bt cotton (T h = 1.17 h). The results in the present study can be applied in the development of management programs targeting S. frugiperda resistance to pyrethroid lambda-cyhalothrin. The integration of Bt cotton concurrent with biological control by the Asopinae P. nigrispinus is important for successfully managing S. frugiperda resistance to lambda-cyhalothrin.

Foliar Resistance to Fall Armyworm in Corn Germplasm Lines that Confer Resistance to Root- and Ear-Feeding Insects*

ABSTRACT A holistic approach to developing new corn germplasm that confers multiple insect resistance in various plant tissues at different growth stages was examined. Eight corn germplasm lines were examined for their foliar resistance to fall armyworm [Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)] and natural enemy attraction at V6–V8 (or 6–8 leaf) stages in 2008 and 2009. Four corn germplasm lines with known levels of resistance to root- and ear-feeding insects [‘CRW3(S1)C6’, ‘B37*H84’, ‘SIM6’ and ‘EPM6’], and four germplasm entries with different levels of S. frugiperda resistance (‘Mp708’, ‘Ab24E’, ‘FAW7061’ and ‘FAW7111’) were evaluated in the study. All plants were manually infested with 15–20 neonate S. frugiperda larvae per plant, and injury was rated 7 and 14 d after infestation. Based on cluster analysis of S. frugiperda injury rating and predator survey data, ‘Mp708’ and ‘FAW7061’ were the most resistant, whereas ‘Ab24E’ and ‘EPM6’ were the most susceptible to fall armyworm fee...

Spodoptera frugiperda resistance to oral infection by Autographa californica multiple nucleopolyhedrovirus linked to aberrant occlusion-derived virus binding in the midgut

Spodoptera frugiperda larvae are highly resistant to oral infection by Autographa californica multiple nucleopolyhedrovirus (AcMNPV) (LD(50), approximately 9200 occlusions), but extremely susceptible to budded virus within the haemocoel (LD(50), <1 p.f.u.). The inability of AcMNPV occlusion-derived virus (ODV) to establish primary infections readily within midgut cells accounts for a major proportion of oral resistance. To determine whether inappropriate binding of AcMNPV ODV to S. frugiperda midgut cells contributes to lack of oral infectivity, the binding and fusion properties of AcMNPV ODV were compared with those of the ODV of a new isolate of Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) obtained from a field-collected larva (oral LD(50), 12 occlusions). By using a fluorescence-dequenching assay conducted in vivo, it was found that AcMNPV ODV bound to the midgut epithelia of S. frugiperda larvae at approximately 15 % of the level of SfMNPV ODV, but that, once bound, the efficiencies of fusion for the two ODVs were similar: 60 % for AcMNPV and 53 % for SfMNPV. Whilst the difference in binding efficiencies was significant, it could not account entirely for the observed differences in infectivity. Competition experiments, however, revealed that, in S. frugiperda larvae, SfMNPV ODV bound to a midgut cell receptor that was not bound by AcMNPV ODV, indicating that ODV interaction with a specific receptor(s) was necessary for productive infection of midgut columnar epithelial cells. Fusion in the absence of this ligand-receptor interaction did not result in productive infections.

Selection of the Fall Armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) for Survival on Cry La(B) Bt Toxin

Transgenic maize hybrids expressing Bacillus thuringiensis (Bt) toxin are considered an important technology to control lepidopteran pests of maize. Bt maize hybrids expressing the Cry1A(b) toxin have shown a significant level to fall armyworm (FAW), Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), resistance, although larvae survival has been observed on these hybrids. In addition, S. frugiperda resistance to different insecticides has been reported.