Lepidopteran larva consumption of soybean foliage: basis for developing multiple-species economic thresholds for pest management decisions.
BACKGROUND
Defoliation by Anticarsia gemmatalis (Hübner), Pseudoplusia includens (Walker), Spodoptera eridania (Cramer), S. cosmioides (Walker) and S. frugiperda (JE Smith) (Lepidoptera: Noctuidae) was evaluated in four soybean genotypes. A multiple-species economic threshold (ET), based upon the species' feeding capacity, is proposed with the aim of improving growers' management decisions on when to initiate control measures for the species complex.


RESULTS
Consumption by A. gemmatalis, S. cosmioides or S. eridania on different genotypes was similar. The highest consumption of P. includens was 92.7 cm(2) on Codetec 219RR; that of S. frugiperda was 118 cm(2) on Codetec 219RR and 115.1 cm(2) on MSoy 8787RR. The insect injury equivalent for S. cosmoides, calculated on the basis of insect consumption, was double the standard consumption by A. gemmatalis, and statistically different from the other species tested, which were similar to each other.


CONCLUSIONS
As S. cosmioides always defoliated nearly twice the leaf area of the other species, the injury equivalent would be 2 for this lepidopteran species and 1 for the other species. The recommended multiple-species ET to trigger the beginning of insect control would then be 20 insect equivalents per linear metre.
Bueno
Regiane Cristina Oliveira de Freitas
RC
University of Rio Verde (FESURV), Rio Verde, Goiás, Brazil.
Bueno
Adeney de Freitas
Ade F
Moscardi
Flávio
F
Parra
José Roberto Postali
JR
Hoffmann-Campo
Clara Beatriz
CB
D000818:Animals; D005838:Genotype; D007300:Insect Control / Q000191:economics* / Q000379:methods; D007814:Larva / Q000254:growth & development / Q000502:physiology; D007915:Lepidoptera / Q000254:growth & development / Q000502:physiology*; D010935:Plant Diseases / Q000469:parasitology*; D013025:Glycine max / Q000191:economics / Q000235:genetics / Q000469:parasitology*