Sublethal effects of different fungal isolates on Helicoverpa armigera (Lepidoptera: Noctuidae)

Abstract Background Broad-spectrum pesticides and Bt crops have been used against the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), but their effect on the environment and the development of resistance are the main limitations for these control measures. The use of mycobiopesticides is an ecofriendly and efficient alternative. Fungicides have a wide distribution and a high genetic variability, which allows their screening for more virulent isolates. Therefore, the objective of this work was to evaluate the interactions of H. armigera larvae with Metarhizium anisopliae and Beauveria bassiana, on mortality, virulence, sublethal effects, and life table aspects. Main body The isolates that caused mortality rates of H. armigera above 80% were selected for further assays. Virulence was measured by LC50 estimates, using Probit analysis to sublethal effects, and the bootstrap procedure to estimate the biological parameters: time for development, fertility, longevity, pre-ovipositional period, egg viability, and sex ratio. The H. armigera mortality rates caused by B. bassiana and M. anisopliae ranged from 45 to 100% and from 40 to 90%, respectively. Longevity, fertility, and survival rates are affected in all treatments. The pupal weight of individuals treated with fungi was lower than in the control. Deformations were observed in H. armigera pupae developed from larvae treated with B. bassiana. Conclusion The use of sublethal concentrations of isolates of M. anisopliae and B. bassiana resulted in an adverse effect on the biological parameters of H. armigera.

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Toxicity of Andira paniculata (Fabaceae) Extracts to Helicoverpa armigera (Lepidoptera: Noctuidae)

Journal of Agricultural Science ◽

10.5539/jas.v10n6p264 ◽

2018 ◽

Vol 10 (6) ◽

pp. 264

Author(s):

Maurilio de Sousa Neto ◽

Franciele Cristina da Silva ◽

André Cirilo De Sousa Almeida ◽

Antônio Carlos Severo Menezes ◽

Márcio Da Silva Araujo ◽

...

Keyword(s):

Ethyl Acetate ◽

Helicoverpa Armigera ◽

Larval Stage ◽

Dry Matter ◽

Larval Period ◽

Pupal Weight ◽

Biological Parameters ◽

Helicoverpa Armígera ◽

Soybean Plants ◽

Lepidoptera Noctuidae

Helicoverpa armigera is one of the most important pests of soybean crop in Brazil. The purpose of this work was to evaluate the effect of organic Andira paniculata extracts on its biology, feeding and the attractiveness of soybean plants to H. armigera. Hexane, dichloromethane, ethyl acetate and hydroalcoholic fractions at concentrations of 0.01, 0.1, 0.5 and 1% were evaluated. For the biological parameters the period and viability of larval stage, caterpillar weight at ten days, period, viability and pupal weight at 24 hours, total longevity, LC50 and deterrence were evaluated. The non-preference for feeding and attractiveness, the number of caterpillars and the dry matter consumed in each fraction of the extracts were evaluated. The extract of A. paniculata in hexane (0.01%) resulted up to 85% mortality of H. armigera. The A. paniculata extract did not affect the larval period, weight, pupal period and mortality or the consumption of H. armigera. The hydroalcoholic extracts obtained the better results for deterrence. The A. paniculata extract in dichloromethane fraction had the lowest LC50. The A. paniculata extracts in the hexane fractions (0.1%), ethyl acetate (0.01 and 0.5%) and hydroalcoholic (0.01 and 0.5%) were fagodeterrents for H. armigera. Thus, A. paniculata extract in hexane fraction is the most promising for use in the control of H. armigera in soybean.

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