Effects of nucleopolyhedrovirus infection on the development of Helicoverpa armigera (Lepidoptera: Noctuidae) and expression of its 20-hydroxyecdysone– and juvenile hormone–related genes

Authors

  • Songdou Zhang Department of Entomology, China Agricultural University, Beijing, 100193, China
  • Fengming Wu Department of Entomology, China Agricultural University, Beijing, 100193, China
  • Zhen Li Department of Entomology, China Agricultural University, Beijing, 100193, China
  • Zhenqiang Lu Department of Entomology, China Agricultural University, Beijing, 100193, China
  • Xinfeng Zhang Department of Entomology, China Agricultural University, Beijing, 100193, China
  • Qingwen Zhang Department of Entomology, China Agricultural University, Beijing, 100193, China
  • Xiaoxia Liu Department of Entomology, China Agricultural University, Beijing, 100193, China

Keywords:

NPV infection, insect hormone, transcript level, qRT-PCR, development

Abstract

In recent years, the interactions between baculoviruses and their insect hosts have become a research focus because baculoviruses can suppress the development and manipulate the behavior of insects. Many studies reported that nucleopolyhedrovirus (NPV) infection might disrupt the hormone balance in insects, but the effect of NPV infection on the development and expression of hormone-related genes in larvae of Helicoverpa armigera Boddie (Lepidoptera: Noctuidae) remains unclear. In this study, the mortality, development time, and pupal weight of H. armigera were recorded after 4th and 5th instars had been treated per os with different concentrations of Helicoverpa armigera single NPV (HaSNPV). Results showed that mortality increased and development time was prolonged to different degrees along with increasing concentrations of HaSNPV. The pupal weight did not differ between the HaSNPV-infected and control insects when 4th instars were infected but was significantly reduced when 5th instars were infected with HaSNPV at concentrations of 109 and 1010 polyhedral inclusion bodies (PIB) per milliliter. Compared with the healthy control group, larval body weight was significantly reduced from the 3rd day after infection when 4th instars had been treated with HaSNPV at concentrations of 108 and 109 PIB/mL. Results from quantitative reverse-transcriptase polymerase chain reaction assays revealed that 20-hydroxyecdysone–related genes (ECR, USP, E75, and NTF2) were down-regulated and juvenile hormone–related genes (MET, JHi, and HSP90) were up-regulated after HaSNPV infection. This study improves our understanding of the interactions between baculoviruses and host insects.

 

Resumen

En los últimos años, las interacciones entre los baculovirus y sus hospederos de insectos han convertido en un enfoque de investiga­ción porque los baculovirus pueden suprimir el desarrollo y manipular el comportamiento de los insectos. Muchos estudios informan que la infección nucleopoliedrovirus (NPV) podría alterar el equilibrio hormonal en insectos, pero el efecto de la infección por el NPC en el desarrollo y la expresión de genes relacionados con las hormonas en las larvas de Helicoverpa armigera Boddie (Lepidoptera: Noctuidae) sigue siendo no clara. En este estudio, se registraron la mortalidad, el tiempo de desarrollo, y el peso de pupa de H. armi­gera después de cuarto y quinto estadios habían sido tratados por vía oral con diferentes concentraciones de Helicoverpa armigera NPV singular (HaSNPV). Los resultados mostraron que la mortalidad incrementó y el tiempo de desarrollo se prolongó a diferentes grados a lo largo con concentraciones crecientes de HaSNPV. El peso de pupa no fue diferente entre los insectos infectados por HaSNPV y de control cuando se infectaron el cuarto estadios, pero se redujo significativamente cuando las larvas del quinto estadio fueron infectados con HaSNPV en concentraciones de 109 y 1010 cuerpos de inclusión poliédricos (CIB) por mililitro. En comparación con el grupo de control sano, el peso corporal de las larvas se redujo significativamente desde la tercera día después de la infección cuando las larvas del cuarto estadio habían sido tratados con HaSNPV a concentraciones de 108 y 109 CIB/ml. Los resultados de los ensayos de reacción en cadena de la polimerasa cuantitativa la transcriptasa inversa revelaron que los genes relacionados con el 20-hidroxiecdisona (ECR, USP, E75 y NTF2) fueron reguladas hacia abajo y los genes relacionados con las hormonas juveniles (MET, JHI y HSP90) fueron reguladas después de la infección HaSNPV. Este estudio mejora nuestra comprensión de las interacciones entre los baculovirus e insectos huésped.

 

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Issue

Vol. 98, No. 2 (June 2015)

Section

Research Papers

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