Symbionts and immune defence in lepidopteran crop pests

Noctuid lepidopterans are responsible for billions of dollars in economic losses across worldwide agriculture. These pest species are constantly being dispersed and generate great concern due their resistance against chemical pesticides and Bt crops. These factors emphasize the importance to the development of technologies for rapid field diagnosis and specific environmentally-safe pest control. Here we show that different molecular and biochemical tools can be widely useful in studies of these pests. First, using PCR, PCR-RFLP and gene sequencing, we confirmed the presence of the Old World bollworm Helicoverpa armigera in Minas Gerais state and identified the prevalence and genetic diversity of symbionts with potential use for noctuid biocontrol such as densovirus, baculovirus and Wolbachia. Secondly, we identified that in non-infected individuals prophenoloxidase gene expression (a crucial enzyme of noctuid immune defence) did not vary with age or population density. Additionally, we verified that gene knockdown methodologies based on interference RNA (RNAi) did not silence this gene; in fact one of them contrary increased its expression. Lastly, we found that Spodoptera littoralis, another noctuid that exhibits density- dependent prophylaxis and phase polyphenism, presents higher immune levels in the presence of a haemocoel invader when reared gregariously. We also found that biochemical activity of main humoral immune defences of this species vary according to species and condition of invader bacteria showing signals of immune specificity.

Grantor dc:publisher

Universidade Federal de Viçosa

Year dc:date.issued

2016

Author dc:creator

• Pinto, Fábio de Assis

Advisor dc:contributor.advisor

• Elliot, Simon Luke

Contributors dc:contributor

• Wilson, Kenneth
• Graham, Robert

• Lepidoptera Noctuidae
• Helicoverpa armigera
• Baculovirus
• Wolbachia
• Controle de pragas - Biotecnologia
• Controle biológico

Statement dc:rights

• Acesso Aberto

Language dc:language.iso

eng

Repository record dc:identifier.uri

https://locus.ufv.br//handle/123456789/26673

OAI identifier oai:identifier

oai:locus.ufv.br:123456789/26673