Journal of Applied Entomology (2016) 140, 142-149

X.-Y. Ji, N.-F. Wan, J. Liu and J.-X. Jiang (2016)
Nucleopolyhedrovirus infection and/or parasitism by Microplitis pallidipes affected haemolymph titre of 20-hydroxyecdysone in Spodoptera exigua larvae
Journal of Applied Entomology 140 (1-2), 142-149
Abstract: This study examined the physiological effects of joint and separate parasitism and infection by the endoparasitoid Microplitis pallidipes Szépligeti and the nucleopolyhedrovirus (NPV), respectively, on haemolymph 20-hydroxyecdysone (20-E) titre in Spodoptera exigua (Hübner) larvae. The results indicated that in parasitized larvae, virus-infected larvae (5.7 × 10³ and 5.7 × 10⁵ OB/ml) and parasitized larvae infected with virus at 5.7 × 10⁵ OB/ml, compared to healthy larvae, the 20-E all declined during the first 3 days but began to increase from day 4 after treatment, while in jointly parasitized and infected larvae (5.7 × 10³ OB/ml), the 20-E declined during the first 4 days but began to increase on day 5 after treatment. Meanwhile, compared to parasitized larvae, the 20-E declined during the first 4 days but significantly increased on day 5 in jointly parasitized and infected larvae (5.7 × 10³ OB/ml), while significantly increased during the first 2 days but began to decrease from day 3 after treatment in jointly parasitized and infected larvae (5.7 × 10⁵ OB/ml). Finally, in larvae that were both parasitized and virus infected (5.7 × 10³ OB/ml), compared to just virus-infected larvae (5.7 × 10³ OB/ml), the 20-E was lower on days 3 and 4 but higher on other days after treatment; in larvae that were both parasitized and virus infected (5.7 × 10⁵ OB/ml), compared to just virus-infected larvae (5.7 × 10⁵ OB/ml), the 20-E was significantly higher at the first 2 days but lower from day 3 after treatment. Our results revealed that 2nd instar larval M. pallidipes in host bodies may release 20-E into the haemolymph of S. exigua larvae and that NPV infection may stimulate S. exigua to release more 20-E during its third to fourth instar larval moulting. We found that this stimulatory effect was greater with higher virus concentrations.
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Link to article at publishers website

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Spodoptera exigua	Brassica - other species	China (south)
Alphabaculovirus spexiguae (entomopathogen)	Spodoptera exigua
Microplitis pallidipes (parasitoid)	Spodoptera exigua	Brassica - other species	China (south)