BioControl (2004) 49, 517-536

Wedad E. Khafagi and Esmat M. Hegazi (2004)
Effects of juvenile hormone I and precocene I and II on Microplitis rufiventris when administered via its host, Spodoptera littoralis
BioControl 49 (5), 517-536
Abstract: We investigated the effect of juvenile hormone I (JHI) and precocene I and II (PI and PII) on the endo-developmental stages, reproductive performance and longevity of Microplitis rufiventris Kok. after topical treatment of host larvae of Spodoptera littoralis (Boisd.). Host larvae were treated with each of the test compounds by a single dose 2-4 h after parasitization or 1 day prior to parasitoid emergence, or by repeated daily applications 2-4 h after parasitization to parasitoid emergence. JHI-treatments increased parasitoid developmental time, induced developmental abnormalities and inhibition of parasitoid egression. Interestingly, one of the causal factors that inhibited the parasitoid egression was the moulting of some parasitoid larvae into a supernumerary instar. Applications of PI or PII to parasitized S. littoralis larvae did not affect parasitoid developmental time, but some developmental abnormalities were noted. Melanin formation in host's blood was greater in PI-treatments than in PII-treatments. PII-treatments arrested development of some first instar parasitoid larvae typical of JHI excess. Adult female wasps that emerged from JHI-treated hosts lived for significantly longer periods than control females, but did not produce more offspring. The longevity and reproductive capacity of females which developed in hosts treated by precocenes were reduced compared with the females emerged from control hosts. Even the small number of adult wasps from PII-treated hosts which lived for the same period as control wasps, showed a significant reduction in their reproductive performance. Repeated daily applications of the test compounds reduced wasp fecundity and longevity to a significantly greater degree than the single applications, except for a low dose of JHI (1 µg). The study demonstrates that growth disrupters, such as JHs and precocenes have a delayed developmental effect on M. rufiventris and points out the need to be aware of these effects in implementing control strategies of S. littoralis in natural habitats.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Esmat M. Hegazi

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
health/environmental effects of pesticides
Research topic(s) for beneficials or antagonists:
resistance to pesticides

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Spodoptera littoralis		Egypt
Microplitis rufiventris (parasitoid)	Spodoptera littoralis		Egypt