Bulletin of Entomological Research (1994) 84, 509-513

Helen J. Hutt, H.F. van Emden and T. Baker (1994)
Stimulation of plant growth and aphid populations by a formulation ingredient of 'Cymbush' (cypermethrin)
Bulletin of Entomological Research 84 (4), 509-513
Abstract: Similar increases in the height and aerial fresh weight of cowpeas compared with control plants were obtained when plants were sprayed with either 50 ppm ad. (active ingredient) of the pyrethroid insecticide 'Cymbush'® containing cypermethrin, or, the equivalent dilution of a blank formulation without the a.i.. With broad beans, similar growth stimulation was obtained with the blank at the same or half dose, but not at a quarter dose. Testing the four formulation components separately showed that only the non-ionic emulsifier caused stimulation. A comparison of the stimulation of plant growth by the blank and the non-ionic emulsifier showed that plant height, shoot fresh weight, leaf fresh weight, leaf dry weight and leaf area were each equally increased by both treatments. The non-ionic emulsifier thus accounted for the entire stimulation caused by blank solution. Populations of Aphis fabae Scopoli (Homoptera: Aphididae) were twice as high on broad bean plants sprayed with the non-ionic emulsifier as on the controls. 'Cymbush' (the complete formulation) sprayed at 25 ppm a.i.. was shown to increase the intrinsic rate of natural increase of the aphid through a 22% increase in fecundity; aphid development time was not affected. The results do, however, suggest that residual effects of cypermethrin may have partly counteracted the stimulatory effects of the non-ionic emulsifier. Nevertheless, it is possible that outbreaks of aphids and mites following pyrethroid application, and often assumed without evidence to have been due to natural enemy mortality, may at least in part reflect the plant stimulation caused by the non-ionic emulsifier in the formulation.
(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): Helmut F. van Emden

Research topic(s) for pests/diseases/weeds:
control - general
health/environmental effects of pesticides

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Aphis fabae	Cowpea and relatives (Vigna)
	Aphis fabae	Broad/faba bean (Vicia faba)