Nitrogen fertilisation improves growth of Chromolaena odorata (Asteraceae) and the performance of the biological control agent, Pareuchaetes insulata (Erebidae)

^†Current address: Department of Animal and Environmental Biology, University of Benin, P.M.B. 1154, Benin City, Nigeria.

ABSTRACT

Recent studies have demonstrated, through their contrasting results, that relationships between nitrogen levels in host plants and phytophagous insect performance are not simple. This study examined the effect of varying fertilisation regimes on the invasive alien plant, Chromolaena odorata (L.) (Asteraceae) and the response of a specialist folivore (a biological control agent), Pareuchaetes insulata (Walker) (Lepidoptera: Erebidae). C. odorata plants were treated with 3 different levels of fertilisation and plant characteristics were measured within 2–3 months of fertiliser application. Leaves from each of the three treatments were fed to newly hatched larvae until pupation in order to determine the effect of nitrogen fertilisation on herbivore performance metrics such as survival, development time, fecundity and longevity. High and medium fertilisation significantly increased foliar nitrogen concentrations, basal stem diameter, leaf length, shoot height and above-ground biomass of C. odorata plants relative to low fertilisation. When individuals of P. insulata were fed on leaves from medium- or high-fertilisation treatments, they developed faster, grew to a larger size (by 8%) and achieved higher fecundity (19–22%) than leaves from the low-fertilisation treatment. The results suggest that in mass-rearing, increased production of this biological control agent will occur in high- or medium-fertilised plants.

KEYWORDS:

• Invasive alien weed
• nitrogen fertilisation
• herbivore and plant performance
• weed biological control
• mass-rearing

Acknowledgements

The authors thank the Department of Environmental Affairs: Natural Resource Management Programmes and ARC-Plant Protection Research Institute, South Africa for providing funding and facilities.

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

The financial support given to the first author by the German Academic Exchange Service (DAAD) is acknowledged with appreciation.

Notes

^† Current address: Department of Animal and Environmental Biology, University of Benin, P.M.B. 1154, Benin City, Nigeria.