Accessibility navigation


Mirid feeding preference as influenced by light and temperature mediated changes in plant nutrient concentration in cocoa

Awudzi, G., Hadley, P., Hatcher, P. and Daymond, A. (2020) Mirid feeding preference as influenced by light and temperature mediated changes in plant nutrient concentration in cocoa. Annals of Applied Biology. ISSN 0003-4746 (In Press)

[img] Text - Accepted Version
· Restricted to Repository staff only
· The Copyright of this document has not been checked yet. This may affect its availability.

333kB

It is advisable to refer to the publisher's version if you intend to cite from this work. See Guidance on citing.

Abstract/Summary

Cocoa mirids are the most important insect pests of cocoa in West Africa. This study investigated the effect of environmental parameters that are modulated by overhead shade, i.e. light intensity and temperature, on nutrient and phenolic concentrations in cocoa and their subsequent effect on mirid feeding. Eight-month-old cocoa seedlings were maintained for 50 days in two growth chambers set to day temperatures of 25oC or 30oC. Each chamber had sections with different light intensities (541, 365 and 181 µmolm-2s-1 PAR). For the field studies at Akim-Tafo in Ghana, eight-month-old plants of three cocoa clones were subjected to shaded (PAR= 180 µmol m-² s-1, between 11:00 and 12:00) and unshaded (PAR= 1767 µmol m-² s-1 between 11:00 and 12:00) treatments for 50 days after which nutrient measurements and mirid choice tests were carried out. No significant effect of environment was observed on the phenolic concentration of stems under controlled environment chamber conditions. However, in the field, the phenolic concentration of stems was significantly greater for unshaded compared with shaded plants (P=0.04). Under controlled conditions, the leaf nitrogen concentration increased slightly with light intensity (P=0.003). The same trend was seen in stems but only at 30oC. In the field, the impact of overhead shade on nitrogen varied between cocoa clones. The concentration of carbohydrates in both leaves and stems in the field was higher under unshaded conditions. When subjected to feeding tests, stems from unshaded cocoa had significantly more mirid feeding lesions (P=0.003) after 24 hours exposure to mirids compared to shaded cocoa. Mirid feeding therefore appears not to be deterred by the higher phenolic levels but rather there was a preference for cocoa tissue grown under unshaded conditions. These findings highlight the need to consider the growing environment of cocoa clones when screening for varieties with resistance to mirids.

Item Type:Article
Refereed:Yes
Divisions:Faculty of Life Sciences > School of Biological Sciences > Ecology and Evolutionary Biology
Faculty of Life Sciences > School of Agriculture, Policy and Development > Biodiversity, Crops and Agroecosystems Division > Crops Research Group
ID Code:92391
Publisher:Wiley

University Staff: Request a correction | Centaur Editors: Update this record

Page navigation