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German wasp | Vespula germanica

German wasp

Vespula germanica

Coral bush | Ardisia crenata

Coral bush

Ardisia crenata

Purple loosestrife | Lythrum salicaria

Purple loosestrife

Lythrum salicaria

Pom pom weed | Campuloclinium macrocephalum

Pom pom weed

Campuloclinium macrocephalum

Canarybird bush | Crotalaria agatiflora

Canarybird bush

Crotalaria agatiflora

Peanut butter cassia | Senna didymobotrya

Peanut butter cassia

Senna didymobotrya

Rubber vine | Cryptostegia grandiflora

Rubber vine

Cryptostegia grandiflora

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Environmental Programmes

In order to tackle our country’s socio-economic challenges, the government adopted the Outcomes based approach to improve government performance and providing focus on service delivery. find out more

Exacerbation of photosynthetic damage through increased heat–light stress resulting from Gargaphia decoris sap-feeding

Exacerbation of photosynthetic damage through increased heat–light stress resulting from Gargaphia decoris sap-feeding 
Blair COWIE, Marcus J. Byrne, Ed Witkowski, Nic Venter
School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa

Solanum mauritianum (Bugweed) is one of the world’s worst ecological weeds and has been targeted for biological control efforts in South Africa since 1984. One of two promising biological control agents released against Bugweed was the sap-sucking lace bug, Gargaphia decoris (Hemiptera: Tingidae). Few studies have assessed the physiological effects induced by biological control agents feeding damage on their target weeds. Chlorophyll removal by G. decoris feeding caused metabolic impairment which resulted in a reduction of photosynthetic rates of Bugweed leaves, with a greater effect on plants growing in full-sun conditions compared to plants growing in shade. This difference was related to higher leaf temperatures experienced under full-sun conditions. Herbivory caused a 52% reduction in Bugweed transpiration rates, impeding the ability of leaves cool via evaporation. Although G. decoris’s feeding rates were greater on plants in the shade, feeding per unit area was significantly more damaging to plants continually exposed to full sunlight. The increased physiological damage experienced by full-sun plants may be a combination of stresses, particularly the direct effect of chlorophyll removal via herbivory and the indirect effect of accumulated heat–light stress. Given the effectiveness of G. decoris for biological control, factors constraining its current performance in the field need to be identified and addressed.

Read 2812 times Last modified on Tuesday, 03 May 2016 12:29

General News Updates

2019 National Symposium on Biological Invasio…


This is your invitation to South Africa's 2019 National Symposium on Biological Invasions. The convention is hosted by the Centre for Invasion Biology (CIB), University of Stellenbosch, and the Biolo... Read more

2019 Invasive Species Training


During the past five years (2014-2018), ISSA invasive species trainers have trained 4 000 in the identification of invasive species and laws pertaining to invasive species across South Africa.  ... Read more

Alien Grass Working Group


Who are we? The South African National Alien Grass Working Group was jointly initiated by the South African Biodiversity Institute (SANBI) and the Centre for Excellence in Invasion Biology (C·I·B) in... Read more

Permits for planting indigenous Cynodon?


On 16 February, 2018, South Africa's Department of Environmental Affairs issued amendments to the regulations and lists relating to the National List of Invasive Species.  Updates to the draft&n... Read more

Invasive species training 2018 dates released


Interested in invasive species?  How much do you know about NEMBA invasive species compliance for landowners and organs of state? The South African Green Industries Council (SAGIC) have released... Read more

Communications post for Africa advertised


The Nature Conservancy has advertised a brand new post:  Communications Manager, Africa Region. Knowledge of invasive species and water would be an asset in this post. See details below:    Job Titl... Read more