Thesis (MScAgric (Conservation Ecology and Entomology))--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Ant infestations comprising the Argentine ant Linepithema humile (Mayr), common
pugnacious ant Anoplolepis custodiens (F. Smith) and cocktail ant Crematogaster
peringueyi Emery are a widespread pest problem in South African vineyards.
Integrated Pest Management (IPM) programmes aimed at suppressing the
problematic honeydew excreting vine mealybug Planococcus ficus (Signoret)
(Hemiptera: Pseudococcidae) on grapes must include ant control to optimize the
effectiveness and efficacy of mealybug natural enemies. If ants are eliminated,
natural enemies are able to contain mealybugs below the Economic Threshold Level
(ETL). Current strategies for ant control are limited and generally include the
application of long term residual insecticides that are detrimental to the environment,
labour intensive to apply and can disrupt natural biological control if applied
incorrectly. A more practical method of ant control using low toxicity baits was
therefore investigated. Field bait preference and bait acceptance assessments
aimed at determining bait repellency and palatability, respectively, were carried out
during spring, summer and autumn in three vineyards of the Cape winelands region
during 2007/08. Five toxicants comprising gourmet ant bait (0.5%), boric acid
(0.5%), fipronil (0.0001%), fenoxycarb (0.5%) and spinosad (0.01%) dissolved in
25% sugar solution were tested against a 25% sucrose solution control. Gourmet ant
bait was significantly more preferred and accepted by all ant species than the other
baits. Laboratory bait efficacy assessments using four insecticides (gourmet, boric
acid & spinosad) at concentrations of 0.25; 0.5; 1; 2 and 4 times the field dose and
fipronil at 0.015625; 0.03125; 0.0625; 0.125; 0.25 times the field dose were carried
out. Results revealed that boric acid (2%), gourmet ant bait (2%) and fipronil (1.0 X
10-5%) exhibited delayed toxicity for L. humile and C. peringueyi while spinosad
(0.01%) showed delayed action on L. humile. Field foraging activity and food
preference tests were also carried out for the three ant species during 2007/08.
Foraging activity trials revealed that vineyard foraging activity of L. humile is higher
relative to A. custodiens and C. peringueyi. This means fewer bait stations are
required for effective L. humile control making low toxicity baits a more affordable
and practical method of controlling L. humile than the other two ant species. Food
preference trials showed that L. humile and C. peringueyi have a high preference for
sugar while A. custodiens significantly preferred tuna over other baits. However, all
ant species had a preference for wet baits (25% sugar water, 25% honey, tuna & agar) as opposed to dry ones (fish meal, sorghum grit, peanut butter & dog food).
This research concludes that low toxicity baits show potential in ant pest
management and can offer producers with a more practical, economical and
environmentally friendly method of ant control which is compatible with vineyard IPM
programmes. / AFRIKAANSE OPSOMMING: Mierbesmetting wat uit die Argentynse mier Linepithema humile (Mayr), die gewone
malmier Anoplolepis custodiens (F. Smith) en die wipstertmier Crematogaster
peringueyi Emery bestaan, is ’n plaagprobleem wat wydverspreid in Suid-Afrikaanse
wingerde voorkom. Programme vir geïntegreerde plaagbeheer (GPB) wat daarop
gemik is om die wingerdwitluis Planococcus ficus (Signoret) (Hemiptera:
Pseudococcidae) – wat ’n probleem is weens die heuningdou wat dit afskei – op
druiwe te beheer, moet mierbeheer insluit om sodoende die uitwerking en
doeltreffendheid van die witluis se natuurlike vyande die beste te benut. As miere
uitgeskakel kan word, sal dit vir die natuurlike vyande moontlik wees om die witluis
sodanig te beheer dat dit onder die ekonomiese drempelvlakke (EDV) bly. Huidige
strategieë om miere te beheer, is beperk en sluit gewoonlik die toediening van
insekdoders in wat lank neem om in die grond af te breek, wat skadelik vir die
omgewing is, waarvan die toediening arbeidsintensief is en wat die natuurlike
biologiese beheer kan versteur indien dit verkeerd toegepas word. Daarom is ’n meer
praktiese metode ondersoek waar miere deur die gebruik van lae toksisiteit lokase
beheer word. Ondersoeke na lokaasvoorkeure en lokaasaanvaarbaarheid in die
praktyk, wat daarop gemik is om te bepaal of die lokaas onderskeidelik afstootlik en
smaaklik bevind word, is oor lente, somer en herfs in drie verskillende wingerde in
die Kaapse wynlandstreek gedurende die 2007/08-seisoen uitgevoer. Vyf gifstowwe,
bestaande uit gourmet ant bait (0.5%), boorsuur (0.5%), fiproniel (0.0001%),
fenoksiekarb (0.5%) en spinosad (0.01%) wat in ’n 25%-suikeroplossing opgelos is,
is getoets teenoor ’n kontrole wat uit ’n 25%-sukrose-oplossing bestaan. Al die
mierspesies het gourmet ant bait bo die ander lokase verkies en aanvaar. In die
laboratorium is ondersoeke gedoen om die doeltreffendheid van die lokase te bepaal
deur vier insekdoders (gourmet ant bait, boorsuur en spinosad) te gebruik in
konsentrasies van 0.25; 0.5; 1; 2 en 4 keer die dosis in die praktyk en fiproniel teen
0.015625; 0.03125; 0.0625; 0.125; 0.25 keer die dosis in die praktyk. Resultate het
getoon dat boorsuur (2%), gourmet ant bait (2%) en fiproniel (1.0 X 10-5%)
vertraagde toksisiteit getoon het vir L. humile en C. peringueyi, terwyl spinosad
(0.01%) ’n vertraagde uitwerking getoon het op L. humile. Toetse om
kossoekaktiwiteite in die praktyk en die voedselvoorkeure van die drie mierspesies te
ondersoek, is ook gedurende die 2007/08-seisoen gedoen. Proewe oor
kossoekaktiwiteite het getoon dat hierdie aktiwiteite in die wingerd by L. humile hoër is in verhouding met A. custodiens en C. peringueyi. Dit beteken dat minder
lokaasstasies nodig is om L. humile doeltreffend te beheer en lei daartoe dat lae
toksisteit lokaas ’n beter manier is om L. humile te beheer as die ander twee
mierspesies. Proewe oor voedselvoorkeure het aangedui dat L. humile en
C. peringueyi ’n groot voorkeur toon vir suiker, terwyl A. custodiens ’n duidelike
voorkeur vir tuna het. Alle mierspesies het egter ’n voorkeur vir nat lokaas (25%
suikerwater, 25% heuning, tuna en agar), eerder as droë lokaas (vismeel,
sorghumgruis, grondboontjiebotter en hondekos) getoon. Uit hierdie navorsing word
afgelei dat lae toksisteit lokaas potensiaal toon in mierbeheer en dat dit produsente ’n
meer praktiese, ekonomiese en omgewingsvriendelike metode van mierbeheer kan bied wat met GPB-programme in die wingerd versoenbaar is.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/4496 |
| Date | 12 1900 |
| Creators | Nyamukondiwa, Casper |
| Contributors | Addison, P., Addison, M. F., Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | Unknown |
| Type | Thesis |
| Rights | Stellenbosch University |
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