Dissertation (PhD(Agric))--Stellenbosch University, 2003. / ENGLISH ABSTRACT: The codling moth, Cydia pomonella (L.) has been a major pest of pome fruits since before the turn
of the last century. However, despite its high economic profile little is known about the bionomics and .
behaviour of this pest in apple orchards in South Africa, information required for the development of
a sustainable integrated management programme.
In field trials there was contingency between the time of year and the upper and lower half of the tree.
First generation moths laid significantly more eggs in the bottom half of the tree while second and third
generation moths laid significantly more eggs in the top half of the tree. The preferred oviposition sites
on Granny Smith (GS) and Golden Delicious (GD) cultivars, in order of preference, were leaves, fruit
and wood. More eggs were laid on the fruit ofGS spurs (35.6 %) than on those ofGD spurs (10.7
%). On fruit spurs there was a significant increase in the number of eggs on GD leaves and GS fruit
over the season, whereas the number of eggs on GS leaves and GD fruit remained constant. On
branches there was an increase in the number of eggs on GD and GS leaves, but not on the fruit or
wood. The preferred oviposition site on the fruit was the fovea of the stalk insertion and the rounded
cheek area surrounding the fovea. The distribution within different fruit bearing classes (1 - 4 fruit per
spur) was random only for one fruit per spur, while on the other spur classes clustering occurred.
In laboratory studies of the embryonic and immature stages there was a linear relationship between rate
of development and constant temperatures of 15, 17,20,25 and 30·C ± l·C. The lower threshold
temperatures for embryonic, larval and pupal development were 11.1, 7.9, 9.9°C respectively. The
degree-days required to complete embryonic, larval and pupal development were 80.5, 345, and 279
respectively. The response of the different stages to constant temperatures was similar to that under
fluctuating temperatures.
At temperatures below 16°C or abouve 27°C moths did not mate and few eggs were laid. Moth
longevity decreased with increasing temperature. There was seasonal variation in longevity and
oviposition at constant and fluctuating temperatures. Summer adults produced significantly more eggs
than spring adults at constant temperatures.
At a constant temperature of2S·C and fluctuating temperatures there were five distinct larval instars.
The similarity between the mean head capsule width and ranges for each instar reared on fruit of different stages of development at fluctuating temperatures indicates that fruit development and
temperature have little influence on mean head capsule width.
From sleeve-cage studies in the orchard there was no significant difference in the fecundity of spring
and summer moths. In the beginning of October spring moths produced significantly fewer eggs than
in November. Egg mortality increased from 8.2 %in spring to 21.2 %in summer. Failure of 1st instar
larvae to penetrate the fruit ranged from 4.9 % to 19.5 %, while mortality oflarvae from egg hatch
to emergence from the fruit ranged from 29.7 % to 42.9 %. Mortality of 5th instar larvae after
emerging from the apples ranged from 0 % to 8.7 % and pupal mortality from 0 % to 3.5 %.
On large 27-year old trees more overwintering larvaewere found on Golden Delicious (13.9) than on
Granny Smith trees (5.7), with over 70 % oflarvae being found in pruning wounds on both cultivars.
On small 7-year old Golden Delicious and Granny Smith trees the mean number oflarvae was 0.5 and
2.0 per tree.
A combined mating disruption and insecticide control programme reduced codling moth resistant
populations to levels requiring a minimum to no insecticide intervention for several seasons. The
efficacy of a pheromone based strategy, number of pheromone treatments, number of dispenserslha
and level of insecticide intervention required are strongly influenced by prevailing weather conditions.
Fruit infestation in orchards under a mating disruption programme and under an insecticide programme
were greater along the borders compared to the interior.
The presence of horticultural mineral oil on the leaves and branches did not have a detrimental effect
on oviposition nor was there any significant ovicidal effect. A significant ovicidal effect was obtained
when applied after oviposition. In field trials, insecticides with lower levels of efficacy than the primary
insecticide, azinphos-methyl, provided acceptable control when successfully incorporated into a spray
programme which followed a policy of alternation of insecticides across generations.
The least variation in the number of degree-days between biofix and first egg hatch of the spring flight
was when the second trap catch (Biofix 2) was used as the biofix. A biofix based on the first evening
when the temperature reached or exceeded 1TC at 18:00 after first trap catch also showed less
variation than when the biofix was based on first trap catch. The mean number of degree-days
accumulated between Biofix 2 and first egg hatch was found to be 139.1 ° D. The number of degreedays
between the first and second flight biofixes varied between 531.2 and 488.87°D with a mean of
508.1°D. / AFRIKAANSE OPSOMMING: Kodlingmot (Cydia pomonella) is reeds sedert die vorige eeu 'n sleutelplaag van kemvrugte. Ten
spyte van die hoë ekonomiese profiel, is daar min kennis betreffende die bionomie en gedrag van
hierdie plaag in appelboorde in Suid-Afrika. Hierdie inligting is noodsaaklik vir die ontwikkeling
van 'n volhoubare geïntegreerde bestuursprogram.
Tydens veldproewe is 'n korrelasie tussen die tyd van die jaar en eierlegging in die boonste of
onderste helfte van bome gevind. Eerste-generasie motte het betekenisvol meer eiers in die
onderste helfte van die bome gelê, terwyl tweede- en derde-generasie motte meer eiers in die
boonste helfte van die bome gelê het. In toenemende volgorde was die voorkeur
eierleggingsposisies op Granny Smith (GS) en Golden Delicious (GD) appels die blare, vrugte en
hout. Meer eiers is op vrugte van GS spore (35.6%) as op dié van GD spore (10.7%) gelê. Op
vrugspore was daar 'n betekenisvolle toename in aantal eiers op GD blare en GS vrugte deur die
seisoen, terwyl die getal eiers op GS blare en GD vrugte konstant gebly het. Op takke was daar 'n
toename in aantal eiers op GD en GS blare, maar nie op vrugte of hout nie. Die voorkeur
eierleggingsposisie op vrugte was die fovea van die steelaanhegting en die wang rondom die fovea.
Die verspreiding tussen verskillende vrugdraende klasse (1 - 4 vrugte per spoor) was slegs in die
een-Vrug-per-spoorklas ewekansig, terwyl daar in die ander spoorklasse groepering voorgekom het.
In laboratoriumstudies van embrioniese en onvolwasse stadia is 'n lineêre verband tussen
ontwikkelingskoers en konstante temperature van 15, 17,20,25 en 30°C±I°C gevind. Die onderste
drempel-temperature vir embrioniese, larwale en papie-ontwikkeling was onderskeidelik II. 1°C,
7.f?C en 9.9°C. Graaddae benodig vir voltooiing van embrioniese, larwale en papie-ontwikkeling
was onderskeidelik 80.5,345 en 279. Die respons van verskillende stadia by konstante temperature
het ooreengestem met hul respons onder wisselende temperature.
Motte het nie gepaar nie en min eiers is gelê by temperature onder 16°C of bo 27°C. Die
lewensverwagting van motte het afgeneem met toename in temperatuur. Seisoenale variasie in
. lewensverwagting en eierlegging het voorgekom by konstante sowel as wisselende temperature. By
konstante temperature het somer-volwassenes betekenisvol meer eiers as lente-volwassenes
geproduseer.
By 'n konstante temperatuur van 25°C, sowel as by wisselende temperature, het vyf duidelik
onderskeibare larwale instars voorgekom. Die ooreenkoms tussen die gemiddelde kopkapsulewydte
en wydte-reeks vir elke instar wat op vrugte van verskillende stadiums van ontwikkeling by wisselende temperature geteel is, dui daarop dat vrugontwikkeling en temperatuur weinig invloed
op gemiddelde kopkapsule-wydte het.
Tydens mou-hok studies in die boord is geen betekenisvolle verskil in die fekunditeit van lente- en
somer-motte waargeneem nie. Vroeg in Oktober het lente-motte betekenisvol meer eiers as in
November geproduseer. Eiermortaliteit het van 8.2% in die lente tot 21.2% in die somer
toegeneem. Faling van 1ste instar larwes om vrugte te penetreer het van 4.9% tot 19.5% gewissel,
terwyl mortaliteit van larwes vanaf uitbroei tot uitkoms uit die vrug van 29.7% tot 42.9% gewissel
het. Mortaliteit van Sde instar larwes na uitkoms uit die vrug het van 0% tot 8.7% gewissel, en
papie-mortaliteit van 0% tot 3.5%.
Op groot, 27-jaar oue bome is meer oorwinterende larwes op Golden Delicious (13.9) as op Granny
Smith (5.7) gevind, en meer as 70% van die larwes op beide kultivars is op snoeiwonde gevind. Op
klein, 7-jaar oue bome was die gemiddelde aantallarwes op Golden Delicious en Granny Smithbome
0.5 en 2.0 onderskeidelik.
'n Gekombineerde paringsontwrigting- en insekdoder beheerprogram het weerstandbiedende
kodlingmot-populasies verminder tot 'n vlak waar minimum tot geen insekdoder-toedienings vir
verskeie seisoene gemaak is. Die effektiwiteit van 'n feromoon-gebaseerde strategie, aantal
feromoonbehandelings, aantal vrystellers/ha en vlak van insekdoder-toediening word sterk deur
heersende weersomstandighede beïnvloed. Die rande het hoër vruginfestasie as die middel getoon
in boorde onder paringsontwrigting sowel as boorde onder insekdoder-programme. Die
teenwoordigheid van minerale olie op blare en takke het geen nadelige effek op eierlegging gehad
nie en dit het geen betekenisvolle eierdodende effek gehad nie. Indien die olie ná eierlegging
toegedien is, is daar wel 'n betekenisvolle eierdodende effek waargeneem. Tydens veldproewe het
insekdoders met laer effektiwiteit as die primêre insekdoder, azinfos-metiel, aanvaarbare beheer
verskaf indien dit suksesvol geïnkorporeer is in 'n spuitprogram deur 'n beleid van afwisseling van
insekdoders oor generasies.
Die kleinste variasie tussen die aantal graaddae tussen biofix en eerste uitbroei van eiers is gevind
indien die tweede lokvalvangs as biofix gebruik is. 'n Biofix gebaseer op die eerste aand na die
eerste lokval vangste wat die temperatuur 17°Cofhoër was teen 18:00, het ook 'n kleiner variasie
getoon as die eerste lokvalvangs. Die aantal graaddae tussen die tweede en derde vlug biofix het
tussen 531.2 en 488.87°D gewissel, met 'n gemiddelde van 508.1°D.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/53312 |
| Date | 03 1900 |
| Creators | Blomefield, Thomas Loftus |
| Contributors | Giliomee, J. H., Pringle, K. L., Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 294 p. : ill. |
| Rights | Stellenbosch University |
Page generated in 0.0036 seconds