Eelneva aasta rapsipõldude kauguse mõju naeri-hiilamardika arvukusele ja parasiteerituse tasemele
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Kuupäev
2021
Kättesaadav alates
02.09.2021
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Naeri-hiilamardikas (Brassicogethes aeneus Fabricius) on laialt levinud ristõielistele
taimedele spetsialiseerunud rapsikahjur Euroopas. Rapsi kasvupindala suurenemise
tulemusel on naeri-hiilamardika populatsioonid kasvanud ja nad on muutunud suuremaks
probleemiks rapsikasvatajatele. Hiilamardika tõrjumiseks kasutatakse peamiselt
püretroididel põhinevaid insektitsiide. Tihti manustatakse neid profülaktiliselt
tõrjekriteeriumeid arvesse võtmata, mille tulemusel on naeri-hiilamardikatel tekkinud
resistentsus selle toimeaine suhtes. Järjest enam otsitakse loodussäästlikumaid alternatiive
kahjurite tõrjel ning üks keskkonnasäästlikumaid viise on looduslike vaenlaste
soodustamine, kellest olulisemad on kiletiivalised parasitoidid. Peamised parasitoidid, kes
on kõige edukamad naeri-hiilamardikate bioloogilises tõrjes on Phradis interstitialis,
Phradis morionellus ja Tersilochus heterocerus.
Käesoleva töö eesmärgiks oli välja uurida kas ja kuidas mõjutab eelneva aasta rapsipõllu
kaugus naeri-hiilamardikate arvukust ja nende parasiteerituse taset talirapsil. Lisaks oli
esitatud ka kolm hüpoteesi: (I) eelmise aasta rapsipõllu lähedus suurendab hiilamardika
vastsete arvukust rapsitaimedel; (II) eelmise aasta rapsipõllu lähedus suurendab
hiilamardikate vastsete parasiteerituse taset; (III) parasitoidide liigiline koosseis ei ole
mõjutatud eelmise aasta rapsipõllu lähedusest. Katses oli kokku oli 12 põldu, millest
kuus asusid lähemal kui 500 meetrit eelmise aasta talirapsi põldudest ning kuus põldu
asusid kaugemal kui 500 meetrit eelmise aasta talirapsi põllust. Leiti, et oluliselt rohkem
oli naeri-hiilamardika vastseid põldudelt, mis asusid eelmise aasta põldudest kaugemal
kui 500 meetrit. Eelmise aasta rapsipõllu lähedus suurendas hiilamardikate vastsete
parasiteerituse taset. Parasitoidide liigiline koosseis ei olnud mõjutatud eelmise aasta
rapsipõllu lähedusest. Käesolevas töös leiti, et domineerivaks liigiks oli Tersilochus
heterocerus.
The pollen beetle (Brassicogethes aeneus Fabricius) is one of the most abundant pest of oilseed rape in Europe. Due to the increase in the growing area of oilseed rape, the pollen beetle is becoming an increasing problem, which is mainly controlled by pyrethroid-based insecticides. They are often managed prophylactically and without regard to economic threshold criteria; and therefore pollen beetles have begun to develop resistance to this active ingredient. Therefore, more environmentally friendly alternatives for pest control have been sought, one of the most effective of which is the promotion of natural enemies, the most important of which are hymenopteran parasitoids. The three key parasitoids of the pollen beetle are Phradis interstitialis, Phradis morionellus and Tersilochus heterocerus. The aim of this study was to find out whether and how the distance from the previous year’s oilseed rape fields affect the abundance of pollen beetles, their larvae and their parasitism rate. The hypotheses was that (I) the proximity of last year's winter oilseed rape field increases the number of pollen beetle larvae in oilseed rape fields; (II) the proximity of the previous year's oilseed rape field increases the level of parasitism of pollen beetle larvae; (III) the species composition of the parasitoids was not affected by the proximity of the previous year's oilseed rape field. There were 12 winter oilseed rape fields in the experiment, six of which were located closer than 500 meters from the previous year's winter oilseed rape fields and six fields were located farther than 500 meters from the previous year's winter oilseed rape field. It was found that there were significantly more pollen beetle larvae in the fields located farther than 500 meters from the previous year's fields. The proximity of last year's winter oilseed rape field increased the level of parasitism of pollen beetle larvae. The species composition of the parasitoids was not affected by the proximity of the previous year's winter oilseed rape field. In this work, it was found that the dominant parasitoid species was Tersilochus heterocerus.
The pollen beetle (Brassicogethes aeneus Fabricius) is one of the most abundant pest of oilseed rape in Europe. Due to the increase in the growing area of oilseed rape, the pollen beetle is becoming an increasing problem, which is mainly controlled by pyrethroid-based insecticides. They are often managed prophylactically and without regard to economic threshold criteria; and therefore pollen beetles have begun to develop resistance to this active ingredient. Therefore, more environmentally friendly alternatives for pest control have been sought, one of the most effective of which is the promotion of natural enemies, the most important of which are hymenopteran parasitoids. The three key parasitoids of the pollen beetle are Phradis interstitialis, Phradis morionellus and Tersilochus heterocerus. The aim of this study was to find out whether and how the distance from the previous year’s oilseed rape fields affect the abundance of pollen beetles, their larvae and their parasitism rate. The hypotheses was that (I) the proximity of last year's winter oilseed rape field increases the number of pollen beetle larvae in oilseed rape fields; (II) the proximity of the previous year's oilseed rape field increases the level of parasitism of pollen beetle larvae; (III) the species composition of the parasitoids was not affected by the proximity of the previous year's oilseed rape field. There were 12 winter oilseed rape fields in the experiment, six of which were located closer than 500 meters from the previous year's winter oilseed rape fields and six fields were located farther than 500 meters from the previous year's winter oilseed rape field. It was found that there were significantly more pollen beetle larvae in the fields located farther than 500 meters from the previous year's fields. The proximity of last year's winter oilseed rape field increased the level of parasitism of pollen beetle larvae. The species composition of the parasitoids was not affected by the proximity of the previous year's winter oilseed rape field. In this work, it was found that the dominant parasitoid species was Tersilochus heterocerus.
Kirjeldus
Magistritöö
Maastikukaitse ja -hooldus õppekaval
Märksõnad
magistritööd, hiilamardikas, raps, looduslikud vaenlased, parasitoidid, kiletiivalised