Hiilamardikate (Meligethes aeneus Fab) munemiseelistused erinevatel ristõielistel kultuuridel - püüniskultuuri strateegia väljatöötamiseks suvirapsil
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Kuupäev
2013
Kättesaadav alates
ainult raamatukogus, only in library
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
Rapsi, kui Euroopa tähtsaima õlikultuuri, kasvupindala on Eestis viimase 12 aasta jooksul suurenenud ligikaudu neli korda. See on toonud kaasa rapsikahjurite (peamiselt naeri-hiilamardika) arvukuse märkimisväärse suurenemise. Naeri-hiilamardika tõrje põhineb sünteetilistel insektitsiididel (enamasti püretroididel), mille liigse kasutamise tagajärgedeks on insektitsiidide suhtes resistentsete kahjurite kujunemine ja põldude bioloogilise mitmekesisuse vähenemine. Üheks võimaluseks nende probleemidega võitlemisel on kahjurite toitumis- ja munemiseelistustega manipuleerides põhikultuurilt kahjurite ära meelitamine, mis ongi püüniskultuuri strateegia toimimise põhimõtteks.
Töö eesmärgiks on uurida erinevate ristõieliste taimede – raps (Brassica napus L.), rüps (Brassica rapa L.), rukola (Eruca vesicaria L.), õlirõigas (Raphanus sativus var. oleifera), kapsasrohi (Brassica juncea L.), valge sinep (Sinapis alba L.), must sinep (Brassica nigra L.) ja õlituder (Camelina sativa L.) – atraktiivsust hiilamardika munemispaikadena ja hinnata vastsete parasiteerituse taset, et välja selgitada, millised taimeliigid sobiksid kõige paremini püüniskultuurideks suvirapsi kaitseks naeri-hiilamardika vastu. Püünis- ehk lõksukultuurideks nimetatakse taimeliike, mis on mõnedele kahjuriliikidele atraktiivsemad kui põllul kasvatatav põhikultuur ja mis takistavad kahjureid jõudmast põhikultuurile või aitavad neid koguda ühte põllu osasse, et neid sealt seejärel hävitada
Korraldati põldkatse kolmes korduses. Hiilamardikate munemisaktiivsuse ja vastsete parasiteerituse taseme hindamiseks korjati taimede õitsemise lõppstaadiumis (KS 67–69) iga katselapi kümnelt taimelt õisikud, millest korjati välja ja loendati kõik vastsed. Vastsed lahati mikroskoobi all, neist leitud parasitoidide vastsed ja munad loendati, määrati ja arvutati parasiteerituse määr.
Uurimustööst selgus, et hiilamardikate munemiseelistused sõltusid taimeliigist ja nad eelistasid munemistaimena rapsile rüpsi, musta sinepit ja kapsasrohtu. Üheks oluliseks põhjuseks on nende taimede kiirem areng võrreldes rapsiga. Kõrgeim parasiteerituse tase oli samuti rüpsi- ja musta sinepi taimedelt leitud vastsetel. Kõige rohkem leiti hiilamardikate vastsetest parasitoidi liigi Phradis morionellus esindajaid. Katses kasvatatud kultuuridelt leitud vastsete keskmine parasiteerituse tase oli 11,65%. Õlirõikalt ja rukolalt ei leitud ühtegi parasiteeritud vastset.
Vastsete arvu ja nende parasiteerituse taseme põhjal otsustades on meie klimaatilistes tingimustes kõige rohkem potentsiaali püüniskultuurina kasvatamiseks suvirapsi kaitseks rüpsil ja mustal sinepil. Selleks, et püüniskultuuri strateegia kasutegur maksimumini viia tuleb edaspidi täpsemalt uurida potentsiaalsete lõksukultuuride toimimise mehhanisme, proovida kasvatada mitut erinevat lõksukultuuri koos, et näha nende koosmõju efektiivsust ja leida milline peaks olema püünis- ja põhikultuuri vahekord põllul, et strateegia end ka majanduslikult ära tasuks.
The aim of this thesis was to assess oviposition preferences of the pollen beetle (Meligethes aeneus Fab) on different cruciferous plants – to develop the trap crop strategy for spring oilseed rape. Brassica napus is the most important oilseed crop in Europe. In Estonia the growth area of oilseed rape has increased almost four times during twelve years. This has led to an increase in the abundance of oilseed rape pests. The pollen beetle is one of the most important pests of oilseed rape. Control of pollen beetles relies heavily on synthetic insecticides (mainly pyrethroids). An excessive overuse of insecticides can result in pests evolving pyrethroid resistance. In addition, the use of pesticides has detrimental effects on beneficials and it can also decrease biodiversity on agricultural landscapes. One way to fight these problems is to lure pests away from the main crop by manipulation of feeding and oviposition preferences of pests, which is the principle of trap crop strategy. The main goal of the thesis was to study the attractiveness of different cruciferous plants (Brassica napus, Brassica rapa, Eruca vesicaria, Raphanus sativus var. oleiformis, Brassica juncea, Sinapis alba, Brassica nigra, Camelina sativa) as oviposition sites for pollen beetles and to evaluate the level of parasitism of their larvae, to examine which plants would be best-suited as trap crops for the protection of spring oilseed rape against pollen beetle. A small-scale field trial with three randomly placed replicates was carried out. In order to evaluate the oviposition activeness of pollen beetles and the level of larval parasitism, flower heads were gathered from 10 randomly chosen plants on each plot during the end of the flowering stage of plants (GS 67–69). All flowers were dissected, all found larvae were gathered and counted. The larvae were dissected under a microscope and the larvae and eggs of parasitoids were counted-, identified and the level of parasitism was calculated. The study showed that the oviposition preferences of pollen beetles depended on the plant species: they preferred B. rapa, B. nigra and B. juncea over B. napus. The main reason for this was the faster development of those plants compared to B. napus. The highest level of parasitism was found from the larvae on B. rapa and B. nigra. The most numerous parasitoid species was P. morionellus. Average level of parasitism was 11.65%. No parasitized larvae were found on R. sativus var. oleiformis and E. sativa. Considering the number of larvae and their parasitism rate, it can be concluded that the crops with most potential to be grown as trap crop for B. napus, could be B. rapa and B. nigra. In order to maximize the efficiency of trap crops, further studies are needed: the working mechanisms of potential trap crops must be studied in detail, different types of trap crops must be grown together to determine the efficiency of their concurrence, also, the relation of trap crop and main crop on a field must be regulated in such a way that it would be economically rational.
The aim of this thesis was to assess oviposition preferences of the pollen beetle (Meligethes aeneus Fab) on different cruciferous plants – to develop the trap crop strategy for spring oilseed rape. Brassica napus is the most important oilseed crop in Europe. In Estonia the growth area of oilseed rape has increased almost four times during twelve years. This has led to an increase in the abundance of oilseed rape pests. The pollen beetle is one of the most important pests of oilseed rape. Control of pollen beetles relies heavily on synthetic insecticides (mainly pyrethroids). An excessive overuse of insecticides can result in pests evolving pyrethroid resistance. In addition, the use of pesticides has detrimental effects on beneficials and it can also decrease biodiversity on agricultural landscapes. One way to fight these problems is to lure pests away from the main crop by manipulation of feeding and oviposition preferences of pests, which is the principle of trap crop strategy. The main goal of the thesis was to study the attractiveness of different cruciferous plants (Brassica napus, Brassica rapa, Eruca vesicaria, Raphanus sativus var. oleiformis, Brassica juncea, Sinapis alba, Brassica nigra, Camelina sativa) as oviposition sites for pollen beetles and to evaluate the level of parasitism of their larvae, to examine which plants would be best-suited as trap crops for the protection of spring oilseed rape against pollen beetle. A small-scale field trial with three randomly placed replicates was carried out. In order to evaluate the oviposition activeness of pollen beetles and the level of larval parasitism, flower heads were gathered from 10 randomly chosen plants on each plot during the end of the flowering stage of plants (GS 67–69). All flowers were dissected, all found larvae were gathered and counted. The larvae were dissected under a microscope and the larvae and eggs of parasitoids were counted-, identified and the level of parasitism was calculated. The study showed that the oviposition preferences of pollen beetles depended on the plant species: they preferred B. rapa, B. nigra and B. juncea over B. napus. The main reason for this was the faster development of those plants compared to B. napus. The highest level of parasitism was found from the larvae on B. rapa and B. nigra. The most numerous parasitoid species was P. morionellus. Average level of parasitism was 11.65%. No parasitized larvae were found on R. sativus var. oleiformis and E. sativa. Considering the number of larvae and their parasitism rate, it can be concluded that the crops with most potential to be grown as trap crop for B. napus, could be B. rapa and B. nigra. In order to maximize the efficiency of trap crops, further studies are needed: the working mechanisms of potential trap crops must be studied in detail, different types of trap crops must be grown together to determine the efficiency of their concurrence, also, the relation of trap crop and main crop on a field must be regulated in such a way that it would be economically rational.
Kirjeldus
Märksõnad
naeri-hiilamardikas, suviraps, munemiseelistused, püüniskultuur, vastsete parasiteeritus, magistritööd