Biological control of potato cyst nematodes using plants

Abstract

Potato cyst nematodes (PCN), Globodera rostochiensis and G. pallida are important pests of potato. They are present in most of potato growing regions, including Europe. Either still absent or present, they have a quarantine pest status. Pesticides were never self-sufficient and sustainable measure for PCN control. Therefore, an integrated control approach is implemented for already decades of combating PCN. This integrated concept has two classical goals. The first is to prevent spread of pests to uninfested areas, and is based on statutory regulations of seed potatoes production and trade. The second goal, complementing the first, is performing control and eradication measures in infested areas. Within eradication measures, plants have an important role in several ways. PCN are highly specialized plant root parasites, very competitive in arable land, yet having two weaknesses - limited mobility and host range. Therefore, a logical and also sustainable approach is to let them starve to death in a field, using non host, but sometimes also host plants. Non host crop species are used in crop rotation, including resistant cultivars of host crops species, neither practice traditionally being regarded as a biological control measure sensu stricto. However, resistant and susceptible potato cultivars, as well as other host or non host plant species may act as 'trap-crops' for nematodes. Optionally, plants or their products may be used to just provoke faster emergence from cysts and subsequent death of dormant PCN infective juveniles if the absence of host plants. The later practices directly exterminate pests and merit a status of biological control measures.

Krompirove cistolike nematode (KCN), Globodera rostochiensis i G. pallida, važne su karantinske štetočine krompira širom sveta. Njihovo suzbijanje pesticidima nikada nije bilo ekotoksikološki prihvatljivo ni dovoljno efikasno da samo rešava problem. Zato je već decenijama kontrola KCN bazirana na jednom integralnom sistemu mera, u kome je upotreba pesticida na začelju. Biljke se mogu na razne načine koristiti protiv KCN, zahvaljujući nekim slabim tačkama ovih visoko specijalizovanih parazita korena. To su, pre svega, njihova veoma slaba pokretljivost u zemljištu i uzan spektar domaćina. Zato je široko prihvaćen jednostavan i održiv pristup iskorenjivanju da nematode tokom nekoliko godina same izumiru na parceli, ako im se uskrate biljke domaćini da se na njima hrane i razmnožavaju. To se nekada može postići i gajenjem biljaka koje jesu domaćini KCN. Taktički cilj je ubrzano aktiviranje dormantnih larvi, koje zatim uginu pre završetka životnog ciklusa. Plodored sa biljnim vrstama koje nisu domaćini KCN, ali i sa otpornim sortama biljaka domaćina, tradicionalno se svrstava u agrotehničke, a ne u biološke mere zaštite, u užem smislu reči. Ipak, i neke osetljive i otporne sorte krompira, kao i drugih biljaka, bile one domaćini KCN ili ne, mogu biti upotrebljene kao tzv. biljke klopke za nematode. Takođe, biljke mogu delovati samo kao provokator ubrzane aktivacije dormantnih invazionih larvi KCN, koje aktivirane brzo izumiru u odsustvu domaćina. Obe vrste ovih efekata biljaka dovode do uginjavanja KCN i tako ih direktno suzbijaju, pa opravdano zaslužuju status mera biološke kontrole.