Integrated pest management of tomato spotted wilt virus in tobacco

Abstract

Many features of Tomato spotted wilt virus make this virus unique among plant infecting viruses. This virus is considered to be the most widespread virus in the world and that fact is attributed to the rapid expansion of its the most efficient vector Frankliniella occidentalis (Western flower thrips). Tomato spotted wilt virus is extremely polyphagous with, probably, the widest host range of all plant viruses. It causes very destructive diseases of many economically important plants, especially in tobacco, tomato, pepper and ornamentals. It is also responsible for numerous epidemics in tobacco crops in different regions of the world. Since the control of the tomato spotted wilt virus is very complicated, it makes its significance even greater. Considerable efforts have been made in developing resistance or tolerance to Tomato spotted wilt virus infections in certain tobacco cultivars. The results obtained so far in breeding for virus resistance have been disappointed because of the lack of suitable natural forms of resistance, which if there is, is in most cases polygenic and based on the complex interaction among the virus, vector and plant. That is why there is a need for new genetically engineered forms of host plant resistance. However, the extreme variability of Tomato spotted wilt virus is the main cause of breaking the natural or engineered resistance of plants. Also, several biological characteristics of the thrips and rapid development of its resistance to insecticides make its control extremely difficult. It has been discovered recently that an early treatment of tobacco plants with the combination of two chemicals (an insecticide - imidacloprid and a plant defense activator - acibenzolar-S-methyl) could reduce or eliminate the symptoms of Tomato spotted wilt virus on tobacco. This, for the first time, gives the possibility of true control. Good knowledge of the biology and epidemiology of both the virus and its vector is essential for its successful control. An adequate control of Tomato spotted wilt virus can be achieved by integrated pest management including a combination of certain physical, cultural and chemical measures.

Virus bronzavosti paradajza (Tomato spotted wilt virus) je, po mnogim svojim osobinama, jedinstven u odnosu na druge biljne viruse. Smatra se da je najrasprostranjeniji virus u svetu, zahvaljujući brzoj ekspanziji svog najefikasnijeg vektora - kalifornijskog tripsa, Frankliniella occidentalis. Virus bronzavosti paradajza je izrazito polifagan sa, verovatno, najširim krugom domaćina među svim biljnim virusima. Prouzrokuje veoma destruktivna oboljenja mnogih ekonomski važnih gajenih biljaka, a pre svega duvana, paradajza, paprike i ukrasnih biljaka. Na duvanu je izazvao brojne epidemije u različitim delovima sveta. Kontrola oboljenja koje ovaj virus izaziva na duvanu veoma je složena, što čini značaj ovog virusa još većim. Učinjeni su značajni napori da se dobiju rezistentni ili tolerantni kultivari duvana zaraze ovim virusom, ali su rezultati selekcije na otpornost razočaravajući. Razlog leži u nedostatku odgovarajuće forme prirodne otpornosti koja je, ako je uopšte ima, poligenetske prirode i zasniva se na kompleksnoj interakciji virusa, vektora i biljke. Zbog toga se ukazala potreba za iznalaženjem novih vidova otpornosti putem genetičkog inženjerstva. Međutim, teškoće u kontroli pričinjava i velika varijabilnost virusa, što uslovljava brzo slamanje otpornosti biljaka, bilo da je dobijena prirodnim putem ili genetičkim inženjerstvom. Takođe, neke biološke karakteristike tripsa i brzo razvijanje rezistentnosti prema insekticidima, čine kontrolu virusa izrazito teškom. Nedavno je otkriveno da dva jedinjenja, insekticid-imidacloprid i aktivator otpornosti biljaka - acibenzolar-S-methyl, ako se primene zajedno u ranim fazama razvoja duvana, mogu da smanje ili potpuno eliminišu simptome koje ovaj virus izaziva na duvanu. Ovo otkriće pruža mogućnost prave kontrole po prvi put. Uspešna kontrola oboljenja koje ovaj virus izaziva na duvanu podrazumeva dobro razumevanje biologije i epidemiologije i virusa i tripsa kao vektora. Sprovođenjem integralnog programa zaštite kombinacijom određenih fizičkih, agrotehničkih i hemijskih mera može se postići odgovarajuća kontrola virusa bronzavosti paradajza na duvanu.