Abstract
Simple SummaryBemisia tabaci is a key pest of horticultural, fibre and ornamental crops, primarily as a vector of plant viruses. This whitefly is considered as a complex of morphologically indistinguishable species that differ in several biological traits. In Italy, the Mediterranean (MED) and Middle East–Asia Minor 1 (MEAM1) species are known to be present in southern regions as well as in Sicily and Sardinia, where they have been responsible for economically important yield losses to horticultural crops since the 1990s. Recent reports of infestations in some areas of central Italy prompted a reassessment of the species distribution in the country, and several sites have been inspected at different central and southern regions and in the main islands. The survey confirmed that B. tabaci is nowadays established in central Italy even at more northern latitudes than those noticed before, with MED that is clearly prevailing on MEAM1 species throughout the country. The extensive presence of B. tabaci in Italy causes new concerns for the growing number of horticultural and ornamental productive sites that are potentially endangered by whitefly-transmitted viruses. The prevalence of the MED species is even more worrying for its ability to rapidly develop insecticide resistances.Bemisia tabaci is a key pest of horticultural, fibre and ornamental crops worldwide, primarily as a vector of plant viruses. In Italy, B. tabaci has established since the 1980s–1990s in southern regions as well as in Sicily and Sardinia. Recent reports of infestations in some areas of central Italy prompted a new survey to assess the whitefly distribution in the country as well as to update the species and haplotype composition of the populations present in southern Italy and in the main islands. The survey confirmed that B. tabaci is nowadays established in central Italy even at more northern latitudes than those noticed before. Most of the specimens collected throughout the country belonged to the Mediterranean (MED) species. The MEDQ1 and Q2 haplogroups were prevailing in open-field and greenhouse cultivations, respectively, except in Sardinia where only Q1 specimens were found on a wide range of crops and weeds. Population genetics analyses showed that several MEDQ1 haplotypes currently occur in Italy and their distribution is unrelated to evident temporal and geographic trends, except for a new genetic variant which seems to have originated in Sardinia. The MED species is known to better adapt to insecticide treatments and high temperatures, and its northward spread in Italy may have been favoured by the intensive agricultural practices and steady increase in both winter and summer temperatures occurring in the last few decades. The extensive presence of B. tabaci in Italy proves that a strict surveillance for possible new outbreaks of whitefly-transmitted viruses should be addressed to a range of sites that are expanding northwards.
Highlights
Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a global pest that is responsible for economically important losses to horticultural, fibre and ornamental crops worldwide
B. tabaci is considered a complex of at least 40 morphologically indistinguishable species [3,4,5,6,7,8,9]. These cryptic species have been discriminated based on the mitochondrial cytochrome oxidase subunit 1 (COI) sequence variability [3,10,11], and differ in several biological traits such as the host–plant range [12,13,14], the induction of physiological plant disorders [15,16], insecticide resistance [17,18], invasiveness [19,20] and virus transmission efficiency [2,21], with most of these features influenced by the secondary endosymbionts harboured [22]
In the Marche region, several host plants belonging to Asteraceae, Solanaceae and Brassicaceae families were surveyed in open fields, and the MEDQ1 group was abundantly found alone or together with MED haplogroup Q2 (MEDQ2)
Summary
Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a global pest that is responsible for economically important losses to horticultural, fibre and ornamental crops worldwide. MED populations took advantage of tolerance to high temperatures and the ability to rapidly develop insecticide resistances [14,17,18,26], whereas MEAM1 has been more competitive than MED in insecticide-free areas, thanks to reproductive interference mechanisms that increase its mating efficiency [27,28,29] These different biological features led MED to become the predominant cryptic species where intensive farming is applied, and a progressive increase in MED infestations as well as a displacement of MEAM1 have been observed in several countries [30,31,32,33,34]
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