Resistance to Bemisia tabaci (Hemiptera: Aleyrodidae) Mediterranean (Q Biotype) in Landrace and Wild Tomato Populations from Mexico

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Mediterranean (Q biotype) is a major pest of tomato (Solanum lycopersicum L.; Solanaceae) globally. To our knowledge, no whitefly resistant cultivar has been released commercially, and breeding programs are hampered by the lack of resistance sources to this insect which are related closely to the cultivated tomato. Two non-free-choice experiments on B. tabaci with 22 landrace (S. lycopersicum) and wild tomato (S. lycopersicum var. ‘cerasiforme') populations from Mexico were performed to find sources of antibiosis resistance to this insect. Plants were infested with 20 insects per 1 leaflet of each plant using plastic micro-cages. In both assays, the number of adults and eggs were counted at 4 d post infestation, the number of nymphs (12 d post infestation), new adults, and non-glandular trichomes at 28 d post infestation. The highest B. tabaci resistance was detected in the UTC-SV13 population followed by UTC-SV12, UTC-SV1, and UTC-SV3 with a range of 15.0 to 20.0 dead adults, 0.0 to 16.5 eggs, 0.0 to 12.6 nymphs, 0.0 to 9.7 new adults per leaflet, and with a reproduction index of 0.0 to 21.7. Ten populations showed an intermediate level of resistance significantly lower in the number of dead adults, eggs, nymphs, new adults, and reproduction index compared to the commercial cultivar (‘Bonny Best') used as the standard. The remaining 8 genotypes and the commercial cultivar were fully susceptible to B. tabaci. The number of non-glandular trichomes correlated significantly with the number of eggs, nymphs, and new adults emerging from the infested plants, suggesting that the density of non-glandular trichomes is favorable for whitefly reproduction. Those genotypes with moderate to high levels of resistance to B. tabaci are potential candidates for developing commercial tomato cultivars with some resistance levels to this insect.