Solanum habrochaites, S. Knapp & D. M. Spooner, S. Knapp & D. M. Spooner

Wang, Fumin, Park, Yong-Lak & Gutensohn, Michael, 2020, Glandular trichome-derived sesquiterpenes of wild tomato accessions (Solanum habrochaites) affect aphid performance and feeding behavior, Phytochemistry (112532) 180, pp. 1-11 : 3

2.2. Identification of S. habrochaites chemotypes affecting longevity and fecundity of aphids

As a first step to characterize the potential of the different S. habrochaites chemotypes to affect M. euphorbiae , we performed non-choice assays utilizing all S. habrochaites accessions and the two S. lycopersicum cultivars for comparison. Newly emerged M. euphorbiae nymphs were reared in clip cages on the leaf surface of the different tomato accessions, and their longevity and fecundity (represented by the number of offspring) were determined. No significant differences were observed for both performance parameters between the two S. lycopersicum cultivars, c.v. M82 and c.v. Moneymaker ( Fig. 1 ). Compared to S. lycopersicum c.v. M82 the longevity of M. euphorbiae was not significantly different on leaves of the S. habrochaites chemotypes 1 and 3, and accession LA1721 of chemotype 2 ( Fig. 1A ) characterized by the dominant production of 7-epi-zingiberene, germacrene C (δ- elemene), and germacrene B (γ- elemene), respectively (Table S1, S2). Macrosiphum euphorbiae kept on accession LA1927 of chemotype 2 showed only a small reduction in their longevity ( Fig. 1A ). In contrast, the longevity of M. euphorbiae on accessions of chemotype 4 (LA1775, LA1779) and 5 (LA1624, LA2860), characterized by production of α- santalene/α- bergamotene/β- bergamotene and β- caryophyllene/ α- humulene, respectively, was reduced quite significantly (24.6%– 35.3% of the aphid longevity on c.v. M82) ( Fig. 1A ). Similar trends as observed for the longevity of M. euphorbiae were also found for their fecundity on the different S. habrochaites accessions. The numbers of M. euphorbiae offspring were not significantly different on accession LA1691 (chemotype 1), LA1721 (chemotype 2), and both accessions of chemotype 3 compared to S. lycopersicum c.v. M82 ( Fig. 1B ). Accessions LA2650 (chemotype 1) and LA1927 (chemotype 2) had a 53.6% and 45.9% reduction in fecundity, respectively. However, the most severe effect on fecundity was again observed for M. euphorbiae on accessions of the chemotypes 4 and 5 which almost completely lacked the emergence of nymphs ( Fig. 1B ). Thus, the results of the non-choice assays suggested that the sesquiterpenes produced in S. habrochaites accessions of the chemotypes 4 and 5 might have the potential to significantly affect the performance of M. euphorbiae .

Figures

Fig. 1. Longevity (A) and fecundity (B) of M. euphorbiae apterae arrested on the leaf surface of two S. lycopersicum cultivars and different S. habrochaites accessions. Solanum habrochaites accessions represent five chemotypes characterized by the production of different sesquiterpenes in their glandular trichomes. Values for longevity and fecundity are presented as mean ± SE. Different letters indicate that logarithmic values were significantly different (Tukey’s HSD test, α = 0.05).