Pepper previously infested by MED facilitates settling and oviposition by MEAM1 of the Bemisia tabaci species complex

Abstract

MEAM1 (Middle East-Asia Minor 1) and MED (Mediterranean), two cryptic species of the Bemisia tabaci species complex, are highly destructive herbivores worldwide. Attack by herbivorous insects often induces plant defense responses that deter herbivores, recruit natural enemies, or warn other plants of possible herbivore attack. However, recent studies found that herbivores can manipulate and suppress plant defenses for their own benefit. These responses, which differ depending on the herbivore and the plant species, may mediate the preference and performance of later-arriving con- and heterospecific herbivores that attack the same plant. Here, we found that MEAM1 whiteflies preferred to settle and oviposit on MED-infested pepper and avoided conspecific-infested pepper plants. In contrast, MED whiteflies preferred to settle and oviposit on non-infested rather than on MEAM1-infested pepper. MEAM1 infestation significantly increased the contents of JA in pepper plants, which coincided with the increased expression of the following genes in the JA biosynthesis pathway: FAD, LOX6, OPR3, and PDF1.2. MED infestation significantly increased the contents of ABA in pepper plants and reduced the expression of PR1 and NPR1 in the SA biosynthesis pathway. Although MEAM1 infestation increased the transcript levels of C4H, 4CL1, CHS, and CHI3 in the phenylpropanoid biosynthesis pathway, total phenol levels did not increase. The reduction of the total phenols in pepper previously infested by MED, probably contributed to the settling and oviposition preference of the later-arriving heterospecific MEAM1. Overall, these results demonstrate that previous infestation by MEAM1 and MED whiteflies induces different responses in pepper plants that shape the host preference and performance of the later-arriving con- and heterospecific whiteflies.