Virus-Infected Plants Altered the Host Selection of Encarsia formosa, a Parasitoid of Whiteflies

Abstract

The sweetpotato whitefly Bemisia tabaci (Gennadius) is one of the most invasive pest species worldwide. Q and B biotypes are the two most devastating species within the B. tabaci complex. Bemisia tabaci can vector hundreds of plant viruses that seriously threaten crop production. Endoparasitoid, Encarsia formosa Gahan, is widely used to control whiteflies, however, little is known about the effects of virus-infected plants on E. formosa parasitism of B. tabaci. Here, we reported that tomato, which was infected with Tomato Yellow Leaf Curl Virus (TYLCV), altered the host selection of E. formosa between B. tabaci Q and B biotypes. On healthy tomato plants, parasitism and host selection by E. formosa did not differ between the 3rd-instar nymphs of B. tabaci Q and B biotypes. On TYLCV-infected tomato plants, however, B. tabaci Q biotype were significantly more attractive to E. formosa than B biotype. When TYLCV-infected tomato plants were infested with B. tabaci Q or B biotype, volatile profiles differed quantitatively but not qualitatively. Olfactometer assays suggested that the preference of E. formosa to Q over B biotype was associated with an elevated level of β-Myrcene, β-Ocimene, β-Caryophyllene, and α-Humulene from TYLCV-infected tomato plants.

Ca2+ signal contributing to jasmonic acid‐induced direct and indirect defense against the whitefly Bemisia tabaci in tomato plants

“…Relative to untreated controls, plants treated with JA emitted more green leaf volatiles, monoterpenes, and sesquiterpenes. These terpene volatiles have been found to repel B. tabaci and attract E. formosa (Liu et al., 2017; Shi et al., 2017). Here, E. formosa parasitism rates were higher on JA‐treated plants compared with untreated plants.…”

“…The parasitism selection of B. tabaci by E. formosa on tomato plants with combinations of treatments was evaluated as described by Liu et al. (2017). Bemisia tabaci adults were placed in clip‐cages (four clip‐cages per plant, 25 adults per clip‐cage) on the leaves treated with water control, 1 m m JA, or 50 µ m ruthenium red + 1 m m JA, and were allowed to oviposit; after 24 h, all adults were removed.…”

“…Proportional data including parasitism rate of E. formosa , survival rate, and developmental rate of B. tabaci were arcsine√x transformed before analysis. IBM‐SPSS (v.19.0) was used for all statistical analyses and Sigmaplot (v.12.0) was used for figure plotting (Liu et al., 2017).…”

“…Each treatment was repeated 29 with 10 replicates each time. The Y-tube olfactometer assays were performed to assess the preference of the wasp E. formosa to odor sources, as we previously described (Liu et al, 2017). In brief, one 2.5-l flask containing one tomato plant was connected to one arm of the olfactometer, and another 2.5-l flask containing another tomato plant was connected to the other arm of the olfactometer.…”

The Epidemiology of Plant Virus Disease: Towards a New Synthesis

“…Since the published studies listed in Table 1 , further insight into the epidemiological consequences of vector preferences has been obtained. Links with vector-natural enemy associations have been confirmed [ 215 ]. Tomato infected with tomato yellow leaf curl virus changed the host preference of the parasitoid Encarsia formosa between Q- and B-biotypes of B. tabaci : on infected but not healthy plants the Q-biotype was more attractive to the parasitoid than the B-biotype, due to quantitative differences in volatile profiles.…”