Intracellular punctures by the adult whitefly Bemisia argentifolii on DC and AC electronic feeding monitors

Abstract

One of the most biologically important electrical penetration graph (EPG) waveforms recorded from aphids on DC EPG systems is the potential drop (pd), which is correlated with intracellular punctures by the stylet tips. In this study, pds of the adult female Bemisia argentifolii Bellows & Perring (Homoptera: Aleyrodidae), recorded on a DC EPG, are characterized and compared to pds of aphids. Whitefly pds consisted of 3 phases similar to those recorded from probing aphids. The major difference between aphid pds and whitefly pds was that whitefly pds lacked any observable subphases within the second phase of the pd. In addition, whitefly pds differed from aphid pds in that they: (1) did not occur frequently during stylet penetration, (2) did not occur early within probes, (3) did not occur during brief probes (<1 min). Pds produced by probing whiteflies always were preceded by a variant of waveform C which we named the pre‐pd. The differences between pds of aphids and whiteflies are discussed in terms of their implications for virus transmission and host selection. Using a technique where EPG recordings can be switched back and forth between DC and AC systems, we demonstrated that the AC EPG pseudotransition waveform (Pt) was equivalent to the DC pd, and thus was correlated with intracellular punctures. Previously, intracellular punctures by whiteflies had not been detectable on AC EPG systems. The AC Pt consisted of three distinct phases (Pt1, Pt2, and Pt3) and our observations suggest that AC Pt1 correlates with the pre‐pd waveform in DC EPGs and that AC Pt 2 and 3 correlate with the intracellular phase of the DC pd. AC Pts (n = 47) and DC pds (n = 43) were recorded on three separate plant species and were similar on all plant species.

Arabidopsis Transcriptome Changes in Response to Phloem-Feeding Silverleaf Whitefly Nymphs. Similarities and Distinctions in Responses to Aphids

“…Aphid species that more frequently puncture cells, such as the specialist Brevicoryne brassicae, cause PDF1.2 RNAs to accumulate to higher levels (Moran et al, 2002). Consistent with SLWFs performing fewer cellular punctures and triggering elevated SA-regulated gene expression, the SLWF microarrays show that PDF1.2 RNAs declined rather than increased in response to nymph feeding (Johnson and Walker, 1999;Freeman et al, 2001). These data suggested that SLWFs may evade JA-induced defenses by avoiding the tissue damage that activates JA responses or introduce effectors that suppress JA-dependent defenses (Zarate et al, 2007).…”

“…The silverleaf whitefly (SLWF; Bemisia tabaci type B; Bemisia argentifolii) is a good model to study plant responses to phloem-feeding insects. SLWFs are stealthy, as they navigate intercellularly and rarely damage epidermal or mesophyll cells prior to puncturing cells of the phloem (Johnson and Walker, 1999;Freeman et al, 2001); in contrast, aphids frequently probe intracellularly (Pollard, 1973). In addition, while aphids have a short and mobile life history, SLWFs have a long and continuous interaction with the plant.…”

Silverleaf Whitefly Induces Salicylic Acid Defenses and Suppresses Effectual Jasmonic Acid Defenses

“…Although these animals share membership in the same feeding guild, aphid and whitefly feeding are not synonymous. Unlike aphids, which probe extensively and are more mobile in their feeding habits, whitefly nymphs feed continuously from the same location throughout their 28 1 -day nymphal development (Gill, 1990;Byrne and Bellows, 1991;Johnson and Walker, 1999;Freeman et al, 2001). The continuous and long-term interaction between whiteflies and their host results in an intimate relationship and possibly pronounced and distinct defense responses when compared to aphids.…”

Life History, Functional Anatomy, Feeding and Mating Behavior

“…In contrast to aphids, intracellular punctures by whiteflies are much less frequent, and generally occur only after the stylets have penetrated deep into the leaf tissue (Janssen et al 1989;Lei et al 1998;Jiang et al 1999;Johnson and Walker 1999). Furthermore, salivation and ingestion behavior during intracellular punctures has not been detected in whiteflies.…”