Repellent and Antifeedant Activities of Citral-Derived Lactones against the Peach Potato Aphid

Abstract

Citral is well known for its antimicrobial, antifungal, and insecticidal activities. Natural sesquiterpene α-methylenelactones also exhibit a broad spectrum of biological activities. The aim of the study was to explore the effect of structural changes to citral molecules on citral behavior-modifying activity towards Myzus persicae. Specifically, the effects of the introduction of a γ-lactone moiety and methylene groups in α and γ positions of the lactone ring were investigated. The lactones were obtained in five-step (saturated lactone and γ-methylenelactone) or six-step (α-methylenelactone and α,γ-dimethylenelactone) syntheses from citral. The synthetic procedures and physical and spectral data of the lactones are presented. The settling behavior of freely moving aphids in choice and no-choice situations was monitored. The probing behavior of tethered M. persicae using the Electrical Penetration Graph (EPG) technique was also analyzed. Citral appeared a strong repellent and pre-ingestive and ingestive probing deterrent to M. persicae. The incorporation of a lactone moiety caused the loss of the repellent activity. α-Methylenelactone inhibited aphid settling and probing activities at pre-ingestive and ingestive phases. The saturated γ-lactone and α,γ-dimethylenelactone were the settling post-ingestive deterrents to M. persicae, which did not affect aphid probing activity. γ-Methylenelactone did not affect aphid behavior.

Antixenosis in Glycine max (L.) Merr against Acyrthosiphon pisum (Harris)

“…Stylet withdrawal by aphids after a short probe in the outer leaf tissues suggests the presence of probing deterrents in these tissues. This is often observed in incompatible plant-aphid associations 23 , on resistant plant cultivars 48 , or when the non-acceptable xenobiotics are applied to aphid host-plants 50 . The soybean genotypes studied evoked a spectrum of behavioral responses from A. pisum .…”

Antixenosis in Glycine max (L.) Merr against Acyrthosiphon pisum (Harris)

“…Among these cultivars, the frequency of phloem sap ingestion phase on 'Annushka' and 'Augusta' was higher than in 'Madlen', 'Mavka', 'Simona', 'Violetta', and 'Viorica' while the total duration of phloem phase was highest in 'Madlen'. The reduced duration of phloem sap uptake results in the impediment of aphid survival and development, which happened to the cabbage aphid Brevicoryne brassicae L. on resistant rapeseed cultivars 41 . Among soybean cultivars studied, the lowest survival of newborn nymphs was on 'Aldana' and highest on 'Madlen'.…”

Probing behavior of Adelges laricis Vallot (Hemiptera: Adelgidae) on Larix decidua Mill: Description and analysis of EPG waveforms

“…Weak voltage is supplied to the plant and all voltage changes are recorded as EPG waveforms that have been correlated with stylet tip locations and insect-specific activities such as intra-or extracellular penetration, salivation, and ingestion [39]. This technique has been useful mainly in studies of aphid-plant interactions [40][41][42][43][44][45][46][47][48] but also in research on style penetration behavior of other sap-sucking insects, such as psyllids (Hemiptera: Psyllidae) [49,50], mealybugs (Hemiptera: Pseudococcidae) [51,52], thrips (Thysanoptera) [53,54], planthoppers (Hemiptera: Delphacidae) [55], leafhoppers (Hemiptera: Cicadellidae) [56][57][58][59], stink bugs (Hemiptera: Pentatomidae) [60] and phylloxerids [61,62]. EPG studies on Adelgidae were limited to P. boerneri on Pinus taeda L. and only two main waveforms, one extracellular and one intracellular were described [63].…”