Differential preference of Capsicum spp. cultivars by Aphis gossypii is conferred by variation in volatile semiochemistry

Abstract

The aim of this study was to demonstrate that Capsicum spp. cultivars are differentially preferred by the cotton aphid, Aphis gossypii, and to investigate the role of volatile semiochemicals in conferring differences in host preferences. Two preference assays were conducted in 2008 under greenhouse conditions. Fourteen different commercially available cultivars were grown in cages protected by an anti-aphid net, and were infested 60 days after planting, through the release of ten adult female A. gossypii per plant. The results showed that after a five-day infestation period, statistically significant differences in the mean number of A. gossypii between cultivars were observed, with Sweet Pepper Hybrid Green Belt (SPHGB) being one of the cultivars with the lowest number of A. gossypii per plant. To test the hypothesis that the preference of cultivars was associated with release of volatile, Capsicum spp-derived semiochemicals, olfactometer behavior bioassays were conducted with A. gossypii, using volatile organic compounds (VOCs) collected from non-preferred SPHGB and preferred SPAB cultivars. A. gossypii was significantly repelled only by the VOCs of infested SPHGB. Furthermore, coupled gas chromatography-mass spectrometry (GC-MS) analysis of VOCs released by plants prior to, and after, A. gossypii infestation, revealed that the non-preferred SPHGB cultivar released nine additional compounds after infestation, including 6-methyl-5-hepten-2-one, a known plant defense semiochemical involved in plant-aphid interactions. These data suggest that non-preferred cultivars releasing this semiochemical have the potential to be used in breeding programs aimed at producing A. gossypii-resistant Capsicum spp. cultivars.

Behavioural response of green peach aphid Myzus persicae (Sulzer) to volatiles from different rosemary (Rosmarinus officinalis L.) clones

“…Therefore, the rosemary genetics may explain the observed differences in aphid behaviour. This is consistent with several studies reporting that the repulsion (or attraction) of the aphid differs according to the VOC profile produced by different cultivars (Storer & van Emden, ; Wang et al , ; da Costa et al , ; Schröder et al , ). This evidence is also valid for other pests sensitive to the olfactory environment, such as thrips Frankliniella occidentalis (Pergande), (Thysanoptera: Thripidae) in rosebushes (Gaum et al , ) and the whitefly Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) in tomatoes or eggplants (Darshanee et al , ).…”

“…In this sense, genetic selection can be an essential lever for optimizing the effectiveness of rosemary and promoting its use by producers. Indeed, VOC production varies quantitatively and qualitatively according to the cultivars (Satyal et al , ), generating a variable olfactory response from aphids (da Costa et al , ; Staudt et al , ; Rajabaskar et al , ; Schröder et al , ). Still, by the same logic, understanding the action modes of companion plants and identifying the molecules involved should help us to select the most successful genotypes.…”

Attraction of the West Indian fruit fly to mango fruit volatiles

“…However, the attraction of apple, hawthorn, and dogwood flies to host fruit volatile blends decreased when non‐host volatile blends were added to the odour source. On the other hand, less information is available concerning the use of host plant volatiles by phytophagous insects to discriminate between host plant cultivars (Khan et al., 1987; Kalinová et al., 2000; da Costa et al., 2011). The post‐hibernating adults of Anthonomus pomorum (L.) prefer certain apple cultivars to others.…”

Identification of Semiochemicals Released by Cotton, Gossypium hirsutum, Upon Infestation by the Cotton Aphid, Aphis gossypii

“…Coupled GC-electrophysiology with C. lucasina revealed the presence of other electrophysiologically active compounds for which no discernable difference in levels between uninfested and A. gossypii infested samples could be detected by GC analysis (data not shown). These included 6-methyl-5-hepten-2-one, which has been shown in other studies to be an important host derived semiochemical for A. gossypii (da Costa et al, 2011), while octanal and decanal have been shown to be host derived semiochemicals for A. fabae (Webster et al, 2010). Investigations into the behavioral roles of the EAG active compounds other than those used in behavioral studies, i.e., 6-methyl-5-hepten-2-one, (Z)-4,8-dimethyl-1,3,7-nonatriene, octanal, nonanal, decanal, 3-methylhexane, n-heptane, methylcyclohexane, α-pinene, and an ethylbenzaldehyde isomer (Fig.…”