The combination of electronic monitoring and video‐assisted observations of plant penetration by aphids and behavioural effects of polygodial

Abstract

Simultaneous electronic and close‐up video recordings were made of behaviour during the initial 15 min of plant contact by adult, apterous Aphis fabae Scopoli on tick bean seedlings (Vicia faba Moench). Electronic techniques accurately determined stylet penetration of plant tissue and there was a close correlation between penetration and periods during which the insect antennae and body were immobile (r = 0.994, n = 60). Video techniques were then used alone to infer stylet penetration and the behaviour of aphids after various treatments was monitored. In particular, the time to first penetration, the number of penetrations, the mean duration of penetrations and the total time of penetration were observed. Behavioural differences were recorded between tethered (as required for electronic recording) and freely‐moving insects as well as between fed and starved insects. The behaviour of starved aphids placed on beans treated with the plant‐derived antifeedant, polygodial could not be distinguished from aphids on solvent‐treated control beans. However, there were significant differences in behaviour of aphids which had previously been exposed to polygodial on plant or green/yellow paper surfaces for 24 h when compared with insects exposed to solvent alone. The possible modes of action of polygodial are discussed.

Biotransformation of Lactones with Methylcyclohexane Ring and Their Biological Activity

“…This acid was then converted into chloro-2, bromo-3 and iodolactone 4 according to the procedure described earlier [23]. Two of these compounds, chloro-2 and bromolactone 3, were the new ones, only iodolactone 4 was obtained earlier [26] (Scheme 1).…”

“…The experiment was replicated 8 times for each substance and 20 aphids were used in each replicate. The number of aphids that settled, which was determined by the position of their antennae [26], was counted on each leaf 1, 2, and 24 h after the onset of the experiment. The numbers of aphids on control and treated leaves were compared using Student's t-test at p = 0.05 to reveal significant differences in preference for control or treated leaves.…”

Aphid responses to non‐host epicuticular lipids

“…A vision mixer (Electrocraft VMC89) was used to monitor 2 insects simultaneously, using 2 separate cameras, and a time base displayed 0.1 s intervals. Video tapes were later analysed and antennal movements used to score the start of a stylet penetration attempt (Hardie et al, 1992). The time between initial substrate contact and first stylet penetration attempt was calculated.…”

Behavioural correlates of genetic divergence due to host specialization in the pea aphid, Acyrthosiphon pisum

“…I recorded every penetration, bout of walking or immobility and whether aphids produced offspring. Contrary to the black-bean aphid, Aphis fabae (Hardie et al, 1992), antennal and body movements are not reliable indicators of stylet penetration in the pea aphid. Here, penetration was scored when immobile aphids had their (black) rostrum perpendicular to their body and when their antennae made an angle of less than 90 • with their abdomen.…”