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Effects of treatments for electrical penetration graph recordings on behaviour and biology of Aphis craccivora (Aphididae)
Author(s) -
ANNAN I. BILLy,
SCHAEFERS GEORGE A.,
TINGEy WARD M.,
TJALLINGII W. FREDDY
Publication year - 1997
Publication title -
physiological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 57
eISSN - 1365-3032
pISSN - 0307-6962
DOI - 10.1111/j.1365-3032.1997.tb01145.x
Subject(s) - aphid , biology , aphis craccivora , aphididae , phloem , horticulture , botany , penetration (warfare) , homoptera , pest analysis , operations research , engineering
. Two laboratory studies were conducted to investigate effects of treatments for direct “current electrical penetration graph (DC‐EPG) recordings or ‘tether effect’, on behaviour and reproductive performance of cowpea aphid Aphis craccivora Koch. The experiments constituted a control study in application of DC‐EPGs to analyse cowpea aphid feeding behaviour and host plant resistance mechanisms. Resistant (ICV‐12) and susceptible (ICV‐1) cultivars of cowpea Vigna unguiculata (L.) Walp were used. EPG treatments included two groups of aphids: tethered aphids that were exposed to DC electricity via an attachment of a thin, flexible gold wire on their dorsum using a droplet of adhesive silver paint, and ‘free’ (untethered) aphids with a dorsal spot of silver paint only. EPGs of the tethered aphids were recorded continuously for c. ! h, whereas from the ‘free’ aphids recordings were done only for brief periods of 2–5 min, by temporarily contacting a gold wire to the spot of silver paint. Waveform signals generated from resistance fluctuations and electromotive forces, and representing aphid stylet penetration behaviour were recorded. A separate experiment was conducted to investigate effects of EPG treatments on aphid survivorship and population growth. Overall, EPG treatments did not significantly affect aphid stylet penetration behaviour or life‐table parameters. However, effects of crop cultivar on those characteristics were significant. Waveform E2, which denotes aphid ingestion in phloem sieve elements, and non‐penetration behaviour were important indicators of aphid resistance in ICV‐12. Also, apart from the number of aphid generations, other life‐table parameters were useful indicators of ICV‐12 resistance. Thus, DC‐EPGs provided a reliable technique for studying aphid stylet behaviour, and investigation of aphid resistance in cowpeas.