Behavior and Effectiveness of Adult Hippodamia convergens (Coleoptera: Coccinellidae) as a Predator of Acyrthosiphon pisum (Homoptera: Aphididae) on a Wax Mutant of Pisum sativum

Abstract

Adult females of the coccinellid predator Hippodamia convergens (Say) spent more time walking and less time grooming on a line of peas, Pisum sativum L., that has reduced waxbloom on all parts of the plant (due to the mutation well compared with a near-isogenic sister line with normal waxbloom. H. convergens walking was distributed over all parts of the low-wax plants, whereas on normal-wax plants walking occurred mostly on stems and the edges ofleaves and stipules. The beetles were able to generate 30 times the adhesive traction force on leaf surfaces ofJow-wax plants compared with normal-wax plants. In cage studies, H. convergens (4 adults per plant) were more effective at reducing population growth of pea aphid, Acyrthosiphon pisum (Harris), on low-wax plants than on normal-wax plants, but only at initial aphid densities of 10 aphids per plant. At higher initial densities (20 and 40 aphids per plant), differential impact of H. convergens was not observed or disappeared after 4-5 d. The results indicate that reduced waxbloom in peas could improve the effectiveness of H. convergens on peas at low prey densities.KEY WORDS Acyrthosiphon pisum, pea aphid, ladybird beetles, plant waxes, predator behavior, tritrophic interactions 0046-225X/98/0902-0909$02.00/0

Attachment force of the beetle Cryptolaemus montrouzieri (Coleoptera, Coccinellidae) on leaflet surfaces of mutants of the pea Pisum sativum (Fabaceae) with regular and reduced wax coverage

“…No large crystals, but only short ribbons and rather small scales occurred in a great number on the abaxial surface of glossy plants (see Table 1). The reduction in wax crystals we detected on the glossy mutant line 406G (wel homozygote) is not as severe as described previously for this line (Eigenbrode et al 1997(Eigenbrode et al , 1998. The seed stock used for our study was identical with that used in the prior work, and the growing conditions were similar.…”

“…Recent studies, carried out with mutants of Pisum sativum L. (Fabaceae), exhibiting essential differences in the wax coverage, confirmed anti-adhesive properties of the wax bloom (Eigenbrode et al 1998;Rutledge and Eigenbrode 2003). Mutants with a highly reduced wax coverage demonstrated considerable enhancement of the insect attachment force: a multi-fold (from almost 2 to [30) force increase on glossy plants compared to waxy ones was measured, depending on the insect species and method of force measurement.…”

“…In low-wax pea plants, wel mutation (wax eliminator) has been previously described to be unique among wax mutations in peas, since it reduced strongly the wax bloom on all aerial plant surfaces (Marx 1969). Glossy plants had shinier, darker green leaves (White and Eigenbrode 2000a), significantly lower (up to approximately 80%) wax load (Eigenbrode et al 1997(Eigenbrode et al , 2008White and Eigenbrode 2000a, b;Rutledge and Eigenbrode 2003), decreased amount of large crystals (Eigenbrode et al 1997;Eigenbrode 2000a, 2000b) and higher density of minute crystals on both leaf sides (Eigenbrode et al 1997(Eigenbrode et al , 1998. No ribbons, but only 1 lm needles and granules were found on the abaxial surface (Eigenbrode et al 1997).…”

“…Wax in glossy plants was less extractable (White and Eigenbrode 2000a) and showed changed composition with decreased proportions of alcohols and alkanes (Eigenbrode et al 1997(Eigenbrode et al , 1998. This literature contains some contradictions regarding the crystal density and wax micro-structure of the wel mutation: reduced density of small crystals has been reported for the abaxial surface (Eigenbrode et al 1998). Glossy plants (wel) have been described as possessing amorphous wax in one study (Rutledge and Eigenbrode 2003).…”

Influence of intercropping with spring cereals on the occurrence of pea aphids (Acyrthosiphon pisum Harris, 1776) and their natural enemies in field pea (Pisum sativum L.)

“…Budenberg & Powell 1992;Giles et al 1994;Eigenbrode et al 1998;Francis et al 2004;Gilbert 2005;Ekbom 2009). In the present study, we recorded (1) aphidophagous syrphids, whose larvae can plunder aphid colonies very effectively, (2) entomopathogenic fungus Beauveria sp.…”