Efficacy of multicolored Asian ladybeetle (Coleoptera: Coccinellidae) as a control for aphids in pecan orchards.

摘要

Results are presented of a study conducted to measure the efficacy of the multicolored Asian ladybeetle (Harmonia axyridis) adults against cultures of each aphid species, i.e. yellow pecan aphid (Monelliopsis pecanis), blackmargined aphid (Monellia caryella) and black pecan aphid (Melanocallis caryaefoliae), and a mixed culture of the 3 aphid species on intact aphid-infested pecan foliage in the field in Georgia, USA, by comparing the changes in aphid abundance over time in paired sleeve cages with and without ladybeetles. The populations of the 3 aphid species in the field had similar reproductive rates to the higher end of the published range for these species, indicating that the population was healthy. Yellow pecan aphids were controlled by the multicolored Asian lady beetle adults on the first week (11 August), and the control continued for the second (18 August) and third (25 August) weeks. After the fourth week, aphid population in the cages without beetles declined to the same level as the cages with beetles. Black pecan aphid populations were not controlled by the multicolored Asian ladybeetle adults until the third week (25 August), and control continued to the fourth week (1 September). Black-margined aphids were controlled by the multicolored Asian ladybeetle on the fourth week after inoculation; however, blackmargined aphids were significantly higher in the '3 beetle'-treated cages than in the 'no beetle' cages at the time of the inoculation. Mixed cultures of the 3 aphid species were controlled by the multicolored Asian ladybeetle adults after 4 weeks of exposure to the adults. Yellow pecan aphids were controlled on the third and fourth weeks. Black pecan aphids were controlled on the second and third week. Blackmargined aphids were controlled on the fourth week. On 11 August, 1 week after the inoculation of the cages with beetles, all 3 species of aphids were significantly higher in cages with beetles than in cages without beetles. Conversely abundances of all 3 aphid species were significantly lower in sleeves with beetles than sleeves without beetles on 1 September. On 25 August, yellow pecan aphids were significantly lower in sleeves with beetles than sleeves without beetles.