Ecological requirements for hibernatingPropylea quatuordecimpunctata (L.) andCoccinella septempunctata [Col.: Coccinellidae]

Abstract

During 3 successive winters, we studied the dormancy sites of Propylea quatuordecimpunctata (L.) and Coccinella septempunctata L., 2 species of ladybirds which hibernate in leaf litter. Samples of litter were taken from several kinds of forest to study the influence of 3 variables (exposure ; altitude ; sampling place : edge or inner wood) on the abundance of ladybirds.We found the ecological requirements of the 2 species of coccinellids to be quite different : C. septempunctata prefers forest edges orientated towards the South and the West. P. quatuordecimpunctata prefers the inner wood and does not show a preference for station exposure. For each species, the number of ladybirds collected in the samples is positively correlated with station altitude. In addition, some observations were carried out to examine the main mortality factors just before and during dormancy. In maize fields near dormancy sites, the harvest is very harmful for C. septempunctata. During the winter, P. quatuordecimpunctata and C. septempunctata suffer from Beauveria ssp. and some ladybirds have parasitoids.KEY-WORDS: Propylea quatuordecimpunctata, Coccinella septempunctata, hibernation, Beauveria ssp., parasitoids.The aphidophagous Coccinellidae of agricultural biocenosis hibernate in sites whose characteristics vary in relation to the different species. For example, Semiadalia undecimnotata (Schneider) hibernates at the top of hills or mountains (Iperti, 1966a ;Hodek, 1973), Adalia bipunctata (L.) prefers crevices in buildings or in tree bark (Hodek, 1973 ;Brakefield, 1984 ;Hemptinne, 1985) while Propylea quatuordecimpunctata (L.) and Coccinella septempunctata L. are known to spend the winter in forest litter (Bielawski, 1961 ; SavoTskaya, 1960;Sem'yanov, 1965;Hodek, 1973; Larochelle & Larivi~re, 1980;Basedow, 1982).A good knowledge of dormancy sites and ladybird ecology would enable building up aphid control strategies and land management which is compatible with biological control. Hippodamia convergens (Guerin) clearly illustrates these points. Indeed, biological control experiments with this ladybird were inconclusive because of an incomplete understanding of migratory behaviour (Carnes, 1912a, b). Moreover for biological control, a network of dormancy sites and cultures which can be used as breeding places and shelter is preferable

Diapause/Dormancy

“…Very often they can be found at the ends of twigs of young pines (Hodek 1960, Bielawski 1961, Semyanov 1965a,b , Klausnitzer 1967 or between the ear spathes of maize plants left after harvest (Hemptinne 1988 ). In a similar way they stay on the vegetation near the hibernation site before their dispersal in spring.…”

“…Temperature and wind speed were recorded at the same two heights, 0.25 m and 1.25 m, in a study of Cer. undecimnotata , 1988, Iperti 1986. A decrease in Richardson ' s index was positively correlated with a decrease in the incidence of females taking -off for a migratory fl ight.…”

“…Hibernation behaviour of the abundant P. quatuordecimpunctata was not well known until the detailed study on populations from an agricultural but extensively wooded area of the Province of Hainaut in western Belgium (Hemptinne 1988 ). Hemptinne compared litter samples from the forest edge and 20 m into the forest, and found that P. quatuordecimpunctata preferred the inner site for hibernation, with 1.11 beetles/ m 2 at the edge compared with 1.41 beetles/m 2 inside the wood.…”

Introgression and Habitat Segregation in a Pair of Ladybird Beetle Species in the Genus Propylea (Coccinellidae, Coccinellinae) in Northern Japan

“…The primary causes of the altitudinal difference and the habitat difference is unknown. Some studies have reported a certain degree of habitat preference in P. quatuordecimpunctata (Honěk, 1985;Hemptinne, 1988). However, how such habitat preference relates to the observed habitat difference of the present species pair is unknown.…”

Insect Pests and Arthropod Predators Associated with Tree-Turf Landscapes2

“…Information on the use of trees by arthropods has been reported for several crop pests and their predators. For example, certain species of coccinellids and chrysomelids overwinter beneath the trees and understory vegetation (Balduf 1929, Hemptinne 1988, Mahr and Ridgeway 1993. In Texas, the boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), overwinters in leaves and debris beneath shelterbelt trees (Slosser et a1.…”