Mode of overwintering of invasive Harmonia axyridis in the Netherlands
Raak-van den Berg, C.L. ; Hemerik, L. ; Jong, P.W. de; Lenteren, J.C. van - \ 2012
BioControl 57 (2012)1. - ISSN 1386-6141 - p. 71 - 84.
coccinella-septempunctata coleoptera - temperature-dependent development - hippodamia-convergens coleoptera - adalia-bipunctata coleoptera - lady beetle coleoptera - thermal requirements - pallas coleoptera - life-history - photoperiodic response - reproductive di
After establishment of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) in Europe, population densities of native ladybird species have decreased. The post-hibernation onset of female reproduction, a key characteristic influencing population dynamics and competition with related species, was studied. Hibernating individuals were collected and transferred to outdoor cages to continue overwintering. Every two weeks a sample of individuals was transferred to long-day, warm conditions. Intensity of dormancy was studied by determining the pre-oviposition period and ovarian development. Pre-oviposition periods were short throughout our observations, indicating that Harmonia axyridis was not in diapause but in a quiescent state. H. axyridis becomes active rapidly when temperature rises in spring but is not active earlier in the year than native species. Neither the mode of overwintering, nor the onset of spring activity can explain the invasion success of H. axyridis
Functional response and life history parameters of Apanteles taragamae, a larval parasitoid of Maruca vitrata
Dannon, A.E. ; Tamò, M. ; Huis, A. van; Dicke, M. - \ 2010
BioControl 55 (2010)3. - ISSN 1386-6141 - p. 363 - 378.
legume pod-borer - temperature-dependent development - sex-ratio - host-size - fabricius lepidoptera - biological-control - natural enemies - adult longevity - reproductive-biology - density dependence
The legume pod borer Maruca vitrata Fabricius (Lepidoptera: Crambidae) is a serious pest of cowpea in West-Africa. The parasitoid Apanteles taragamae Viereck (Hymenoptera: Braconidae) that originates from Taiwan is a potential candidate for biological control of M. vitrata. We investigated under laboratory conditions the functional response of the parasitoid by offering each experienced female 10, 20, 30 and 40 larvae of M. vitrata. We studied the influence of different host larval ages on the development, longevity, sex ratio, lifetime fecundity and parasitization rate of the wasp. In a comparative study, we also investigated the life history of A. taragamae and M. vitrata at different temperatures in the range of 20–30C. The parasitoid successfully parasitized two- and three-day-old host larvae (first and second instars). Younger larvae (one-day-old) were parasitized to a lesser extent, and only males developed in them. Older larvae were not parasitized, partly because of defensive host behaviour. The success of arasitization was positively correlated with the density of two-day-old M. vitrata larvae. Parasitoid developmental time and longevity decreased with increasing temperature. The intrinsic rate of population increase (rm) exhibited an optimum curve with a maximum at 24–28C. For the host M. vitrata, rm was maximal at temperatures of 26–30C. The data are discussed in the context of the potential of A. taragamae for biological control of M. vitrata.