How Specific are Host-Produced Kairomones to Host-Seeking Ixodid Ticks?

Ixodid ticks respond to host-produced substances (kairomones) that influence the ticks’ host-finding behavior. In the laboratory adult blacklegged ticks, Ixodes scapularis Say, lone star ticks, Amblyomma americanum L., and American dog ticks, Dermacentor variabilis (Say) became akinetic on residues rubbed from their principal hosts (deer for the former two species and dogs for the latter). However, arrestment also occurred when adults of these species were tested using the same method bioassay, but with host substances reversed (i.e., I. scapularis and A. americanum against canine substances, and D. variabilis against deer gland substances). Although adult D. variabilis exhibited arrestant responses to deer substances and are often found along trails used by deer, they apparently make little use of deer as hosts. It is unclear whether responding to deer-produced kairomones may have disadvantages for D. variabilis. Until the active components of host-produced arrestment kairomones are isolated, identified and evaluated in behavioral tests, this host-finding strategy remains only partially understood. This revised version was published online in July 2006 with corrections to the Cover Date.     

三种有丝分裂抑制剂诱发小鼠骨髓细胞非整倍体的比较研究

以秋水仙素有丝分裂(CM)效应、微核(MN)及染色体畸变(CA)三种体内细胞遗传学指标综合评估了有丝分裂抑制剂(秋水仙素、益康唑及对苯二酚)诱发小鼠骨髓细胞非整倍体的效应。结果表明:秋水仙素是典型的多倍体及非整倍体诱发剂。益康唑对细胞有丝分裂有与秋水仙素相类似的效应,进一步分析表明其在哺乳动物体细胞内无非整倍体诱发效应。对苯二酚在哺乳动物活体实验系统中,可能具有诱发非整倍体及染色体结构畸变的多种遗传毒性。结果提示三种细胞遗传学指标能为非整倍体诱发剂的检出提供依据。     

Behavioural responses of Varroa destructor (Acari: Varroidae) to extracts of larvae, cocoons and brood food of worker and drone honey bees, Apis mellifera (Hymenoptera: Apidae)

Abstract. Varroa destructor is a parasitic mite of the honey bee species Apis cerana Fabr . and A. mellifera L. Mature females reproduce on the immature stages of their hosts, producing more viable female offspring on drone hosts than on worker hosts. Thus, immature drones are more likely to be infested with mites than immature workers. To investigate the hypothesis that differences in host chemistries underlie the biased distribution of mites between worker and drone brood, the arrestment responses of mites to solvent extracts of a number of stimuli normally encountered by a mite during its life cycle were measured. Mites were arrested by cuticular extracts of worker and drone larvae obtained at 0, 24 and 48 h prior to the time when cell capping is completed. Mites were also arrested by extracts of worker and drone, brood food and cocoons, and by a blend of synthetic fatty acid esters previously shown to be active in the host acquisition process. In a wind tunnel bioassay, mites were attracted to odours from living fifth-instar worker and drone larvae, but not to volatiles from cocoons, brood food or a blend of fatty acid esters. The sex of the host was not an important factor affecting the behavioural responses of the mites in any assay. We conclude that host kairomones play a role in the host acquisition process, but we found no evidence to support the hypothesis that mites use these substances to differentiate between worker and drone brood.     

Host frass as arrestant chemicals in locating host Mythimna separata by the tachinid fly Exorista japonica

We investigated the response of the tachinid fly, Exorista japonica (Townsend), to host frass or its extracts in order to clarify the host location mechanisms of female flies in a potential host habitat. Host searching time in a patch and the number of patch visits were analyzed by using a frass-containing patch which was excreted by host larvae, Mythimna separata (Walker) (Lepidoptera: Noctuidae), and patches to which host frass extracts were applied. E. japonica females were arrested in response to the host-frass-containing patch after contacting the frass with their front tarsi, thereby spending most of the time to search the patch and to revisit the host-frass patch. While host-searching time in the patch by the females was longest at their first visit of a patch with host frass, searching time decreased with successive visits. The female flies also exhibited area-restricted searching with methanol extracts of the host frass. Area-restricted searching activity increased with the concentration of host-frass extract, i.e., total searching time in the patch and the number of patch visits varied in a dose-dependent manner. E. japonica females likely employ chemicals in host frass as arrestants in host location.     

Behavioural activity of pure chiral 3-octanol for the ants Myrmica scabrinodis Nyl. and Myrmica rubra L.

ABSTRACT. The mandibular glands of Myrmica ants contain, among other substances, 3-octanol, a chiral substance, 90% of it being the R -enantiomer in M. scabrinodis Nyl., ruhra L. and ruginodis Nyl. (Cammaerts et al. , 1985). Pure R and S 3-octanol has been prepared and tested on M. rubra and scabrinodis , workers. Both species react specifically only to the R enantiomer; in M. rubra this constituent arrests foragers briefly, and in M. scahrinodis it attracts them and incites them to walk more quickly. It is shown that, in M. scahrinodis , the naturally produced mixture of R and S 3-octanol (proportions of 9:1, v/v) is more active than the pure R enantiomer or a mixture of R and S 3-octanol (5:5 v/v).