摘要:

Abstract.1Single males, single females or pairs of dung beetles,Onthophagus vacca, were released on artificial small (100 g) or large (1000 g) dung pats in the laboratory. Emigrating beetles were trapped at 12 h intervals, and the number and size of the brood chambers were recorded after each replicate.2Emigration of males was delayed if females were present in the same dung pats, whereas emigration times of females were independent of the presence or absence of males.3A residency of 60 h proved to be a threshold value. Females emigrating before this time did not breed, whereas those emigrating later had built at least two brood chambers.4Females paired with males built more brood chambers than single females.5The reproductive success of pairs was not influenced by the size of the dung pats.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1996.tb00269.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.1The occurrence of raspberry beetles (Byturus tomentosus) on the host plantRubus idaeusis extremely variable between seasons, between days and within days, with occupancy of the available raspberry flowers (the feeding and oviposition sites) varying from 0 to 60%.2This variation could not be explained by plant chemistry or food quality (leaf nitrogen, carbon or water levels, or floral nectar reward); however, beetle distributions were in part attributable to microclimatic constraints acting via the insects’physiological constraints.3Initial ascent into raspberry canes from soil emergence sites was limited by the three‐fold higher water loss rates from recently eclosed young adult beetles as compared with mature beetles. Young adults reduced their hygric stress by remaining in the humid microclimate of tightly furled primocane leaftips.4Mature beetles spread upwards over the plant, but showed a preference for insolated sites (tops of canes, east or west facing according to time of day). In such sites their body temperatures could rise above the threshold for flight (requiring aTbof 15°C in laboratory studies). Flight activity was therefore common only in the early afternoon of warm days. Later in the day, beetles moved down and sometimes off the plants, starting to return at around dawn.5Thus physiological constraints, even on adult beetles (relatively well‐protected insect stadia), can be important components in predicting insect movements and locations on a host plant; they are likely to be even more crucial to less highly sclerotized plant‐feeding adult insects and many larval herbivoro

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1996.tb00270.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Abstract.1The interaction between coleopteran predators and baculovirus‐infected larvae was studied in the laboratory and the field in order to assess the potential role of predators in the dissemination of a nucleopolyhedrovirus (NPV).2Preference tests using three carabid species,Harpalus rufipesDe Geer,Pterostichus melanariusIlliger andAgonum dorsalePont, showed no evidence of discrimination between healthy and diseased larvae of the cabbage mothMamestra brassicaeL. (Lepidoptera: Noctuidae) as prey items.3Virus infectivity was maintained after passage through the predator's gut. NPV mortality ranged from 97% to 20% when test larvae were exposed to faeces collected immediately after and 15 days post‐infected meal respectively.4The potential for transfer of inoculum in the environment was estimated in the laboratory by soil bioassay. Carabids continuously passed infective virus to the soil for at least 15 days after feeding on infected larvae.5Field experiments showed that carabids which had previously fed on diseased larvae transferred sufficient virus to the soil to cause low levels of mortality in larval populations of the cabbage moth at different inst

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1996.tb00271.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1996.tb00272.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY