摘要:

ABSTRACT.1A parthenogenic strain ofAphis chlorisKoch, imported into Australia for the biological control of St John's wortHypericum perforatumL. was found, under laboratory conditions, to develop over a temperature range of 8.5–33°C.2Optimal performance, as measured by fecundity, survival andrmoccurred in the range 20–30°C, and at temperatures above 26°CA.chlorisperformed better than the majority of aphids for which comparable data was available.3Under crowded conditionsA.chlorisproduced smaller apterae, a high proportion of alatae, and a low number of oviparae, but no males. Sexually‐reproducing forms could not be induced under conditions of short photoperiod or low temperatures in the absence of crowding.4Apterae were larger and more fecund when fed on older flowering stems of the host‐plant, than when fed on new rosette growth.5The high potential rate of increase, ability to disperse, and good performance ofA.chlorisat high temperatures and on the phenological stage of the host‐plant present over summer, suggest that it could contribute to the biological control of St John's wort in Australia, especially during the warmer part of the year when the principal existing control agents (Chrysolinaspp.)

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1988.tb00368.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.1The preference ofCorythucha arcuata(Say) (Heteroptera: Tingidae) for the foliage ofQuercus albaL. (Fagaceae) grown under water deficit was examined. PottedQ.albasaplings were grown under controlled levels of water deficit in a glasshouse. AdultC.arcuatawere exposed to excisedQ.albafoliage under controlled conditions in a growth chamber, and feeding preference assessed by recording the percentage of individuals feeding on leaves from each level of water deficit.2Two experiments were performed. In the first, all foliage was supplemented with water (via the petiole) to alleviate physical changes in the leaves that accompany plant water deficits. In the second experiment, leaves were not supplemented with water.3C.arcuatahad no preference when presented water supplemented leaves, but preferred leaves that were fully hydrated when presented leaves that were not supplemented with water.4These results suggest that plant water deficits are important in determining the feeding preference ofC.arcuatabecause they lead to avoidance of drought grown foliage. This avoidance may be caused by an increase in the metabolic cost to the herbivore of maintaining water balance when ingesting drought grown foliage or to an increase in foliage toughness.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1988.tb00369.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.1The occurrence of pseudogamous triploid females in populations of the diploid speciesRibautodelphax pungens(Ribaut) was studied throughout Europe.2Considerable differences in triploid frequencies were found between populations but no regular geographic pattern was discerned.3Within populations triploid frequencies proved to be stable from generation to generation.4The twofold reproductive advantage of the pseudogamous triploid females is counterbalanced by active mate discrimination by diploid males against the pseudogamous triploid females in populations with high triploid frequencies.5Sexual diploid and pseudogamous triploid females showed no differences in phenology.6Differential winter mortality was found between diploid and triploid larvae.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1988.tb00370.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.1Several references indicate that the period of flight of the European satyrine butterflyHipparchia semele(L.) (Nymphalidae, Satyrinae) starts earlier in southern latitudes, where summers are longer and drier than in the north. However, summer drought has an adverse effect on the growth of grasses on which larval feeding depends. Growth of the grasses is delayed as long as the drought lasts.2From laboratory and field observations in a mid altitude area near the centre of the Iberian Peninsula, a mechanism that can be interpreted as an adjustment of this insect's life cycle to the host plant's phenology has been observed, i.e. delayed gonadal maturation of adult females. This delay is not associated with female diapause. Although the mean delay in oviposition after copulation was 43 days some captive females were able to oviposit much earlier, and this suggests variability in oviposition dates which might have an environmental or a genetic basis.3A mechanism of delayed ovarian maturation similar to that ofH.semeleis also known to occur in the satyrineManiola jurtina(L.); it is suggested that this adaptation enables these species to occupy wider geographical ranges than other univoltine satyrines in Europe.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1988.tb00371.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.1A negative relationship between intrinsic rate of increase,r, and body size has only clearly been shown using data for species drawn from a number of phyla and covering several orders of magnitude in size. Analyses for more closely related species are equivocal.2Data for ninety‐one species of insects, from nine orders, were used to examine the correlation between intrinsic rate of increase and size.3Intrinsic rate of increase was negatively correlated with both length and weight across orders, but no relationship could be shown within orders.4Generation times were positively related to body size, but there was no relationship between net reproductive rate (RQ) and size.5These results support the hypothesis that documented relationships between species size and colonization success in insects could be a consequence of the scaling of intrinsic rate of increase with siz

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1988.tb00372.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.1The behaviour of nectar‐collectingBombus hypocrita sapporensisCockerell queens was observed on a population of a spring ephemeral plantCorydalis ambiguaCham, et Schlecht.2Daily patterns of activity and behaviour changed with the progress of flowering. Activity peaked shortly before sunset early in the flowering season but approximately at noon towards the end of flowering. In the peak flowering period the queens tended to visit nearby plants and to change direction often, whereas early or late in the flowering period they flew further between visits and were less likely to change direction.3Each plant was visited 0 to 24 times (mean 9.4 ±SD 5.2) by the queens during the whole flowering season.4The queens collected nectar, rarely through the front of the flowers but mostly through the spurs perforated by themselves or predecessors. At the beginning of the flowering season the illegitimate foragers often visited the front of the flowers before moving to the spurs; later, most queens quickly learned to land directly on the spurs.5Even the 59.7% of plants that were visited only by illegitimate foragers set seeds. Close observation confirmed that the illegitimate foragers opened the inner petals enclosing anthers and stigma frequently when visiting the front of the flowers before robbing, or occasionally when walking about on the flowers or collecting nectar through the perforated spu

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1988.tb00373.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.1We investigated effective thermal environments and behavioural and physiological mechanisms for thermoregulation in two sympatric desert robber flies,Promachus giganteus(Hine) andEfferia texana(Banks). Although similar in body shape and colour,P. giganteusare 4–8 times heavier thanE. texana.2During midday, operative temperatures near the ground were substantially higher forP. giganteus(56–73°C) than forE. texana(54–63°C). Correspondingly,P. giganteusgenerally perched at greater heights above the ground than didE. texana.3Both species maintained thoracic temperatures between 40 and 45°C during most of the day. However, differences between thoracic and abdominal temperatures for individual flies were significantly lower inP. giganteusthan inE. texana.4In the laboratory,P. giganteusregulated thoracic temperature by pumping haemolymph into the abdomen. This ability may have accounted for the smaller differences observed between thoracic and abdominal temperatures inP. giganteusand may have allowed this species to search for food and mates during midday whenE. texanasoug

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1988.tb00374.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.1Conferred insect resistance arises from a mutualistic relationship between claviciptaceous endophytic fungi and various grasses. A number of secondary compounds are responsible for the insect resistance. This paper describes studies of the relationship between the endophytic fungusAcremonium loliiLatch, Christensen&Samuels and the Argentine stem weevilListronotus bonariensis(Kuschel) (Curculionidae); in particular, the effects on larval feeding behaviour, growth and survival.2Larvae are stem borers. Tunnel length and distance bored into the basal sheath zone of ryegrass was reduced when the plants were infected byA. lolii.3Lolitrem B, a potent mammalian neurotoxin, levels were highest inA. loliiinfected grasses and ranged from 2.61 to 7.08 μg/g dry wt, the higher value being recorded in summer.4Lolitrem B extracted from A. lolii‐infected perennial ryegrass reduced larval growth rates and survival.5Lolitrem B acted via the insect stomach rather than by absorption through the integument.6The potential role of endophytic fungi in plants is discussed briefly in relation to herbivo

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1988.tb00375.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.1Polistes metricusSay (Hymenoptera: Vespidae, Polistinae) field colonies were supplemented with dilute honey during the pre‐emergence and early post‐emergence phases of colony development.2Supplementation did not increase number of nest cells constructed or rates of loss to predation or foundress disappearance compared with controls.3Colonies receiving honey supplementation produced first offspring earlier in the season than control colonies. The difference is due to a shorter time span between founding and first emergence.4Foundresses of supplemented and control colonies did not differ in wing length or per cent body fat.5Offspring of both supplemented and control colonies had shorter wing lengths than did foundresses of supplemented colonies. Offspring of control colonies had shorter wing lengths than did foundresses of control colonies but not foundresses of supplemented colonies.6The per cent body fat of offspring from control colonies was lower than that of all foundresses and of offspring from supplemented colonies.7The per cent body fat of offspring from supplemented colonies was higher than that of all foundres

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1988.tb00376.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

ABSTRACT.1In a field survey of 1 year the intertidal collembolanAnurida maritima(Guérin) was found to be a univoltine species. Every year in early May a new generation emerges from eggs that overwinter. The first animals become adult in July. Almost all eggs laid in summer do not hatch, but undergo a period of diapause. Diapause is terminated in autumn by temperatures below 5°C. However, due to the low temperatures in winter further egg development is suppressed until spring.2The adult animals die, mainly in autumn. One of the causes of mortality may be starvation. In late autumn body size decreases and glycogen and lipid content are lower.3It is argued that in autumn due to low temperaturesA.maritima, which forages during low tide on the open shore and seeks refuge underground before the incoming tide, is too sluggish to find food in the limited period of low water. This probably explains why this cosmopolitan species has developed a strategy to survive the winter in the temperate zone in the egg stag

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1988.tb00377.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY