摘要:

AbstractFeeding responses of the stable fly (Stomoxys calcitransL., Diptera: Muscidae) to blood fractions and saline‐based diets were studied in an artificial feeding device. Flies fed equally on whole blood, plasma and erythrocyte fractions while resuspended platelets or the buffy layer did not stimulate feeding. Evidence from filtration studies indicates that plasma contains both less‐than‐5000D and greater‐than‐100,000D phagostimulatory components. ATP, ADP and AMP in saline stimulate feeding in this insect in a dose‐dependent manner. cAMP also stimulates feeding in the range of concentrations tested. It is argued that the less‐than‐5000D phagostimulant may be one or more of these aden

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1990.tb00513.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractHypochlora alba(Dodge) is a specialist grasshopper that lives and feeds almost exclusively onArtemisia ludovicianaNutt., a sage plant mostly avoided as food by generalist or polyphagous grasshoppers, such asMelanoplus sanguinipes(Fabr.). Adaptations to feeding on the pubescent sage foliage containing high levels of allelochemics may involve behavioural as well as physiological specialization. Using an electronic device to monitor feeding activity, we compared feeding periodicity, bout length, bout frequency, and overall time spent feeding byH.albaon sage foliage and byM.sanguinipeson seedling ryegrass (Lolium perenneL.), the plants on which they had been reared. Although both species fed for about the same amount of time per day (c. 4–5%), they achieved this by two different feeding patterns.H. albahad feeding bouts averaging c. 10 min each, compared to c. 4–5 min forM.sanguinipes.Bout frequency was reversed, withM.sanguinipesfeeding about once every hour andH.albaabout half as often. Bout length for both species was unaffected by phase of the photoperiod while bout frequency, and consequently the rate of feeding in min/h, was typically reduced by two‐thirds or more during the dark phase. The relationship of grasshopper feeding behaviour to host plant specialization is disc

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1990.tb00514.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA post‐feeding diuretic response has been observed in adultHeliothis zea(Boddie) (Lepidoptera: Noctuidae). 2‐day‐old starved adults which were allowed to feed to repletion on a 10% (w/v) sucrose solution lost 49.1% (females) and 85.8% (males) of the weight of the ingested meal during the first hour following feeding. Ligation between head and thorax or frontal ganglionectomy, when performed immediately following feeding, each resulted in a significant and permanent reduction in this normal weight‐loss. Injection of homogenates of the corpora cardiaca/corpora allata (CC/CA) complex into non‐ligated insects immediately after feeding also reduced significantly the post‐feeding weight‐loss, but this inhibition was transient and disappeared after 1 h. Dissection and weighing of the crop from either ligated, frontal ganglionectomized, or CC/CA‐injected insects confirmed the crop as the predominant site of fluid retention in each case. We suggest that a soluble antidiuretic factor from the CC/CA acts in conjunction with the frontal ganglion to control the rate of crop emptying and subsequent diuresis by regulating the volume of ingested fluid that is passed into the haemolymph from

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1990.tb00515.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractElectroantennograms were recorded from the antennae of adult male and female corn earworms,Heliothis zea(Boddie). A total of seventeen female moth sex pheromone components from several species were tested. Of these, two components elicited significantly greater responses than the other fifteen. These were (Z)‐11‐hexadecenal, a conspecific component, and (Z)‐9‐tetradecenal, a component found in the pheromone blend of a sympatric speciesH.virescens(F.) that inhibits attraction ofH.zeamales. The results from dose‐response and selective adaptation studies indicate that there are separate populations of receptors for these two chemical signals on the antenna of maleH.zea.The more sensitive population is selective for (Z)‐11‐hexadecenal, while the less sensitive one responds to (Z)‐9‐tetradecenal. These findings provide a physiological basis by whichH.zeamales can distinguish the interspecific repellent from the conspecific pheromone blend. It is likely that this discrimination contributes to reproductive isolation between

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1990.tb00516.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractMany bruchids distribute their eggs uniformly among the host seeds available to them and tend to avoid adding eggs to seeds bearing any eggs if pristine seeds remain. Several authors have postulated that the adult cowpea seed beetles,Callosobruchus maculatus(F.) (Coleoptera: Bruchidae), produce pheromones inhibiting oviposition by females exposed to them. It is shown that both sexes produce compounds which can be washed from glass surfaces in a variety of organic solvents which do not deter oviposition as such, but seeds coated with such washings are avoided by ovipositing females when they are selecting seeds for egg‐laying and uncoated seeds are available. Some components, at least, of the products persist for at least 30 days, longer than the normal development time of insects in the seeds. The compounds affect the distribution of eggs among the available seeds. At least three different biotypes of the species produce, recognize, and respond in the same way to each other's products. It is emphasized that the eggs themselves may not be the site of the product produced by females but that the physical presence of eggs cannot be overlooked in any discussion of the possible role of pheromones in oviposition and egg distribution by bruchid

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1990.tb00517.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe relative potencies, with respect to mobilization of lipids inLocusta migratoriaL. and inSchistocerca gregariaForsk. and of carbohydrates inPeriplaneta americanaL., of eleven naturally‐occurring members of the AKH/RPCH‐family of peptides and of some analogues that lacked the N‐terminal pyroglutamate residue or had a free threonine acid at the C‐terminus instead of an amide are assessed. The time courses for carbohydrate and lipid release shown for the peptides suggest that their transport and degradation rates are similar. Therefore, their relative activities reflect most probably the different abilities to bind to the receptors on the fat body cells of the cockroaches and locusts tested. The results show clearly that the N‐ and C‐terminally modified analogues give poor or almost no responses regardless of the bioassay employed. Compared with the structural requirements of the cockroach receptor(s), the receptor(s) of the locusts appear more specific. In the cockroach bioassay, only the two octapeptides Lom‐AKH‐II and Grb‐AKH, both lacking a proline residue at position 6, have high ED50values, whereas the ED50values of all other peptides are between 0.4 and 2.7 pmol. The exception is the nonapeptide Mas‐AKH, lacking proline and having a serine residue at position 7 (a unique feature compared with the other peptides): no activity is exerted below 100 pmol and only a poor response is elicited with higher dosages. TheL. migratoriareceptor(s) bind the decapeptides best (exception: Bld‐HrTH). Octapeptides, even Scg‐AKH‐II and Grb‐AKH which lack a proline residue, elicit a maximum response, but ED50values are 7–15‐fold higher than with Lom‐AKH‐I. Lom‐AKH‐II, however, gives only a truncated response. The nonapeptide Mas‐AKH is able to elicit a maximum response, but 50 pmol are needed instead of 2 pmol (Lom‐AKH‐I). In 5.gregariaa maximum response is achieved with Lom‐AKH‐I and Grb‐AKH, but injections of Scg‐AKH‐II, Lom‐AKH‐II and Rom‐CC‐I result in only truncated responses. The importance of a β‐turn in the molecules and the presence of proline is discussed. No evidence is found for an antagonistic effect o

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1990.tb00518.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe effect of colour on the attractiveness of cloth targets forG.tachinoidesWestwood was investigated, using electrified nets. The ages and nutritional states of tsetse caught by different targets were also studied. With targets of cloth and mosquito netting panels, phthalogen blue was the most attractive colour, and yellow the least, with black, red, violet and white intermediate. The strongest landing responses in females occurred on UV‐reflecting white cloth. In males, landing was high with all colours except yellow. Colour combination targets were no better than all‐blue targets when mosquito netting side‐panels were present; in their absence, blue‐and‐white targets were over twice as good as all‐blue targets. No consistent differences in ages or nutritional states were found between tsetse caught by differently coloured targets, but those landing directly on the cloth portion of a target had lower fat reserves than those intercepted on an adjacent ne

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1990.tb00519.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractHost‐plant colonization by winged, summer forms ofAphis fabaeScop, involves the resumption of embryogenesis and larviposition, leading eventually to flight muscle degeneration. Topical application of Juvenile Hormone I to young adults which (a) had access to the host plant, (b) were starved, (c) were starved and treated with precocene III, or (d) were decapitated shortly after the final ecdysis suggests that embryogenesis and flight muscle histolysis may be stimulated by an increase in Juvenile Hormone titres after settling. The duration of the pre‐reproductive period and the initial reproductive rate were not significantly affected, possibly because other neuroendocrine factors are involved in parturit

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1990.tb00520.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractFully‐sighted honeybees and bees with all ocelli occluded were trained to fly through an arena to arrive at a feeding place. After training, the bees were exposed to side‐light flashes during their feeding flights. The flight paths were recorded on video and analysed frame by frame at 40 ms intervals with reference to the main parameters, the coordinates of the thorax and the yaw angle of the bee. Course angles, translational course velocities and accelerations were calculated, and the responses to side light flashes evaluated with respect to ‘on’ and 'off.Immediately after light on, fully‐sighted bees respond slightly positively by yawing and flying toward the side light. Bees in which all ocelli are occluded are greatly disturbed and respond with negative yawing and flight path directions.The ocelli apparently help to control phototactic alertness in the bee. They determine whether phototactic orienting or pattern‐induced orienting behaviour is more important in a particular state of motivation. They help to minimize the level of disturbance in flight course control, obviously by activating a neuronal circuit with comparator attributes. It is assumed that this kind of compensation or suppression of phototactically guided reflexes occurs only for a few 100 ms. Consequently, the biological significance of light flashes shorter than 400 ms is very slight.Fully‐sighted bees decelerate strongly when a side light is switched on. Bees in which the ocelli are occluded behave less cautiously: they generally fly faster and need more reaction time. Thus, the ocelli help the bee to react photokinetically to photic stimuli in a much shorter time than do the compou

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1990.tb00521.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractAdult femalePanolis flammeawere kept at 2oC either immediately after emergence from the pupae or immediately after mating, for periods ranging from 5 to 20 days and then placed at 15oC together with a male moth, food supply and suitable oviposition site (Pinus contortafoliage). Weight loss over the storage period was directly proportional to the time spent at 2oC irrespective of whether the moths were virgin or mated. Pre‐oviposition period decreased significantly from the control after more than 5 days at 2oC, but there was no significant difference between late mated and early mated moths. The post‐storage life span of late mated and early mated moths decreased in proportion to the time spent at 2oC but late mated moths had significantly longer life spans than early mated moths. Moths mated prior to storage were significantly less fecund than moths mated after storage except those moths kept at 2oC for 20 days where the fecundities of both treatments were identical (c. 45 eggs/female). These results are discussed in relation to the conditions likely to be experienced byP.flammeain the field and their bearing on the population dynamics of this ins

ISSN:0307-6962    

DOI:10.1111/j.1365-3032.1990.tb00522.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY