bluuebunny/crossref_metadata_2025 huggingface dataset:
Drinking rate regulation in some fresh‐water mosquito larvae
Authors: ALY C. , DADD R. H.
Published: March 2008

ABSTRACT.Drinking rates were determined with four species of freshwater mosquito larvae by colorimetric measurement of the dye ingested after groups of fourth instars were allowed access for set periods to 2% amaranth solutions. The rate of drinking for the saline‐tolerantAedes aegypti, 309±113 nl per h per individual, was comparable with rates given in the literature for several saline‐water species, but rates forCulex quinquefasciatus, Culex molestusandAnopheles albimanuswere markedly lower (167±30, 48±17 and 108±28m per h, respectively). When larvae ofA.aegyptiandC. quinquefasciatuswere glutted with kaolin (allowed to replace all food in the gut by filter‐feeding in kaolin suspension), drinking rates were little affected at first, but after 1 day of fasting (holding in water after glutting), drinking rates were 50% lower and were reduced by a further 20% with fasting for up to 3 days. ForA.aegypti, C.quinquefasciatusandC. molestus, drinking rates were approximately doubled with kaolin dispersed in the dye solution, and after fasting, were increased by up to 100% in solutions containing 0.05% of water‐soluble yeast extract. A similar phagostimulant effect of 10‐3M adenylic acid was demonstrated forA. aegyptiandC. quinquefasciatus.A single experiment indicated similar stimulatory effects of kaolin and adenylic acid for,A. albimanus.With 0.01‐0.05% agarose in the dye solutions, drinking rates forA. aegyptiandC. quinquefasciatuswere more than doubled, and a similar though weaker effect was demonstrated for another colloid, methylcellulose. In constrast, both colloids markedly reduced the rate of drinking withA.albimanus.These findings are discussed in relation to whether drinking and filter‐feeding are necessarily coupled. The possible significance of this with respect to larvae that feed in different microhabitats, providing different levels of dissolved and colloidal nutrient organic matter, is considered. The implications of drinking rates for biotests of solubilized bacterial toxins as mosquito larvicides are noted.
Behavioural evidence for hygro‐ and mechanoreception by ovipositor sensilla of Dacus tryoni (Diptera: Tephritidae)
Authors: EISEMANN C. H. , RICE M. J.
Published: March 2008

ABSTRACT. Gravid female Queensland fruit flies Dacus tryoni (Froggatt) readily oviposit when the ovipositor sensilla are stimulated either by a relatively thick (≥2 mm) surface layer, or by moisture under a relatively thin (<0.5 mm) or thick surface layer. A single layer of Parafilm over dry air elicits almost no oviposition; significantly more oviposition occurs when the underside of the Parafilm is coated with a 2 mm thick layer of petroleum jelly; even more oviposition occurs when the Parafilm is floated on liquid paraffin; greatest oviposition is elicited when moist media (agar gel, water or moist air) are presented under the Parafilm. Hollowed‐out domes of apple skin elicit significant oviposition only when sealed basally, to give high internal concentrations of water vapour. The previously identified groove sensilla on the tephritid ovipositor are inferred as being a source of mechanical and chemical information used by the fly in such ovipositional decisions. The ovipositor also has two other types of tactile sensilla. The three types of ovipositor sensilla of tephritids are considered to play roles analogous to those of certain labial receptors of flies with piercing mouthparts.
Electrophysiological investigations of sex pheromone reception and release in Bruchidius atrolineatus
Authors: POUZAT J. , IBEAS D. NAMMOUR
Published: March 2008

ABSTRACT. Male antennal sensitivity to female sex pheromone in Bruchidius atrolineatus was investigated electrophysiologically (EAG). The existence of receptors for this pheromone was shown in the antennae of males. (No such receptors exist in the antennae of females.) Young (age < 24h) males gave an EAG of amplitude 25–30% of the response of older males. Diapausing males several days old gave a much smaller response than active males of the same age.

EAGs were used to test the production/release of pheromone by groups of twenty females. Before they are 24 h old, active females do not produce/release the pheromone; older females release it at an almost constant rate. Sexually diapausing females do not produce and/or release the sex pheromone.

In sexually active females, mating inhibits pheromone release almost immediately. There is a correlation between reproductive status of the females (development of ovaries, oogenesis) and the production or release of the pheromone. A corresponding correlation also exists in the males whose antennae show a very low sensitivity when they are young or when they are in reproductive diapause.
Factors affecting the antennal and behavioural responses of the saw‐toothed grain beetle Oryzaephilus surinamensis to food odour and aggregation pheromone
Authors: WHITE PETER R.
Published: March 2008

ABSTRACT. The effects of insect age, sex, mated state and culture density on the attraction of adult saw‐toothed grain beetles, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae), to sources of food odour and synthetic aggregation pheromone were investigated. In single‐insect behavioural assays, insect age affected the attraction to the food odour, but not to the synthetic aggregation pheromone. Conversely, there were sexual differences in the attraction to the aggregation pheromone, but not to the food odour. The effects of the same factors on the antennal response to food odour and synthetic pheromone were also investigated, using the electroantennogram (EAG) technique. Insect age affected the EAG response to food odour, but not to the synthetic pheromone. There were no sexual differences in the EAG responses to either food odour or synthetic pheromone.

The correlation of factors affecting both behavioural and antennal responses, and the possible role of changes in peripheral olfactory receptor sensitivity in the modulation of behaviour are discussed.
Post‐eclosion diuresis in adult Heliothis zea
Authors: BUSHMAN DAVID W. , RAINA ASHOK K. , NELSON JUDD O.
Published: March 2008

ABSTRACT. The marked weight loss that follows adult eclosion in Heliothis zea (Boddie) (Lepidoptera: Noctuidae) was found to be the result of diuresis. This diuretic weight loss amounted to 18.2% of the emergence weight in females and 22.5% in males. Ligation between head and thorax immediately following emergence resulted in a significant reduction in this weight loss. Injection of homogenates of brain (BR) or suboesophageal ganglion (SOG) partially restored the weight loss in ligated insects, indicating potential neurohormonal regulation of this phenomenon.

Because injection of homogenates of nervous and neuroendocrine tissues other than BR and SOG did not result in increased weight loss over controls, the activity present in BR and SOG was probably a tissue‐specific phenomenon. We speculate that a factor at least partially responsible for the enhanced diuretic weight loss is present in the fused BR/SOG.
Thermoregulation in army ant bivouacs
Authors: FRANKS NIGEL R.
Published: March 2008

ABSTRACT. The temporary nests (bivouacs), of Eciton burchelli (Westwood) thermoregulate with considerable precision. Temperatures at the core of the bivouac are maintained at 28.5±1d̀C even though ambient temperatures in their tropical rainforest home change during the day over a range of 7d̀C. Temperatures just under the mantle of the bivouac vary much more than at the core. Calculations suggest that the basal metabolic rate of the army ants in bivouac will generate all the heat that they need to keep warm when ambient temperatures drop. The army ants probably regulate heat loss by opening up ventilation channels within the nest.
The effect of larval temperature and photoperiod on the incidence of larval diapause in the blowfly, Calliphora vicina
Authors: NUNES M. VAZ , SAUNDERS D. S.
Published: March 2008

ABSTRACT. The blowfly, Calliphora vicina Meigen (Diptera: Calliphoridae), displays a maternally induced larval diapause. Progeny of adults exposed to short days enter diapause if the larval temperature is 15d̀C or below; exposing adults to long days, or larvae to temperatures above 15d̀C, results in non‐diapause. By keeping progeny from short‐day parents at the parental temperature of 23.5d̀C for various lengths of time before transfer to 11d̀C, it could be shown that the diapause‐averting effect of high temperature operates in the late wandering stage of larva, possibly at the moment of the decision for the brain‐ring gland complex to release PTTH/ecdysone at the diapause/non‐diapause stage.

Although photoperiodic induction in the blowfly is maternal, previous work had shown that the larvae were also slightly sensitive to photoperiod. From the present study it is evident that also the eggs are photo‐sensitive.
Desiccation resistance in arboreal and terrestrial ants
Authors: HOOD W. GREGORY , TSCHINKEL WALTER R.
Published: March 2008

ABSTRACT Arboreal and terrestrial ants were exposed to 0, 25, 50, 75 and 100 (control)% r.h., at 30oC. Desiccation resistance increased with body size (as dry weight0.55), but not as quickly as expected from the consequences of the surface area and volume relationship (as dry weight0.67). Arboreal ants took 8 times longer to die than terrestrial ants of comparable size. Even after size effects were removed, desiccation resistance differed between various terrestrial species and showed a correlation with foraging patterns.

Arboreal and terrestrial ants whose waterproofing epicuticular lipids were removed by chloroform: methanol extraction had equally high water loss rates at 0% r.h. Unextracted arboreal ants had water loss rates half those of unextracted terrestrial ants, suggesting that differences between them were based on differences in epicuticular lipids. The lower water loss rates of arboreal ants contributed significantly to their longer survival under desiccation. Arboreal ants also had greater total rectal pad area than terrestrial ants, suggesting that they may be able to reclaim faecal water more effectively. There were no differences in the minimum viable water content between the two groups of ants. Both had water loss tolerances comparable with those of arthropods adapted to xeric environments. Initial water loss rates could not account for all of the differences in desiccation resistance between arboreal and terrestrial ants. Other adaptations to desiccation stress by arboreal ants are likely.

Comparisons of water loss rates and desiccation resistance between arboreal and desert ants suggest that the arboreal habitat is at least as stressful as the desert habitat.
Behavioural and electrophysiological activity of unsaturated analogues of the pheromone tetradecyl acetate in the small ermine moth Yponomeuta rorellus
Authors: LÖFSTEDT CHRISTER , HANSSON BILL S. , DIJKERMAN HENDRIK J. , HERREBOUT WIM M.
Published: March 2008

ABSTRACT In field‐trapping experiments the unsaturated analogues (E)‐6‐, (E)‐12‐, and (Z)‐12‐tetradecenyl acetate were as attractive to male Yponomeuta rorellus Latr. as the native pheromone component tetradecyl acetate. All four analogues attracted more males than virgin females did, whereas (Z)‐6‐, (E)‐11‐, (Z)‐10‐ and (Z)‐11‐tetradecenyl acetate were essentially non‐attractive. Addition of 1–30% of (Z)‐11‐tetradecenyl acetate to the pheromone tetradecyl acetate reduced the attraction to less than 2%. Flight tunnel experiments with Y. rorellus confirmed the activity of the (E)‐6‐ and (E)‐12‐tetradecenyl acetates and demonstrated the activity of (E)‐7‐tetradecenyl acetate as well. These analogues elicited orientation behaviour, upwind flight and landing at the odour source as frequently as the native pheromone did. Single sensillum recordings from male Y. rorellus showed two types of cells in most sensilla. A large spike amplitude cell was stimulated by tetradecyl acetate and the unsaturated analogues (E)‐11‐, (E)‐6‐ and (E)‐12‐tetradecenyl acetate, and to a lower extent by the (Z)‐6‐, (Z)‐11‐ and (Z)‐12‐isomers. A cell with medium spike amplitude was stimulated by (Z)‐9‐tetradecenyl and (Z)‐11‐hexadecenyl acetate. Some sensilla contained a third cell firing with a small spike amplitude which was activated by (Z)‐11‐tetradecenol. Thus the tetradecyl acetate receptor was stimulated not only by the behaviourally active analogues, but also by behavioural antagonists. The interaction of (E)‐11‐tetra‐decenyl acetate and tetradecyl acetate with the same antennal receptor cell was also demonstrated in Y.cagnagellus. Electrophysiological discrimination between behavioural attractants and antagonists and the role of behavioural antagonists in the interspecific relations between Y.rorellus and sympatric closely related species are discussed.
The use of video equipment to record in three dimensions the flight trajectories of Heliothis armigera and other moths at night
Authors: RILEY J. R. , SMITH A. D. , BETTANY B. W.
Published: March 2008

ABSTRACT A simple method of recording stereoscopically the behaviour of moths in nocturnal, low‐altitude flight in the field is described. Sample results, showing the flight of Heliothis armigera (Hiibner) and other noctuids at 2–11 m above a crop of pigeon‐pea in India are presented. Flight trajectories, reconstructed in three dimensions, demonstrated that most of the moths flew close to the horizontal, in straight lines, and that their average air (flight) speed was 5.0 ± 1.9 m s‐1. There was no evidence of mass climbing flight away from the crop.
Dose responses of tsetse flies (Glossina) to carbon dioxide, acetone and octenol in the field
Authors: TORR S.J.
Published: March 2008

ABSTRACT Studies were conducted in Zimbabwe of the catch of Glossina pallidipes Austen from an electric net plus target baited with mixtures of acetone plus carbon dioxide or 1‐octen‐3‐ol (octenol) plus carbon dioxide. For acetone dispensed alone at 5–50, 000 mg h‐1, ten‐fold increments in the dose increased the catch 1.7 times. For carbon dioxide dispensed alone, dose increments from 12 to 1201 h‐1 doubled the catch, but the catch was not further increased by dispensing carbon dioxide at 600–1200 1 h‐1. For mixtures of these two odours, ten‐fold increments in the dose of carbon dioxide between 12 and 12, 0001 h‐1 increased the catch c. 2.5 times if acetone was also dispensed at >50 mg h‐1; changes in the dose of acetone between 50 and 50 000 mg h‐1 did not affect the catch. The addition of octenol (0.05 mg h‐1) to carbon dioxide (12–12001 h‐1) doubled the catch. Ten‐fold increments in the dose of octenol between 0.05 and 5 mg h‐1 did not increase the catch significantly and the catch was independent of changes in the dose of carbon dioxide between 120 and 12001 h‐1. The behavioural basis of the dose‐response curves was investigated using an incomplete ring of electric nets to assess the flight orientation of tsetse in different odours. Upwind flight was not elicited by acetone or octenol alone, or by carbon dioxide unless it was at very high doses, however, mixtures of carbon dioxide with acetone or octenol elicited upwind flight. It is suggested that the attractiveness of mixtures of acetone and carbon dioxide is a function of the region of overlap of these two odours at above threshold concentration. Acetone and octenol on their own appear to increase the responsiveness of flies to visual cues.
Sperm precedence in the deer tick Ixodes dammini
Authors: YUVAL BOAZ , SPIELMAN ANDREW
Published: March 2008

ABSTRACT We determined whether female deer ticks Ixodes dammini Spielman, Clifford, Piesman & Corwin (Acari: Ixodidae) can be inseminated repeatedly and whether sperm from first or second matings take precedence in fertilizing eggs. Such information is essential to the design of attempts to reduce the fertility of these vectors of Lyme disease. Although spermatophores are present in about half of questing female ticks, they are present in virtually all those found on deer; the abundance of males on deer exceeds that of females and copulation is common. Females must be inseminated before commencing the rapid engorgement phase of feeding. Males need not be in attendance during feeding, provided that the female has been inseminated preprandially. Thus, preprandial insemination suffices to stimulate rapid engorgement, but less blood is taken than when the female is perprandially inseminated. Both types of insemination effectively fertilize eggs. Eggs from females sequentially inseminated by irradiated and non irradiated males, were fertilized mainly by sperm from the last male. Cobalt‐irradiated males mate effectively and their sperm compete with those of non‐irradiated males. Sperm from the second two sequential inseminations fertilize most of the eggs. By infesting deer with such irradiated male I.dammini, the abundance of these vector ticks may effectively be reduced.
Effect of photoperiod on the first‐instar development in the lacewing Nineta pallida
Authors: CANARD MICHEL
Published: March 2008

ABSTRACT Nineta pallida (Schneider) (Neuroptera: Chrysopidae) larvae were reared at 21CC under various stationary photoperiods. The duration of the first stadium varied with daylength. Long‐day regimes (LD 18:6 and 16:8 h) induced the fastest development, whereas the first ecdysis was more or less delayed in LD 14:10 and 13:11 h. Medium days (LD 12:12 h) resulted in the longest duration of the first stadium and high mortality, and all shorter days (LD 10:14, 8:16 and 6:18 h) in a moderate delay in the first ecdysis in all individuals. The facultative delay in development is thought to be a diapause, and viewed as a factor contributing to the annual synchronization of the life cycle.
Selection for increased pheromone titre in the pink boll worm moth, Pectinophora gossypiella Lepidoptera: Gelechiidae)
Authors: COLLINS R. D. , ROSENBLUM S. L. , CARDÉ R. T.
Published: March 2008

ABSTRACT The genetic basis of pheromone titre in the pink bollworm moth, Pectinophora gossypiella (Saunders), was examined through artificial selection for females that produce greater amounts of the sex pheromone [a mixture of (Z, E)‐ and (Z, Z)‐7,11 ‐hexadecadieny 1 acetates]. Mean (±SD) pheromone titre increased by 91%, from 24.0±8.1 to 45.8±7.9 ng per female, in six generations of selection. No change in component ratio was observed within the selected line. The duration of male wing fanning, measured in a still‐air bioassay, did not change in the female‐selected line.
Physiological basis for sterilizing effects of constant light in Lymantria dispar
Authors: GIEBULTOWICZ J. M. , RIDGWAY R. L. , IMBERSKI R. B.
Published: March 2008

ABSTRACT Females of gypsy moth, Lymantria dispar L. (Lepidoptera: Lymantriidae), mated to males kept in constant light (LL) as pharate adults fail to oviposit. In males, a rhythm of sperm release from the testis that occurs in light‐dark (LD) cycles is abolished in LL, and the total amount of sperm released from the testis is approximately half of that of LD males. Moreover, any sperm that may be released from the testis of LL males tend to remain in the vasa deferentia instead of moving into the duplex as in LD males. Consequently, in LL very few sperm bundles are transferred to the bursa copulatrix during mating; furthermore, these bundles fail to disperse into spermatozoa and sperm do not reach the spermatheca. The presence of a spermatheca filled with sperm must play an important role in controlling oviposition because their removal from mated females prevents egg‐laying. Our results indicate that the rhythm of sperm release from the testis is essential for the ability of sperm to migrate in male and female reproductive tracts. The rhythms may help to synchronize final stages of sperm development with the activity of phagocytic and secretory cells lining the reproductive tract.
Differential staining for live and dead sperm of honey bees
Authors: PENG YING‐SHIN , LOCKE SARAH J. , NASR MEDHAT E. , LIU T. P. , MONTAGUE MARY ANN
Published: March 2008

ABSTRACT Seven staining techniques were modified and tested for differentially staining the live and the dead sperm cells for the honey bee (Apis mellifera L.). The eosin Y staining method was found to be a simple technique by which the live cells stain bluish purple whereas the dead cells stain bright yellow to greenish yellow. Therefore, it produces a strong contrast between the dead and live sperm cells, and appears to be the most suitable supravital staining method for evaluating the viability of honey bee sperm cells. The significance of supravital staining techniques in assessing the quality of sperm cells during cryopreserving sperm cells is discussed.
The effects of simultaneous variation in protein, digestible carbohydrate and tannic acid on the feeding behaviour of larval Locusta migratoria (L.) and Schistocerca gregaria (Forskal). I. Short‐term studies
Authors: RAUBENHEIMER D. , SIMPSON S. J.
Published: March 2008

ABSTRACT The influence of simultaneously varying the levels in artificial diets of protein, digestible carbohydrate (14% or 28%) and tannic acid (absent or 10%) on the feeding behaviour of the oligophagous Locusta migratoria (L.) and the polyphagous Schistocerca gregaria (Forskal) (Acrididae) was investigated. Total consumption and detailed feeding behaviour were recorded over a 12 h period in choice and no‐choice experiments. In addition, amounts eaten by Schistocerca of the 14% protein, 14% carbohydrate diet with and without tannic acid were measured at regular intervals throughout the fifth stadium, and insect growth over this period was recorded. There were no interactive effects of nutrient levels and tannic acid, despite the fact that both species compensated for dilution of dietary protein by increasing consumption. Only male Locusta compensated for dilution of dietary carbohydrates, and this compensation was much less marked than for protein. Tannic acid did influence feeding as a main effect, however. It caused an increase in amounts eaten by Schistocerca in both choice and no‐choice experiments. This increased consumption was due to an increase in the number of meals taken. A shorter latency period before and a longer duration of the first meal by naive insects suggested a phagostimulatory rather than a post‐ingestive effect of tannic acid. The stimulatory effect was only apparent for the first 24 h of continuous exposure, but this temporary enhancement none the less resulted in the insects being heavier at adult ecdysis. Stadium duration was also somewhat reduced. In a no‐choice situation, no effect of tannic acid on the feeding behaviour of Locusta was observed. When given a choice, however, this species took significantly more meals on the tannic acid‐free diet, these being of similar average size to meals taken on the tannic acid diet. Significantly more insects took their first meals on the tannic acid‐free diet in the choice test, indicating a deterrent effect of tannic acid in Locusta.
Compensatory dietary selection occurs in larval Locusta migratoria but not Spodoptera littoralis after a single deficient meal during ad libitum feeding
Authors: SIMPSON S. J. , SIMMONDS M. S. J. , BLANEY W. M. , JONES J. P.
Published: March 2008

ABSTRACT Final instar nymphs of Locusta migratoria (L.) and larvae of Spodoptera littoralis (Boisduval) were given an artificial diet deficient in either protein or digestible carbohydrate for a single meal during ad libitum feeding, after which they were provided with a choice of two diets, one containing protein but no digestible carbohydrate and the other containing carbohydrate but no protein. Detailed analyses of feeding behaviour showed that locusts exhibited a degree of compensatory dietary selection following the single deficient meal. No such response was evident for the caterpillars, although previous work (Simpson et al., 1988) has demonstrated that compensatory selection behaviour is marked in this species after periods of 4 h or more on the same deficient diets. These results show that locusts are able to respond extremely rapidly to the nutritional quality of their food by utilizing nutritional feedbacks. This capability may have important implications for the study of foraging strategies in other herbivorous insects.
A learning‐related variation in electroantennogram responses of a parasitic wasp
Authors: VET LOUISE E. M. , JONG RUURD DE , GIESSEN WILANT A. VAN , VISSER J. H.
Published: March 2008

ABSTRACT Odour responses of parasitic insects, in search of their hosts, can change due to experience. Leptopilina heterotoma (Thomson) (Hymenoptera; Eucoilidae), a parasitic wasp of drosophilid larvae, is known to alter its preference for odours emanating from host food substrates through learning. These kinds of behavioural modifications in insects are assumed to be the result of complex processes in the brain. The results presented in this report, however, suggest that this learning‐related behavioural variation is not restricted to brain processes but that it involves changes in sensitivity of olfactory receptor neurones.
Feeding patterns of a specialist and a generalist grasshopper: electronic monitoring on their host plants
Authors: BLUST MICHAEL H. , HOPKINS THEODORE L.
Published: March 2008

Abstract Hypochlora alba (Dodge) is a specialist grasshopper that lives and feeds almost exclusively on Artemisia ludoviciana Nutt., a sage plant mostly avoided as food by generalist or polyphagous grasshoppers, such as Melanoplus 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 by H.alba on sage foliage and by M.sanguinipes on seedling ryegrass (Lolium perenne L.), 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. alba had feeding bouts averaging c. 10 min each, compared to c. 4–5 min for M.sanguinipes. Bout frequency was reversed, with M.sanguinipes feeding about once every hour and H.alba about 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 discussed.
Oviposition deterrents of Callosobruchus maculatus (Coleoptera: Bruchidae)
Authors: CREDLAND PETER F. , WRIGHT ANDREW W.
Published: March 2008

Abstract Many 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 bruchids.
Structure–function studies on hypertrehalosaemic and adipokinetic hormones: activity of naturally occurring analogues and some N‐ and C‐terminal modified analogues
Authors: GÄDE GERD
Published: March 2008

Abstract The relative potencies, with respect to mobilization of lipids in Locusta migratoria L. and in Schistocerca gregaria Forsk. and of carbohydrates in Periplaneta americana L., 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 ED50 values, whereas the ED50 values 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. The L. migratoria receptor(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 ED50 values 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.gregaria a 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 on binding of those peptides that fail to achieve maximum responses.
Juvenile Hormone and host‐plant colonization by the black bean aphid, Aphis fabae
Authors: HARDIE JIM , MALLORY ANNE C. L. , QUASHIE‐WILLIAMS CAROL A.
Published: March 2008

Abstract Host‐plant colonization by winged, summer forms of Aphis fabae Scop, 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 parturition.
The ocelli control the flight course in honeybees
Authors: KASTBERGER GERALD
Published: March 2008

Abstract Fully‐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 compound eyes alone.
Feeding behaviour of the horsefly Tabanus nigrovittatus (Diptera: Tabanidae): effects of dissolved solids on ingestion and destination of sucrose or ATP diets
Authors: FRIEND W. G. , STOFFOLANO J. G.
Published: March 2008

Abstract Wild caught female horseflies, Tabanus nigrovittatus Macq. (Diptera: Tabanidae), were fed solutions containing either sucrose or ATP as a phagostimulant. The sucrose diets were presented as free liquids at room temperature. The ATP in the other diets was dissolved in 0.15 M NaCl, or in 0.3 M or 1 M cellobiose and was presented covered with a Parafilm membrane at 38oC. The content of dissolved solids in some diets was adjusted with added cellobiose, which had no phago‐stimulatory effect. Diets of 1 M or 0.6 M sucrose were ingested in large amounts and were directed to the crop. Diets of 0.3 M or 0.1 M sucrose induced lower levels of ingestion, and the diet was directed to the midgut. The addition of cellobiose to give a 1 M total concentration of dissolved solids in these sucrose diets induced many insects responding to the lower concentrations of sucrose to direct the diet to the crop. Diets of ATP in saline or in 0.3 M cellobiose were directed to the midgut. ATP in 1 M cellobiose caused many of the insects to put the diet in both the crop and the midgut. Two behavioural models are presented that integrate interactions between the level of phagostimulation, the concentration of dissolved solids, and an endogenous feeding factor. The dissolved solids effect is most likely a response to osmotic pressure.
Fixation and optomotor response of walking colorado beetles: interaction with spontaneous turning tendencies
Authors: LÖNNENDONKER U. , SCHARSTEIN H.
Published: March 2008

Abstract The paths of Colorado beetles (Leptinotarsa decemlineata Say) in a featureless environment are circular, like those of other species studied. The turning velocity may reach 35o/s and is due to an internal asymmetry, which may change spontaneously. Normally, all control loops of the insect, like fixation or optomotor responses, must work against this asymmetry to stabilize the insect's path. Stationary vertical patterns damp this turning tendency, but their effect is not strong enough to induce a straight path. Only 70% of the turning tendency can be so eliminated. This reaction is termed optomotor response because it can be adequately described with the parameter turning velocity alone. The insect's path was stabilized more effectively when pattern wavelengths were greater than 60o. The insects seemed to fixate these wider stripes. This reaction is termed fixation because the correlation between pattern components and insect's course becomes prominent.

A comparison was made between these reactions to stationary patterns and to turning patterns. No differences could be found in the behavioural reactions to the different situations. This suggests that the insect does not use an internal representation of its spontaneous turning tendency to discriminate between the type of turning of the optical environment. These results can be explained by a simple feedback control loop with an additive interaction between the internal turning command and feedback signals from the eyes.
Odour‐mediated upwind flight of Culex quinquefasciatus mosquitoes elicited by a synthetic attractant
Authors: PILE M. M. , SIMMONDS M. S. J. , BLANEY W. M.
Published: March 2008

Abstract A wind tunnel and video equipment are used to study the long‐range and close‐range responses of gravid females of Culex quinquefasciatus Say to a synthetic pheromone, eryrthro‐6‐acetoxy‐5‐hexadecanolide. In response to water and acetoxyhexadecanolide, together or independently, in the presence of wind, females follow meandering flight paths upwind. Females have a higher rate of turning and a lower flight‐speed when landing at a site containing pheromone than at a comparable site without pheromone. Females stay longer at oviposition sites containing the attractant than at sites with no attractant.
Effects of age and mated status on flight potential of Helicoverpa armigera (Lepidoptera: Noctuidae)
Authors: ARMES N. J. , COOTER R. J.
Published: March 2008

Abstract The effects of ageing and female mated status on the flight potential of Helicoverpa armigera (Hübner), collected as larvae from a pigeonpea crop in southern India, were investigated using a tethered‐flight technique. In non‐mated moths fed sugar solution, from the first night after adult eclosion, the durations of both total and longest continuous flight per night increased up to night 4 and remained at this level until at least night 6. Ovarian maturation was rapid with 77% of unmated moths having commenced oviposition by the third night. On the basis of field evidence it is likely that most females would be mated by the third or fourth night, provided plants with nectar or sugary exudates were locally available. In successfully‐mated females a 15‐fold decrease in total flight duration and a 28‐fold decrease in longest continuous flight duration was observed in contrast to non‐mated females of similar age. As host plants suitable for adult feeding and oviposition were locally available during the time of feral adult emergence, synchronous pre‐reproductive migration was unlikely to occur in the population studied.
Purinoceptors in blood feeding behaviour in the stable fly, Stomoxys calcitrans
Authors: ASCOLI‐CHRISTENSEN ANN , SUTCLIFFE JAMES F. , ALBERT PAUL J.
Published: March 2008

Abstract Both sexes of the stable fly, Stomoxys calcitrans L. (Diptera: Muscidae), have receptors on their mouthparts that mediate blood feeding. The potency ranking of the adenine nucleotides (ATP > ADP > AMP > adenosine) in eliciting feeding and suppressing the NaCl‐sensitive cell may indicate the involvement of a P2‐type receptor. This is supported by the lack of effect on feeding by methyl xanthines. Feeding‐related behavioural and electrophysiological results demonstrate that the potency of CH3‐S‐ATP is not greater than that of ATP. These ATP‐mediated responses are antagonized by ANAPP3. Results support the conclusion that the putative ‘ATP receptor’ involved in stable fly phagostimulation resembles the P2x purinoceptor of vertebrates.
Effects of age, sex and hunger on the antennal olfactory sensitivity of tsetse flies
Authors: OTTER C. J. DEN , TCHICAYA T. , SCHUTTE A. M.
Published: March 2008

Abstract The effects of age on electroantennogram (EAG) responses were investigated in male and female Glossina morsitans morsitans and comparative studies on the effects of starvation and sex on the EAG in G.m. morsitans, G.austeni, G.tachinoides and G.fuscipes fuscipes were made. Stimuli were the vapours of l‐octen‐3‐ol, 4‐heptanone, 3‐nonanone and acetone. EAG decreased with age in both sexes of G.m.morsitans, responses in 5‐day‐old flies already being significantly lower than those in 1‐day‐old flies. In G.m.morsitans and G.tachinoides, EAG responses of males were higher than those of females. In G.austeni and G.f.fuscipes, however, the reverse was found. With increasing starvation EAG sensitivity increased in both sexes of G.m.morsitans and G.tachinoides. In G.austeni and in G.f.fuscipes no clear effects of starvation were observed. Response spectra of the individual species to the four odour substances did not change with increasing hunger. It is concluded that receptor sensitivity may be modulated depending on the insect's needs. Possible mechanisms of regulation and significance of this modulation are discussed.
Factors influencing the onset of egglaying in a cecidomyiid fly
Authors: HARRIS M. O. , ROSE S.
Published: March 2008

Abstract The timing of the onset of egglaying in the Hessian fly, Mayetiola destructor (Say), is influenced by several exogenous and endogenous factors. Mated females initiated egglaying 48 h earlier than virgins and laid 3–4 times more eggs before dying. The effects of mating on the onset of egglaying were further modified by several other factors whose effects were measured in hours rather than days. Increases in ambient temperatures experienced by mated females shortened the post‐mating pre‐ovipositional transition phase; however, the effects of temperature were not linear throughout the temperature range. Age of females at the time of mating also influenced the onset of egglaying. Females that mated1, 2 and 3 h after eclosion spent190, 160 and 120 min in the post‐mating transition phase, respectively. Effects of age were also observed when females were mated over the three calling periods that comprise the 3‐day lifespan of the adult female. Linear regressions of transition times on time of mating had similar slopes for first and second day post‐eclosion females but were offset such that first‐day females mated late in the morning had similar transition times to second‐day females mated early in the morning. By the third day post‐eclosion, transition times showed no significant changes when females were mated throughout the calling period. Possible mechanisms underlying the effects of mating, temperature, and female age on post‐mating pre‐oviposition transition times are discussed.
Caste regulation in the pharaoh's ant Monomorium pharaonis: recognition and cannibalism of sexual brood by workers
Authors: ADAS J. P. EDWARDS
Published: March 2008

Abstract In colonies of the pharaoh's ant Monomorium pharaonis (L), new males and queens can be produced at any time by the removal of the inhibitory effect of the presence of existing fertile queens. When queens are absent, workers rear sexual larvae and will also accept sexual larvae introduced from other nests. However, in the presence of fertile queens workers cannibalize sexual brood, and will not accept male or queen larvae or pre‐pupae from other nests, although worker brood is always accepted and reared. Worker larvae are covered in bifurcated hairs, whereas sexual larvae are essentially hairless. Workers may use these morphological cues to distinguish between sexual and worker brood stages.
Effects of endogenous esterases and an allatostatin on the products of Manduca sexta larval corpora allata in vitro
Authors: JANZEN WILLIAM P. , MENOLD MARISA , GRANGER NOELLE A.
Published: March 2008

Abstract A rapid and simple method has been developed for the simultaneous measurement of juvenile hormone (JH) and JH acid synthesized in vitro by larval corpora allata (CA) of the tobacco hornworm, Manduca sexta. An organic solvent partition of incubation medium efficiently separates JH acid from JH, and a radioimmunoassay which recognizes the two moieties equivalently is then employed to quantify each. The change in the biosynthetic product of the CA from JH to JH acid appears to begin slowly at the time of ecdysis to the last (fifth) larval stadium and is not complete until just prior to wandering (day 4). The inclusion of the JH esterase inhibitor S‐benzoyl‐O‐ethyl phosphoramidothiolate in incubations of corpora allata revealed that the activity of JH esterases from the gland parallels gland activity and that significant hydrolysis of newly synthesized JH by these esterases occurs in incubations of glands taken at the beginnings of the fourth and fifth larval stadia. An allatostatin, which is proposed to inhibit the corpus allatum during the time of the change in its product, inhibits both JH I and JH I acid synthesis.
The effect of male sandfly pheromone and host factors as attractants for female Lutzomyia longipalpis (Diptera: Psychodidae)
Authors: NIGAM YAMNI , WARD RICHARD D.
Published: March 2008

Abstract Male Lutzomyia longipalpis (Lutz & Neiva) pheromone extracted from tergal glands combined with heat, carbon dioxide gas and hamster urine was found to be attractive to virgin female sandflies. The host factors if offered in the absence of pheromone or a heat source were, however, unattractive to female flies. Pheromone stored for 6 days and then combined with the same host components remained attractive to female flies but storage failed to enhance its attractiveness. The effects of carbon dioxide gas, hamster urine, chicken uropygial gland extract and octenol plus acetone on the responses of females were inconsistent. A ceramic battery powered heat source was tested with pheromone and host attractants and showed potential for field application in developing a pheromone trap.
Learning and the role of host‐specific volatiles during in‐flight host‐finding in the specialist parasitoid Microplitis croceipes
Authors: ZANEN P. O. , CARDÉ R. T.
Published: March 2008

Abstract The effect of antennal contact with host‐related stimuli on the subsequent flight response to host‐specific volatiles was examined in the specialist parasitoid, Microplitis croceipes (Cresson) (Hymenoptera: Braconidae). In a choice test between two species of caterpillars feeding on cowpea, free‐flying female M.croceipes lacking prior contact with host cues landed more often on sources of odour from its host, Heliothis tea (Boddie), than from non‐host Spodoptera frugiperda (Smith). After female parasitoids contacted host cues with their antennae, more landings on sources containing hosts were observed only when caterpillars used in the pre‐flight treatment and in the odour sources fed on the same plant species. The degree to which host‐experienced wasps landed more often on hosts as compared with non‐hosts varied with host‐instar and plant species. The role of learning in host finding in specialist parasitoids is discussed.
Phytosterol unsuitability as a factor mediating food aversion learning in the grasshopper Schistocerca americana
Authors: CHAMPAGNE DONALE E. , BERNAYS ELIZABETH A.
Published: March 2008

Abstract Sixth stadium nymphs of the grasshopper Schistocerca americana (Drury) (Orthoptera: Acrididae) were presented with spinach with or without added cholesterol or β‐sitosterol, and the lengths of the first four meals were monitored. Spinach alone evoked a typical aversion learning pattern in which successive meals were of decreasing duration; however, when cholesterol or β‐sitosterol was added the spinach remained acceptable. Nymphs fed spinach for 24h preferred glass‐fibre discs with added cholesterol in a choice test, but nymphs fed wheat (an acceptable food) did not prefer cholesterol‐treated or control discs. Nymphs pretreated with spinach did not distinguish between discs treated with stigmasterol (an unsuitable phytosterol for grasshoppers) and control discs. In no‐choice tests, nymphs pretreated with spinach also fed significantly longer on discs with added 10% cholesterol or 1%β‐sitosterol, compared to meals on discs with stigmasterol or sucrose controls. Detection of appropriate sterols is likely to involve a post‐ingestive feedback mechanism, as significantly longer meals on discs treated with only sucrose resulted when spinach‐fed nymphs, were force‐fed gelatin capsules packed with β‐sitosterol or cholesterol, compared with stigmasterol. Contact chemoreception is unlikely to play a role in this behaviour, as discs (lacking sucrose) treated with cholesterol, β‐sitosterol, stigmasterol, or a chloroform control, all required similar numbers of contacts before feeding was initiated.