bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship Between Migraine, Blood Pressure and Carotid Thickness. A Population-Based Study in the Elderly
Authors: Tzourio C , Gagnière B , El Amrani M , Alpérovitch A , Bousser M-G
Published: October 2003

The relationship between migraine and blood pressure is controversial. We studied the association between migraine and blood pressure in a population-based sample of elderly patients. Participants were 1373 subjects 59-71 years of age. Lifetime migraine was diagnosed according to the International Headache Society criteria by a headache specialist. Blood pressure was measured as well as the carotid intima-media thickness (IMT) which is a good marker of the long-term exposure to high blood pressure. Migraine during life was diagnosed in 140 participants. Mean systolic blood pressure was lower in subjects with migraine than in those without headache (128 mmHg vs. 137 mmHg). There was a significant trend of decreasing frequency of migraine with increasing blood pressure and also with increasing IMT. In this study, migraine was associated with lower levels of blood pressure and with smaller values of carotid wall thickness.
Sporadic Hemiplegic Migraine is an Aetiologically Heterogeneous Disorder
Authors: Thomsen LL , Ostergaard E , Romer SF , Andersen I , Eriksen MK , Olesen J , Russell MB
Published: October 2003

In order to better understand sporadic hemiplegic migraine (SHM) and particularly its relation to familial hemiplegic migraine (FHM), migraine without aura (MO) and typical migraine with aura (typical MA), we investigated the occurrence of MO and typical MA among probands with SHM and their first-degree relatives. The pattern of familial aggregation of MO and typical MA was assessed by population relative risk calculations. A total of 105 SHM probands and 483 first-degree relatives were identified in the Danish population. Compared with the general population, SHM probands had no increased risk of MO, but a highly increased risk of typical MA. First-degree relatives of all SHM probands had an increased risk of both MO and typical MA, whereas first-degree relatives of probands with exclusively SHM had no increased risk of MO but an increased risk of typical MA. Our data suggest that SHM is a genetically heterogeneous disorder.
Perfusion Changes with Photic Stimulation During two Phases of the Menstrual Cycle: A Pilot Study Comparing Controls and True Menstrual Migraine Patients
Authors: Ances BM , Detre JA
Published: October 2003

This pilot study investigated the effect of menstrual cycle phase (late luteal and mid-follicular) on cerebral perfusion changes during photic stimulation in both controls ( n = 5) and true menstrual migraine patients ( n = 5). No significant differences in resting baseline perfusion were observed between the two groups during either phase of the menstrual cycle. During the late luteal phase, changes in perfusion within the occipital lobe due to photic stimulation were similar for both groups. However, during the mid-follicular phase, occipital perfusion during visual stimulation decreased for controls but significantly increased for true menstrual migraine patients ( P < 0.05). A two way repeated measures ANOVA also demonstrated a significant difference between menstrual migraine patients and controls for photic activation ( P < 0.05).
Association Between ACE Inhibitors Use and Headache Caused by Nitrates Among Hypertensive Patients: Results from the Italian Group of Pharmacoepidemiology in the Elderly (GIFA)
Authors: Onder G , Pahor M , Gambassi G , Federici A , Savo A , Carbonin P , Bernabei R ,   on behalf of the GIFA Study
Published: October 2003

Treatment with ACE inhibitors has shown to be effective in the prophylaxis of migraine attacks. The aim of this study was to explore whether among hospitalized hypertensive patients use of ACE inhibitors may reduce the risk of headache caused by nitrates. To this end, we used the GIFA database, that includes patients admitted to academic medical centres throughout Italy. We studied 1537 patients (mean age 75 ± 10 years) receiving treatment with nitrates during a hospital stay and diagnosed with hypertension. Headaches that had a probable or definite causal relation with nitrates use based on the Naranjo algorithm were considered for this analysis. Of the total enrolled sample, 762 patients (50%) used ACE inhibitors during hospital stay. Headache caused by nitrates was recorded in 12/762 (1.6%) ACE inhibitor users and in 24/775 (3.2%) other participants ( P = 0.049). After adjusting for potential confounders, ACE inhibitors use was associated with a significantly lower risk of headache (OR 0.43; 95% Confidence Intervals: 0.20-0.90). This result was confirmed if ACE inhibitors use was compared with use of other antihypertensive agents (OR 0.44; 95% CI 0.20-0.95). In conclusion, this study suggests that among hypertensive subjects use of ACE inhibitors is associated with a reduced risk of headache caused by nitrates.
Dietary constraints on sexual activity, mating success, and survivorship of male Delia antiqua
Authors: McDonald R.S. , Borden J.H.
Published: October 2003

The effects of protein‐deprivation on the sexual activity and reproductive fitness of male onion flies, Delia antiqua (Meigen) (Diptera: Anthomyiidae), were investigated under laboratory conditions. The percentage of males inseminating gravid females, the magnitude of ovipositional response, and the total numbers of eggs deposited in 1:1 or 1:10 male:female matchings over two days was unaffected by deprivation of dietary protein. The LT50's (median survival time) for solitary males provided proteinaceous, sucrose, or water diets were 38.0, 25.8, and 6.0 days, respectively. Yet independent of diet effects, males lost 50% of their wing tissue by fragmentation after 26 days, suggesting that wing condition is more important in determining male reproductive fitness than longetivity. Male mating frequency in single pairings with previtellogenic females deprived of proteinaceous diet for ten days was similar to that of gravid, protein‐fed females. In no‐choice and choice mating bioassays at a 10:1 female:male ratio, however, males inseminated significantly fewer previtellogenic than gravid females over 24 h. Despite evidence for male autogeny, removal of exogenous protein resources in the Allium agroecosystem may have important effects on the reproductive competency and fecundity of D. antiqua.
Comparison of wild type and genetically engineered nuclear polyhedrosis viruses of Autographa californica for mortality, virus replication and polyhedra production in Trichoplusia ni larvae
Authors: Kunimi Yasuhisa , Fuxa James R. , Hammock Bruce D.
Published: October 2003

Virus replication and polyhedra production of two polyhedron‐positive recombinant nuclear polyhedrosis viruses of Autographa californica, AcJHE.KK and AcAaIT which encode juvenile hormone esterase and scorpion toxin, respectively, were compared with those of a plaque purified wild‐type nuclear polyhedrosis virus, AcMNPV‐C6, in Trichoplusia ni larvae. Though average times required to kill the T. ni larvae increased with the age of the larvae, killing time by either recombinant virus was significantly shorter than that by wild‐type virus. Killing time was reduced ca. 30% for AcAaIT‐infected larvae and 5 to 8% for AcJHE.KK‐infected larvae as compared to that for AcMNPV‐C6‐infected larvae. The average weight of larvae infected with AcAaIT was significantly lower than that of larvae infected with AcJHE.KK and AcMNPV‐C6. The mean numbers of polyhedra produced in each larva inoculated with AcAaIT and AcJHE.KK were ca. 20% and 60%, respectively, of those for AcMNPV‐C6. Total virus titers in AcMNPV‐C6‐infected larvae were significantly higher than those in AcJHE.KK‐ and AcAaIT‐infected larvae until 2 days post infection.
The influence of insecticide residues on primary parasitoid and hyperparasitoid foraging behaviour in the laboratory
Authors: Longley Martin , Jepson Paul C.
Published: October 2003

The behaviour of Aphidius rhopalosiphi DeStefani‐Perez (Hymenoptera: Braconidae) was recorded in laboratory bioassays in the presence and absence of both residues of honeydew from the English grain aphid, Sitobion avenae (F.) and the pyrethroid insecticide, deltamethrin. Insecticide concentrations ranged from the field recommended dose rate (6.25 g ai/ha in 200 l water) to 1/16th of field rate. Parasitoids responded strongly to patches of honeydew on filter papers, however the addition of increasing concentrations of deltamethrin caused increasingly early departure from the honeydew‐treated areas. Parasitoids pre‐exposed to field concentration residues for between 1 and 20 min showed shorter retention times and abnormal types of behaviour on honeydew‐treated patches compared to control wasps. Recovery of ‘normal’ behaviour patterns occurred over a 12 h period away from the insecticide source. Further laboratory studies examined the foraging of A. rhopalosiphi and one of its associated hyperparasitoids, Dendrocerus carpenteri (Curtis), on mature wheat plants treated with an artificial honeydew solution and deltamethrin. Wasps exposed to deltamethrin residues were observed to spend shorter visit times, to groom more frequently and to rest less frequently than those on insecticide‐free plants. Differences were found between the distribution of parasitoids on insecticide‐treated and untreated plants, with D. carpenteri showing greater movement down insecticide‐treated plants accompanied with an increase in time spent on abaxial leaf surfaces compared to A. rhopalosiphi. The results are discussed in terms of the repellency of deltamethrin and the implications for integrated pest management of differing sub‐lethal insecticide effects on primary parasitoid and hyperparasitoid behaviour.
When good bugs go bad: intraguild predation by Jalysus wickhami on the parasitoid, Cotesia congregata
Authors: Kester Karen M. , Jackson D. Michael
Published: October 2003

We report a case of direct intraguild predation involving an insect predator and parasitoid in an agricultural system. The spined stilt bug, Jalysus wickhami Van Duzee, feeds on eggs of the tobacco hornworm, Manduca sexta L., and also on prepupal and pupal stages of the gregarious hornworm parasitoid, Cotesia congregata (Say). In two separate trials, mean mortality of attached parasitoids was significantly lower (66%, 73%) than that of their detached siblings (97%, 96%) after a 3 day exposure to stilt bugs, demonstrating that attachment to the host offered some protection against predation. In no‐choice experiments, prepupal parasitoids suffered greater mortality (0 day‐old = 61%, 1 day‐old = 65%) than pupal parasitoids (2 day‐old = 50%, 3 day‐old = 14%). When offered in combination with 0 or 2 day‐old hornworm eggs, respective mortality of 0,1,2 and 3‐day‐old pupal parasitoids showed a similar pattern (67%, 63%, 33% and 23%). In another experiment, mortality of 0‐day‐old pupal parasitoids (64%) was greater than that of 3 day‐old pupal parasitoids (38%). Mortality of pupal parasitoids was not affected by the availability of hornworm eggs, a highly acceptable food. Younger pupal parasitoids (= prepupae) probably suffered greater mortality because they were more easily fed on by stily bugs than older (pupated) ones. Because C. congregata overwinters in the prepupal stage, it may be particularly vulnerable to attack late in the season when stilt bug populations are large and hornworm eggs are relatively uncommon.
Characteristics of oviposition behaviour of the pollen beetle, Meligethes aeneus on four different host plants
Authors: Borg Annika , Ekbom Barbara
Published: October 2003

Oviposition behaviour of Meligethes aeneus F. (Coleoptera: Nitidulidae) is characterised and quantified on four different plant species. Six behavioural components are identified: W – walking, WA – walking with abdomen on surface, R – resting, B – biting, AOH – placing abdomen over the bite hole and OVI – oviposition. Comparison of host acceptance behaviours on Brassica napus L., Brassica juncea (L.) Czern, Brassica nigra (L.) Koch and Sinapis alba L. showed that S. alba was accepted as a host only after a long exposure to the plant. Behaviour on the Brassica species was similar, however on B. nigra beetles spent a high proportion of time actually ovipositing. We conclude that important cues for oviposition are located both on the bud surface and inside the bud.
Foraging behavior and growth of isolated larvae of a social caterpillar, Malacosoma americanum
Authors: Fitzgerald T.D. , Visscher C.R.
Published: October 2003

In laboratory experiments, isolated eastern tent caterpillars, Malacosoma americanum (Fabricius) (Lepidoptera: Lasiocampidae), grew more slowly than their grouped siblings even though factors previously reported to give grouped caterpillars an advantage were eliminated from our experimental design. Analysis of time‐lapse videorecordings of daily foraging bouts showed that, despite their slower growth, isolated individuals fed significantly more often than their grouped siblings. This finding is consistent with previous observations showing that the rate at which tent caterpillars assimilate food is largely independent of foraging frequency and suggests that increased metabolic costs associated with superfluous activity may cause isolated caterpillars to grow slower. More rapid growth of grouped caterpillars also appears attributable to the significantly longer periods of time solitary caterpillars spent inactive during episodes of molting. Our study shows that the distinctive temporal pattern of foraging characteristic of intact colonies of eastern tent caterpillars is a emergent property of the group.
Development of a mite bioassay to evaluate plant resistance and its use in determining regeneration of spider mite resistance
Authors: Harman J. , Paul P. , Craig R. , Cox‐Foster D. , Medford J. , Mumma R.O.
Published: October 2003

The zonal geranium (Pelargonium xhortorum) possesses tall glandular trichomes that secrete anacardic acids, a viscous, sticky exudate which has been suggested as the primary mechanism in two‐spotted spider mite (Tetranychus urticae Koch) resistance. A new bioassay was developed using small Plexiglas® cylinders as chambers for evaluating the resistance of geranium leaves to the two‐spotted spider mite. This bioassay was easy to prepare, required only 24 hours to conduct, exhibited no problems with desiccation, condensation, or mite accountability, and yielded reproducible results. This bioassay was then used to study the regeneration of resistance of attached geranium leaves after they were made mite‐susceptible by removing the excreted anacardic acids with water. Washed leaves regained full resistance after 14 days.
Desensitization of fifth instar Spodoptera litura to azadirachtin and neem
Authors: Bomford Michael K. , Isman Murray B.
Published: October 2003

The deterrence of azadirachtin, in its pure form and as a constituent of neem seed extract, to fifth instar Spodoptera litura (Fab.) larvae, was measured using cabbage, Brassica oleraceae (L.) var. capitata, leaf disc assays. Paired‐choice assays, in which larvae could choose between feeding on a treated (1.3 ng azadirachtin per square cm leaf area) or an untreated leaf disc for 2 h, were conducted at 24 h intervals throughout the fifth instar. In addition, no‐choice assays, in which larvae could feed on only one leaf disc (10 ng azadirachtin per square cm leaf area) for 1.5 h, were conducted consecutively over a six hour period at the beginning of the fifth instar. The effects of hunger and habituation on desensitization in our no‐choice tests were partitioned. After repeated exposures, larvae became desensitized to pure azadirachtinal in both choice and no‐choice tests, but did not desensitize to neem containing the same absolute amount of azadirachtin in choice tests. Hunger was responsible for approximately one third of the desensitization response in the no‐choice tests. Sensitivity to azadirachtin was independent of age within the fifth instar.
Intraspecific larval competition in two solitary parasitoids, Apoanagyrus (Epidinocarsis) lopezi and Leptomastix dactylopii
Authors: van Baaren Joan , Nénon Jean‐Pierre
Published: October 2003

Encyrtid Hymenoptera, Apoanagyrus (Epidinocarsis) lopezi De Santis and Leptomastix dactylopii Howard are strictly solitary endoparasitoids of mealybug larvae and adults, Phenacoccus manihoti Matile‐Ferrero and Planococcus citri Risso (Pseudococcidae), respectively. For both species, the survival rate of the supernumerary parasitoid according to the time interval between the two ovipositions has been determined by dissecting superparasitized hosts. For A. lopezi, the survival rate of the second parasitoid is at least equal to 30% when the time interval between the two ovipositions is less than 2 days, then it drops rapidly down to 10%. For L. dactylopii, the survival rate of the second parasitoid is 23% for a one hour interval between the two ovipositions and thereafter decreases very rapidly to reach a stable value of 7%. Differences between the two species might be partly due to the immunological defense reactions of their respective hosts. In the two Encyrtidae, supernumerary individuals are eliminated partly by physical attack between larvae at the L2 stage and partly by a physiological suppression of the second parasitoid by the first at the egg or larval stage. Earlier findings had shown that females of each species oviposit preferentially in hosts in which their progeny has the highest probability of survival: this would indicate that the adaptive value of conspecific superparasitism depends essentially on the survival rate of the second parasitoid in superparasitized hosts.
Mobility of three generalist predators is greater on cabbage with glossy leaf wax than on cabbage with a wax bloom
Authors: Eigenbrode S.D. , Castagnola T. , Roux M.‐B. , Steljes L.
Published: October 2003

Adult coccinellids Hippodamia convergens Guerrin‐Menneville, adult minute pirate bugs Orius insidiosus (Say), and larval lacewings Chrysoperla carnea (Stephens) have been reported to more effectively reduce populations of Plutella xylostella (L.) (Plutellidae: Lepidoptera) larvae on a cabbage with glossy surface waxes than on a standard cabbage variety. To examine the mechanisms, the behavior of each predator species was quantified on the two cabbage types. All three predators spent less time walking on the standard variety and more time in other activities, including grooming and ‘scrambling’ (ineffective forward locomotion). In addition, walking by each predator was distributed more evenly among the parts of the leaf on the glossy cabbage than on the standard variety. In small enclosures, C. carnea and O. insidiosus found and attacked individual first instar P. xylostella more quickly on the glossy cabbage. Scanning electron micrographs showed debris, probably wax, on the tarsae of C. carnea and O. insidiosus that had walked on the standard variety, but not on those that had walked on glossy cabbage. H. convergens tarsae did not accumulate debris on either cabbage type. Predator mobility and effectiveness were apparently impeded by wax crystals, which are present only on the standard variety. This mechanism can explain the greater effectiveness of these generalist predators against P. xylostella larvae on glossy vs normal‐wax cabbage.
Performance of the predator Delphastus pusillus on Bemisia resistant and susceptible tomato lines
Authors: Heinz Kevin M. , Zalom Frank G.
Published: October 2003

Host plant resistance and biological control are often assumed to act additively to suppress populations of agricultural pests. Using tomato trichome based resistance to the whitefly Bemisia argentifolii, we tested this additivity assumption with Delphastus pusillus, a coccinelid predator of Bemisia. Various life history traits of D. pusillus were measured on the tomato cultivar ‘Alta,’ which possessed foliage with 3‐fold greater trichome densities than the second cultivar ‘VF145B7879.’ Beetles housed on VF145B7879 exhibited significantly greater lifetime fecundities and walking speeds than beetles housed on Alta. No cultivar‐specific differences were observed in D. pusillus longevities or handling times. Combining these observations with previously published reports of reduced B. argentifolii population growth rates on Alta compared to VF145B7879, we tested the hypothesis that increased levels of whitefly biological control could be obtained on VF145B7879 by comparison to Alta through releases of D. pusillus. Analyses of results obtained from replicated population trials detected significant reductions in whitefly populations due to D. pusillus releases, but they did not detect a significant influence of tomato cultivar on the ability of D. pusillus to suppress whitefly populations. Significantly longer beetle residence times on Alta than on VF145B7879 may have compensated for the significantly slower walking speeds and reduced lifetime fecundities observed on Alta and produced a neutral effect of foliar trichome densities on B. argentifolii biological control.
Preference for plants damaged by conspecific larvae in ovipositing cabbage root flies: influence of stimuli from leaf surface and roots
Authors: Baur Robert , Koš?ál Vladimír , Patrian Bruno , Städler Erich
Published: October 2003

In laboratory dual‐choice assays females of the cabbage root fly, Delia radicum, prefer for oviposition plants with roots damaged by conspecific larvae to undamaged controls. Cauliflower and kale plants were inoculated with root fly eggs (25 per plant) and the hatching larvae were allowed to feed on the roots for various periods of time (1‐17 days). After 4 (cauliflower) or 5 (kale) days of larval feeding the oviposition preference was most pronounced and flies laid between 64% and 68% of their eggs near plants with damaged roots. Later, with increasing damage but fewer surviving, and thus actively feeding, larvae, the magnitude of the preference declined. The preference for plants already damaged by conspecific larvae may contribute to the previously observed aggregated distribution of D. radicum eggs in Brassica crop fields.

Further experiments revealed that the sensory cues inducing this oviposition preference originate from the complex consisting of the damaged roots, the surrounding substrate (soil) and associated microbes, rather than from the aerial plant parts. In choice assays using the root‐substrate complex of damaged and control plants (aerial parts removed), the observed preference for damaged roots was similar to that found for the entire plant but was more pronounced. The damaged roots alone, compared to control roots, received up to 72% (cauliflower) and 75% (kale) of the eggs. By contrast, surrogate leaves sprayed with methanolic leaf surface extracts from the most preferred plants which had been damaged were not discriminated from surrogate leaves sprayed with extracts of the respective control plants. Analysis of glucosinolate levels in methanolic leaf surface extracts revealed that root damage resulted in enhanced concentrations of indole‐glucosinolates on the leaf surface in kale but not in cauliflower. Although indole‐glucosinolates are oviposition stimulants for the cabbage root fly, the induced changes were apparently too small to influence oviposition behaviour.
Electroantennogram, wind tunnel and field responses of male Mediterranean corn borer, Sesamia nonagrioides, to several blends of its sex pheromone components
Authors: Sans A. , Riba M. , Eizaguirre M. , Lopez C.
Published: October 2003

The electrophysiological and behavioural responses of male Sesamia nonagrioides Lefèbvre (Lepidoptera: Noctuidae) to several synthetic blends of its sex pheromone components were investigated. Electroantennogram (EAG) recordings showed the greatest response to a 77:8:10:5 blend of the four compounds found in the female glands: (Z)‐11‐hexadecen‐1‐yl acetate, (Z)‐11‐hexadecen‐1‐ol, (Z)‐11‐hexadecenal and dodecyl acetate. A logistic equation was fitted to the dose‐response data and differences in relative EAG responses were analysed by deriving five parameters of this equation. Flight responses of males were also evaluated in a wind tunnel where the proposed blend (77:8:10:5) also elicited the best response. Field tests confirmed the laboratory findings as the 77:8:10:5 blend captured more S. nonagrioides males than other pheromone mixtures and showed more selectivity for male S. nonagrioides over other noctuid species, Discestra trifolii Rottenberg and Lacanobia oleracea L., but not for Mythimna unipuncta Haworth, a species with a sex pheromone composition almost identical to that of S. nonagrioides.
Flight behaviour of Encarsia formosa in response to plant and host stimuli
Authors: Guerrieri Emilio
Published: October 2003

The flight behaviour of Encarsia formosa Gahan (Hymenoptera: Aphelinidae), a parasitoid of Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae) has been studied in response to the following natural components: bean plant (Phaseolus vulgaris L.) infested with T. vaporariorum (PHC, plant host complex), host damaged bean plant from which whiteflies were removed (HDP, host damaged plant), T. vaporariorum third instar larvae (H, host), uninfested bean plant (P, plant) and T. vaporariorum empty pupal cases (EPC, empty pupal cases). A combination of chemical and visual stimuli is necessary in host location from a distance by E. formosa and seems to deeply affect the dispersal of this parasitoid. The presence of host (PHC, H) or of its parts (EPC) led to a substantial increase of oriented flights suggesting the occurrence of host derived chemicals. At a closer range, a combination of visual and chemical stimuli deriving from all the components of the plant host complex elicited the transition flying‐landing and the following landing on the source.
Effects of wind on movement of Diachasmimorpha longicaudata, a parasitoid of tephritid fruit flies, in a laboratory flight tunnel
Authors: Messing R. H. , Klungness L. M. , Jang E. B.
Published: October 2003

Cohorts of mass‐reared adult female Diachasmimorpha longicaudata (Ashmead), parasitoids of tephritid fruit fly larvae, were released in a laminar air flow wind tunnel to study the effects of air movement on flight and walking behaviors. Wind in the tunnel was cycled on and off at intervals to simulate gusty conditions observed in the field. Wind speed influenced parasitoid movement during both the wind‐on periods and during the calm intervals between gusts. Wind speeds of 0.8 m per second suppressed flight and walking behaviors, while wind speeds of 0.4 m/s stimulated both flight and walking behaviors. There was an exponential increase in the ratio of activity in calm to activity in wind as wind speed increased.
The influence of previous host age on current host acceptance in Trichogramma
Authors: Reznik S. Ya. , Umarova T. Ya. , Voinovich N. D.
Published: October 2003

Trichogramma principium Sug. & Sor. females were sequentially offered two portions of the grain moth (Sitotroga cerealella Oliv.) eggs, either young (1‐day old) or old (eggs that had developed 6 days at a temperature of 20 °C). The probability of host acceptance depended not only on current host age, but also on the age of the previously offered host. Particularly, Trichogramma females more often oviposited in old host eggs when previously offered young eggs (35–45% of Trichogramma females laid eggs) compared to females which were sequentially offered two portions of old eggs (15–20% of Trichogramma females laid eggs). In other words, parasitization by Trichogramma was stable even when transferred from young (preferred) to old (usually rejected) eggs. Dissections showed that refusing females had significantly more mature eggs than ovipositing females, independent of host age. Among ovipositing females, wasps provided with young hosts had fewer mature ovarial eggs than wasps provided with old hosts. Supposedly, Trichogramma females offered old hosts require a higher motivation to oviposit and have a correspondingly higher egg load than females offered young (preferred) hosts.
Sex‐allocation behaviour of a solitary ectoparasitoid: effects of host‐patch characteristics and female density
Authors: Gauthier Nathalie , Monge Jean‐Paul , Huignard Jacques
Published: October 2003

The sex‐allocation behaviour of the solitary ectoparasitoid Dinarmus basalis (Hymenoptera: Pteromalidae) was investigated by examining the female's response to two proximal factors: the host‐patch characteristics and the conspecific female density in the patch. The offspring sex‐ratio of single females presented with unparasitised hosts was female biased (approximately three daughters to one son in the progeny) whatever the host density tested. The sex‐ratio in the presence of hosts parasitised by a conspecific 48 h beforehand was male biased. The proportion of male offspring also increased when the number of conspecific females exploiting the patch changed from a single female to a group of females, whatever the group size. No sexual differences in mortality as a result of larval competition on superparasitised hosts were observed. The offspring sex‐ratios observed in response to the host‐patch characteristics were the result of manipulation of the egg fertilisation by the females during the oviposition phase. Thus, the variability of the sex‐ratio in response to an increase in the number of conspecific females in the same patch represented a reduction in egg fertilisation. These results are analysed with regard to the predictions of Local Mate Competition theory and the females' host discrimination ability.
Effects of previous plant infestation on sieve element acceptance by two aphids
Authors: Prado Ernesto , Tjallingii W. Freddy
Published: October 2003

Probing behaviour as affected by a previous infestation was studied in two aphid species on their respective host plants. Probing behaviour by Aphis fabae (reported to have beneficial effects when living in colonies) and Rhopalosiphum padi (without known beneficial effects) was studied using the electrical penetration graph (EPG) technique. In A. fabae the main effects were longer and more continuous sap ingestion, and less salivation into sieve elements before sap ingestion. These suggest phloem factors. Nevertheless, mesophyll and non‐vascular tissues are likely to be involved to a lesser extent, as reflected by fewer non‐probing periods before the first phloem phase on previously colonised leaves as compared to clean leaves. Total honeydew production increased on a previously colonised leaf due to the prolonged sap ingestion periods but the excretion rate was not affected, indicating that the ingestion rate remained unaltered. R. padi did not show responses to previous colonisation. It is hypothesized that the changes in probing behaviour are due to changed plant properties, chemical contents of sieve element sap and/or physiological changes induced by the saliva from the colony.
Effects of lectins, CRY1A/CRY1B Bt δ‐endotoxin, PAPA, protease and α‐amylase inhibitors, on the development of the rice weevil, Sitophilus oryzae, using an artificial seed bioassay
Authors: Pittendrigh B.R. , Huesing J.E. , Shade R.E. , Murdock L.L.
Published: October 2003

An artificial maize seed bioassay was developed to evaluate potential resistance factors against the rice weevil, Sitophilus oryzae. Weevils reared in artificial seeds compared to those reared in whole maize seeds: (i) developed faster, (ii) had similar within‐seed developmental mortalities, (iii) were lighter in weight upon emergence and (iv) oviposited the same number of eggs. Using this bioassay we found that E‐64, a cysteine protease inhibitor, decreased the number of emerged adults per seed and delayed within‐seed developmental time, suggesting that the rice weevil utilizes a cysteine protease to digest its dietary protein. Weevils fed inhibitors of trypsin and chymotrypsin, Bowman‐Birk and Kunitz inhibitors respectively, developed normally. Para‐amino‐l‐phenylalanine (PAPA), a non‐protein amino acid implicated as an insect resistance factor in Vigna vexillata, was lethal at dietary levels of 0.2% (w/w) and higher. An extract from Amaranthus caudatus seeds delayed the developmental time of the rice weevil at dietary levels of 0.2% (w/w) and increased mortality at dietary levels of 1.0% (w/w). Several proteins tested, including Griffonia simplicifolia agglutinin II, phytohemagglutinin extract containing common bean α‐amylase inhibitor, pokeweed agglutinin, Bacillus thuringiensis CRY1A/CRY1B endotoxin, and an α‐amylase inhibitor from wheat, had no effect on the rice weevil. The artificial maize seed bioassay was adapted by pelleting the seed for use with an ultrasonic insect feeding monitor to determine the finding activity of rice weevils as they developed from egg hatch to pupation.
Seasonal abundance of the neotropical brown stink bug, Euschistus heros, in overwintering sites, and the breaking of dormancy
Authors: Panizzi Antônio R. , Vivan Lúcia M.
Published: October 2003

The seasonal abundance of the neotropical brown stink bug, Euschistus heros (Heteroptera: Pentatomidae), in overwintering sites in northern Paraná state, Brazil (latitude 23°11′ S, longitude 51°11′ W) was monitored from September 1994 to August 1995. The breaking of dormancy (oligopause) was studied in the laboratory by comparing the feeding activity and reproduction of adults collected in the field under different physiological conditions (i.e., dormant and non‐dormant). No bugs were found in overwintering sites during the summer (December to February) and during early autumn (March). From mid‐autumn to winter (April – August), the number of E. heros captured in these sites gradually increased, decreasing thereafter with the start of spring in September. Dormant and non‐dormant E. heros taken to the laboratory and maintained at 25 ± 1 °C, 65 ± 5% r.h., and L14: D10 photoperiod, and given suitable food (soybean pods or seeds), began feeding immediately. The number of stylet sheaths deposited/day on the food was greater for non‐dormant than for dormant adults. Feeding activity was greater on immature pods than on mature seeds of soybean. Dormant females placed under suitable biotic and abiotic conditions took ca. 2 weeks to start reproduction, in contrast to non‐dormant females, which reproduced immediately.
Effects of natural enemies on relative fitness of Heliothis virescens genotypes adapted and not adapted to resistant host plants
Authors: Johnson M. Tracy , Gould Fred , Kennedy George G.
Published: October 2003

We investigated the potential of two natural enemies of Heliothis virescens (F.) (Noctuidae) to affect its rate of adaptation to tobacco containing Bacillus thuringiensis Berliner toxin. Larval fitness of two laboratory strains of H. virescens, one adapted to B. thuringiensis toxin and one not adapted, was compared on toxic and nontoxic plants, in the presence of the parasitoid Campoletis sonorensis (Cameron) (Ichneumonidae) or the entomopathogenic fungus Nomuraea rileyi (Farlow) Samson. By exposing larvae to plants and enemies for no more than 24 h, we focussed on the behavioral rather than physiological component of their interaction with toxic plants and natural enemies.

Parasitism of H. virescens larvae by C. sonorensis during exposure periods of 1–4 h was lower on toxic plants than nontoxic plants and was lower for nonadapted larvae than for toxin‐adapted larvae. Decreased larval feeding damage on toxic versus nontoxic plants, and by nonadapted versus adapted larvae, may explain differences in parasitism, because C. sonorensis locates host larvae using cues from damaged plants. Effects of plant toxicity and larval strain on H. virescens survival were numerically consistent with effects on parasitism, but they were not statistically significant. When mean larval survival is used to estimate fitness of the nonadapted genotype relative to the toxin‐adapted genotype, we find that C. sonorensis is expected to delay adaptation to toxic plants.

Percent infection by N. rileyi of H. virescens larvae exposed to fungus‐treated plants for 24 h was greater when plants were toxic, and was greater for nonadapted larvae than toxin‐adapted larvae. There were corresponding decreases in larval survival on toxic compared to nontoxic plants, and of nonadapted compared to adapted larvae. Interaction of effects of plant line and larval strain on survival was significant in the presence of fungus, but not in the absence of fungus, which indicates that the effect of toxic plants on the relative fitness of toxin‐adapted and nonadapted larvae was mediated by fungus. As in the interaction with C. sonorensis, behavior of larvae on plants may explain differences in susceptibility to N. rileyi. Because nonadapted larvae moved more than toxin‐adapted larvae on toxic plants, nonadapted larvae may have been more likely to encounter a lethal dose of conidia. In contrast with C. sonorensis, N. rileyi, which decreased the fitness of the nonadapted genotype relative to the adapted genotype, is expected to accelerate adaptation to toxic plants.
Mechanisms of resistance to Colorado potato beetle in several potato lines and correlation with defoliation
Authors: Horton David R. , Chauvin R.L. , Hinojosa Tonya , Larson Duane , Murphy Clifford , Biever K. Duane
Published: October 2003

Eight potato (Solanum tuberosum L.) lines and a control (cv. Russet Burbank) were screened for suitability to Colorado potato beetle, Leptinotarsa decemlineata (Say) (Chrysomelidae), and for defoliation levels in the field to determine whether laboratory‐obtained measures of performance are useful for predicting defoliation. Several lines caused reduced larval growth rates and survival compared to the control. Forty‐eight hour weight gains by fourth instar larvae, after adjustment for consumption rates, were reduced on three lines, suggesting that these lines had antibiosis‐like effects. Lines having very low suitability in the laboratory showed very low defoliation levels in the field, whereas lines that were highly suitable in the laboratory tended to suffer extensive defoliation in the field. Correlation analyses suggested that fourth instar growth rates or larval survival rates are useful measures for predicting defoliation in the field.
Significance of penetration and metabolism on topical toxicity of diflubenzuron in Spodoptera littoralis and Spodoptera exigua
Authors: Smagghe Guy , Auda Mahroussa , Van Laecke Kristiaan , Degheele Danny
Published: October 2003

Toxicity assays indicated that when diflubenzuron (DFB) was topically applied on larvae of the Egyptian cotton leafworm, Spodoptera littoralis (Boisduval), and the beet armyworm, Spodoptera exigua (Hübner), estimated LD50 values were similar, reaching 0.47 and 0.44 ng/larva, respectively. This study evaluated the importance of the rate of uptake and excretion, and of enzymatic metabolism in building up an insecticidal toxicity after topical application on the insect cuticle in both species. In general, penetration of DFB in S. littoralis was about 2‐fold higher than in S. exigua, whereas metabolic breakdown was of minor importance in S. littoralis as compared with S. exigua. The current data indicate the importance of cuticle penetration and discuss that extrapolation from oral feeding toxicity results to topical toxicity data should be evaluated with caution, especially for insect growth regulators used in integrated pest management.
Effect of mannose‐binding lectin from peanut and pea on the stem borer Chilo partellus
Authors: Law Ian J. , Kfir Rami
Published: October 2003

A mannose‐binding lectin found in vegetative tissues of peanut, Arachis hypogaea, was compared with mannose‐binding lectin from pea, Pisum sativum, for toxic effects on larvae of the stem borer Chilo partellus (Swinhoe). After 10 days, the mortality of larvae fed on artificial diet containing 0.5% (m/m) peanut lectin was 46.2%. The mortality of larvae fed on 1.0% peanut lectin was similar (48.1%) but insects were significantly smaller than those of the 0.5% treatment. Larvae of both lectin treatments stopped feeding within three days. Larval size and mortality was not significantly reduced by 0.1% peanut lectin and 1% heat‐treated lectin did not show toxic effects. The mannose‐binding lectin from pea was not toxic to C. partellus at concentrations up to 1%. Peanut lectin bound to the apical membranes of columnar epithelial cells in the mid‐gut of C. partellus. This suggests that peanut lectin has an antinutritive action and that it may protect vegetative tissues of peanut against insect pests.
A comparison of live versus kill pitfall trapping techniques using various killing agents
Authors: Weeks Ronald D. , McIntyre Nancy E.
Published: October 2003

We compared the efficacies of two arthropod pitfall trapping techniques: live (dry) trapping and kill trapping with three killing agents (water, ethylene glycol, and the recently developed propylene glycol, whose efficacy has not been previously assessed). Kill pitfall traps caught more species than did live pitfalls. Forty‐one species were collected only from kill traps (3 being unique to water, 11 to ethylene glycol, and 8 to propylene glycol), 12 were collected only from live traps, and 32 were collected from both kill and live traps. The same average number of individuals per species was caught for most of those taxa that were collected in both trap types, indicating that better retention of captured arthropods by the killing agent was not responsible for the differences observed in the two pitfall trapping methods. There were no significant differences in captures between propylene and ethylene glycol traps or between water and live traps. Because of species‐specific differences in the efficiencies of live and kill pitfall trapping, cross‐study entomological comparisons made using kill pitfall trapping and live pitfalling may be confounded.
Fungal endophytes of wild barley and their effects on Diuraphis noxia population development
Authors: Clement S.L. , Wilson A.D. , Lester D.G. , Davitt C.M.
Published: October 2003

Laboratory experiments were conducted to compare the expression of Diuraphis noxia (Mordvilko) (Homoptera: Aphididae) resistance in four plant introduction (PI) lines of wild barley (Hordeum) infected with different species or strains of endophytic fungi (tribe Balansieae, family Clavicipitaceae, Neotyphodium gen. nov. [formerly Acremonium]). Aphid densities were significantly lower on endophyte‐infected plants of PI 314696 (H. bogdanii Wilensky) and PI 440420 (H. brevisubulatum subsp. violaceum (Boissier & Hohenacker)), compared with densities on endophyte‐free plants of both PI lines in population growth experiments. This endophyte‐ associated resistance was the result of antibiosis effects or starvation. In other experiments, endophyte‐free plants of PI 269406 and PI 440413 (H. bogdanii) were not superior to endophyte‐infected conspecifics as host plants of D. noxia. Our results demonstrate the influence of host plant species/genotype and endophyte species/strain on expression of aphid resistance, provide an explanation of the high levels of D. noxia resistance in PI 314696 and PI 440420 previously reported in the literature, and underscore the potential importance of endophytic fungi in conferring insect resistance in wild barley.
Oviposition preference of western flower thrips for cucumber leaves from different positions along the plant stem
Authors: Jan, de Kogel Willem , van der Hoek Marieke , Mollema Chris
Published: October 2003

While the distribution of herbivorous insects over leaves along the stem often shows a peak at some distance from the apex this does not necessarily reflect an innate preference as alternative explanations can be provided such as impact of predators and inter‐ or intraspecific competitors. It is of interest to determine which factors shape the distribution of insects over the leaves of a plant. Do leaves from different positions differ in suitability for insects and is that reflected in the insect's preference, or are other factors involved? In this paper we assess how the herbivorous insect western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), chooses among leaves from different positions relative to the apex of cucumber, Cucumis sativus (L.) plants. On leaf discs of a susceptible and three partially resistant cucumber accessions, thrips reproduction was highest on apical leaves and lowest on basal leaves. In dual‐choice essays thrips females preferred younger leaves over older leaves for oviposition in all cucumber accessions tested, as was predicted from the no‐choice assay. This indicates that differences in leaf suitability are an important factor in determining thrips distribution on cucumber plants.
Searching behaviour of Encarsia formosa as mediated by colour and honeydew
Authors: Romeis J. , Zebitz C.P.W.
Published: October 2003

The habitat‐ and host‐searching behaviour of female Encarsia formosa Gahan (Hymenoptera: Aphelinidae) was assessed using an airflow olfactometer and a filter paper test. Responses to different odour cues, colours, host‐produced honeydew, non‐host honeydew and single carbohydrates were determined. The parasitoid was not attracted to or arrested by odours emanating from clean tobacco leaves, tobacco leaves heavily infested with the host Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae) and covered with honeydew, or honeydew alone. However, E. formosa females showed a significant response to green light transmitted through a tobacco leaf. The yellow part of the spectrum was partly responsible for this response. Thus, the long‐range orientation is random with respect to the presence of hosts. Filter paper tests showed that the short‐range searching behaviour is influenced by water soluble, non‐volatile contact‐kairomones contained in the host‐produced honeydew. Contact with honeydew excreted by L3/L4 T. vaporariorum resulted in longer searching times than honeydew from adult T. vaporariorum or L3/L4 Bemisia tabaci Gennadius (Homoptera: Aleyrodidae). No difference was found between the response to honeydew excreted by adult and L3/L4 B. tabaci. The parasitoids' response to honeydew was unaffected by the host plant on which the whiteflies had fed. Non‐host honeydew and single carbohydrates also affected the searching behaviour of E. formosa but to a lower extent than host honeydew. The possible differences in the carbohydrate and amino acid composition of the honeydew excreted by different life‐stages of T. vaporariorum and B. tabaci are discussed.
Cage experiments on Orius tantillus predation of Helicoverpa armigera
Authors: Sigsgaard L. , Esbjerg P.
Published: October 2003

The role of Orius tantillus (Motschulsky) (Hemiptera: Anthocoridae) in the predation of H. armigera was studied on both sorghum (Sorghum bicolor L.) and pigeonpea (Cajanus cajan L.), the predominant intercrop of small farmers in Andhra Pradesh, India. Adult Orius tantillus was observed in cages where there were eggs and first‐instar larvae of H. armigera on sorghum and pigeonpea. We found that O. tantillus had two diurnal peaks of activity, after sunrise and before sunset. O. tantillus was found preying on first‐instar larvae and not on eggs. However, a later immunoassay of O. tantillus collected on sorghum during a peak period of H. armigera oviposition activity showed that predation of eggs did occur under certain conditions. The activity of O. tantillus on sorghum was significantly higher on the flowers than elsewhere but this was not the case on pigeonpea. Therefore O. tantillus was a significantly more efficient predator on sorghum than on pigeonpea. The results indicate that O. tantillus could be an important predator of early stages of an H. armigera infestation, particularly in sorghum.