bluuebunny/crossref_metadata_2025 huggingface dataset:
Larval feeding behavior of Dipel‐resistant and susceptible Ostrinia nubilalis on diet containing Bacillus thuringiensis (Dipel ES™)
Authors: Huang Fangneng , Buschman Lawrent L. , Higgins Randall A.
Published: October 2003

Diet choice tests were conducted to examine the effects of Bacillus thuringiensis Berliner on larval feeding behavior of Dipel‐resistant and susceptible strains of European corn borer, Ostrinia nubilalis (Hübner). Larvae (first through fourth instars) were presented an untreated standard diet and three diets incorporating different concentrations of a commercial formulation of B. thuringiensis, Dipel ES™. Significantly higher proportions of susceptible and resistant larvae were found on the control diet compared to the proportions recorded on any of the Dipel‐treated diets. Soon after release (0.5 to 3 h), the occurrence of larvae on each of the diets was similar across different instars. The number of first and second instars on the control diet increased steadily over 72 h after release, when 43 to 75% of larvae were found on the control diet. The proportion of third and fourth instars on the control diet also increased initially, with an equilibrium occurring 12 to 24 h later when 30 to 40% of larvae were found on the control diet. Both strains appeared to avoid the Dipel‐treated diets and their responses were similar over different Dipel concentrations. The Dipel‐resistant strain showed higher ability to avoid the treated diets than the susceptible strain.
Influence of host log age and refuge from natural enemies on colonization and survival of Phoracantha semipunctata
Authors: Paine T.D. , Millar J.G. , Paine E.O. , Hanks L.M.
Published: October 2003

The eucalyptus longhorned borer Phoracantha semipuncata (F.) is native to Australia and has become established in most of the regions of the world where its Eucalyptus L'Heritier host trees have been introduced. To study the population dynamics of the insect in its native range, we investigated the influence of host log age (fresh or aged), protection from ant predation, and protection from parasitism by specialist larval parasitoids on numbers of initial larval feeding galleries, larval mortality, larval survivorship, and parasitization. There were greater numbers of initial larval galleries when ants were excluded, and greater numbers on fresh logs than on aged logs. However, mortality of larvae was greater in fresh logs, as well as when larvae were exposed to parasitism. Survivorship was greater when ants and parasitoids were excluded. Larvae achieved a larger size in fresh logs and in logs protected from parasitism. Fresh host material may provide a fitness advantage because it is a higher quality resource, but greater infestation of that material also increases the probability of mortality from competition among larvae. The results suggest that there are potential ecological interactions among food quality, host resistance, natural enemies, and competition that must be considered in evaluating the population dynamics of this species in native and novel environments.
Polyandry in field‐collected Spodoptera littoralis moths and laboratory assessment of the effects of male mating history
Authors: Sadek Medhat M.
Published: October 2003

To estimate multiple mating in females in the field, moths of S. littoralis were light‐trapped in June, July, August, and September in 1997 and 1998 in the edge of farming land in Assiut (Egypt). Females were dissected for the spermatophores in their bursae. Virgin females represented 8.04%, whereas once‐mated and multiply‐mated females were 37.2% and 54.76% of the trapped females, respectively. The average number of matings per trapped female (1.68±0.05) was significantly lower than that of laboratory‐reared females (2.48±0.11). As the number of captured males declined from June to September, there was a significant shift towards remating in the captured females. Laboratory mating experiments were performed with reared females that were daily supplied with males of different mating histories, including virgin males (V) or males that had previously mated once (PM1), twice (PM2), or three times (PM3). Females supplied with virgin males exhibited significantly lower numbers of matings acquired during a 5‐day experiment than females supplied with previously mated males. There was also a highly significant association between the frequency of mating among females and the mating history of males involved. Females supplied with previously mated males showed a higher propensity to remate than those supplied with virgin males. Significant increase of the reproductive capacity of females was associated with virginity (versus non‐virginity) of males or multiple mating (versus single mating) by females. Females paired with V or PM1 males exhibited shorter longevity and higher rates of egg laying than those paired with PM2 and PM3 males. The results suggest that females are able to assess the male mating status and, accordingly, alter their mating behavior to achieve higher reproductive capacity.
Pre‐ingestive and post‐ingestive effects of soya bean extracts and rutin on Trichoplusia ni growth
Authors: Hoffmann‐Campo C.B. , Harborne J.B. , McCaffery A.R.
Published: October 2003

Total ethanolic crude extracts from soya bean (Glycine max L. Merrill) PI 227687 and ‘Davis’, three purified fractions (A, B and C) from PI 227687, and pure rutin were tested for their effect on the growth of Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) larvae, from egg hatching to pupation. Analysis of covariance (ANCOVA), followed by bicoordinate utilisation plots, was used to remove the effect of feeding time from consumption and weight of pupae and to separate pre‐ ingestive and post‐ ingestive effects of different diets on T. ni growth. Survival, pupal weight, and feeding time of T. ni were all negatively affected by PI 227687 total extracts. Pupal weight and consumption remained affected by diet, after removing the effect of feeding time by ANCOVA. Larvae fed on the ‘Davis’ extract diet grew larger and consumed more rapidly a larger amount of food than those fed on PI 227687 and control diets. T. ni pupal weight was strongly influenced by consumption. In general, those insects that consumed more food were heavier but larvae fed on diet containing PI 227687 extract grew less than the others, irrespective of the amount of ingested and digested food. The feeding time was adversely affected by PI 227687 fraction A, composed of two flavonol glycosides (rutin and quercetin 3‐O‐glucosylgalactoside) and of an isoflavone glycoside (genistin). Survival and pupal weight were not affected, although the consumption and assimilation of ingested food was lower when larvae were fed on fractions A and C. The toxicity of the higher rutin concentration (2%) was similar to that observed when the insects were fed on unfractioned PI 227687, except that effects on food consumption were not observed. Results indicated that the feeding deterrence of PI 227687 must be caused by other compounds from fractions A and C. Moreover, rutin, acting as an antibiotic, appears to account for the adverse effects of PI 227687 on the physiology of T. ni.
Factors influencing the aggregative response of the blue willow beetle, Phratora vulgatissima
Authors: Peacock Lori , Lewis Mervyn , Herrick Sarah
Published: October 2003

Factors influencing the aggregative response of the blue willow beetle, Phratora vulgatissima (L.) (Coleoptera: Chrysomelidae), on potted plants of Salix dasyclados (Wimm) were investigated in the field. A significantly higher female beetle density was recorded on plants that had a combination of beetle‐feeding damage and conspecific beetles present as compared with control plants and plants having only damage or beetles. Volatile chemicals emitted from undamaged S. dasyclados (Wimm) leaves were found to be benzaldehyde and the green leaf volatiles (GLVs) cis‐3‐hexenyl acetate and cis‐3‐hexenol. Upon beetle‐feeding damage, there was a higher concentration of these compounds and an increase in the number of different volatile chemicals emitted. These results are discussed in relation to the behavioural ecology of the willow beetle.
Effects of the aphid Rhopalosiphum padi on the leafhopper Psammotettix alienus under laboratory conditions
Authors: Alla S. , Moreau J.P. , Frérot B.
Published: October 2003

The aphid Rhopalosiphum padi (L.) coexists with the leafhopper Psammotettix alienus (Dahlbom) in the same cereal crops. However, dense populations of the aphid were never observed to be associated with dense populations of the leafhopper. This laboratory study focuses on the effect of the aphid at various densities on the development and reproductive biology of the leafhopper and constitutes a preliminary test to understand the interactions between these insects in the field.

Independently of food quantity, an increase in aphid numbers caused a lengthening of development duration and increased mortality of leafhopper nymphs. In the absence of aphids, leafhopper nymphs preferred to feed on the lower part of the plant. In the presence of aphids, the leafhoppers moved towards the upper part of the plant. An increase in aphid numbers had no significant influence on the longevity of leafhopper females, although the daily fecundity decreased significantly. These data demonstrate the negative effect of R. padi on the development and fecundity of P. alienus and corroborated the field observations. Because food quantity was not the limiting factor, further experiments are underway to elucidate the factors modifying leafhopper biology. Such factors could be used to manipulate leafhopper populations.
Food consumption, utilization and detoxification enzyme activity of larvae of three polyphagous noctuid moth species when fed the botanical insecticide rotenone
Authors: Wheeler G.S. , Slansky F. , Yu S.J.
Published: October 2003

We assessed the effects of the isoflavonoid rotenone, an insecticidal allelochemical occurring in various legumes, on larval performance of three polyphagous noctuid species: the corn earworm (CEW), the fall armyworm (FAW) and the southern armyworm (SAW). As rotenone concentration was increased up to 1% fresh mass in an artificial diet, neither mortality (for all three species) nor food consumption (for SAW and FAW) was significantly affected, but developmental time of the latter two species was prolonged. In contrast, for CEW developmental time was shortened and food consumption declined, especially at the two highest rotenone concentrations. Final biomass of all three species declined as dietary rotenone increased.

Analysis of covariance (ANCOVA) was used to evaluate larval food utilization analogous to, but without the potential statistical problems of, the traditional ratio‐based indices approximate digestibility (AD) and efficiency of conversion of digested food (ECD). Frass output, statistically adjusted to account for differences in consumption, increased with rotenone concentration for all three species, suggesting that, when ingested, this allelochemical interfered with the digestion and/or absorption of ingested food, especially at the higher concentrations tested.

Significant statistical interactions in the ANCOVA necessitated the use of utilization plots to examine the linear regressions between biomass gain and absorption at each rotenone concentration. At the two highest concentrations, rotenone tended to reduce the amount of food absorbed by the larvae, as well as their ability to convert the absorbed food to biomass.

When piperonyl butoxide, an inhibitor of the polysubstrate monooxygenase (PSMO) system known to metabolize rotenone, was added to the diet along with 0.5 or 1% rotenone, mortality increased significantly only for FAW, approaching or exceeding 50%. The only apparent effects of dietary rotenone on PSMO (aldrin epoxidase) activity (adjusted by ANCOVA for the covariate, crude homogenate protein) were for CEW, where activity decreased in all rotenone treatments compared to the control, and for SAW, where activity at the 3 lowest rotenone concentrations (0.001–0.1% fm) declined about 50% below that of larvae on the control diet, whereas at 0.5 and 1% rotenone, it increased approximately 2‐fold over that on the control diet.
Effects of a juvenile hormone analog, pyriproxyfen, on the apterous form of Lipaphis erysimi
Authors: Liu Tong‐Xian , Chen Tian‐Ye
Published: October 2003

Effects of a juvenile hormone analog, pyriproxyfen, on various developmental stadia of the apterous form of the turnip aphid, Lipaphis erysimi (Kaltenbach), were bioassayed at three concentrations (50, 100, and 150 mg [AI]/l) in the laboratory. Supernumerary‐molted nymphs with 1‐3 extra molts were found when the first three nymphal instars were treated, and all these nymphs died prematurely. In contrast, all treated fourth instar nymphs molted normally to adults. The longevity of all pyriproxyfen‐treated L. erysimi nymphs and adults and the fecundity of treated adults were reduced by ≈50%. Higher concentrations of pyriproxyfen (100 and 150 mg [AI]/l) caused sterility in adults from treated fourth instars; whereas the lowest concentration (50 mg [AI]/l) did not cause any adult sterility. A majority of adults from treated fourth instars and treated adults produced normal nymphs, and some adults produced dead nymphs with normal appendages or dead and deformed nymphs without any appendages. Normal nymphs produced by the adults from treated adults or treated at fourth instars developed more slowly from first instar to adult than the water‐treated nymphs, and all adults in the new generation apparently reproduced normally. The potential role of pyriproxyfen in a vegetable aphid IPM program was discussed.
Geographic variability in diapause response of Japanese Orius species
Authors: Shimizu Toru , Kawasaki Kenjiro
Published: October 2003

Interspecific and latitudinal variation in diapause characteristics were examined in 12 strains of Orius species (Heteroptera: Anthocoridae) including O. sauteri (Poppius), O. nagaii Yasunaga, O. minutus (L.), O. strigicollis (Poppius), and O. tantillus (Motschulsky) from Japan. A latitudinal cline was found in the photoperiodic response controlling reproductive diapause: the lower the latitude, the lower the diapause incidence and the shorter the critical daylength. To examine the overwintering success, eight strains including four species derived from different latitudes (26–43° N) were reared outdoors in Tsukuba (36° N), central Japan from the autumn of 1998 to the summer of 1999, and their winter survival and spring fecundity were recorded. Most females of the northern strains entered diapause in the autumn when the temperature was still high, and died before winter without oviposition. In the southern strains including a nondiapause Okinawa (26° N) strain of O. strigicollis, females overwintered as well as native strains in a state of quiescence. In all strains, the winter survival was significantly lower in males than in females, and eggs and nymphs failed to overwinter.
Orientation of Heterorhabditis megidis to insect hosts and plant roots in a Y‐tube sand olfactometer
Authors: Boff Mari I.C. , Zoon Frans C. , Smits Peter H.
Published: October 2003

The host‐searching behaviour of Heterorhabditis megidis strain NLH‐E 87.3 in the presence of insect hosts and plant roots, offered individually and in combination, was studied using a newly developed Y‐tube olfactometer filled with sand. Within a period of 24 hours infective juveniles (IJs) were significantly attracted to living G. mellonella larvae and caused 100% larval mortality. Otiorhynchus sulcatus larvae, however, did not elicit host‐oriented movement of IJs and no larval mortality was observed. Roots of strawberry plants induced a negative response in IJs. The combination of strawberry roots and O. sulcatus larvae, however, strongly attracted IJs leading to 37% host mortality. It was shown that this type of Y‐tube choice arena is a useful tool in studying the searching behaviour of entomopathogenic nematodes in a semi‐natural habitat.
A differential interaction study of Bemisia tabaci Q‐biotype on commercial tomato varieties with or without the Mi resistance gene, and comparative host responses with the B‐biotype
Authors: Nombela G. , Beitia F. , Muñiz M.
Published: October 2003

Three tomato varieties (Motelle, Ronita, and VFN8) bearing the Mi‐1.2 gene providing resistance to nematodes Meloidogyne spp. and to the potato aphid Macrosiphum euphorbiae Thomas, and three varieties not bearing this gene (Moneymaker, Roma, and Río Fuego), were compared by choice assay for host preference using the Q‐biotype of Bemisia tabaci (Gennadius). The most preferred hosts, determined by infestation levels and numbers of feeding adults were Moneymaker, Río Fuego and Roma, all of which were not carrying the Mi gene. Ronita and Motelle, both of which bore the Mi gene, were the least preferred hosts. In a no‐choice assay, B. tabaci females laid a significantly lower number of eggs on the varieties that carried the Mi gene than on those lacking the gene. Differences were more dramatic when plants carrying the Mi gene were pooled together and compared with pooled plants without this gene. Significantly greater values were obtained for the Mi‐lacking group for all parameters tested. Comparing these results with those from a previous study on the B‐biotype of B. tabaci, Q‐biotypes were found to produce higher daily infestation rates on most of the tomato varieties. When results from plants carrying Mi were pooled, they showed lower infestation levels of Q‐biotypes than B‐biotypes. The Q‐biotype infested less Mi‐plants and more non‐Mi plants than B‐biotype. Q‐biotype females produced significantly less pupae than the B‐biotype females on both groups of plants. These results suggest the existence of an antixenosis and antibiosis‐based resistance to the Q‐biotype of B. tabaci in Mi‐bearing commercial tomato varieties, which is greater than that previously reported for the B‐biotype.
Development and evaluation of an enzyme‐linked immunosorbent assay to detect Pieris rapae remains in guts of arthropod predators
Authors: Schmaedick M.A. , Ling K.S. , Gonsalves D. , Shelton A.M.
Published: October 2003

An enzyme‐linked immunosorbent assay (ELISA) was developed to detect remains of Pieris rapae L. (Lepidoptera: Pieridae) immature stages in the guts of field collected arthropod predators. The assay can be used to help ascertain the relative importance of arthropod predator species in suppressing P. rapae in cabbage, Brassica oleracea var. capitata L. The ELISA is sensitive to all immature stages of P. rapae, although first and fifth instars can be detected more readily than eggs or pupae and third instars showed intermediate detectability. Assays on whole body homogenates of predators readily detected predation on P. rapae first instars by all seven of the predator species tested, although response generally declined with increasing predator size. Together the results show that the P. rapae ELISA possesses a sufficiently high level of sensitivity and specificity to be a useful tool in helping to elucidate the roles of arthropod predator species in reducing populations of P. rapae in cabbage.
Cry1Ab protein levels in phytophagous insects feeding on transgenic corn: implications for secondary exposure risk assessment
Authors: Head Graham , Brown Christopher R. , Groth Mark E. , Duan Jian J.
Published: October 2003

Enzyme‐linked immunosorbent assays (ELISA) and bioassays were used to estimate levels of Cry1Ab protein in four species of phytophagous insects after feeding on transgenic Bt‐corn plants expressing Cry1Ab protein or artificial diets containing Cry1Ab protein. The level of Cry1Ab in insects feeding on sources containing the Cry1Ab protein was uniformly low but varied with insect species as well as food source. For the corn leaf aphid, Rhopalosiphum maidis (Fitch), feeding on diet solutions containing Cry1Ab protein, the level of the protein in the aphid was 250–500 times less than the original levels in the diet, whereas no Cry1Ab was detected by ELISA in aphids feeding on transgenic Bt‐Corn plants. For the lepidopteran insects, Ostrinia nubilalis (Hübner), Helicoverpa zea (Boddie), and Agrotis ipsilon (Hufnagel), levels of Cry1Ab in larvae varied significantly with feeding treatment. When feeding for 24 h on artificial diets containing 20 and 100 ppm of Cry1Ab, the level of Cry1Ab in the larvae was about 57 and 142 times lower, respectively, than the original protein level in the diet for O. nubilalis, 20 and 34 times lower for H. zea, and 10 to 14 times lower for A. ipsilon. Diet incorporation bioassays with a susceptible insect (first instar O. nubilalis) showed significant Cry1Ab bioactivity present within whole body tissues of R. maidis and O. nubilalis that had fed on diet containing a minimum of 20 ppm or higher concentrations (100 or 200 ppm) of Cry1Ab, but no significant bioactivity within the tissues of these insects after feeding on transgenic Bt‐corn plants. The relevance of these findings to secondary exposure risk assessment for transgenic Bt crops is discussed.
Chlorogenic acid as an antiherbivore defence of willows against leaf beetles
Authors: Ikonen Arsi , Tahvanainen Jorma , Roininen Heikki
Published: October 2003

In the leaves of 13 Finnish willow species, the content of a phenolic, chlorogenic acid, was found to vary from 0 up to 18 mg g−1 D.W. Effects of pure chlorogenic acid on insect feeding behaviour were tested using four common leaf beetle species which are in the field mainly found on willows with low‐chlorogenic acid leaves. One species, Lochmaea capreae L., was invariably deterred by pure chlorogenic acid applied in naturally occurring concentrations on the willow leaves. Accordingly, in 2‐choice laboratory feeding trials L. capreae was found to prefer low‐chlorogenic acid leaves of four willow species over high‐chlorogenic acid leaves of Salix pentandra L. and S. myrsinifolia Salisb. When presented on the leaves of S. phylicifolia L, pure chlorogenic acid inhibited also the feeding by Phratora polaris Sp.‐Schn. Instead, chlorogenic acid had no significant effect on Ph. polaris when it was presented on the leaves of another willow S. cinerea L. In laboratory, Ph. polaris did not show general preference for willow species with low chlorogenic acid content in their leaves. Thus, the response of Ph. polaris to chlorogenic acid seems to depend on the plant species. Apparently variation in other traits such as leaf hairyness may easily override the potential effect of chlorogenic acid content on Ph. polaris. To two other leaf beetle species, Galerucella lineola F. and Plagiodera versicolora Laich., chlorogenic acid is an ineffective deterrent even at unnaturally high concentrations. In laboratory, G. lineola and P. versicolora did not prefer willows with low chlorogenic acid content in their leaves. Thus, among four studied leaf beetle species, only L. capreae seems to be clearly affected by this phenolic. Therefore, overall importance of chlorogenic acid as a defence against willow‐feeding leaf beetles appears to be very limited.
Effects of elevated CO2 on five plant‐aphid interactions
Authors: Hughes Lesley , Bazzaz Fakhri A.
Published: October 2003

We investigated interactions between five species of phloem‐feeding aphids (Homoptera: Aphididae) and their host plants at elevated CO2; Acyrthosiphon pisum (Harris) on Vicia faba L., Aphis nerii Boyer de Fonscolombe on Asclepias syriaca L., Aphis oenotherae Oestlund on Oenothera biennis L., Aulacorthum solani (Kaltenbach) on Nicotiana sylvestris Speg. & Comes and Myzus persicae (Sulzer) on Solanum dulcamara L. Host plants grown at elevated CO2 generally had greater biomass, leaf area and C:N ratios than those grown at ambient CO2, while plants with aphids had lower biomass and leaf area than those without aphids.

The responses of aphid populations to elevated CO2 were species‐specific with one species increasing (M. persicae), one decreasing (A. pisum), and the other three being unaffected. CO2 treatment did not affect the proportion of alate individuals produced. In general, aphid abundance was not significantly related to foliar nitrogen concentration.

We performed separate analyses to test whether either aphid presence or aphid abundance modified the response of host plants to elevated CO2. In terms of aphid presence, only three of the potential 15 interactions (five aphid species x three plant traits) were significant; A. solani slightly modified the response of the plant biomass to elevated CO2 and M. persicae affected the response of leaf area and allocation. In terms of aphid abundance, only two of the potential 15 interactions were significant with A. nerii modifying the plant response to CO2 in terms of total leaf area and allocation.

We conclude that, in contrast to other insect groups such as leaf chewers, populations of most phloem‐feeders may not be negatively affected by increased CO2 concentrations in the future. The reasons for this difference include the possibility that aphids may be able to compensate for changes in host plant quality by altering feeding behaviour or by synthesizing amino acids. In addition, there is little evidence that aphid herbivory, even at high levels, will substantially modify the response of plants to elevated CO2.
Egg‐laying, pre‐imaginal growth dynamics, and mortality in Eupelmus orientalis and Dinarmus basalis, two solitary ectoparasitoids of Callosobruchus maculatus
Authors: Damiens David , Imbert Eric , Bressac Christophe , Thibeaudeau Christian , Chevrier Claude
Published: October 2003

In Eupelmus orientalis and Dinarmus basalis, two ectoparasitoid species of Callosobruchus maculatus larvae, pre‐imaginal development occurs within a leguminous seed, and is then impossible to observe directly. Offspring sex ratio is normally determined when adults emerge, and mortality during pre‐imaginal stages remains unknown. By using translucent gelatine capsules containing a host larva to mimic the seed, we conducted an experimental study of offspring production and sex ratio with measurements of growth and pre‐imaginal mortality. Mated females were allowed to lay eggs on hosts in seeds or in gelatine capsules. In the gelatine capsules the parasitoid was observed daily and measured to assess if the offspring sex ratio can be determined before emergence of adults. When seeds are replaced with gelatine caps, the number of egg‐laying females decreases (48% in Eupelmus orientalis and 72% in Dinarmus basalis of females ovipositing on seeds lay eggs on gelatine capsules), and the offspring output changes qualitatively in Eupelmus orientalis (egg numbers constant, sex ratio diminishing from 0.75 to 0.46) and quantitatively in Dinarmus basalis (egg numbers diminishing, sex ratio maintained about 0.7). In Eupelmus orientalis, pre‐imaginal mortality occurs principally in the first three days, the critical stage is hatching, and the final mortality is 30.1%. In Dinarmus basalis, mortality of larvae increases gradually from the 2nd to the 7th day, the final mortality being 13.6%. (3) In both species sex of the offspring can be determined before emergence but only after most mortality has occurred.
Evidence of an extractable semiochemical produced by Rhopalosiphum padi acting on Psammotettix alienus
Authors: Alla S. , Moreau J.P. , Frérot B.
Published: October 2003

It has previously been shown that the aphid Rhopalosiphum padi (L.) (Homoptera: Aphididae) adversely affects the biology of the leafhopper Psammotettix alienus (Dahlbom) (Homoptera: Cicadellidae) (Alla et al., 2001). In this work, we demonstrate that this effect was due to chemical components produced by the aphid.

The increase in the number of aphids in the presence of the leafhopper on wheat caused nymphal mortality, an extended duration of the development and a decrease in nymph production of the leafhopper. Extract of aphids in methanol‐water (50/50: v/v), applied on plants significantly increased the mortality in the leafhopper nymphs at both 3AE (3 Aphid Equivalent) and 7AE doses. At the same doses, both the honeydew and water extract of aphids did not have any effect. At the 20AE dose, aphid extracts in methanol‐water led to a longer development time and strong mortality in leafhopper nymphs. In female adults of the leafhopper, neither the aphid extracts in methanol‐water nor the honeydew showed a conclusive result, but generally, daily nymph production decreased with the increase in the extract doses.

These results confirmed the depressive effect of R. padi on P. alienus and showed that this interaction was chemical. The active component(s) is partially extracted in a blend of methanol‐water (50/50: v/v). Further studies to identify this component(s) will be undertaken.
Comparison of gregariousness in larvae and adults of four species of zetoborine cockroaches
Authors: van Baaren Joan , Deleporte Pierre
Published: October 2003

Insects observed in groups in nature may be gathered either by attractants from the environment or by conspecifics. Field distribution data alone are thus insufficient to assess congregation by conspecifics and complementary laboratory tests of spacing patterns are required. Such tests were performed in four species of Zetoborinae (Insecta, Blattaria), for which field studies showed differences in spatial distribution (Schultesia lampyridiformis Roth, Phortioeca nimbata Burmeister, Lanxoblatta emarginata Burmeister and Thanatophyllum akinetum Grandcolas). Gregariousness, mobility, and sticking to shelters were compared between these four species. Tests were performed on pairs of adults of the same sex and opposite sexes, and also on first instar larvae, either in isolation or in groups of two and four individuals. In S. lampyridiformis, adults were strongly gregarious, whereas larvae dispersed early after birth and were very mobile during the first instar. In P. nimbata, larvae and adults were gregarious, while in L. emarginata larvae were weakly gregarious, and gregariousness decreased when density increased. Adults of L. emarginata seemed to be indifferent to each other. Larvae and adults of T. akinetum were solitary and they actively dispersed. The varying levels of gregariousness among species are discussed according to the known ecological habits in Zetoborinae.
Protection of lodgepole pines from mass attack by mountain pine beetle, Dendroctonus ponderosae, with nonhost angiosperm volatiles and verbenone
Authors: Huber D.P.W. , Borden J.H.
Published: October 2003

A number of angiosperm nonhost volatiles (NHVs) and green leaf volatiles (GLVs) were tested alone and as supplements to the antiaggregation pheromone, verbenone, for their ability to disrupt attack by the mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins (Coleoptera: Scolytidae), on lodgepole pine, Pinus contorta Dougl. ex Loud. var. latifolia Engel. Preliminary experiments led to a refined NHV blend [benzyl alcohol, guaiacol, benzaldehyde, nonanal, salicylaldehyde, and conophthorin] and a refined GLV blend [(Z)‐3‐hexen‐1‐ol and (E)‐2‐hexen‐1‐ol]. In a 20‐replicate experiment, NHV and GLV groups both singly, and verbenone alone, significantly reduced MPB mass attack on pheromone‐baited trees and on trees within 5 m of the pheromone‐baited trees. Both blends in combination with verbenone reduced the number of mass attacked, baited trees to three out of 20 compared to 20 out of 20 of the baited controls. Each binary combination was also effective at reducing mass attack. In these experiments, all tested repellents were released from devices stapled to trees at the same point as the pheromone bait, suggesting that the repellency could have been to a point source, rather than to the whole tree. Therefore, in two further experiments bands of release devices were wrapped around the treated trees and the pheromone bait was removed from the treated trees. In one experiment, when the aggregation pheromone bait was suspended between pairs of trees treated with the NHV blend plus GLV blend plus verbenone, only three out of 25 treated pairs had mass attack on at least one member of the pair. In the other 60‐replicate experiment, with no pheromone baits present, attack occurred on 13 untreated and 11 banded trees, all in the path of a large advancing infestation. However, the mean attack density on the banded trees was significantly reduced to a level below the 40 attacks m−2 of bark surface required to kill a healthy lodgepole pine. As a result of these experiments, operational trials are recommended.
Genetic analysis of larval survival and larval growth of two populations of Leptinotarsa decemlineata on tomato
Authors: Lu Wenhua , Kennedy George G. , Gould Fred
Published: October 2003

The genetics of adaptation to tomato in Leptinotarsa decemlineata (Say) were investigated in reciprocal F1, F2, and backcross populations generated from crosses between beetles from a tomato adapted population and from a population that was poorly adapted to tomato. Larvae from the parent and test populations were reared on tomato for four days, after which survivorship and larval weights were recorded. Most results indicate that differences in larval growth and survival on tomato between the parent populations are largely determined by autosomal, polygenic mechanisms, the inheritance of which involves a significant dominance component. However, results from F2 crosses are not consistent with this conclusion. A significant difference in larval weights, but not in survival, between reciprocal F1 populations in an analysis of combined data from four separate experiments suggests that maternal cytoplasmic effects may contribute to differences in larval performance on tomato between the adapted and unadapted populations. The unusual results obtained from F2 crosses in this study are not atypical of results from previous studies of the genetics of adaptation to host plants by the Colorado potato beetle. Host plant adaptation by Colorado potato beetles may therefore involve unusual genetic mechanisms that are not easily assessed by classical Mendelian analysis.
Body colour and genetic variation in winged morph production in the pea aphid
Authors: Weisser Wolfgang W. , Braendle Christian
Published: October 2003

Aphids (Homoptera: Aphidoidea) produce a number of different phenotypes in their life‐cycle, among which are winged (alate) and wingless (apterous) morphs. Lowe & Taylor (1964) and Sutherland (1969a, b) were the first to suggest that aphid clones differ in their propensity to produce the winged morph and that in the pea aphid (Acyrthosiphon pisum Harris), this propensity is linked to the colour of the phenotype. We tested for the occurrence of genetic variation in winged morph production by rearing individuals from red and green clones of pea aphid under wing‐inducing (crowding) and control conditions, and scored the phenotypes of their offspring. Clones differed significantly in alate production and red clones produced on average a higher proportion of winged morphs than green clones. Importantly, however, there was considerable variation between clones of the same colour. Broad‐sense heritabilities of winged morph production were 0.69 (crowding treatment) and 0.63 (control). Clones also differed in the number of offspring they produced. When exposed to the crowding stimulus, aphids deferred offspring production, resulting in a higher number of offspring produced in the crowding treatment than in the control.
Receptor based models for spontaneous colour choices in flies and butterflies
Authors: Kelber Almut
Published: October 2003

Colour is one of several stimuli used by herbivorous insects in host choice. Insects have between 2 and 5 different types of photoreceptors to catch quanta of different wavelengths of the spectrum. Many insects have been shown to possess opponent neural interactions between the receptors that enable them to see colour. I present simple models to describe colour choices as functions of the receptor quantum catches and linear interactions of the receptor types. Models are applied to data sets obtained from own experiments and from the literature, on Pieris brassicae and P. rapae (Lepidoptera, Pieridae), Papilio aegeus (Papilionidae), Dacus oleae (Diptera, Tephritidae) and Eristalis tenax (Syrphidae). In fruit flies, detection of green fruit is based on an inhibitory interaction between a green‐sensitive receptor type and a blue‐sensitive receptor type. This might explain the preference many herbivorous insects have for yellow over green stimuli. Pollen feeding in hoverflies might have evolved from yellow pollen being a super‐normal stimulus for herbivorous insects. In butterflies, an additional red‐receptor is involved in the colour choice for an oviposition substratum and leads to them choosing green and not yellow. The models introduced in this study open new perspective for a physiological understanding of the design of visual stimuli for monitoring and trapping pest insects.
Effects of augmentative releases of the coccinellid, Adalia bipunctata, and of insecticide treatments in autumn on the spring population of aphids of the genus Dysaphis in apple orchards
Authors: Kehrli P. , Wyss E.
Published: October 2003

The impact of augmentative releases of indigenous predators and insecticide applications to control the autumn aphid forms of the genus Dysaphis (Homoptera: Aphididae), major pest insects on apple trees, was assessed in one‐year field experiments in Switzerland. Eggs and larvae of the two‐spot ladybird beetle Adalia bipunctata (L.) (Coleoptera: Coccinellidae) were released on 4‐year old apple trees in various numbers at five different dates in autumn 1998 when sexuales of the aphids were present. Additionally, Pyrethrum HP was sprayed at the same five dates to compare the effectiveness of these augmentative releases to a commonly applied insecticide. Augmentative releases of larvae before mid‐October significantly prevented the deposition of overwintering eggs by aphids of the genus Dysaphis and consequently reduced the number of hatched fundatrices in spring, 1999. There was a significant negative functional response among the number of released coccinellid larvae in autumn 1998 and the number of observed fundatrices on apple trees in spring 1999. Applications of Pyrethrum HP before mid‐October were more effective than augmentative releases of larvae of A. bipunctata. The release of coccinellid eggs had no impact on the number of fundatrices of the genus Dysaphis in the next spring because they did not hatch due to bad weather conditions. The weather conditions in autumn seemed to have an impact on the autumn migration of the winged aphids back to their primary host. The prevention of egg deposition of aphids in autumn is a promising control strategy and deserves further exploration for practical use.
Analysis by DC–EPG of the resistance to Bemisia tabaci on an Mi‐tomato line
Authors: Jiang Y.X. , Nombela G. , Muñiz M.
Published: October 2003

The tomato Mi gene confers resistance to nematodes, Meloidogyne spp., and to the potato aphid, Macrosiphum euphorbiae (Thomas). Previous greenhouse choice assays with Bemisia tabaci (Gennadius) showed that tomato commercial varieties carrying this gene had significantly lower values of host suitability and whitefly reproduction than varieties lacking Mi. This indicated that Mi, or another gene in its region, could regulate partial resistance. In order to characterise this resistance, probing and feeding behaviour of Bemisia tabaci B‐biotype was studied with DC Electrical Penetration Graph (EPG) technique on the near‐isogenic tomato lines Moneymaker (without Mi) and Motelle (carrying Mi). Significant differences (P < 0.05) between tomato lines were found in EPG parameters related to epidermis and/or mesophyll tissues. On Motelle, a lower percentage of whiteflies achieved phloem phase and they made more probes before attaining first phloem phase, had a higher ratio (number of probes before first phloem phase)/(total number of probes), had a longer total duration of non‐probing time, and a longer time before making the first intracellular puncture and before making the first phloem phase. In contrast, most of the parameters related to phloem phase were found not to differ significantly between these near‐isogenic lines. The behavioural data strongly suggest that the partial resistance in the variety Motelle is due to factors in the epidermis and/or mesophyll that inhibit the whiteflies from reaching phloem sieve elements. However, once the stylets reach a sieve element, whitefly behaviour did not differ between the two varieties. Thus, phloem sap of the two varieties appears to be equally acceptable to the whiteflies. Further studies are necessary to provide a better understanding of these mechanisms of resistance to whiteflies in tomatoes.
Vector‐pathogen‐host plant relationships of chrysanthemum yellows (CY) phytoplasma and the vector leafhoppers Macrosteles quadripunctulatus and Euscelidius variegatus
Authors: Palermo Simona , Arzone Alessandra , Bosco Domenico
Published: October 2003

Chrysanthemum yellows (CY) phytoplasma is a plant‐pathogenic mollicutes belonging to the 16Sr‐IB genetic group which infects a variety of dicotyledonous plants and is transmitted in nature by some species of Cicadellidae Deltocephalinae. The transmission characteristics of CY and the factors influencing the vector efficiencies of the leafhoppers Macrosteles quadripunctulatus Kirschbaum and Euscelidius variegatus Kirschbaum are described in the present study using transmission experiments and phytoplasma‐specific polymerase chain reaction (PCR) assays. Vector insects were allowed to acquire CY under different experimental conditions and then transferred to healthy test plants for inoculation and/or sampled for DNA extraction and amplification. The transmission efficiency of CY was very high and almost all the leafhoppers became infective following acquisition on CY‐infected daisies. The latent period in the vector ranged from 16 to 20 days after the start of the acquisition and infectivity lasted, in general, for life. The PCR assay was successful in detecting CY phytoplasmas in the insects well before they became infective (5 versus 16–18 days) and was used to estimate the proportion of infective insects. When analysed for CY presence by PCR, all the leafhoppers fed for 7–18 days on source daisy reacted positively while, following one day of acquisition, some insects failed to provide amplification. Host‐plant species influenced CY acquisition, and daisy appeared a more efficient source for both leafhoppers compared to periwinkle. Life stage did not appear to be critical for CY acquisition, although newly‐hatched nymphs of E. variegatus acquired CY less efficiently than fifth instar nymphs.
Photoperiod‐ and temperature‐dependent induction of larval diapause in a multivoltine bruchid, Bruchidius dorsalis
Authors: Kurota Hiroyuki , Shimada Masakazu
Published: October 2003

The wild bruchid beetle, Bruchidius dorsalis Fahraeus (Coleoptera: Bruchidae), has a multivoltine life cycle and overwinters in several developmental stages in the middle part of Japan. We investigated the incidence of diapause under different conditions of photoperiod (from L8:D16 to L16:D8) and temperature (at 20 °C and 24 °C). Our experiments revealed the following results: (1) B. dorsalis entered diapause at the final (late fourth) instar larva under short photoperiods, (2) the larval diapause incidence was dependent on temperature (critical photoperiods were 12.5 h at 20 °C and 12 h at 24 °C), (3) some individuals did not enter diapause under short‐photoperiod conditions at 24 °C, and (4) the sensitive stages to the photoperiod were from the late egg stage to the early first instar larva. Based on these results, we discuss not only the evolution of a complex overwintering strategy inB. dorsalis but also the domestication process of stored‐bean pests.
Pleiotropy of insecticide resistance in the codling moth, Cydia pomonella
Authors: Boivin Thomas , D'Hières Cécile Chabert , Bouvier Jean C. , Beslay Dominique , Sauphanor Benoît
Published: October 2003

The codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), has developed resistance to various insecticides. Relative fitness of one susceptible strain (Sv) and two strains selected for resistance to diflubenzuron (Rt) and deltamethrin (Rv), respectively, was measured in the absence of insecticide selection pressure. Mating rate, fecundity, fertility, developmental time, fifth instar weight, and adult longevity were compared. Both resistant strains were less fecund and fertile, developed more slowly, weighed less, and had shorter life‐spans than the susceptible strain. These results indicate that biological constraints are associated with insecticide resistance in the codling moth. We also found that fitness estimates of the Rv strain did not differ statistically from those of the Rt strain. Enhanced mixed‐function oxidase and glutathione‐S‐transferase activities have been shown to be involved in insecticide resistance in both Rt and Rv strains. This suggests that the fitness cost described in both resistant strains was mainly associated to metabolic resistance. The impact of such deleterious pleiotropy of insecticide resistance in C. pomonella in terms of resistance management in the field is discussed.
Interspecific and intraspecific variation in the performance of three pest aphid species on five grain legume hosts
Authors: Edwards Owain R.
Published: October 2003

The suitability of five grain legume species (narrow‐leafed lupin, chickpea, faba bean, field pea, lentil) as hosts for three aphid species (green peach aphid, cowpea aphid, bluegreen aphid) was evaluated by measuring the mean relative growth rate (MRGR) and survivorship of nymphs over a 5 day period. For each aphid species, intraspecific (interclonal) variation was also determined by independently measuring the performance of 30 clones collected from a variety of hosts and from different parts of the Western Australia (WA) wheatbelt. The suitability of the grain legumes varied among aphid species. Chickpea was not a suitable host for any of the aphids tested. Averaged over all clones, lentil and faba bean were the most suitable hosts for cowpea aphid, and narrow‐leafed lupin was the most suitable host for green peach aphid. Field pea was a suitable host for all three species, but only at a suboptimal level. Cowpea aphid showed the greatest amount of intraspecific variation, with significant variation in MRGR among clones on all hosts except chickpea and significant variation in survivorship on chickpea and lupin. For green peach aphid, there was significant variation in MRGR among clones on field pea and lupin, but in survivorship on lupin only. Bluegreen aphid clones showed significant variation only for MRGR on faba bean and lupin. There were positive correlations in performance of green peach aphid clones on faba bean and lentil, and of cowpea aphid clones on faba bean and lentil. Bluegreen aphid clones showed a negative correlation in performance on field pea and faba bean. These results show the importance of screening cultivars against a wide variety of aphid clones when assessing aphid susceptibility in breeding programmes. The implications of these results on the adaptability of parthenogenetic aphids are discussed.
Resistance of three wild tuber‐bearing potatoes to the Colorado potato beetle
Authors: van Pelletier Y , Clark Catherine , Tai Georges C.
Published: October 2003

The resistance of Solanum okadae Hawkes & Hjert. (PI 458367), Solanum oplocense Hawkes (PI 473368), and Solanum tarijense Hawkes (PI 414150) to the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Chrysomelidae: Chrysomelini), was studied. In replicated field trials all three accessions showed a high level of resistance to the beetle. No significant genetic variability between genotypes of the same species was found. Results from host acceptance behavior experiments, suitability for larval development tests, foliage consumption tests, and adult survival and oviposition tests supported the hypothesis that the mode of resistance differs between the three wild Solanum species. Solanum okadae and S. oplocense affected host acceptance and consumption. Because the beetle reacted differently to these two species it was hypothesized that the antifeedant chemical(s) differed in nature or quantity. S. tarijense contrasted with the other two species by affecting mostly adult colonization and oviposition.