bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of parasitism by encyrtid parasitoids on the feeding behaviour of the cassava mealybug Phenacoccus herreni
Authors: Calatayud P.‐A. , Seligmann C.D. , Polanía M.A. , Bellotti A.C.
Published: October 2003

Three encyrtid parasitoids Apoanagyrus (Epidinocarsis) diversicornis, Aenasius vexans, and Acerophagus coccois (Hymenoptera: Encyrtidae) are used to control the cassava mealybug Phenacoccus herreni Cox & Williams (Sternorrhyncha: Pseudococcidae), an important pest of cassava in South America. The influence of parasitism on the feeding behaviour of mealybugs was studied by observing honeydew secretion and by the electrical penetration graph technique (EPG, DC‐system). Honeydew secretions were observed after parasitism until mummy transformation. No strong EPG parameter differences were found between parasitised and control insects. All results indicated that parasitised mealybugs keep feeding on the phloem sap after parasitism until mummy transformation. The main influence of parasitism on EPG parameters is the appearance of a new pattern resembling the E2 pattern at the extracellular level and labelled H. This pattern was also produced with control insects located on an unfavourable feeding site and could be associated with a stress response. It might be related to the still unclear E(c) pattern of aphids. The relationship of H to stylet activities is discussed.
The relationship between outbreaks, rainfall and low density populations of the African armyworm, Spodoptera exempta, in Kenya
Authors: Dewhurst Charles F. , Page William W. , Rose Derek J.W.
Published: October 2003

This study has demonstrated that low numbers of African armyworms (Spodoptera exempta) (Walker) (Lepidoptera: Noctuidae) can be found throughout the year in parts of the coastal and highland regions of Kenya where there is frequent rainfall. During the study period the numbers of moths caught in pheromone traps in these regions built up during the short and long rains, and decreased dramatically during the intervening dry seasons. There was a lag of one to two months between the peaks for rainfall and moth numbers. This contrasts with the situation at sites of the seasonal outbreaks of armyworm larvae, where a sudden preceding influx of moths coincides with the rainfall. A positive correlation was found, for the long rains seasons only, between the number of armyworm outbreaks throughout the country and the peak numbers of moths in coastal and highland regions.

It is suggested therefore that the peak numbers of moths trapped in the eastern highlands and coastal regions during the rainy seasons arise principally from outbreaks in the extensive seasonal grasslands. These grassland areas diminish considerably during the prolonged dry periods between the two rainy seasons, and it is only the eastern highland and coastal regions that are likely to provide suitable habitats for breeding during the dry seasons. The significance of these populations for initiating the first outbreaks of the following season is discussed.
Biology of the shore fly Scatella stagnalis in rockwool under greenhouse conditions
Authors: Vänninen Irene
Published: October 2003

The development times and survival of immature stages in rockwool and the fecundity and longevity of adult Scatella stagnalis were determined and stage‐specific life‐tables constructed for the species at constant 20 and 25 °C and at a fluctuating temperature (23–34 °C, mean 28.5 °C). Development time from egg to adult decreased with temperature, being 15.9±0.1 days at 20 °C, 11.4±0.1 days at 25 °C and 10.1±0.2 days at fluctuating temperature with mean of 28.5 °C. The lower threshold for egg‐to‐adult development was 6.4±2.7°C and the total quantity of thermal energy required to complete development was 212.8±.0 °C. The proportion of females in two populations studied was 0.521. High temperature increased the mortality of pupae from 7% (20 °C) and 10% (25 °C) to 29% at 28.5 °C. At 25 °C, female longevity was 15.5±0.7 days and fecundity 315±19 eggs/female (20.4 eggs/female/day). Males lived for 22.0±1.1 days. At constant 25 °C, the net reproductive rate was 126.1 female eggs/female, generation time was 18.4 days, the doubling time of the population 5.3 days, and the intrinsic rate of increase (rm) 0.263 day−1.
Effect of cotton nitrogen fertilization on Bemisia argentifolii populations and honeydew production
Authors: Bi J.L. , Ballmer G.R. , Hendrix D.L. , Henneberry T.J. , Toscano N.C.
Published: October 2003

The impact of nitrogen fertilization on cotton plants, Gossypium hirsutum L., silverleaf whitefly, Bemisia argentifolii Bellows & Perring, population dynamics and honeydew production were investigated in the field at Riverside, California, USA. Treatments were soil applications of 0, 112, 168 and 224 kg nitrogen per hectare, and a soil application of 112 kg of nitrogen plus a foliar application of 17 kg nitrogen per hectare. Increased numbers of both adult and immature whiteflies occurred during population peaks with increasing amounts of applied nitrogen. Higher numbers of whiteflies resulted in increased levels of honeydew. Increasing plant nitrogen also enhanced cotton foliar photosynthetic rates and stomatal conductance, and altered concentrations of glucose, fructose and sucrose in cotton petioles. However, at our treatment levels nitrogen had no effect on seedcotton yield. Petiole glucose levels were significantly correlated with numbers of whitefly adults on leaves during their peak populations. Significant correlations between whitefly numbers and other cotton physiological parameters occurred on only a few sampling dates.
Kairomonal range of generalist predators in specialized habitats: responses to multiple phloeophagous species emitting pheromones vs. host odors
Authors: Erbilgin Nadir , Raffa Kenneth F.
Published: October 2003

We evaluated responses of the predominant predators of pheromone‐producing bark beetles (Coleoptera: Scolytidae) to chemical cues associated with other phloeophagous species that colonize the same trees. This study considered the range of chemical signals exploited by a category of predators that may be viewed either as specialists, because they feed almost exclusively within trees killed by bark beetles, or as generalists, because they feed on a diverse fauna of primary and secondary insects within this habitat. It also evaluated one aspect of a broader model of predator‐prey coevolution, that proposes altered semiochemistry as a source of partial escape from predators that exploit kairomones. The predators, Thanasimus dubius (F.) (Coleoptera: Cleridae) and Platysoma cylindrica (Paykull) (Coleoptera: Histeridae), were attracted to cues associated with feeding on bark‐phloem disks by two scolytids that produce adult pheromones, Ips pini (Say) and Ips grandicollis (Eichhoff). These predators were not attracted to beetles that feed on lower stems or roots and are not known to produce adult pheromones, Dendroctonus valens LeConte, Hylastes porculus Erickson (Coleoptera: Scolytidae), and Hylobius pales (Herbst) (Coleoptera: Curculionidae). The predator Tenebroides collaris (Sturm) (Coleoptera: Trogositidae) was attracted to I. pini and I. grandicollis, and also to D. valens, H. porculus, and H. pales. Ips pini was attracted to conspecifics only, but I. grandicollis was attracted both to its conspecifics and to volatiles associated with feeding lower stem and root insects. Lower stem and root insects were not or only weakly attracted to cues associated with their conspecifics. These results are consistent with a dynamic coevolved interaction between T. dubius and P. cylindrica and Ips spp.
Effects of plant spacing and interplanting with oilseed rape on colonisation of dwarf hops by the damson‐hop aphid, Phorodon humuli
Authors: Campbell Colin A.M. , Ridout Martin S.
Published: October 2003

The pattern of colonisation of dwarf hops (Humulus lupulus) by damson‐hop aphid (Phorodon humuli (Schrank)) migrating from Prunus spp. was investigated at six plant spacings and where some of the hops were replaced by oilseed rape (Brassica napus L.), a non‐host of the aphid. The number of migrant aphids that accumulated on hop stems (bines) increased with increasing bine size and density. The numbers of aphids that colonised hops interplanted with oilseed rape reflected the density of the hop plants only and not the overall plant density. As the physical size of the wind shadow within which flying aphids can manoeuvre and land was unimportant unless provided by a host plant, the finding supports the theory that flying aphids respond to olfactory stimuli associated with their hosts. Variation in bine height (as a measure of plant size) explained 29–93% of the variance in aphid counts during the 3 years' study and bine density 1–14%. Standardising the data as the numbers of aphids per metre of bine and taking a square‐root transformation of these standardised counts improved the precision of the analyses and, by stabilising variances, facilitated comparisons between years as growth became more vigorous as the plants matured. Each year, the rate of increase in numbers of aphids settling on plots of hops declined curvilinearly with increasing bine density. Maximum colonisation by P. humuli occurred at a bine density of five per metre row, a density similar to that used commercially by growers of dwarf hops.
Effect of orange peel substances on mating competitiveness of male Ceratitis capitata
Authors: Papadopoulos Nikos T. , Katsoyannos Byron I. , Kouloussis Nikos A. , Hendrichs Jorge
Published: October 2003

The response of wild Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) males to orange peel chemicals and their effect in mating competitiveness of males exposed to these chemicals was studied in the laboratory (25±2 °C, 65±5%, r.h.). Males were attracted, landed, and arrested on ripe oranges that were superficially wounded in the flavedo region of the peel, and fed on the wounds. Exposure to wounded oranges conferred to males a mating advantage over unexposed males. In flies of 1 to 10 days of age, this advantage was independent of the age of the flies during exposure and lasted at least 10 days following exposure. Twenty‐four hours of exposure ensured this effect. Exposure to intact oranges, or to wounded oranges covered with a wire‐screen, which allowed olfactory response and landing on the screen but not direct contact with the fruit, did not confer any mating advantage. Apparently, males required direct contact with wounded oranges in order to increase their mating competitiveness. It is suggested that the acquisition of certain substances of the flavedo, most probably through their ingestion, is responsible for the observed phenomenon. Our findings are discussed in relation to the sexual behaviour of this fly. Implications of these findings for the enhancement of the mating competitiveness of released sterile males and of the effectiveness of the Sterile Insect Technique programs are discussed as well.
Genetic variation in Myzus persicae populations associated with host‐plant and life cycle category
Authors: Zitoudi Kiriaki , Margaritopoulos John T. , Mamuris Zissis , Tsitsipis John A.
Published: October 2003

Random amplified polymorphic DNA (RAPD) analysis was applied on 96 clones of Myzus persicae (Sulzer) (Homoptera: Aphididae) representing seven populations collected from different host‐plants and regions of Greece. Ten decamer random primers were used to evaluate genetic variation among the examined samples. Despite the variability found between clones, no specific RAPD marker was detected to discriminate the different populations. A significant finding was that aphids from peach and pepper, which were collected far away from tobacco‐growing regions, especially those from peach, showed genetic divergence from the tobacco‐feeding clones. Moreover, data analysis revealed a significant genetic divergence between holocyclic and anholocyclic populations from tobacco. Lastly, holocyclic clones showed higher level of estimated heterozygosity than the nonholocyclic (anholocyclic, androcyclic and intermediate) ones.
Host specificity and comparative foraging behaviour of Aenasius vexans and Acerophagus coccois, two endo‐parasitoids of the cassava mealybug
Authors: Dorn Brigitte , Mattiacci Letizia , Bellotti Anthony C. , Dorn Silvia
Published: October 2003

Two encyrtid parasitoids, Aenasius vexans Kerrich (Hymenoptera: Encyrtidae) and Acerophagus coccois Smith (Hymenoptera: Encyrtidae), were compared for their degree of dietary specialisation and the impact this has on their foraging strategies. Both parasitoid species are significant for biological control of the cassava mealybug, Phenacoccus herreni, Cox & Williams (Homoptera: Sternorrhyncha) a major Latin American pest of cassava, Manihot esculenta Crantz, an important root crop. Host acceptance and parasitism were analysed in seven mealybug species (with different levels of polyphagy) occurring in and around cassava fields. Results demonstrate that, in this ecosystem, An. vexans is a specialist for P. herreni while Ac. coccois is a generalist on the first and second trophic level. Of the seven mealybug species, P. herreni and P. madeirensis Green were the most acceptable hosts for Ac. coccois, followed by Ferrisia virgata Cockerell. Ac. coccois did not accept the other four mealybug species.

The foraging and oviposition behaviour of individual parasitoids was observed in bioassays with cassava leaves infested by P. herreni. The two species used different strategies to locate their host. Aenasius vexans spent significantly more time walking and standing on an infested leaf and examined a host longer than did Ac. coccois. Acerophagus coccois, in contrast, spent more time for oviposition. As a consequence An. vexans parasitised more hosts in a given time than did Ac. coccois. Because the rate of offspring production of the two species did not differ, we conclude that the gregarious Ac. coccois's strategy to deposit several eggs at once might compensate for its relatively low number of ovipostitions, compared with the solitary An. vexans. These findings suggest that, given the advantages and limitations of each species, a multi‐species approach to biological control of P. herreni may yield best results.
Learning of host‐infested plant volatiles in the larval parasitoid Cotesia kariyai
Authors: Fukushima Junji , Kainoh Yooichi , Honda Hiroshi , Takabayashi Junji
Published: October 2003

The ability to learn plant volatiles in Cotesia kariyai females was examined by wind tunnel bioassays. Searching experience on a host‐infested corn plant increased subsequent flight responses of females to the infested plant. Females experiencing host by‐products together with the volatiles extracted from infested leaves one time showed an increased response. However, such behavioral changes were not observed in females which experienced only the host by‐products or the volatiles. Thus, the increased response is considered to be preference learning. Multiple experiences of C. kariyai with host by‐products together with the volatiles did not increase their flight response to the volatiles. Furthermore, this learned response gradually decreased within 2 days. These behavioral modifications based on experience would be advantageous for C. kariyai to locate their polyphagous hosts efficiently.
Effects of metal contamination on the activity and diversity of carabid beetles in an ancient Pb‐Zn mining area at Plombières (Belgium)
Authors: Lock Koen , Desender Konjev , Janssen Colin R.
Published: October 2003

Carabid beetles were monthly sampled with pitfall traps in the ancient Pb‐Zn mining area of Plombières during one year. Based on the total soil concentrations of lead, zinc, cadmium and copper, it was expected that zinc would probably have the most adverse effects on the populations. Activity and species richness of carabid beetles were, however, not significantly correlated with total zinc concentration nor with the water soluble and the calciumchloride extractable concentration. In fact, despite the high soil concentrations, carabid beetles did not seem to be affected in the study area. The apparent lack of effects at the high observed zinc concentrations is probably caused by the low bioavailability of zinc to the beetles in the litter of the study sites which was also reflected in the low observed water soluble zinc concentrations.
Development of European corn borer larvae on Event 176 Bt corn: influence on survival and fitness
Authors: Siegfried Blair D. , Zoerb Amelia C. , Spencer Terrrence
Published: October 2003

European corn borer larvae, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) that have completed development on Event 176 Bt corn hybrids have survived exposure to sublethal doses of the Cry1Ab Bt toxin or are exploiting plant tissues that do not express the toxin. To evaluate the impact of such exposure, diapausing larvae were collected from Event 176 and conventional hybrids and compared for rates of pupation, parasitism, fitness (pupal weight, longevity, and fecundity) and susceptibility to the Cry1Ab toxin. Larvae completing development on Event 176 corn exhibited approximately 10% higher survival rates and correspondingly lower parasitism rates than larvae completing development on conventional hybrids. No significant differences were detected in pupal weight, fecundity, longevity or susceptibility to the Cry1Ab Bt toxin. These results indicate that survival on Event 176 corn are not adversely affect fitness and does not cause increased tolerance to the Cry1Ab toxin in subsequent generations.
Visual and olfactory disruption of orientation by the western pine beetle to attractant‐baited traps
Authors: Strom B.L. , Goyer R.A. , Shea P.J.
Published: October 2003

Olfactory deterrents have been proposed as tree protectants against attack by bark beetles, but their development has been hindered by a lack of knowledge of host selection behavior. Among the primary tree‐killing (aggressive) Dendroctonus, vision appears to be an integral part of the host selection process. We evaluated the importance of vision in host finding by D. brevicomis LeConte, and our ability to affect it by modifying the visual stimulus provided by attractant‐baited multiple‐funnel traps. White‐painted traps caught ∼42% fewer D. brevicomis than black traps in California, USA (P < 0.05). Visual treatments were less effective (P < 0.0001) than olfactory disruptants (verbenone with ipsdienol), which reduced catch by about 78%. When combined, olfactory and visual disruptants resulted in ∼89% fewer D. brevicomis being caught, but this combination was not more effective than olfactory disruptants alone (P > 0.05). Our results demonstrate that the visual component of D. brevicomis host finding behavior can be manipulated, but that D. brevicomis may be more affected by olfactory than visual disruptants. In contrast, visual disruption is more pronounced in the southern pine beetle, Dendroctonus frontalis Zimmermann, suggesting that non‐insecticidal tree protection strategies for these related species should differ.
Intraguild predation by aphidophagous predators on parasitised aphids: the use of multiple video cameras
Authors: Meyhöfer R.
Published: October 2003

A video technique that allows simultaneous behavioural observations of several experimental replicates under field and laboratory conditions is described. The technique was used to analyse predation risk of parasitised aphids in a sugar beet field. The images of 16 black and white video cameras were recorded by a video multiplexer in combination with a time‐lapse video recorder. Each camera was weather protected and equipped with a single infrared diode to allow observations during night times. Single leaves carrying aphid mummies only or mummies and unparasitised aphids were monitored. All colonies were exposed to predation and parasitation by the community of natural enemies in the field. Colonies with mummies and unparasitised aphids were visited significantly more often by predators than those without additional aphids. Predators also stayed significantly longer in patches with unparasitised aphids. Although an equal proportion of aphid mummies were destroyed in both treatments, the video analysis showed differences in predator species spectrum between treatments. In patches with aphids, coccinellid and hemipteran predators preyed on mummies, while in patches with only mummies, chrysopids accounted for most of the damage. The decrease in parasitoid survival could be attributed to the increasing number of predator visits in aphid patches and to a lesser extent to the decreasing number of unparasitised aphids (alternative prey). Parasitoid survival in colonies without alternative prey was correlated with the number of predator visits and the time predators spent on a leaf.

Continuous video observations gave additional behavioural information for the interpretation of field data. Other prospective research fields for the use of the multi video camera technique are outlined and general advantages and disadvantages are discussed.
Identification of novel sex pheromone components from a tussock moth, Euproctis pulverea
Authors: Wakamura Sadao , Arakaki Norio , Ono Hiroshi , Yasui Hiroe
Published: October 2003

Two EAG‐active compounds were found in the solvent extract of abdominal tips of virgin females of the tussock moth Euproctis pulverea (Leech) (Lepidoptera: Lymantriidae), and identified as (Z,Z,Z)‐11,14,17‐icosatrienyl isobutyrate and (Z,Z,Z)‐11,14,17‐icosatrienyl 4‐methylvalerate at 190 and 80 ng female−1, respectively, by means of GC‐MS analyses and chemical derivatization. Esters of n‐butyric acid, n‐valeric acid, n‐hexanoic acid and a methylheptanoic acid were also found at 3, 2, 0.4 and 9 ng female−1 as minor EAG‐inactive compounds. Two active compounds were also detected in the hexane extract of female anal tufts at 17 and 6 ng female−1, respectively. In Okinawa, the binary blend of the synthetic compounds attracted male moths to the sticky traps, but single compounds did not. The significance of these findings in relation to parasitism by Telenomus euproctidis (Hymenoptera: Scelionidae) is discussed.
Performance of adult psyllids in no‐choice experiments on juvenile and adult leaves of Eucalyptus globulus
Authors: Brennan Eric B. , Weinbaum Steven A.
Published: October 2003

The presence of glaucous juvenile leaves and glossy adult leaves in the canopy of the heteroblastic plant Eucalyptus globulus Labill., is a source of within‐tree variation that affects herbivory by three psyllid species (Ctenarytaina eucalypti Maskell, C. spatulata Taylor and Glycaspis brimblecombei Moore) (Homoptera, Psyllidae). In no‐choice field experiments with adult female psyllids in clip‐on cages, we compared (1) leaf‐settling, honeydew production, and survival of the Ctenarytaina species on juvenile and adult leaves of E. globulus, (2) leaf‐settling and survival of G. brimblecombei on juvenile and adult leaves, (3) leaf‐settling and survival of the three species on waxy (untreated) juvenile leaves and de‐waxed (rubbed) juvenile leaves, and (4) leaf‐settling and survival of C. spatulata on juvenile leaves from which wax was repeatedly removed. Leaf‐settling by C. eucalypti was significantly greater on juvenile than adult leaves, however, honeydew production and survival were equal on both leaf types. In contrast, leaf‐settling, honeydew production, and survival by C. spatulata were significantly greater on adult than juvenile leaves. Similarly, leaf‐settling and survival by G. brimblecombei were significantly greater on adult than juvenile leaves. Wax removal from juvenile leaves significantly increased leaf‐settling and survival of C. spatulata and G. brimblecombei. Although wax removal decreased leaf‐settling by C. eucalypti, it did not affect survival. Repeated removal of regenerating wax from juvenile leaves did not affect leaf‐settling or survival of C. spatulata. These results suggest that the epicuticular wax of juvenile leaves plays a role in resistance to C. spatulata and G. brimblecombei, however other unknown factors are probably also involved.
Mating disruption of the Japanese giant looper in tea gardens permeated with synthetic pheromone and related compounds
Authors: Ohtani Kazuya , Witjaksono  , Fukumoto Takehiko , Mochizuki Fumiaki , Yamamoto Masanobu , Ando Tetsu
Published: October 2003

The Japanese giant looper, Ascotis selenaria cretacea, is a serious defoliator of tea gardens in Japan. The females produce racemic (Z,Z)‐6,9‐cis‐3,4‐epoxynonadecadiene (epo3,Z6,Z9‐19:H, main component) and (Z,Z,Z)‐3,6,9‐nonadecatriene (Z3,Z6,Z9‐19:H, minor component). The orientation of the males to the synthetic pheromone placed in a trap was strongly disrupted by Z3,Z6,Z9‐19:H or a mixture of its monoepoxy derivatives (epoxydiene mixture, EDM) impregnated in septa and placed around the trap. Based on this result, polyethylene tubes containing Z3,Z6,Z9‐19:H or EDM were prepared and effect of these dispensers was examined in a field. Disruption of male orientation to synthetic pheromone traps was achieved in orchards permeated with Z3,Z6,Z9‐19:H at dispenser density of 3000 and 5000 tubes ha−1 (release rate: 0.55–0.61 mg day−1 tube−1) and with EDM at every tested dose, 250–5000 tubes ha−1 (release rate: 0.25–0.39 mg day−1 tube−1). Furthermore, disruption of mating in tethered females was observed in these orchards; particularly, the mating was perfectly inhibited in the areas treated with EDM at 3000 and 5000 tubes ha−1. This is the first formulation for the mating disruption of a geometrid pest.
Experimental simulation of some visual and physical components of a hedge and the effects on butterfly behaviour in an agricultural landscape
Authors: Dover J.W. , Fry G.L.A.
Published: October 2003

Experiments on the corridor function of linear features in real landscapes are difficult and expensive to carry out using the classic replicated and controlled experimental regimes usually required as formal proof of a concept. We describe two experiments using model structures to simulate different attributes of hedges for their potential role in initiating corridor movement.

We examined: (i) the visual signal or link provided by flowering plants associated with hedges (represented by a narrow red‐and‐white builder's warning tape) and (ii) the physical presence of the body of the hedge itself (represented by green horticultural windbreak). Removable, 100 m long, links were created between two habitat patches (Åkerholmer) in an arable field in Vestby, Norway. We recorded the effect of the links on the behaviour of three ‘species’ of the free‐flying butterfly community of the study area: the scarce copper (Heodes virgaureae), the heath fritillary (Mellicta athalia) and, as a complex, the high brown (Fabriciana adippe) and niobe fritillaries (F. niobe).

The visual link did not elicit a uniform response by the different ‘species’. Significantly more high brown/niobe fritillaries flew along the visual link than along the control (no link) and mean distances traveled along the tape were significantly longer than for the control. The heath fritillary and scarce copper did not react in this way. The tape had a slight, but statistically significant, barrier effect on the scarce copper but did not act as a barrier to the other species.

All three ‘species’ were strongly affected by the presence of the physical link. A significant barrier effect was detected for all three ‘species’ as was a corridor effect with an increased proportion of butterflies moving along the windbreak compared with the control. Mean distances traveled along the windbreak were significantly longer compared with the control, the response being strongest for the scarce copper.

The results demonstrated that simple structures could modify the behaviour of species moving through the landscape and that individual species reacted in different ways to the same structure. The experimental approach of using model structures may have promise for modeling aspects of landscape elements in natural situations for a range of species. The results are discussed in relation to butterfly population structure, mate finding, dispersal and corridor design.
Life history study of Thrips setosus
Authors: Murai Tamotsu
Published: October 2003

Development, reproduction and population growth of Thrips setosus Moulton (Thysanoptera, Thripidae), reared on a leaf of kidney bean, was studied under six different constant temperatures, and the effect on reproduction of short photoperiod during immature stages was examined. Survival rates from hatch to adult were more than 67.5% at temperatures between 17.5 and 27.5 °C, but less than 55% at 30 °C. Developmental rates increased linearly as rearing temperature increased. A total of 181.1 degree‐days, above a developmental zero of 12.5 °C, were required to complete development from egg to adult oviposition. These data were related to records of field temperatures in Kurashiki in western Japan, and an estimate produced that, under outdoor conditions, a maximum of between seven and 12 generations could have developed annually between 1990 and 1999. There were no significant differences in mean adult longevity and mean fecundity among three temperatures (20, 22.5 and 25 °C). The intrinsic rate of natural increase (rm) was 0.1997 at 25 °C. Reproductive diapause was induced by a photoperiod less than 12 h at 20 °C.
Attraction of the fungus gnat Bradysia optata to cantharidin
Authors: Frank Jürgen , Dettner Konrad
Published: October 2003

The toxic terpenoid cantharidin has been reported to attract some specimens of undetermined fungus gnats. In order to investigate this phenomenon, the fungus gnat Bradysia optata Rudzinski, 1994 (Diptera: Sciaridae) was reared and its attraction to cantharidin was registered. Significant attractivity of the substance to males could be confirmed with both sticky baits in a greenhouse and an olfactometer under laboratory conditions. Ingestion of the toxic compound for chemical defence, which has been shown for some so‐called canthariphilous insects, was not observed. However, a high toxicity of cantharidin for the attracted species B. optata could be demonstrated. These unusual findings could be the result of the mycetophagous sciarids mistaking the terpenoid for certain structurally related fungal metabolites. These secondary metabolites might indicate a convenient meeting‐place for mating and oviposition.
Response of Eretmocerus eremicus to skylight and plant cues in a vertical flight chamber
Authors: Blackmer J.L. , Cross D.
Published: October 2003

In the southwestern United States, Eretmocerus eremicus (Hymenoptera: Aphelinidae) is a native parasitoid of the Bemisia complex (Homoptera: Aleyrodidae). However, little information currently exists on its potential as a biological control agent of whiteflies or on the factors that influence its tendencies to disperse. In this study, we examined the flight behavior of male and female E. eremicus in response to skylight (here simulated by a mercury‐vapor lamp) and plant cues (a 550‐nm filtered light) in a vertical flight chamber. Approximately 90% of the parasitoids took off in response to the skylight cue. Both sexes were capable of sustained flights in excess of 60 min; however, males had higher rates of climb than females (3.31±0.17 and 2.63±0.19 cm s−1, respectively). When a plant cue was presented during the parasitoid's phototactic flight, four relatively distinct responses were observed. Fifty‐one percent of the individuals responded to the plant cue throughout their flight by flying toward or by landing on the cue. The majority of these parasitoids were females. Approximately 12% of the wasps exhibited an intermittent, positive response to the plant cue. Twenty percent exhibited a ‘migratory’ response. These parasitoids, which were predominantly males, failed to respond to the plant cue until they had flown for a considerable period. Finally, 17% failed to respond to the target during their flight. Approximately 37% of the individuals that showed a positive response to the plant cue actually landed on it and the majority of these were female. The differential response to the plant cue by male and female parasitoids could be, in part, because females are driven to locate hosts in which to oviposit, and males are driven to find mates.
Survival in Dalbulus leafhopper vectors improves after exposure to maize stunting pathogens
Authors: Ebbert Mercedes A. , Nault Lowell R.
Published: October 2003

Using D. maidis and pathogen isolates collected at three field sites along an altitudinal gradient in Mexico, we compared survival in leafhoppers exposed to healthy maize to those exposed to maize infected with one of four isolates of maize stunting pathogens: two isolates of the corn stunt spiroplasma (CSS, Spiroplasma kunkelii) and two of the maize busby stunt phytoplasma (MBSP). Survival improved after exposure to either plant pathogen under both the cooler and warmer environmental conditions D. maidis is likely to encounter during the dry season. Survival varied among leafhoppers from the different field sites, suggesting that gene flow between these populations is limited. The leafhoppers responded differently to the four isolates (i.e., we noted significant population by exposure interactions), but we found no difference between MBSP and CSS exposure. Finally, we found evidence of local adaptation in one leafhopper population to sympatric, as compared to allopatric, plant pathogens. We have shown with this and our earlier study that aspects of the interaction phenotype in the association between D. maidis and the plant pathogens are mutualistic and that this association has considerable potential as a model for studies of local adaptation.
Host plant selection by Helicoverpa spp. in chickpea‐companion cropping systems
Authors: Sequeira R.V. , McDonald J.L. , Moore A.D. , Wright G.A. , Wright L.C.
Published: October 2003

The potential of companion crops to serve as diversionary hosts for ovipositing Helicoverpa spp. moths in chickpea cropping systems was evaluated in a field experiment. Patterns of egg distribution by Helicoverpa spp. within paired combinations of chickpea and each of six companion crop species were documented in a split‐plot design sampled four times during the 1999 winter growing season. Chickpea was attractive to ovipositing Helicoverpa moths from as early as 14 days after planting and throughout the experimental period. The companion crop species varied in relative attractiveness to ovipositing moths but none was able to effectively divert Helicoverpa egg pressure away from chickpea for the duration of the experiment. Of all Helicoverpa spp. larvae recorded from all samples and crop combinations, 98.3% were found on chickpea. A marked aggregative oviposition behaviour of Helicoverpa spp. on tall weeds growing through the chickpea canopy was recorded. The relevance of observed patterns of host selection and inferred moth behaviour to management of Helicoverpa populations on chickpea are discussed.
Dispersal of Acalitus essigi to blackberry (Rubus fruticosus agg.) fruit
Authors: Davies Jamie T. , Allen Geoff R. , Williams Margaret A.
Published: October 2003

The eriophyoid mite, Acalitus essigi (Hassan), is hypothesised to be responsible for redberry disease of blackberry (Rubus fruticosus L. agg.) fruit. Infested fruit ripen unevenly with affected drupelets becoming hard, inedible and bright red, whereas unaffected drupelets ripen evenly. As a first step toward possible control of this disease, the method and timing of dispersal of A. essigi onto developing blackberry fruit was examined. No mites were found on unopened flower buds or open flowers. However, infestation of fruit was found to commence during the green stage of fruit development and significantly increase during the red fruit stage. Although redberry symptoms were not observed, experimental exclusion of A. essigi to prevent the mite moving up the pedicel of open flowers by a sticky barrier significantly reduced A. essigi populations within the resultant fruit by over five fold that of control fruit. Although very low levels of aerial dispersal onto fruit cannot be discounted it was concluded that non‐aerial or crawling dispersal via the fruit pedicel was the dominant method of blackberry fruit infestation.
Response of Oligota kashmirica benefica, a specialist insect predator of spider mites, to volatiles from prey‐infested leaves under both laboratory and field conditions
Authors: Shimoda Takeshi , Takabayashi Junji
Published: October 2003

We investigated the response of the specialist insect predator Oligota kashmirica benefica (Coleoptera: Staphylinidae) to volatiles from lima bean leaves infested with the spider mite Tetranychus urticae (Acari: Tetranychidae), both in a Y‐tube olfactometer and in a field in Kyoto, Japan. Adult male and female predators were significantly more attracted to T. urticae‐infested leaves than to clean air. Adult male and female predators were not more attracted to uninfested leaves, artificially damaged leaves, or the spider mites and their visible products when compared to clean air. In a field trap experiment, 12 adult predators were caught in three traps containing T. urticae‐infested lima bean plants over 13 days, whereas no adult predators were trapped in three traps containing uninfested lima bean plants during the same period. These results showed that O. kashmirica benefica adults responded to herbivore‐induced plant volatiles from T. urticae‐infested lima bean leaves under both laboratory and field conditions.
Host‐recognition kairomone from Sogatella furcifera for the parasitoid Anagrus nilaparvatae
Authors: Lou Yong‐gen , Cheng Jia‐an
Published: October 2003

A kairomone produced by the rice white‐backed planthopper Sogatella furcifera (Horvath) for the mymarid egg parasitoid Anagrus nilaparvatae Pang et Wang was investigated. Eggs, female and male adults, nymphs, exuvia, honeydew, nymph‐damaged plants and plants with S. furcifera eggs all elicited searching behavior in the parasitoid. Eggs, female adults and plants with eggs were the most attractive, while exuvia and honeydew evoked the weakest responses. The active compound(s) from S. furcifera female adults, nymphs and plants with eggs could be effectively extracted with methanol, acetone, n‐hexane, ethyl ether and dichloromethane. Isolation of the active chemical(s) in three solvent extracts, the acetone and n‐hexane extracts of S. furcifera female adults, and the acetone extract of S. furcifera nymphs, was accomplished by thin‐layer chromatography. Only one fraction was active and had the same chemical properties in the three solvent extracts. Infra‐red analysis of this fraction revealed a kind of ester with saturated and unsaturated fatty acids, which was previously found to be active in the same compound as the extracts from the nymphs and female adults of the rice brown planthopper, Nilaparvata lugens (Stål), and identified as palm oil. The results are discussed in relation to host location by A. nilaparvatae.
The effects of laboratory culturing on (Z)‐9‐tricosene (muscalure) quantities on female houseflies
Authors: Noorman Nico , Den Otter Cornelis J.
Published: October 2003

Using gas chromatography the relative amounts of (Z)‐9‐tricosene (muscalure) and some other hydrocarbons on the cuticle of 1‐ to 20‐day‐old houseflies (Musca domestica L.) from different strains were determined. Flies from a WHO strain, in culture since 1961, and first‐generation laboratory‐cultured flies from two wild‐type strains from a poultry breeding and a cow‐house with pigsty, respectively, were compared. On WHO females hydrocarbons with 23–25 C atoms constituted about 65% of the total hydrocarbons, whereas on wild‐type females less than 2% of these compounds was present. (Z)‐9‐tricosene comprised up to 20–30% of the total hydrocarbons on 5‐ to 20‐day‐old WHO females, whereas less than 0.5% (Z)‐9‐tricosene was present on the wild‐type females. We also compared the amounts of (Z)‐9‐tricosene and some other hydrocarbons on female houseflies, kept in culture in the laboratory for several generations. It appeared that whereas on first‐generation wild‐type females hardly or no (Z)‐9‐tricosene could be detected, the amounts of this substance had increased considerably after some tens of generations in the laboratory. It is suggested that this was due to selection in subsequent generations of high‐density populations. Production of (Z)‐9‐tricosene and of tricosane was shown to be closely linked. Selection did not affect the production of other cuticular hydrocarbons by the females. It is suggested that in mixed populations (both sexes together in a cage) in the course of time (Z)‐9‐tricosene is transferred from females to males and (Z)‐9‐heptacosene from males to females. It is concluded that reproductive ability of houseflies does not primarily depend on the amounts of (Z)‐9‐tricosene on females, although higher amounts of this substance may increase contacts between males and females.
Macrolophus caliginosus: Functional response to whiteflies and preference and switching capacity between whiteflies and spider mites
Authors: Enkegaard Annie , Brødsgaard Henrik F. , Hansen Dorthe L.
Published: October 2003

Laboratory experiments were performed with adult female Macrolophus caliginosus Wagner (Heteroptera: Miridae) at 22°C on bean plants to determine the functional response towards whiteflies, as well as the preference and switching capacity between the two prey species: whiteflies and spider mites. Predation of females presented with first instars of Trialeurodes vaporariorum Westwood (Homoptera: Aleyrodidae) was of a Type III functional response. The observed maximum predation was approximately 75 first instars at high prey densities within a 24‐h period. The preference of M. caliginosus females between eggs of T. vaporariorum and Tetranychus urticae Koch (Acarina: Tetranychidae) changed with the ratio of offered prey. The preference for T. vaporariorum eggs increased non‐linearly with increasing proportions of this prey type. The average maximum predation of whitefly and spider mite eggs were approximately 166 and 111 eggs per day, respectively, at the highest ratio of the two preys. The proportion of M. caliginosus females found on the test plants at the end of the experiment increased with prey density suggesting that this mirid spends more time in areas with high prey density. Macrolophus caliginosus females are voracious predators of eggs and first instars of T. vaporariorum as well as of spider mite eggs and may thus be a valuable addition to existing methods of biological control of T. vaporariorum and T. urticae.
Identification of further sex pheromone synergists in the codling moth, Cydia pomonella
Authors: Witzgall Peter , Bengtsson Marie , Rauscher Stefan , Liblikas Ilme , Bäckman Anna‐Carin , Coracini Miryan , Anderson Peter , Löfqvist Jan
Published: October 2003

Pheromone gland extracts of codling moth females were examined by gas chromatography coupled with mass spectrometry and electroantennography. Nine compounds elicited antennal activity: the main pheromone compound codlemone (E,E)‐8,10‐dodecadienol, the E,Z and Z,E isomers of codlemone, codlemone acetate (E,E)‐8,10‐dodecadienyl acetate, codlemone aldehyde (E,E)‐8,10‐dodecadienal, the monounsaturated alcohols (E)‐8‐dodecenol and (E)‐9‐dodecenol, and dodecanol. In wind tunnel experiments, addition of dodecanol, the E,Z isomer of codlemone and codlemone acetate augmented male attraction to codlemone at the proportions found in female glands. Larger amounts of the E,Z isomer of codlemone and codlemone acetate had a strong antagonistic effect on male attraction. The identification of pheromone synergists in codling moth is of importance for the development of pheromone‐ based control methods.
Effect of juvenile hormone on caste determination and colony processes in the bumblebee Bombus terrestris
Authors: Bortolotti L. , Duchateau M.J. , Sbrenna G.
Published: October 2003

To investigate the role of juvenile hormone (JH) in caste determination, first and second instar larvae of Bombus terrestris were topically treated with one of three doses (2, 10, or 20 μg/larva) of JH dissolved in acetone. Treated larvae belonged to very young colonies that had just been started by their queen. Therefore, all larvae were supposedly destined to develop into workers. Our study demonstrates that a single application of JH in the first or second instar can lead to the development of queens and that this effect is dose‐ and instar‐dependent. The brood (second, or third brood of the colony) to which the larvae belonged also had an effect. A clear size dimorphism of the female castes exists in B. terrestris. In this study, however, intermediates also developed from treated larvae. In fact, even untreated larvae in a treated colony developed into queens and intermediates, depending on the total dose of JH applied to the colony. There are no indications that a larva, once determined to become a queen, can be forced to become a worker by means of malnutrition. Treatment with JH also had an influence on colony processes. For instance, the appearance of queen larvae resulted in the advanced start of reproduction by workers and egg robbery, the so called competition point. This indicates again the close relationship between queen rearing and the queen‐worker conflict. However, the ultimate function of this casual connection is still unclear. Further, the queen reacted to the treatment by switching to the laying of haploid eggs at an earlier date in the colony development compared to untreated colonies.
Exploring the foraging environment of a natural enemy of Callosobruchus maculatus: Spatial egg distribution in stored cowpea
Authors: Stolk C. , Stein A. , Slumpa S.B. , Tiase S.K. , van Huis A.
Published: October 2003

Knowledge of the spatial distribution of stored product insects may reduce the dependency on chemicals for control of these insects. Biological control, for instance, could be improved based on such knowledge. In this paper we describe the three‐dimensional spatial oviposition pattern of Callosobruchus maculatus in stored cowpea. Individual C. maculatus females oviposited in clusters of 70 ± 15 (SD) eggs. These clusters were variable in shape. In any cluster 90 to 95% of the eggs fitted into a volume of 19.1 ± 3.5 cm3. The egg density was highest (0.6 eggs bean−1) at the center of a cluster and decreased towards the periphery. A statistically significant relationship existed between the number of eggs n in a cluster and the cluster volume, V(cm3): V= 11.5 + 0.11n. We also investigated the spatial egg distribution of beetles which emerged from egg clusters such as those produced by individual females. Their oviposition was not confined to one specific area but was scattered throughout the bean mass. A point pattern analysis showed that the density of the ‘parent’ cluster had no effect on the spatial egg pattern. These results give insight into the foraging environment which the egg parasitoid Uscana lariophaga, a promising candidate for biological control of C. maculatus, is facing. We argue that the probability p of encountering at least one other bean with eggs after a parasitization is a function of the number n of beans that are visited: p= 1 − 0.42 (0.37)(n−1).