bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of variation in photoperiodic response on diapause induction and developmental time in the willow leaf beetle, Plagiodera versicolora
Authors: Ishihara Michihiro
Published: October 2003

The willow leaf beetle, Plagiodera versicolora (Coleoptera: Chrysomelidae) overwinters in adult diapause. In this study, the photoperiodic responses for diapause induction and developmental time were examined in the Ishikari (Hokkaido, Japan) population of P. versicolora. All females entered reproductive diapause under short daylength (L10:D14), but 31.7% of females did not enter diapause under long daylength (L16:D8). The developmental time from oviposition to adult emergence was significantly longer at L10:D14 than that at L16:D8. Norm of reaction curves illustrated variation among families in the photoperiodic responses for diapause induction and for developmental time. ANOVA indicated significant family × photoperiod interactions in the developmental time. At L16:D8, developmental time was positively correlated with the incidence of diapause in females. This means that a female having a longer developmental time tends to have a longer critical photoperiod. Such variation may be maintained by differences in selection pressures on the growth rate and the critical photoperiod for diapause induction between univoltine and bivoltine genotypes because Ishikari is located in a transitional area between populations with univoltine and bivoltine life cycles.
Foundations of spatial ecology: the reification of patches through quantitative description of patterns and pattern repetition
Authors: Dalthorp D. , Nyrop J. , Villani M.G.
Published: October 2003

Insect populations tend to be patchy, and the nature of the patches is a critical component of ecology. Predator‐prey interactions, coexistence of competing species, survival of rare species as habitat is destroyed, and damage to crops are just a few examples of spatially‐dependent ecological processes. For want of tractable quantitative approaches, understanding of spatial ecology has lagged far behind recognition of its importance. We assert that a quantitative foundation of a spatial ecology involves the reification of patches as objects of study. We introduce two new measures of patch dynamics: total covariance for comparing degrees of patchiness between populations, and quantile variance for quantifying the constancy of dispersion patterns through time. These new measures, in combination with the long‐established spatial covariance from geostatistics, comprise a rudimentary toolbox for reification of patches and empirical field studies in spatial ecology.
Spatial ecology of the Japanese beetle, Popillia japonica
Authors: Dalthorp D. , Nyrop J. , Villani M.G.
Published: October 2003

A cornerstone of spatial ecology is the quantification of the patchy nature of animal and plant populations in space. By using spatial covariance, total covariance, and quantile variance, we found that patchiness of Japanese beetle grub populations varied more between years than between fairways at a central New York golf course. We also observed that populations tended to shrink and swell around patches with perennially low density, that locations with perennially low grub density were associated with high soil organic matter content, and that locations with frequently high grub density were associated with intense adult beetle activity in the vicinity.
Host suitability, quality and host size preference of Leptomastix epona and Pseudaphycus flavidulus, two endoparasitoids of the mealybug Pseudococcus viburni, and host size effect on parasitoid sex ratio and clutch size
Authors: Karamaouna Filitsa , Copland Michael J.W.
Published: October 2003

Five host size classes which mostly consisted of one host stage (first, second, third instar nymph, young adult and preovipositing adult) of the mealybug Pseudococcus viburni (Signoret) Fernald, 1903 [Hemiptera: Pseudococcidae] were tested for susceptibility and suitability for the solitary parasitoid Leptomastix epona (Walker) Graham, 1969 and the gregarious Pseudaphycus flavidulus (Brèthes) De Santis, 1964 [both of them Hymenoptera: Encyrtidae] in no choice experiments. Hosts larger than 1 mm (third instar) were suitable for the development of the parasitoids. Choice experiments with all the host size classes offered simultaneously showed that L. epona and P. flavidulus are parasitoids of mainly larger hosts (>1 mm, third instar nymphs) therefore the parasitoids exploit the same host range. In L. epona, a faster development and a larger size of wasps occurred in host size class 1.83–2.33 mm (young adult mealybugs) indicating a greater host quality compared to other sizes. Proportion of male offspring decreased with the host size following the host size distribution models. In P. flavidulus there was no effect of host quality (size at parasitism) on developmental time, sex ratio or parasitoid size and fecundity. Larger clutch sizes of P. flavidulus emerged from larger hosts but overall this parasitoid was able to parasitize smaller hosts (<1 mm, second instar nymphs) compared to L. epona. Experience of oviposition for 24 h does not seem to affect host size preference or sex ratio of the offspring in L. epona. Implications of the findings for mass‐rearing and single applications of the parasitoids for the purpose of a biological control programme are discussed.
Wolbachia‐induced parthenogenesis in the egg parasitoid Telenomus nawai
Authors: Arakaki Norio , Noda Hiroaki , Yamagishi Kenzou
Published: October 2003

Two egg parasitoid species, Telenomus nawai and Telenomus spec. are similar morphologically but they have been treated as different species because of their different reproductive forms, arrhenotoky and thelytoky. Male progeny were produced from the thelytokous colony of Telenomus spec. (TT) by heat and antibiotic treatments. These males mated successfully with females of arrhenotokous colony of T. nawai (AT) and the females produced on average 19.1% males. This percentage did not differ from that obtained from AT females mated with AT males (19.4%). Diagnostic PCR indicated that TT is infected with Wolbachia; antibiotic treatments eliminated Wolbachia from TT. These facts suggest that Wolbachia causes thelytoky and Telenomus spec. (TT) is conspecific with T. nawai (AT).
Increasing the effectiveness of spring trap crops for Leptinotarsa decemlineata
Authors: Hoy C.W. , Vaughn T.T. , East D.A.
Published: October 2003

Insecticide resistance problems have increased interest in trap crops as a cultural control strategy for overwintered Colorado potato beetle adults, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae). Growers in the north central United States have noticed and treated concentrations of adults at the edge of some of their potato fields each spring. Based on sampling in commercial potato fields over a 2‐year period, early planted fields that are adjacent to the previous year's potato crop are most likely to have concentrations of adults at the field edge. Frequency of fields with significantly more adults at the edges than in the center sections as well as adult population density in the center sections of fields declined with both distance from the previous potato field and later planting date. The effects of both physical and chemical barriers to movement into potato fields from the field edges were studied in small plot trials and at the edges of commercial potato fields. In small plot trials, physical barriers had a greater impact than chemical barriers on adult beetle movement from a potato trap crop to the protected potatoes beyond the barrier. Barrier treatments reduced beetle numbers in and just beyond the barrier in commercial fields, but the effects were localized and no significant reduction of beetles was observed further into the field. Beetle flight was hypothesized to be responsible for the localized effects of barrier treatments and the lack of edge concentrations in later planted and more distantly rotated fields. In field studies, larger potato plants attracted more colonizing potato beetles than smaller plants. Attracting Colorado potato beetles to trap crops containing potato plants that were larger than those in the remainder of the field, however, provided no significant reduction of beetles in the remainder of the field. We found little opportunity to reduce beetle populations with trap crops at the edges of potato fields without controlling the adults in the trap crop itself. Growers can exploit naturally occurring concentrations of adults at the edges of early and adjacent potato plantings if they are prepared to monitor and regularly treat the field edges.
Comparison of DIMBOA concentrations among wheat isolines and corresponding plant introduction lines
Authors: Ni Xinzhi , Quisenberry Sharron S.
Published: October 2003

The concentration of a hydroxamic acid, also known as DIMBOA (2,4‐dihydroxy‐7‐methoxy‐1, 4‐benzoxazin‐3‐one), in 6‐d old wheat seedlings was examined using reverse‐phase high performance liquid chromatography (HPLC). Wheat plant introduction (PI) lines PI 137739 (Dn1 gene), PI 262660 (Dn2 gene), and PI 294994 (Dn5 gene), the corresponding near‐isogenic lines‘Betta’‐Dn1, Betta‐Dn2 and Betta‐Dn5, and susceptible Betta wheat were used in the study. The Dn2 gene conferring Russian wheat aphid, Diuraphis noxia (Mordvilko) (Hemiptera: Aphididae), tolerance was not related to DIMBOA concentration in wheat. Of the lines with Dn1 and Dn5 genes that confer antibiosis to D. noxia, only lines with the Dn5 gene showed increased DIMBOA accumulation. However, the Dn5 and the DIMBOA biosynthesis genes are not located in the same chromosome group. Possible relationship between the Dn5 gene and DIMBOA accumulation was discussed. This study indicates that DIMBOA concentration does not completely explain D. noxia resistance in the wheat lines examined and a comprehensive examination of other allelochemicals (e.g., phenolics) is necessary.
A comparison between two strains from Japan and Europe of Aphidius ervi
Authors: Takada Hajimu , Tada Eri
Published: October 2003

A European strain of Aphidius ervi shall be introduced into Japan for the control of Macrosiphum euphorbiae on greenhouse tomatoes. We compared this strain, which is originating from The Netherlands (EVP), with a native strain from Hokkaido, Northern Japan (SPR) in several characteristics. The percentage of parasitism of SPR and EVP was significantly different, when attacking three aphid species: 13% and 30% on M. euphorbiae on tomato, 68% and 93% on Acyrthosiphon pisum on broad bean and 10% and 42% on Aulacorthum solani on sweet pepper, respectively. SPR and EVP differed morphologically (in the colouration of the petiole) and in the esterase banding patterns. Furthermore, cross mating experiments showed that SPR and EVP are partially reproductively isolated from each other. Complete reproductive isolation is evident in the one direction cross (EVP females and SPR males).
Host instar, body size and fitness in the koinobiotic parasitoid Aphidius nigripes
Authors: Cloutier C. , Duperron J. , Tertuliano M. , McNeil J.N.
Published: October 2003

In aphidiine parasitoids, resources for growth and adult body size increase with host instar used by ovipositing females, but the fitness consequences of body size on fitness are poorly documented. We compared the fitness of male and female A. nigripes adults that varied in size as a consequence of developing in different instars of their host Macrosiphum euphorbiae. When reproductive fitness was measured without considering time, female wasps from small and large hosts performed similarly, contributing 125–175 foundresses plus 100–180 sons to the next generation. However, when expressed as the innate capacity for increase (rm), female fitness correlated with host‐induced variation of wasp size, indicating that micropopulations initiated by large wasps would increase faster. In a wind‐tunnel, a sex pheromone plume from large female wasps induced more males to fly upwind when released at a distance of 50 cm downwind than small females, indicating that large females were sexually more attractive. With respect to male body size effects on fitness, large individuals performed similar to small ones, whether fitness was measured by lifetime mating frequency, fertile inseminations, or proportion of daughters among progeny born from their mates. When young naive males of unequal size were directly competing for mating with a virgin female, small and large males had equal mating success, and large individuals were no more successful than small ones at displacing a competitor already positioned on a receptive female. In a wind‐tunnel test where males were scored on their ability to reach a female pheromone source, small and large males were equally affected by wind speed but reached the source located 50 cm downwind in equal proportions, suggesting similar capacity for finding mates by flying upwind. Our results indicate that despite host resources not being fixed at the time of attack for the koinobiont A. nigripes, fitness consequences of resource limitation by the mother may be perceived to be greater for daughters than sons, which would explain male‐biased sex ratio in early‐instar hosts.
Foraging behaviour, host plant and host location in the aphid hyperparasitoid Euneura augarus
Authors: Völkl Wolfgang , Sullivan Daniel J.
Published: October 2003

Euneura augarus is a specialized ectohyperparasitoid of conifer lachnids, which causes considerable mortality in mummies of conifer lachnid parasitoids. For the search on a large scale, E. augarus females rely mainly on volatile secondary plant compounds of conifers to locate potential host plants. In the medium‐range (i.e., on a given host plant), females detect the presence of hosts either during spiral search flights or during search by walking. Search flights were more effective when mummies were dispersed, while clumped mummies were mainly found by walking. On ant‐attended trees, E. augarus was not able to forage successfully. Choice experiments with Aphidius ervi‐mummies showed that E. augarus is able to develop in species that are not attacked in the field. We hypothesize that the proximate mechanism of host plant specificity, and as a consequence, host aphid specificity seems to be the use of typical conifer volatiles for host finding which provide the ‘search image’ for the species.
Hyperparasitoid defense strategies against spiders: the role of chemical and morphological protection
Authors: Hübner Gerhard , Dettner Konrad
Published: October 2003

The aphid endohyperparasitoid Alloxysta brevis (Thomson) (Hymenoptera: Charipidae) applies defensive chemicals stored in mandibular gland reservoirs against attacking ants. Alloxystines can be divided into species capable of exploiting ant‐attended resources and into species exclusively reared from unattended aphid‐parasitoid systems. Mandibular secretions are found in species of both groups, with little variation in chemical composition. We show that the mandibular gland secretion does not only protect against ant attacks but acts as an overall defense agent against generalist predators like spiders. The protective success differed with the spider species. The web‐building spider Agelena labyrinthica (Clerck) (Araneae: Agelinidae) killed 57% of attacked A. brevis females, but sucked out only 8%. The smaller free‐hunting jumping spider Salticus scenicus (Clerck) (Araneae: Salticidae) failed in overwhelming or severely injuring A. brevis. The pattern of interactions showed striking similarities with interactions between A. brevis and the ant Lasius niger (Hymenoptera: Formicidae). Primary parasitoids which are lacking chemical defense and sufficient morphological protection suffered significantly higher mortality due to spider predation. Our results indicate that – additional to chemical defense‐ parasitoid survival depends on the specific morphological resistance against grip pressure during capture, and on the predator – prey size relationship.
Intraguild interactions in aphid parasitoids
Authors: Brodeur Jacques , Rosenheim Jay A.
Published: October 2003

We reviewed the literature on aphid parasitoids to determine the occurrence, nature and outcome of intraguild interactions. Intraguild interactions were described for larval, pupal and adult aphid parasitoids and by the type of natural enemy (fungus, predator, or parasitoid). They appear to be prevalent in most aphid parasitoid systems and, except for parasitoid‐parasitoid interactions, they are mostly asymmetric, with aphidophagous predators and pathogens killing parasitoids. The limited experimental evidence from field studies is insufficient to provide a comprehensive pattern of the consequences of intraguild interactions for aphid parasitoid populations in general and, more specifically, for the efficacy of biological control. However, because intraguild interactions are widespread in aphid‐natural enemy communities and mostly detrimental to aphid parasitoids, we conclude that intraguild interactions have a primary effect in driving fluctuations in aphid parasitoid populations. Drawing on case studies, we further argue that intraguild interactions can substantially alter the effectiveness of aphid parasitoids as biological‐control agents.
Effect of wheat resistance, the parasitoid Aphidius rhopalosiphi, and the entomopathogenic fungus Pandora neoaphidis, on population dynamics of the cereal aphid Sitobion avenae
Authors: Fuentes‐Contreras Eduardo , Niemeyer Hermann M.
Published: October 2003

The influence of wheat (Triticum aestivum L.) resistance, the parasitoid Aphidius rhopalosiphi De Stephani‐Perez (Hymenoptera: Braconidae) and the entomopathogenic fungus Pandora neoaphidis (Remaudière et Hennebert) Humber (Zygomycetes: Entomophthorales) on the density and population growth rate of the cereal aphid Sitobion avenae (F.) (Hemiptera: Aphididae) was studied under laboratory conditions. Partial wheat resistance was based on hydroxamic acids, a family of secondary metabolites characteristic of several cultivated cereals. The partial resistance of wheat cultivar Naofén, the action of the parasitoid and the joint action of the parasitoid and fungus, reduced aphid density. The lowest aphid densities were obtained with the combination of the parasitoid and the fungus, but wheat resistance under these circumstances did not improve aphid control. Significant reductions of population growth rate (PGR) of aphids were obtained with the joint action of wheat resistance and natural enemies. In particular, the combined effects of parasitoids and fungi showed significantly lower PGR than the control without natural enemies in both wheat cultivars. Our results support the hypothesis that wheat resistance and the utilization of biological control agents could be complementary strategies in an integrated pest management program against cereal aphids.
Effects of intraguild predation on aphid parasitoid survival
Authors: Meyhöfer R. , Hindayana D.
Published: October 2003

To assess the potential selection pressure caused by intraguild predation between predators and parasitoids of aphids an estimate was made of the predation risk to Aphis fabae Scop. mummified by Lysiphlebus fabarum (Marshall, 1896) on sugar beet. Mummified aphids were exposed to a natural community of predators. Their survival time was estimated during a 10‐day field survey. Additionally, the role of alternative prey on parasitoid survival was investigated by adding unparasitised aphids to half of the mummy aggregations.

The field data were evaluated by survival analysis. Two covariates were tested within a Cox proportional hazard model: (i) the presence of the alternative prey and (ii) the patch structure (number of proximal mummies attacked). Within 4–5 days after exposure predators destroyed approx. 50% of the mummies. The model with both covariates revealed a significant difference concerning survival of the mummies in the two treatments (Likelihood ratio test, χ2= 78.03, P = 0.0001). Alternative prey reduced the predation risk on mummies by 29%, while a high level of predation on proximal mummies increased the individual predation risk by 4%. The results are discussed in the context of prey location by predators and the evolution of anti‐predator mechanisms.
A comparison of the developmental and reproductive biology of two soybean pod borers, Etiella spp. in Indonesia
Authors: Edmonds R.P. , Borden J.H. , Angerilli N.P.D. , Rauf A.
Published: October 2003

Experiments conducted in West Java, Indonesia investigated the developmental biology and reproductive behavior of two sympatric soybean pod borers, Etiella zinckenella Treitschke and E. hobsoni Butler (Lepidoptera: Pyralidae). It was determined that: (1) significant interspecific differences occurred between the egg, larval, pupal and total egg‐to‐adult developmental periods of laboratory raised E. zinckenella and E. hobsoni; (2) the pre‐pupal and total egg‐to‐adult development periods of female E. zinckenella were significantly shorter than for males; (3) the longevity of virgin female E. zinckenella was significantly longer than that of virgin males, or virgin male and female E. hobsoni; (4) interspecific differences occurred in the female: male sex‐ratios of laboratory raised adults; (5) peak mating for both species occurred on the second night after eclosion; (6) interspecific differences occurred in the temporal distribution of calling and mating behaviors; (7) repeated mating was observed for both species at a very low frequency; (8) interspecific mating did not occur; (9) female E. zinckenella were significantly more fecund than E. hobsoni; (10) the duration in copulo of E. zinckenella was significantly longer than that of E. hobsoni; and (11) wingtraps baited with virgin females caught only conspecific males, and reduced numbers of males were captured in traps simultaneously baited with virgin females of both species. This study demonstrates distinct biological differences and reproductive isolation between the two Etiella spp.
Leaf damage and prey type determine search effort in Orius tristicolor
Authors: Van Laerhoven Sherah , Gillespie David R. , McGregor Robert R.
Published: October 2003

Components of search effort were determined for adult females of Orius tristicolor (White) (Hemiptera: Anthocoridae) on bean, Phaseolus vulgaris L., leaves with either western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) or twospotted spider mites, Tetranychus urticae (Koch) (Acari: Tetranychidae) as prey. In the absence of prey, females of O. tristicolor allocated significantly more search time to leaves damaged by western flower thrips than to leaves damaged by twospotted spider mites, artificially damaged leaves or undamaged leaves. In the presence of prey, search time increased with increasing amounts of leaf damage for both prey species, but was not affected by prey species. Amounts of leaf damage or type of prey did not affect giving‐up‐time. The proportion of predators that successfully located thrips increased with increasing amounts of thrips damage on leaves. Females of O. tristicolor appeared to follow some simple, behavioural rules‐of‐thumb for allocation of search effort. The presence and type of damage determined the initial effort allocated to searching a leaf. Subsequent effort was determined by successful capture of prey, regardless of species. The implications of these results for application of Orius spp. for biological control are discussed.
Sex allocation and clutch size in the gregarious larval endoparasitoid wasp, Cotesia glomerata
Authors: Tagawa Jun
Published: October 2003

The ability of the gregarious larval endoparasitoid Cotesia glomerata L. (Hymenoptera: Braconidae) to adjust progeny sex ratio and clutch size was investigated. The sex ratios (proportion of males) of field clusters were diverse, but many (70%) were female‐biased. Nearly 10% yielded males only, suggesting a low percentage of unmated females in the field. In over half of the clusters containing females, the sex ratio was below 0.3. Superparasitism was common in the field, and females were believed to increase progeny sex ratio when attacking previously‐parasitized hosts. However, in a single oviposition bout, sex allocation was not precisely controlled both in the field and laboratory. In the laboratory, the number of eggs laid in a day tended to decrease with increasing female age. For females which were offered two hosts per day and for those offered three hosts per day, this value became nearly the same several days after the start of oviposition. The total number of hosts which a female could parasitize during her lifetime was often less than 40. Some of the old females which attacked more than 40 hosts produced male‐biased clutches; this was due to sperm depletion, because sperm remained viable throughout a female's lifetime. The amount of sperm used in a single oviposition bout seemed fixed and was not dependent on the number of eggs laid. Females with much oviposition experience did not produce new eggs to compensate for deposited eggs, and the efficiency of egg use (deposited eggs/total eggs) was more than 80%.
Multitrophic effects of herbivore‐induced plant volatiles in an evolutionary context
Authors: Dicke Marcel , van Loon Joop J.A.
Published: October 2003

Herbivorous and carnivorous arthropods use plant volatiles when foraging for food. In response to herbivory, plants emit a blend that may be quantitatively and qualitatively different from the blend emitted when intact. This induced volatile blend alters the interactions of the plant with its environment. We review recent developments regarding the induction mechanism as well as the ecological consequences in a multitrophic and evolutionary context. It has been well established that carnivores (predators and parasitoids) are attracted by the volatiles induced by their herbivorous victims. This concerns an active plant response. In the case of attraction of predators, this is likely to result in a fitness benefit to the plant, because through consumption a predator removes the herbivores from the plant. However, the benefit to the plant is less clear when parasitoids are attracted, because parasitisation does usually not result in an instantaneous or in a complete termination of consumption by the herbivore. Recently, empirical evidence has been obtained that shows that the plant's response can increase plant fitness, in terms of seed production, due to a reduced consumption rate of parasitized herbivores. However, apart from a benefit from attracting carnivores, the induced volatiles can have a serious cost because there is an increasing number of studies that show that herbivores can be attracted. However, this does not necessarily result in settlement of the herbivores on the emitting plant. The presence of cues from herbivores and/or carnivores that indicate that the plant is a competitor‐ and/or enemy‐dense space, may lead to an avoidance response. Thus, the benefit of emission of induced volatiles is likely to depend on the prevailing faunal composition. Whether plants can adjust their response and influence the emission of the induced volatiles, taking the prevalent environmental conditions into account, is an interesting question that needs to be addressed. The induced volatiles may also affect interactions of the emitting plant with its neighbours, e.g., through altered competitive ability or by the neighbour exploiting the emitted information.

Major questions to be addressed in this research field comprise mechanistic aspects, such as the identification of the minimally effective blend of volatiles that explains the attraction of carnivores to herbivore‐infested plants, and evolutionary aspects such as the fitness consequences of induced volatiles. The elucidation of mechanistic aspects is important for addressing ecological and evolutionary questions. For instance, an important tool to address ecological and evolutionary aspects would be to have plant pairs that differ in only a single trait. Such plants are likely to become available in the near future as a result of mechanistic studies on signal‐transduction pathways and an increased interest in molecular genetics.
Oviposition experience on a host‐infested plant affects flight and antennal searching behavior of Cotesia kariyai toward the host‐plant complex
Authors: Fujiwara Chiaki , Takabayashi Junji , Yano Shuichi
Published: October 2003

The flight response of Cotesia kariyai Watanabe (Hymenoptera: Braconidae), a parasitoid of the polyphagous herbivore, Mythimna separata Walker (Lepidoptera: Noctuidae), to pairs of different plant species infested by M. separata larvae was tested under a dual choice condition in the laboratory. The oviposition‐inexperienced (naive) wasps showed preference in the order: corn > kidney bean > Japanese radish. Wasps that had previously oviposited on the less preferred plant in a pair were found to have shifted their preference to this plant at 2 h after oviposition. However, this shift became indistinct at 17 h after oviposition. Prior oviposition on a plant species other than those being compared also affected the preference. These data suggest that learning is involved in the wasp's flight response. Prior oviposition was also observed to have an effect on the antennal searching behavior of the wasp on corn leaves. Such behavioral plasticity may enhance the effciency by which C. kariyai searches for polyphagous hosts.
Prevalence of fungal infections in adult Delia radicum and Delia floralis captured on the edge of a cabbage field
Authors: Klingen I. , Meadow R. , Eilenberg J.
Published: October 2003

Brassiceye® traps baited with ethylisothiocyanate were modified and used to collect live adults of Delia radicum (L.) and Delia floralis (Fallén) (Diptera: Anthomyiidae) from the field to observe the prevalence of Entomophthora muscae (Cohn) Fresenius and Strongwellsea castrans Batko & Weiser. The traps were highly effective and selective for D. radicum and D. floralis. Of the flies identified, 98.4% in 1996 and 93.7% in 1997 were either D. radicum or D. floralis. In 1997 the maximum mean catch was as high as 82 flies per trap per day, and more than 80% of these were females.

During both seasons E. muscae caused relatively high levels of mortality in adult populations of D. radicum and D. floralis. The fungus caused a total infection level of 17.9% in 1996 and 47.7% in 1997 with infection peaks of 82.4% in 1996 and 87.5% in 1997. Both years, a significant positive correlation was found between E. muscae prevalence and temperature. One infection peak was observed for S. castrans in 1996, and during that season the total S. castrans infection level was 18.0%. In 1997, the total S. castrans infection level was as low as 8.1%. There is no strong indication that the prevalence of E. muscae or S. castrans differs between either the fly species or sexes within species.
Feeding preferences and related types of behaviour of Neomegalotomus parvus
Authors: Ventura Maurício U. , Montalván Ricardo , Panizzi Antônio R.
Published: October 2003

Laboratory studies with Neomegalotomus parvus (Westwood) (Hemiptera: Alydidae) with one nymph per Petri dish in multiple‐choice tests indicated that seeds of pigeon pea [Cajanus cajan (L.) Mills.], lablab (Dolichos lablab L.), and soybean [Glycine max (L.) Merrill] were visited before seeds of common bean (Phaseolus vulgaris L.) and rice (Oryza sativa L.). The percentage of individuals engaging in dabbing/antennation resulting in probing, and percentage probing resulting in feeding, were higher on common bean (97%) and pigeon pea (87%) seeds than on lablab (55%), soybean (50%), or rice (5%) seeds. No significant differences were found in preference (number of flanges) among pigeon pea, common bean, and lablab, and preference (insects on foods) varied throughout the assessment period (5 d). In tests using 10 nymphs per dish, pigeon pea was the preferred food (number of flanges and insects on plants) throughout the period (5 d). In no‐choice tests, the average duration of a feeding session and the longest feeding session were greater on lablab and common bean than on pigeon pea, soybean, or rice seeds. The number of feeding sessions was greater on seeds of common bean, pigeon pea, and soybean than on those of lablab or rice. Laboratory tests with N. parvus adults indicated that pigeon pea seeds were located faster, followed by common bean, soybean, and rice. When pods were tested, dabbing/antennation time was shorter on pigeon pea than on soybean, and probing time was longer on soybean than on pigeon pea or common bean. On pigeon pea, 100% of the insects probed the host, while on common bean and soybean pods, and on rice panicles, these values dropped to 71.8%, 46.0%, and 10.5%, respectively. Adults showed similar feeding times on pigeon pea, common bean, and soybean pods, but did not feed on rice panicles. Electronmicroscopical analysis showed the presence of two apical lobes with 12 peg sensilla on the labial tip. Sensillum tips were stained with silver nitrate solution, indicating a permeability of the cuticle and, therefore, their function as taste receptors.
Partial age‐specific life tables for Monochamus titillator in Dendroctonus frontalis infested loblolly pines
Authors: Dodds Kevin J. , Stephen Frederick M.
Published: October 2003

Partial age‐specific life tables were constructed for Monochamus titillator (Fabricius) (Coleoptera: Cerambycidae) in Dendroctonus frontalis Zimmermann (Coleoptera: Scolytidae) infested loblolly pine (Pinus taeda L.) trees. Successive life stages including egg, early larvae, mid‐stage larvae, late larvae, and adult emergence were sampled within six sample trees. Generation mortality ranged from 60.94% to 98.61% in sample trees. Highest mortality typically occurred to eggs and mid‐stage larvae. Possible mortality factors included resinosis, predaceous beetles, parasitoids, and woodpeckers. Dendroctonus frontalis brood stages were determined for consecutive M. titillator sampling. Monochamus titillator and D. frontalis coexisted and likely interacted in the phloem of host trees for at least 20 days.
Retention, capture and consumption of experimental prey by orb‐web weaving spiders in coffee plantations of Southern Mexico
Authors: Henaut Y. , Pablo J. , Ibarra‐Nuñez G. , Williams T.
Published: October 2003

This study focuses on the predatory capacity of four sympatric species of web‐ building spiders that inhabit coffee plantations in Southern Mexico: Gasteracantha cancriformis, Cyclosa caroli, and the morphologically similar species pair Leucauge mariana and L. venusta which were considered as one species group. The retention capabilities of the webs of these species and the incidence of prey capture and consumption were measured using eight types of insect prey belonging to the orders Coleoptera (1 species), Hymenoptera (3), Diptera (2) Lepidoptera (1) and Homoptera (1). The different characteristics of each prey such as body weight, body size, defensive behaviour, etc., were recorded. The incidence of prey retention, capture and consumption were significantly higher in G. cancriformis than in any of the other species. The lowest rates of retention, capture and consumption were observed in C. caroli, while L. mariana/venusta were intermediate in their predatory capabilities. Significant negative correlations between prey size and percent consumption were detected in L. mariana/venusta and in G. cancriformis; in both cases, large prey were less likely to be immediately consumed than small prey items. The results can be interpreted in the light of the morphological characteristics of the spiders. G. cancriformis possesses long legs and a carapace and appeared to have few difficulties to manipulate all types of prey. In contrast, C. caroli showed lesser abilities to manipulate and subdue aggressive prey items, perhaps due to the short leg length and unprotected body of this species. The consumption of prey items may be related to the predatory strategy of each spider. G. cancriformis constructs a new web every morning and prey storage was never observed. The absence of prey storage behaviour could explain why this species consumes prey soon after capture. In contrast, C. caroli constructs a permanent web and stores captured prey on a stabilimentum that may explain the very low incidence of immediate consumption of prey observed in this species.
Antifeedant and toxic activity of Trichilia americana extract against the larvae of Spodoptera litura
Authors: Wheeler Deborah A. , Isman Murray B.
Published: October 2003

The biological activity of a crude methanolic extract of Trichilia americana (Sesse and Mocino) Pennington (Meliaceae) was assessed using the Asian armyworm, Spodoptera litura (Fabr.) (Lepidoptera: Noctuidae). The extract exhibited strong antifeedant activity in a choice leaf disc bioassay with 0.18 μg cm−2 extract deterring feeding by 50%. In nutritional assays, the crude extract reduced growth, consumption and the utilisation of ingested and digested food in a dose‐dependent manner when fed to larvae, suggesting both antifeedant and toxic activities. When relative growth rates were plotted against relative consumption rates, the growth efficiency of the S. litura fed on diet containing T. americana crude extract was significantly less than that of control larvae. This result further indicates that the extract acts as both an antifeedant and chronic toxin. Toxicity is only seen following ingestion and was not observed following topical application or injection into the hemocoel. Larvae reared initially on extract‐containing diet then transferred to control diet showed nutritional indices comparable to those of larvae fed continuously on control diet. This suggests that the extract is not permanently damaging the insect's digestive tract. The mode‐of‐action of the extract as a chronic toxin remains unknown.
Interspecific interactions in a tri‐trophic arthropod system: effects of a spider on the survival of larvae of three predatory ladybirds in relation to aphids
Authors: Yasuda Hironori , Kimura Takuji
Published: October 2003

The effects of the crab spider, Misumenops tricuspidatus (Fabricius), on the larval survival of three ladybird species, Harmonia axyridis Pallas, Coccinella septempunctata L., and Propylea japonica L., in relation to aphids were investigated in the laboratory. Predation by the spider on the three ladybird species differed. All the larvae of C. septempunctata, none of H. axyridis, and an intermediate number of P. japonica were attacked and eaten by the spider. All the larvae of H. axyridis suffered mortality due to cannibalism or starvation in the treatments with and without a spider. In case of C. septempunctata, however, mortality in the early instars was significantly greater in the treatment with a spider than without a spider and no larvae developed into pupae due to predation. In the treatment without a spider, the majority of the larvae in the former treatment suffered mortality due to cannibalism or starvation, and only 13.3% of larvae developed into the adult stage. In the case of P. japonica, mortality was mainly attributed to predation in the treatment with a spider and only 26.7% became adult. In comparison, 86.7% of larvae survived to the adult stage in the treatment without a spider. In addition, in both H. axyridis and C. septempunctata, the development of young larvae was significantly slower in the presence of a spider, but this was not the case with the older larvae of H. axyridis, which indicates that the effect of the spider on larval development changed with the developmental stage of the larvae in this species. However, the spider had no significant effect on the developmental time of P. japonica larvae. Although both the spider and the ladybirds significantly affected the number of aphids, they did not have an additive effect on aphid abundance. The interactions between the spider and the ladybirds, such as intraguild predation or competition, caused them to reduce aphid population density less than the ladybirds did on their own. The effect of the spider on the larval performance of three predatory ladybirds was found to be unequal in terms of their vulnerability to predation and rate of larval development and it depended on the species and developmental stage of the ladybird.
Comparative biology and life tables of Trichogramma evanescens and T. cacoeciae with Ephestia elutella as host at four constant temperatures
Authors: Schöller Matthias , Hassan Sherif A.
Published: October 2003

The age‐specific fecundity of Trichogramma evanescens Westwood and T. cacoeciae Marchal (Hymenoptera: Trichogrammatidae) with Ephestia elutella (Hübner) (Lepidoptera: Pyralidae: Phycitinae) as host and the life span of the adults with and without hosts was determined at 20, 26, 30 and 35 °C and 75 ±5% r.h. in the laboratory. At 35 °C, no progeny emerged. The availability of hosts prolonged the longevity in both species. Longevity, percentage of parasitism, fecundity, and the intrinsic rate of natural increase were higher in T. evanescens than in T. cacoeciae. Trichogramma evanescens is expected to be more effective than T. cacoeciae for use in biological control of Ephestia spp., especially at low and high temperatures.
Oviposition behavior of Coccidoxenoides peregrinus, a parasitoid of Planococcus ficus
Authors: Joyce A.L. , Hoddle M.S. , Bellows T.S. , González D.
Published: October 2003

The encyrtid parasitoid, Coccidoxenoides peregrinus has been used as a biological control agent against the mealybugs Planococcus citri and Planococcus ficus. This study examined the behavior and host selection of C. peregrinus attacking P. ficus. Adult parasitoids were fed a 0.1% solution of acridine orange, a DNA binding dye used to label C. peregrinus eggs. In a choice test, adult parasitoids were offered equal numbers of first through fourth instars of P. ficus and behavior of C. peregrinus was filmed and analyzed. Acridine orange labeled ova of the parasitoids found within mealybug hosts fluoresced green under fluorescence microscopy and presence of fluorescing eggs in hosts was used to determine oviposition events. A time budget prepared for C. peregrinus indicated that this parasitoid spent the majority of its time searching (71.64%) and grooming (15.06%). The average probing duration over all instars which led to oviposition from single visits was 4.93±0.62 s. A total of 35.51% of probes from all attacks led to ovipositions, whereas 33.72% of single visits to hosts resulted in ovipositions. Detection of fluorescing acridine orange labeled eggs showed all instars of P. ficus were acceptable for oviposition by C. peregrinus. There was a significant preference to probe second, third, and fourth instars rather than first instars of P. ficus. Host feeding was not observed for this parasitoid.
Insecticidal activity of avidin and streptavidin against four species of pest Lepidoptera
Authors: Markwick N.P. , Christeller J.T. , Dochterty L.C. , Lilley C.M.
Published: October 2003

Two biotin‐binding proteins, avidin and streptavidin, were found to be insecticidal to the larvae of four species of Lepidoptera – light brown apple moth, Epiphyas postvittana (Walker) (fam. Tortricidae), green‐headed leaf‐roller, Planotortrix octo (Dugdale) (fam. Tortricidae), brown‐headed leaf‐roller, Ctenopseustis obliquana (Walker) (fam. Tortricidae) and potato tuber moth, Phthorimaea operculella (Zeller) (fam. Gelechiidae). Mortality occurred in all species, but there was a wide range in susceptibility. P. operculella larvae were the most susceptible with an LC50 of respectively, 2.3 μg ml−1 for avidin and 1.4 μg ml−1 for streptavidin after 9 days. E. postvittana larvae had an LC50 of 43.4 μg ml−1 for avidin after 21 days, and C. obliquana larvae of 45.7 μg ml−1 for avidin after 28 days. Although significant mortality occurred in P.octo at the highest doses of avidin, there was no sufficient dose‐mortality response to calculate an LC50 for this species. For all species mortality curves were steep over a close range of doses followed by a plateau where mortality did not increase significantly with dose and did not reach 100%. Mortality was significantly affected by the amount of biotin in the diet on which the parental generation had been reared. Where this was rich in biotin, significant mortality of the offspring was much lower: larval offspring of a colony of E. postvittana, reared for five generations on a biotin‐free diet had an LC50 of 5.1 μg ml−1 after 14 days compared with 76.7 μg ml−1 for larvae from a colony reared on general purpose diet. The implications for use of these proteins to confer insect resistance on transgenic plants are discussed.
Economic injury levels for the scarabaeid Maladera matrida infesting peanut fields in Israel
Authors: Harari Ally Rachel , Ben‐Yakir David , Chen Michael , Rosen David
Published: October 2003

Control of Maladera matrida Argaman (Coleoptera: Scarabaeidae) in peanut fields in the Negev region, Israel, relies on the ‘rule of thumb’ use of insecticides. The aim of this study was to develop an economic injury level (EIL) for a more judicious application of insecticides. Field studies were conducted from 1991 to 1993 to determine the relationship between the cumulative number of different immature stages and the damage of peanuts (Arachis hypogaea L.). Observed damage to peanut yield was found to relate best to second‐ and third‐instars (white grubs). This was supported by grub infestation experiments on potted peanut plants. Three different EIL levels for second‐ and third‐instars of M. matrida were established in connection with the peanut plant developmental stages as follows: an average of 13 grubs per soil sample (25 by 25 by 60 cm) taken during the first 3 weeks of nut development, of 4 grubs per soil sample during week 4 to 6, and of 1.5 grubs per soil sample from week 7 until harvest.
Determining numbers of active carabid beetles per unit area from pitfall‐trap data
Authors: Raworth David A. , Choi Man‐Young
Published: October 2003

Movement of Pterostichus melanarius (Illiger) (Coleoptera: Carabidae) was studied in the laboratory, and a simulation model developed. The model was calibrated and validated using mark‐release‐recapture within a grid of pitfall traps in a commercial raspberry field. Rate of movement increased linearly with both temperature and starvation. The temperature threshold for movement, pooling all starvation levels was 3.8 °C ± 0.78 (s.e.). When beetles were released at various distances from a trap in the simulation model, the probability of capture during one day was about 0.13 at a release distance of 10 cm and fell rapidly with distance and temperature. At 5, 10, 15, and 20 °C, the maximum radius sampled by a trap in one day was about 8, 17, 24, and 29 m, respectively. Density was linearly related to catch, but the slope of the line and the variance of the density estimate increased rapidly at lower temperatures. Equations for determining density per m2 (±s.d.) were developed from the model, incorporating temperature, number of beetles caught per trap, and number of traps.