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In order for successful biological pest control using parasitoids, the most suitable naturally available food resources, as well as the fitness of parasitoids feeding on these resources, need to be ascertained. The goal of this study was to improve the understanding of the ecological requirements and consequent fitness of one such parasitoid, Telenomus podisi Ashmead ( Hymenoptera: Platygastridae), a predominant stink bug ( Heteroptera: Pentatomidae) egg parasitoid native to southeastern USA. We assessed the effects of carbohydrate resources readily available in the wasp's natural habitat on longevity and fecundity of female T. podisi under laboratory conditions. Carbohydrate diets included in the study were buckwheat, Fagopyrum esculentum Moench ( Polygonaceae) nectar and honeydew from cowpea aphid, Aphis craccivora Koch ( Hemiptera: Aphididae), compared with honey or water controls, which are normally used for laboratory rearing of this species. Eggs of Podisus maculiventris Say ( Hemiptera: Pentatomidae) were provided as hosts for oviposition. Honeydew of cowpea aphid proved to be as good a nutrition source as buckwheat nectar, in enhancing wasp longevity and fecundity. We also assessed the importance of honeydew freshness on the biological attributes of T. podisi, as honeydew becomes crystallized or highly viscous on drying up and therefore may pose an issue for uptake by parasitoids. We found that fresh honeydew of the pea aphid, Acyrthosiphon pisum Harris ( Hemiptera: Aphididae) significantly enhanced wasp longevity when compared to a diet of 1-day-old honeydew and the fava bean leaf (control). However, fresh honeydew of green peach aphid, Myzus persicae Sulzer ( Hemiptera: Aphididae) had the same effect on wasp longevity, fecundity, and proportion of male progeny as radish leaf (control). The potential of certain ubiquitously available food resources, in enhancing biological control of economically damaging pests by parasitoids, is being highlighted in this study; information which could be valuable in similar parasitoid-host systems as well. [ABSTRACT FROM AUTHOR]

This study examines the nature of intraspecific interactions among Nilaparvata lugens ( Stål) ( Hemiptera: Delphacidae) planthoppers feeding on resistant and susceptible rice varieties. Planthopper nymphs produced less honeydew and gained less weight when feeding on rice variety IR62 (resistant) compared to susceptible rice varieties. A series of bioassays was conducted that varied N. lugens nymph densities on IR62 and IR22 (susceptible). Increasing nymph density facilitated feeding by conspecifics; however, intraspecific competition increased mortality of nymphs on IR62 (but rarely on IR22). Furthermore, nymph weights declined with increasing conspecific density on IR22, and the effects were weak on IR62. More female nymphs than males survived on IR62 but this was not affected by density. Nitrogenous fertilizer increased competition among N. lugens on young plants of IR22, but not on IR62. Results indicate that nymphs have a low efficiency in accessing resources when feeding on IR62, even where the plants have received fertilizer. Female-biased survival and biomass compensation for mortality may promote population recovery after development on the resistant plant and accelerate adaptation to the resistant variety. [ABSTRACT FROM AUTHOR]

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), transmits the citrus greening pathogen 'Candidatus Liberibacter asiaticus' (CLas) by feeding on citrus phloem sap. Because phloem sap is rich in sugars but low in amino acids, ACP sucks large quantities and excretes most of it as honeydew. We studied the chemical composition of ACP honeydew on various host plants. Honeydew samples were analyzed with gas chromatography-mass spectrometry. Fourteen sugars, 13 amino acids, and six organic acids were detected in the honeydew of ACP. Sugars composed about 95% of the total compounds. Sucrose and trehalose were the predominant sugars, composing about 58 and 23% of the total sugars, respectively. Proline, asparagine, aspartic acid, and glutamic acid were the most abundant amino acids in ACP honeydew. The host plant and its infection with CLas had some effect on the honeydew composition. Glucose, chiro-inositol, myo-inositol, inositol, maltose, and turanose were lower in honeydew collected from CLas-infected citrus compared to that collected from non-infected trees. In CLas-infected citrus (pineapple sweet orange, Citrus sinensis L. Osbeck) and Bergera koenigii (L.) Spreng. [curry leaf tree (both Rutaceae)] honeydews, valine, alanine, serine, glutamine, glycine, and the organic acids were lower than in honeydew from healthy citrus. Mannose, galactose, inositol, mannitol, an unknown disaccharide, and proline were higher in the honeydew collected from B. koenigii than in honeydew collected from healthy citrus (pineapple sweet orange), whereas fructose, chiro-inositol, myo-inositol, trehalose, and lactic acid were lower. The findings of this study help us understand the metabolism and the nutrient needs of ACP that transmits CLas, the pathogen of huanglongbing in citrus. [ABSTRACT FROM AUTHOR]

The introduction of invasive social wasp species of the genus Vespula ( Hymenoptera: Vespidae) to New Zealand has caused a major ecological problem, particularly in the beech forests ( Nothofagus spp.) of the South Island, where they have destabilized the native bird and invertebrate biodiversity. New attractants are under investigation as part of a search for pest management solutions. Fermenting brown sugar has been previously reported as a social wasp attractant. This work was undertaken to identify compounds from fermented brown sugar attractive to social wasps. Raw fermented brown sugar was confirmed to be attractive in a field trial and 10 chemical compounds present in the headspace were positively identified by coupled gas chromatography-mass spectrometry and synthetic references. During electroantennogram experiments, 3-methyl-1-butanol, 3-methylbutyl acetate, and ethyl hexanoate elicited high electrophysiological responses from Vespula vulgaris ( L.) antennae. These compounds mediated attraction of V. vulgaris wasps in forest margins by trapping. A blend of these compounds could be used as a lure in a monitoring tool, or even a local suppression method if combined with a toxin. [ABSTRACT FROM AUTHOR]

Feeding behavior of Melanaphis sacchari Zehntner ( Hemiptera: Aphididae) was studied on sugarcane, Saccharum spp. ( Poaceae), cultivars HoCP 91-555 (resistant), LCP 85-384 (moderately resistant), and L 97-128 (susceptible) using the electrical penetration graph ( EPG) technique. Constitutive concentrations of total phenolics and available carbohydrates, water potential at the whole-leaf tissue level, and free amino acids (FAAs) in phloem sap extracts, and in honeydew produced by aphids fed on L 97-128 and HoCP 91-555 were determined. Cultivar did not influence time for M. sacchari to access phloem sieve elements. Total time in sieve elements was ca. two-fold greater on L 97-128 than on HoCP 91-555, whereas it did not differ from LCP 85-384 in either cultivar. The mean duration of individual events associated with phloem sap ingestion was ca. 50% shorter on both HoCP 91-555 and LCP 85-384 than on L 97-128. Although cultivar effects were not detected for levels of total phenolics, available carbohydrates, and water potential, two free essential amino acids, histidine and arginine, were absent from phloem sap in HoCP 91-555. Two free essential amino acids, leucine and isoleucine, and two free non-essential amino acids, tyrosine and proline, were absent from honeydew of aphids fed on HoCP 91-555. These results suggest that despite apparent biosynthesis of some FAAs, the absence of important FAAs in the phloem sap of HoCP 91-555 and the inability of M. sacchari and its endosymbionts (e.g., Buchnera) to derive specific free essential and non-essential amino acids from other ingested molecules, possibly along with other unidentified factors, underlie the pest's decreased phloem sap ingestion and consequently reduced growth potential on HoCP 91-555. [ABSTRACT FROM AUTHOR]

Mutualistic interactions between ants and Hemiptera are mediated to a large extent by the amount and quality of sugar-rich honeydew produced. Throughout the neotropics, the predaceous fire ant Solenopsis geminata ( Fabricius) ( Hymenoptera: Formicidae) is found in association with colonies of the pineapple mealybug, Dysmicoccus brevipes ( Cockerell) ( Hemiptera: Pseudococcidae), which they actively tend and protect from attack by natural enemies. In this study, we evaluate the effects of access to a sucrose solution on the mutualistic association between S. geminata and D. brevipes. Ten colonies of either species were established, with D. brevipes maintained on pumpkin, Cucurbita maxima Duchesne ( Cucurbitaceae), in screen cages. Five of the S. geminata colonies were permitted access to vials with 20% sucrose solution and a pumpkin with 20 adult mealybugs. The remaining ant colonies were allowed access to mealybug-infested pumpkins. Ant colonies with access to the sucrose solution attended mealybugs significantly less than those without additional sugar sources. Mealybug survival rates were similar under both treatments. Total body sugars and fructose were nearly twice as high in ants with access to honeydew and sucrose vs. those with access to honeydew and water. Fructose accumulated on the pumpkins over time in both treatments, suggesting that honeydew was not fully exploited by the ants. In conclusion, D. brevipes enjoy lower degrees of ant attendance when S. geminata have alternative sources of carbohydrates. We further discuss the significance of these findings for the conservation of predaceous ants and mealybug biological control. [ABSTRACT FROM AUTHOR]

The invasive Middle East-Asia Minor 1 ( MEAM1) cryptic species (formerly referred to as the B 'biotype') of the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) complex has become a major crop pest worldwide due to its global invasion as well as epidemics of begomoviruses it transmits. Previous studies demonstrated that MEAM1 performed better on tobacco [ Nicotiana tabacum L. (Solanaceae)] plants infected by Tomato yellow leaf curl China virus ( TYLCCNV) than on uninfected plants. However, mechanisms underlying the interactions are not completely understood. In this study, we compared the composition of sugars and amino acids in the phloem sap of uninfected and TYLCCNV-infected tobacco plants with or without whiteflies feeding on the plants. No significant differences were detected in terms of amino acid profiles, percentage of essential amino acids, and sugars:amino acids ratio. However, whiteflies feeding on TYLCCNV-infected plants excreted comparatively a lower percentage of amino acids, especially essential amino acids, or proportionally a higher level of sugars than those feeding on uninfected plants, suggesting that whiteflies feeding on virus-infected plants are able to achieve a more balanced nutritional assimilation. We also compared the honeydew excreted by viruliferous and non-viruliferous whiteflies feeding on cotton [ Gossypium hirsutum L. (Malvaceae)], a non-host plant for TYLCCNV, to test the direct effects of the virus on whiteflies. Although the amino acids profiles in honeydew were similar between viruliferous and non-viruliferous whiteflies, the sugars:amino acids ratio in honeydew excreted by viruliferous whiteflies was lower than that of non-viruliferous whiteflies, suggesting that the viruliferous whiteflies assimilated a more imbalanced nutrition with proportionally more sugar. Taken together, our data indicate that although a plant virus may exert negative direct effects on its vector, feeding by the vector on virus-infected plants may improve nutritional assimilation and consequently performance of the vector. [ABSTRACT FROM AUTHOR]

Honeydew-producing psyllids are an important pest of eucalyptus (Myrtaceae) in California, USA, and may influence surrounding litter arthropod communities. In particular, the introduced Australian psyllids Glycaspis brimblecombei Moore and Eucalyptolyma maideni Froggatt (both Hemiptera: Psyllidae) may facilitate the prevalence of invasive ant species. We examined ground-dwelling arthropod communities under eucalyptus trees infested by psyllids. We used a model comparison approach to examine the association of psyllid infestation, ant abundance, and environmental factors with ground arthropod abundance and richness. We found a significant positive association between ant activity on eucalyptus trees and psyllid abundance. Higher psyllid abundance and higher Argentine ant abundance were associated with increased arthropod richness. Irrigation was also associated with increased arthropod richness and abundance. Regardless of location collected, arthropod communities collected in pitfall traps under trees with high psyllid abundance had high similarity to arthropod communities under trees with high ant activity. Abundance of isopods was positively associated with both ant and psyllid abundance. Other arthropod groups differed in their association with ants and psyllids. Argentine ants may exacerbate pest impacts and may also decrease the effectiveness of biological control programs for eucalyptus lerp psyllids. [ABSTRACT FROM AUTHOR]

Variation in phloem sap composition is important in determining aphid performance and is known to occur at both diurnal timescales and in response to plant age. For field grown potato plants, Solanum tuberosum L. (Solanaceae), we determined diurnal variation in components of phloem sap, measured by ethylene diamine tetra-acetate exudation, and tested for impacts of plant age. The effects of plant age and diurnal cycles on honeydew production by Macrosiphum euphorbiae (Thomas) and Myzus persicae (Sulzer) (both Hemiptera: Aphididae) were also quantified. Both the ratio of sucrose to amino acids and the composition of amino acids in phloem sap varied significantly with time of day. Dietary essential amino acids contributed a smaller proportion of amino acids in the phloem sap of older plants and during early phases of the diurnal cycle. The only significant effect on aphid honeydew production was of the diurnal cycle for Ma. euphorbiae, although increased honeydew production during the day when compared with the production at night, was consistent across the two species. In contrast with studies carried out at seasonal scales, we found limited evidence for variation in phloem sap composition in response to plant age, consistent with our results for honeydew production. These data highlight the need for improved understanding of how seasonal and diurnal physiology of plants influence performance in phloem sap feeding insects. [ABSTRACT FROM AUTHOR]

Honeydew from phloem-feeding insects and fruit fly insecticidal baits may serve as adult food resources for some insect species. In California (USA) olive orchards, the black scale [ Saissetia oleae (Olivier) (Hemiptera: Coccidae)] is a common honeydew producer, and spinosad-based fruit fly bait (GF-120) is used to control the olive fruit fly [ Bactrocera oleae (Rossi) (Diptera: Tephritidae)]. We investigated the effects of black scale honeydew and GF-120, as food resources, on adult foraging behaviour and survival of the olive fruit fly and two parasitoids in the olive agroecosystem: Scutellista caerulea (Fonscolombe) (Hymenoptera: Pteromalidae), a natural enemy of black scale, and Psyttalia humilis (Silvestri) (Hymenoptera: Braconidae), a parasitoid of the fruit fly. In food choice tests, female flies did not show a preference between GF-120 bait and honeydew, whereas male flies and the parasitoids we tested preferred honeydew. Adults of the three insect species readily fed on honeydew, but the natural enemies never ( P. humilis) or rarely ( S. caerulea) fed on GF-120 bait. Olfactometer tests further confirmed that the tested natural enemies were not attracted to GF-120 bait. The presence of honeydew significantly reduced fruit fly mortality when both honeydew and GF-120 were provided, compared with GF-120 given alone. A single meal of honeydew increased longevity in all insect species tested. The mean longevities of honeydew-fed insects were not significantly different from those feeding on clover honey. Our results suggest that the presence of honeydew would benefit the three insect species and may reduce the efficacy of GF-120 for fruit fly control because of preference of honeydew rather than fruit fly bait as a food resource. [ABSTRACT FROM AUTHOR]

As food items can vary in nutrient composition, diet selectivity can be an important trait to optimize nutrition. Most parasitoids depend as adults on various sugar-rich food sources such as nectar and honeydew. Nectar is often superior as a food source to honeydew, yielding higher parasitoid longevity. Little is known, however, of a preference parasitoids may have for one of these sugar sources and how this affects variation in their life-history traits. In this study, a combined empirical and modelling approach was adopted. First, it was investigated whether parasitoids show a feeding preference for nectar or honeydew in the laboratory and whether feeding history affects the preference of parasitoids. Second, using a process-based spatially explicit simulation model, it was evaluated how preference for nectar affects parasitoid life-history variables in fields with varying flower densities. The laboratory study revealed that naïve parasitoids showed no preference for either nectar or honeydew. However, when parasitoids had fed previously on honeydew and were then given the choice between nectar and honeydew, they preferred feeding on nectar to honeydew (with marginal statistical significance). Model simulations indicated that when nectar sources were present in the field, parasitoids that showed preference for nectar had a 1.3–1.8 times longer life span and parasitised up to 1.4 times more hosts than parasitoids that did not distinguish between honeydew and nectar. These combined empirical and modelling data suggest that aphid parasitoids may be able to discriminate between nectar and honeydew, and that a preference for nectar may enhance their longevity and reproduction in fields where nectar sources are available. [ABSTRACT FROM AUTHOR]

Feeding behavior of beet leafhopper, Circulifer tenellus (Baker) (Homoptera: Cicadellidae), was studied with a DC electrical penetration graph. Nine different electrical penetration graph waveforms associated with feeding were identified and characterized. Waveforms were correlated with specific feeding behaviors using a number of techniques, including high magnification video recording, honeydew analysis, stylectomy, and histological processing. Waveforms were grouped into three phases based on feeding behavior: pathway phase (waveforms A, B1, B2, and C), non-phloem ingestion phase (waveform G), and phloem phase (waveforms D1, D2, D3, and D4). No ingestion was found to occur during waveforms A, B1, B2, and C. Waveform G was associated primarily with ingestion of xylem sap and occasionally with ingestion of mesophyll sap. Stylet tips were located in phloem during waveforms D1, D2, and D3, and waveforms D2 and D3 were correlated with ingestion of phloem sap. Waveform D4 probably also plays a role in phloem ingestion, because D4 is very brief and always occurs embedded in either waveform D2 or D3. In contrast to most other homopteran insects, rate of honeydew production (and hence rate of ingestion) was much lower on phloem than on xylem. More rapid rates of ingestion are expected on phloem, because its high turgor pressure drives sap into the feeding insect whereas the negative pressure of xylem sap is expected to cause a slow rate of ingestion. The very slow ingestion rate of beet leafhopper feeding on phloem suggests that it is not able to exploit the high turgor pressure of phloem to achieve the high rate of ingestion that is typical of phloem ingestion by other insects. [ABSTRACT FROM AUTHOR]

One of the most important issues in ecology is understanding the causal mechanisms that shape the structure of ecological communities through trophic interactions. The focus on direct, trophic interactions in much of the research to date means that the potential significance of non-trophic, indirect, and facilitative interactions has been largely ignored in traditional food webs. There is a growing appreciation of the community consequences of such non-trophic effects, and the need to start including them in food web research. This review highlights how non-trophic, indirect, and facilitative interactions play an important role in organizing the structure of plant-centered arthropod communities. I argue that herbivore-induced plant responses, insect ecosystem engineers, and mutualisms involving ant–honeydew-producing insects all generate interaction linkages among insect herbivores, thereby producing complex indirect interaction webs on terrestrial plants. These interactions are all very common and widespread on terrestrial plants, in fact they are almost ubiquitous, but these interactions have rarely been included in traditional food webs. Finally, I will emphasize that because the important community consequences of these non-trophic and indirect interactions have been largely unexplored, it is critical that indirect interaction webs should be the focus of future research. [ABSTRACT FROM AUTHOR]

Feeding on sugar-rich foods such as nectar and honeydew is important for survival of many adult parasitoids. Especially in agricultural systems, honeydew is often the most prevalent carbohydrate source. However, relative to plant nectar, honeydew may be relatively unsuitable, as a result of an unfavourable sugar composition or the presence of secondary plant compounds. We studied survival of the aphid parasitoid Aphidius ervi Haliday (Hymenoptera: Braconidae) on honeydew collected from various aphid species feeding on potato ( Solanum tuberosum L., cv. Desiree) (Solanaceae), wheat ( Triticum aestivum L., cv. Bobwhite) (Poaceae), or artificial diet, as well as the sugar composition of the different honeydews. Honeydews from the tested aphid species on potato, wheat, or artificial diet were found to be relatively suitable food sources for adult A. ervi, although not always as suitable as a 2 M sucrose solution. There were differences in honeydew sugar composition among the different aphid species on the various host plants. Multivariate statistics showed that the factor ‘aphid species’ had a significant influence on the sugar composition of the honeydew, explaining 27% of the variation in the potato system and 89% in the wheat system. When exploring the relationship between carbohydrate composition of the honeydews from aphids on potato and wheat plants, and their nutritional value for A. ervi, data revealed that differences in parasitoid longevity can to some extent be explained by carbohydrate composition. Furthermore, our results confirm that sucrose and its hexose components glucose and fructose are very suitable carbohydrate sources for hymenopteran parasitoids and show that parasitoid survival on an equimolar solution of the two monosaccharides glucose and fructose does not exceed performance on the disaccharide sucrose. [ABSTRACT FROM AUTHOR]

In response to herbivory by insects, several plant species have been shown to produce volatiles that attract the natural enemies of those herbivores. Using a Y-tube olfactometer, we investigated responses of the aphid parasitoid Diaeretiella rapae MacIntosh (Hymenoptera: Aphidiidae) to volatiles from Arabidopsis thaliana Columbia (Brassicaceae) plants that were either undamaged, infested by the peach-potato aphid, Myzus persicae Sulzer (Homoptera: Aphididae), or mechanically damaged, as well as to volatiles from just the aphid or its honeydew. In dual-choice experiments, female D. rapae given oviposition experience on A. thaliana infested with M. persicae were significantly attracted to volatiles from A. thaliana infested with M. persicae over volatiles from undamaged A. thaliana and similarly were significantly attracted to plants that had been previously infested by M. persicae, but from which the aphids were removed, over undamaged plants. Diaeretiella rapae did not respond to volatiles from M. persicae alone, their honeydew, or plants mechanically damaged with either a pin or scissors. We conclude that an interaction between the plant and the aphid induces A. thaliana to produce volatiles, which D. rapae can learn and respond to. Poor responses of D. rapae to volatiles from an A. thaliana plant that had two leaves infested with M. persicae, with the two infested leaves being removed before testing, suggested the possibility that, at this stage of infestation, the majority of volatile production induced by M. persicae may be localized to the infested tissues of the plant. We conclude that this tritrophic interaction is a suitable model system for future investigations of the biochemical pathways involved in the production of aphid-induced volatiles attractive to natural enemies. [ABSTRACT FROM AUTHOR]

In studies of foraging behaviour in a multitrophic context, the fourth trophic level has generally been ignored. We used four aphid hyperparasitoid species:Dendrocerus carpenteri(Curtis) (Hymenoptera: Megaspilidae),Asaphes suspensusWalker (Hymenoptera: Pteromalidae),Alloxysta victrix(Westwood) (Hymenoptera: Alloxystidae) andSyrphophagus aphidivorus(Mayr) (Hymenoptera: Encyrtidae), to correlate their response to different cues with their ecological attributes such as host range and host stage. In addition, we compared our results with studies of primary parasitoids on the same plant–herbivore system. First, the olfactory response of females was tested in a Y-tube olfactometer (single choice: plant, aphid, honeydew, parasitised aphid, aphid mummy, or virgin female parasitoid; dual choice: clean plant, plant with aphids, or plant–host complex). Second, their foraging behaviour was described on plants with different stimuli (honeydew, aphids, parasitised aphids, and aphid mummies). The results indicated that olfactory cues are probably not essential cues for hyperparasitoid females. In foraging behaviour on the plant, all species prolonged their total visit time and search time as compared to the control treatment (clean plant). OnlyA. victrixdid not react to the honeydew. Oviposition in mummies prolonged the total visit time because of the long handling time, but the effect of this behaviour on search time could not be determined. No clear correlation between foraging behaviour and host stage or host range was found. In contrast to specialised primary aphid parasitoids that have strong fixed responses to specific kairomones and herbivore-induced synomones, more generalist aphid hyperparasitoids seem to depend less on volatile olfactory stimuli, but show similarities with primary parasitoids in their use of contact cues while searching on a plant. [ABSTRACT FROM AUTHOR]

Host feeding is the consumption of host tissue by the adult female parasitoid. We studied the function of destructive host feeding and its advantage over non-destructive feeding on host-derived honeydew in the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae). We allowed parasitoids to oviposit until they attempted to host feed. We either prevented or allowed host feeding. Parasitoids had access to sucrose solution, with or without additional access to honeydew. Parasitoids that were allowed to host feed did not have a higher egg load 20 or 48 h after host feeding than parasitoids prevented from host feeding. Host feeding did not increase the number of eggs matured within these periods, nor did the time spent host feeding positively affect any of these response variables. On the other hand, the presence of honeydew did have a positive effect on egg load 20 and 48 h after host feeding compared with parasitoids deprived of honeydew. Parasitoids with access to honeydew matured more eggs within these periods than honeydew-deprived parasitoids. Host feeding increased life expectancy, but this effect was nullified when honeydew was supplied after the host-feeding attempt. In conclusion, feeding on honeydew could be an advantageous alternative to host feeding in terms of egg quantity and longevity. This applies especially to parasitoids exploiting Homoptera, because these parasitoids can obtain honeydew from the host itself. It is possible that destructive host feeding has evolved to enable females to sustain the production of high-quality anhydropic eggs, which may be important in the parasitoid's natural environment. We argue that future studies should take natural alternative food sources into more consideration. [ABSTRACT FROM AUTHOR]

Female adults of the aphidopagous gall midge, Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae), showed an olfactory response to honeydew excreted by the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae) under laboratory conditions. The response was only elicited by treatments with honeydew, whereas aphids, aphids with pepper plants or leaves, and pepper plants or leaves were not attractive to the midges. Dose-dependent responses were observed from whole honeydew, honeydew volatiles extracted in pentane, and honeydew volatiles captured on Porapak Q®. When honeydew was eluted with three sequential pentane washes, a positive response was only observed from the midges for the first wash. Female midges laid more eggs on pepper plants infested with higher densities of M. persicae. The olfactory response of midges to honeydew is discussed with respect to prey location. [ABSTRACT FROM AUTHOR]

An earlier study showed that two phytoseiid species, Euseius scutalis (Athias-Henriot) and Typhlodromips swirskii (Athias-Henriot) (Acari: Phytoseiidae), are capable of suppressing populations of Bemisia tabaci (Gennadius) (Hemiptera: Aleurodidae) on isolated cucumber plants supplied with Typha latifolia L. pollen. However, the predators did not exterminate their prey, and this may be caused by the existence of invulnerable B. tabaci stages. Little is known of the differential vulnerability of the immature B. tabaci stages. Here, we quantified their vulnerability by assessing the rate of predation on each of the immature stages when offered alone at a density high enough to allow for a maximal predation rate. All immature stages of B. tabaci were vulnerable to predation by each of the two predator species. However, the per capita predation rates, the oviposition rates of phytoseiids, as well as the percentage of predators feeding and the percentage ovipositing decreased with increasing stages of B. tabaci. Compared to that of eggs and 1st instars, the vulnerability of 2nd and later B. tabaci instars is an order of magnitude lower. To investigate how the presence of alternative food changes the rates of predation, we added pollen to a diet of 1st instars, one of the most vulnerable instars. This resulted in a decrease in the predation rate of E. scutalis, but not of T. swirskii, while the oviposition rate of both phytoseiid species remained equally high. The decreased predation of the 1st instars probably resulted from E. scutalis switching to pollen feeding. [ABSTRACT FROM AUTHOR]