Resistance to Melanaphis sacchari in the sugarcane cultivar R 365

This study focuses on the resistance of sugarcane, Saccharum spec. (Poaceae), to the sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), which vectors Sugarcane yellow leaf virus (SCYLV). Resistance was characterized in cultivar R 365, using a 3‐year field trial and laboratory experiments on potted plantlets and excised leaves. R 365 reduced aphid populations in the field by antixenosis and antibiosis. Using the electrical penetration graph technique, we detected delayed aphid salivation in phloem and inhibition of passive phloem sap uptake in R 365. The resistance factors also proved to be effective against the corn leaf aphid, Rhopalosiphum maidis (Fitch) (Hemiptera: Aphididae), another vector of SCYLV.     

New alien insect pests to Portugal on urban ornamental plants and additional data on recently introduced species

The spread of invasive pests is an important topic in pest control and early detection is crucial for containment of invasive aliens. In this study the results of recent surveys on alien insects of ornamental urban plants in Portugal are reported. Overall, 13 alien species associated with allochthonous ornamental plants were recorded. Seven of these pests are new to the Portuguese fauna: Tinocallis kahawaluokalani (Kirkaldy); Illinoia liriodendri (Monell); Appendiseta robiniae (Gillette) (Hemiptera: Aphididae); Acizzia jamatonica (Kuwayama) (Hemiptera: Psyllidae); Dasineura gleditchiae (Osten Sacken); Obolodiplosis robiniae (Haldeman) (Diptera: Cecidomyiidae); and Phytoliriomyza jacarandae Steyskal & Spencer (Diptera: Agromyzidae). Additional distribution data are also provided for other recently introduced alien pests in Portugal: Myzocallis (Lineomyzocallis) walshii (Monell) (Hemiptera: Aphididae); Platycorypha nigrivirga Burckhardt; Glycaspis brimblecombei Moore (Hemiptera: Psyllidae); Calophya schini Tuthill (Hemiptera: Calophyidae); Corythucha ciliata (Say) (Hemiptera: Tingidae); and Lantanophaga pusillidactylus (Walker) (Lepidoptera: Pterophoridae). Three species in particular (Illinoia liriodendri, Obolodiplosis robiniae and Phytoliriomyza jacarandae) were not previously found in the Iberian Peninsula. Details on current distribution, host plants and biological remarks are given for each species. Possible origin areas, pathways and impacts are also discussed.     

Unique haplotypes in ant‐attended aphids and widespread haplotypes in non‐attended aphids

Aphid species within the genus Tuberculatus Mordvilko (Hemiptera: Aphididae) exhibit a variety of interactions with ants, ranging from close associations to non‐attendance. A previous study indicated that despite wing possession, ant‐attended Tuberculatus species exhibited low dispersal rates compared with non‐attended species. This study examined if presence or absence of mutualistic interactions and habitat continuity of host plants affected intraspecific genetic diversity and genetic differentiation in mitochondrial DNA cytochrome oxidase I (COI) sequences. Sympatric ant‐attended Tuberculatus quercicola (Matsumura) (Hemiptera: Aphididae) and non‐attended Tuberculatus paiki Hille Ris Lambers (Hemiptera: Aphididae) were collected from the daimyo oak Quercus dentata Thunberg (Fagales: Fagaceae) in Japan and examined for haplotype variability. Seventeen haplotypes were identified in 568 T. quercicola individuals representing 23 populations and seven haplotypes in 425 T. paiki representing 19 populations. Haplotype diversity, which indicates the mean number of differences between all pairs of haplotypes in the sample, and nucleotide diversity were higher in T. quercicola than T. paiki. Analysis of molecular variance (AMOVA) showed higher genetic differentiation among populations within groups of T. quercicola (39.8%) than T. paiki (22.6%). The effects of attendant ant species on genetic differentiation in T. quercicola were not distinguishable from geographic factors. Despite low dispersal rates, host plant habitat continuity might facilitate widespread dispersal of a T. quercicola haplotype in Hokkaido. These results suggested that following T. quercicola colonization, gene flow among populations was limited, resulting in genetic drift within populations. However, frequent T. paiki dispersal is clearly evident by low genetic differentiation among populations within groups, resulting in lower haplotype diversity.     

Partial characterization of the X chromosome of Diuraphis noxia (Hemiptera: Aphididae)

We present the first sequencing results after separation of the X chromosome of Diuraphis noxia (Kurdjumov) (Hemiptera: Aphididae), the largest known X chromosome described to date, using flow cytometry. The X chromosome of D. noxia is 0.1824 pg (1C) and an estimated 178.4 Mb (1C) in size. Mapping confirmed that the X chromosome contains 13,799 protein coding genes, but with a slight bias towards GC richness when compared to the complete D. noxia genome.     

The influence of cultivar and cultivar-aphid odours on the olfactory response of the parasitoid Aphidius colemani

The olfactory response of the parasitoid Aphidius colemani (Viereck) (Hymenoptera: Braconidae) to odours in a tritrophic system involving three cultivars of common cabbage, Brassica oleracea var capitata, characterized by different levels of susceptibility to Myzus persicae (Sulzer) (Hemiptera: Aphididae) was studied in a four‐way olfactometer. Odours influenced A. colemani response in the olfactometer to varying degrees. The magnitude of parasitoid response to odours of uninfested cabbage depended on cultivar, with Derby Day [green‐leaved, susceptible to M. persicae and the crucifer specialist, Brevicoryne brassicae (Linnaeus) (Hemiptera: Aphididae)] and Minicole (green‐leaved, partially resistant with known antibiosis factors for B. brassicae) preferred over Ruby Ball (red‐leaved with antixenosis factors for M. persicae and B. brassicae). The odour of the cabbage cultivar on which the parasitoid had been reared was preferred over the other cultivars. However, when provided with a choice between odours of infested plants, parasitoids did not show a significant preference for the cultivar on which they were reared. Results from the study show that parasitioids differentiated between odour of the three cultivars in dependence of their rearing history when the plant is uninfested.     

Soil seed densities and emergence patterns in pastures in the seasonally dry tropics of northeastern Australia

Germinable seed densities in the surface (0–10 cm) soil of pasture communities growing at Lansdown, near Townsville, were measured during the late dry season before the first germinating rain and again during the following wet season after germination but before the input of new seed. Seedlings emerging in the field were counted at approximately weekly intervals during this period to determine emergence patterns. Twelve communities were sampled in 1980–81 and six were re-sampled in 1981–82. During the late dry season germinable seed densities ranged from 5000 to 40 000 seeds m^-2. Seeds of the introduced legume, Stylosanthes hamata, were present in all pastures. There were many seeds of annual grasses (Digitaria ciliaris and Brachiaria miliiformis) and sedges (Cyperus and Fimbristylis spp.) but only few seeds of perennial grasses (both native and introduced). Soil seed densities were much lower during the wet season than during the preceding dry season, particularly for the grasses. Emergence commenced and approximately 70% of all seedlings emerged on the first major rainfall of the wet season. The subsequent emergence pattern varied between years. In 1980–81 there was a gradual and continuous increase in seedling numbers under the continuously moist conditions which prevailed. In 1981–82 further emergence occurred in discrete events related to rainfall and intervening dry periods. Maximum seedling densities exceeded 34 000 seedlings m^-2 including 29 000 grass seedlings (mainly annual species). The implications of these results for species survival and pasture composition are discussed.     

Flowers for better pest control? The effects of apple orchard ground cover management on green apple aphids (Aphis spp.) (Hemiptera: Aphididae), their predators and the canopy insect community

Effects of habitat diversification through ground cover management on green apple aphids (Aphis spp.) (Hemiptera: Aphididae), woolly apple aphid (Eriosoma lanigerum [Haussmann]) (Hemiptera: Aphididae), their insect natural enemies and the most abundant canopy insects (in the Neuroptera, Fulgoromorpha, Cicadomorpha, Heteroptera, Coleoptera and Formicidae) were studied in an apple orchard over 6 years. The composition and diversity of the main functional groups of canopy insects was also compared. Habitat diversification was achieved by changing ground cover conditions within the orchard. In the treatment termed FLOWER, annual and/or perennial flowering plants were sown in the alleys of an apple orchard. Other ground cover treatments were weed-free bare ground (termed BAREgr) and orchard plots with alleys of mowed grass (termed GRASS), which served as control treatments. We found no evidence that habitat diversification enhanced the biological control of green apple aphids compared to the control treatments. However, the greater plant cover in FLOWER resulted in increased woolly apple aphid infestations compared to BAREgr or GRASS. The abundance of various beneficial or neutral canopy insects – Chrysoperla carnea sensu lato (Neuroptera, Chrysopidae) adults, leafhoppers and treehoppers, planthoppers, herbivorous (non-apple feeding) beetles, dipterans and parasitoid wasps – also increased in FLOWER as compared to BAREgr, with GRASS being intermediate between the other treatments. Significantly greater species richness and diversity was found in FLOWER than in BAREgr for most of the functional groups sampled, although the number of predacious insect species was similar among treatments. The composition of the studied functional groups showed high similarity in FLOWER and GRASS, but these treatments were different from BAREgr. Effects of groundcover management on the dominant insect species are discussed.     

Effect of fire regime on plant abundance in a tropical eucalypt savanna of north‐eastern Australia

Abstract Changes in plant abundance within a eucalypt savanna of north‐eastern Australia were studied using a manipulative fire experiment. Three fire regimes were compared between 1997 and 2001: (i) control, savanna burnt in the mid‐dry season (July) 1997 only; (ii) early burnt, savanna burnt in the mid‐dry season 1997 and early dry season (May) 1999; and (iii) late burnt, savanna burnt in the mid‐dry season 1997 and late dry season (October) 1999. Five annual surveys of permanent plots detected stability in the abundance of most species, irrespective of fire regime. However, a significant increase in the abundance of several subshrubs, ephemeral and twining perennial forbs, and grasses occurred in the first year after fire, particularly after late dry season fires. The abundance of these species declined toward prefire levels in the second year after fire. The dominant grass Heteropogon triticeus significantly declined in abundance with fire intervals of 4 years. The density of trees (>2 m tall) significantly increased in the absence of fire for 4 years, because of the growth of saplings; and the basal area of the dominant tree Corymbia clarksoniana significantly increased over the 5‐year study, irrespective of fire regime. Conservation management of these savannas will need to balance the role of regular fires in maintaining the diversity of herbaceous species with the requirement of fire intervals of at least 4‐years for allowing the growth of saplings >2 m in height. Whereas late dry season fires may cause some tree mortality, the use of occasional late fires may help maintain sustainable populations of many grasses and forbs.     

Field overwintering biology of Spiroplasma kunkelii (Mycoplasmatales: Spiroplasmataceae) and its vector Dalbulus maidis (Hemiptera: Cicadellidae)

We studied the corn stunt spiroplasma (CSS), Spiroplasma kunkelii (Mycoplasmatales: Spiroplasmataceae) and its vector the corn leafhopper Dalbulus maidis (Hemiptera: Cicadellidae) under field conditions in Mexico. We surveyed for the presence of CSS in D. maidis by using PCR on samples of adults collected during the 2000–01 and 2003–04 winter (dry) seasons from irrigated low‐elevation sites and un‐irrigated high‐elevation sites. Also, we determined the body size and number of mature eggs of D. maidis females collected during the dry season in 2004 and in females collected on maize seedlings in the first months (June and July) of the wet (summer) season in 2005. Our PCR results showed that CSS was present in leafhopper adults collected during the 2000–01 and 2003–04 dry seasons in irrigated low‐elevation sites. However, in un‐irrigated high‐elevation sites, CSS was present in corn leafhopper adults caught before, but not during, the dry seasons. In these un‐irrigated high‐elevation sites, adult leafhoppers without CSS were recovered during the first 2 months (November and December) of the dry season from the foliage of wild perennial grasses. Females collected on wild perennial grasses in December 2004 showed similar head width and wing length to females caught on maize seedlings in June 2005. However, females collected on maize seedlings in July 2005 had the widest heads, longest wings and highest number of mature eggs. The largest body size of these females that arrived in July 2005 indicates that they are immigrants and support the Roff’s hypothesis that insect migrants should be larger than nonmigrants.     

Patch residence decisions made by Aphidius colemani in the presence of a facultative predator

One of the key questions in ecology is how animals optimally allocate their time in an environment with patchily distributed resources and competing organisms. Here we investigate the effects that an aphid predator, Macrolophus caliginosus (Wagner) (Hemiptera: Miridae), has on the searching behavior and the patch residence decisions of an aphid parasitoid, Aphidius colemani (Viereck) (Hymenoptera: Aphidiidae). A computer programme was designed that allowed the recording and saving of direct observations. The time allocated to different activities by a female parasitoid wasp in the presence or absence of the predator M. caliginosus was investigated. The experiments were conducted under controlled environment conditions using leaves of sweet pepper, Capsicum annuum L. (Solanaceae) and Myzus persicae (Sulzer) (Hemiptera: Aphididae) as the host plant–prey species system. The parasitoid spent significantly less time on ‘secondary’ activities, such as preening and resting, when the predator was present. Survival analysis showed that the parasitoid had a higher patch-leaving tendency when the predator was present.     

Dispersal of aphids, whiteflies and their natural enemies under photoselective nets

Integrated Pest Management of insects includes several control tactics, such as the use of photoselective nets, which may reduce the flight activity of insects. Limiting the dispersal of pests such as aphids and whiteflies is important because of their major role as vectors of plant viruses, while a minor impact on natural enemies is desired. In this study, we examined for the first time the dispersal ability of three vector species, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), Macrosiphum euphorbiae (Thomas) (Hemiptera: Aphididae) and Myzus persicae (Sulzer) (Hemiptera: Aphididae), in cages covered with photoselective nets. Contrary to the results obtained with aphids, the ability of the whitefly B. tabaci, to reach the target plant was reduced by photoselective nets. In a second set of experiments, the impact of UV-absorbing nets on the visual cues of two important predator species, Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae), was evaluated. The anthocorid was caught in higher numbers in traps placed under regular nets, whereas the mites preferably chose environments in which the UV radiation was attenuated. We have observed a wide range of effects that impedes generalization, although photoselective nets have a positive effect on pest management of whiteflies and aphids under protected environments.     

Olfactory response by the aphidophagous gall midge, Aphidoletes aphidimyza to honeydew from green peach aphid, Myzus persicae

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.     

Mating or ovipositing? A crucial decision in the life history of the cabbage aphid parasitoid Diaeretiella rapae (M’Intosh)

1. The reproductive fitness of a parasitoid depends on its mating and ovipositing success. Virgin haplodiploid females can reproduce, but produce only males, and may diminish fitness by producing more male offspring than required. Therefore, females must decide on whether to mate or oviposit first. 2. This study was conducted to assess the mating versus ovipositing decision and its impact on the reproductive fitness of Diaeretiella rapae (Hymenoptera: Aphididae), an endoparasitoid of the cabbage aphid Brevicoryne brassicae (Hemiptera: Aphididae). 3. When newly emerged females were given a choice between mating and ovipositing, about 62% of D. rapae females preferred to mate before ovipositing. Those females who oviposited before mating parasitised only 10% of the available aphids. After mating, females superparasitised their hosts with fertilised eggs, which resulted in a highly female‐biased sex ratio in the offspring. 4. Mating success was very high (91%) in the presence of hosts (cabbage aphid nymphs) compared with that in the absence of aphids. However, mating success was not influenced by the quality (size) of the hosts present in the mating arena, despite a parasitoid preference for larger hosts during oviposition. The time between pairing and mating was also shorter in the presence of host aphids. The mean number of aphids parasitised and the parasitism rate were significantly greater after mating.     

Feeding behaviour of the staphylinid beetle Tachyporus hypnorum in relation to its potential for reducing aphid numbers in wheat

Aphid consumption by larval and adult Tachyporus hypnorum (Coleoptera: Staphylinidae) in different reproductive states was compared under laboratory conditions. Post-overwintering (spring/summer) adults had a higher consumption rate of first/second instar Sitobion avenae (Hemiptera: Aphididae) than did overwintering adults. Choice experiments incorporating Isotoma viridis (Collembola: Isotomidae) and Sciara thomae (Diptera: Mycetophilidae) as alternative prey items showed that T. hypnorum had a strong preference for aphids at a range of prey frequencies. Numbers of aphids consumed were reduced when leaves infected with Erysiphe graminis f.sp. tritici (powdery mildew of wheat) were offered to beetles with aphids in choice experiments. Behavioural studies of adult T. hypnorum showed that foraging rates on wheat plants increased with increasing amounts of both mildew and aphids on plants. Feeding upon only the conidia of E. graminis was observed. Results are discussed in relation to previous data derived from gut dissection, to a field survey of alternative foods and to the phenology of T. hypnorum in relation to that of aphids in the wheat crop.     

New structure in cell puncture activities by aphid stylets: a dual‐mode EPG study

Intracellular punctures by aphid stylets appear as potential drop (pd) waveforms in DC electrical penetration graph (EPG) recordings. We used a dual‐EPG device that recorded in one channel the ‘full EPG’ with R‐plus emf‐components (i.e., the usual DC EPG) and concurrently in a second channel the ‘R‐EPG’ with R‐components only. The circuit of the latter channel was an optimised amplitude modulation (AM) version derived from early (before 1990) AC systems. We also made some ‘emf‐EPG’ recordings using a separate high input resistance ‘emf‐amplifier’ sensitive to emf‐components only. The intracellular pd waveforms have previously been divided into three subphases, and we aimed to distinguish and separate these subphases more accurately by the dual‐EPG recordings than with the normal full EPG only. In this study, we temporarily distinguished five subphases (α–ε), but unequivocal distinction of only a few of these appeared possible, in spite of the information coming from the two signals. The lack of clearly separable features in R‐EPG signals often provided serious difficulties in pd recognition without the concurrent full EPG, but once located, only subphase II‐2 features were clear and supported the II‐2 data from the full EPG. Consequently, we could not distinguish subphases of complete pd waveforms better with additional R‐EPG information during cell punctures by Aphis gossypii Glover (Hemiptera: Aphididae). In Brevicoryne brassicae (L.) (Hemiptera: Aphididae), however, distinguishing II‐2 subphases in the full EPG was sometimes a problem. Our detailed dual‐EPG observations showed some waveform continuity from halfway into the II‐1 subphase (start of the newly recognised subphase β) until the end of the pd, with a strong but variable emf origin. This waveform tended to overrule other subphase waveforms in B. brassicae more than in A. gossypii and Myzus persicae (Sulzer) (Hemiptera: Aphididae). Subphase waveforms in full EPGs were especially difficult to recognise when pd periods had been interrupted in a virus inoculation experiment and additional R‐EPG information could then be useful. This inoculation experiment showed again that only the first subphase (II‐1) contributes to virus (Cucumber mosaic virus) inoculation by A. gossypii. In B. brassicae, the benefit of concurrent R‐EPG information in such virus experiments is presently under further investigation. Apart from this special application to virus experiments, we do not recommend the routine use of the dual‐EPG device. Furthermore, we do not advocate the distinction of more than the previously recognised three intracellular pd subphases as a feasible option in future studies. Analysis of EPGs with concurrent R‐EPGs requires substantially more analysis work without yielding consistently useful additional insights. This confirms earlier dual‐EPG results from thrips.     

Functional responses of aphid parasitoids,Aphidius colemani (Hymenoptera: Braconidae) and Aphelinus asychis (Hymenoptera: Aphelinidae)

We evaluated the functional responses of two aphid parasitoids: Aphidius colemani on the green peach aphid Myzus persicae (Hemiptera: Aphididae), and Aphelinus asychis on M. persicae and the potato aphid, Macrosiphum euphorbiae (Hemiptera: Aphididae). Parasitoid oviposition occurred at host densities of 5, 10, 20, 30, 50, 80 or 100 aphids for A. colemani and 5, 10, 20, 30 or 50 aphids for A. asychis. More M. persicae were parasitized by A. colemani than by A. asychis at an aphid density of 50. Among the three types of functional response, type III best described the parasitoid response to the host densities both in A. colemani and A. asychis. The estimated handling time was shorter for A. colemani than for A. asychis (0.017 and 0.043 d, respectively). The proportion of aphids that were parasitized exhibited the same characteristic curve among the three host-parasitoid combinations: a wave form that appeared to be a composite of a decelerating (as in type II) response at low host density and an accelerating-and-decelerating (as in type III) response at medium to high host density. We hypothesize that the novel host species (and its host plant), density-dependent superparasitism, and/or density-dependent host-killing may have induced the modified type III response.     

Laboratory and field tests of predation on the cereal leaf beetle,Oulema melanopus (Coleoptera: Chrysomelidae)

The cereal leaf beetle (CLB), Oulema melanopus (L.) (Coleoptera: Chrysomelidae), is an invasive pest in North America recently reported in the Canadian Prairies. We performed a series of laboratory assays to identify potential predators and a field study to quantify predation of CLB eggs. In no-choice Petri dish assays, ground beetles (Carabidae), rove beetles (Staphylinidae), and several common lady beetle species (Coccinellidae) were the most consistent predators of eggs and larvae. Nabis spp. (Hemiptera: Nabidae) and wolf spiders (Araneae: Lycosidae) consumed many larvae, but did not consume eggs. Hippodamia spp., Coccinella septempunctata (L.) (Coleoptera: Coccinellidae), and Pterostichus melanarius (Illiger) (Coleoptera: Carabidae) also fed on CLB eggs on potted plants when an alternative food source was available, Sitobion avenae (Fabricius) (Hemiptera: Aphididae). In our field study, we found an average of 24.5% of sentinel eggs disappeared over a 24?h period, likely due to predation. Our results suggest that generalist predators can play an important role in the biological control of CLB, and warrant further study.     

Genetic population structure of sugarcane aphid,Melanaphis sacchari,in sorghum,sugarcane, and Johnsongrass in the continental USA

In 2013, an outbreak of Melanaphis sacchari Zehntner (Hemiptera: Aphididae) was reported in sorghum in Texas, USA. Although this aphid has been reported in the continental USA for nearly a century, its occurrence was limited to Florida and Louisiana sugarcane. After 2013 and within just 3 years M. sacchari was reported in almost all sorghum growing regions from south central to southeastern states in the USA. Sorghum fields in affected areas have sustained considerable losses. This aphid has also been reported on Johnsongrass and other feral grasses. The speed at which this aphid has spread raises serious concerns about future infestations. Many aphid species present genetically distinct populations when feeding on different host plants. Thus, it was hypothesized that the recent outbreak in sorghum could be explained by a recent introduction of a sorghum‐specialized genotype. In this study, we genetically characterized M. sacchari in three of its most common host plants – sorghum, sugarcane, and Johnsongrass – across its geographic distribution in the continental USA. Although M. sacchari specimens were grouped within three genetically distinct clusters, we did not find evidence of host plant or geographic population structure. Our characterization of the genetic structure of this pest provides baseline data aimed to help explain its recent outbreak in sorghum, as well as information that may aid in the design of sustainable control strategies.     

Effect of host plant,prey species and intergenerational changes on the prey preferences of the predatory mirid <Emphasis Type="Italic">Macrolophus caliginosus</Emphasis>

The outdoor establishment of non-native biocontrol agents released for inundative control of glasshouse pests is determined primarily by two factors: ecophysiological compatibility with local climate, particularly winter cold tolerance, and ability to locate and utilise wild prey. Observations on the number and diversity of acceptable wild prey as part of an assessment of establishment potential therefore overlap with more focused studies to determine host range. This study investigated two aspects of the interactions between biocontrol agents and non-target prey that are rarely considered in tests for establishment or host range: the role of different host plant–prey associations in modifying the development and reproduction of biocontrol agents, and the longer term sustainability of such relationships beyond the single generation observed in most laboratory studies. Using the glasshouse whitefly (Trialeurodes vaporariorum) predator Macrolophus caliginosus Wagner (Hemiptera: Miridae) as a case study, the mirid was able to sustain viable populations over three generations on the related cabbage whitefly Aleyrodes proletella (Linnaeus) (Hemiptera: Aleyrodidae) and the aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae), including when these prey were feeding on different host plants (Chinese cabbage, cabbage and Brussels sprout). However, the rate of development, fecundity and mortality of the predator varied between the different prey and host plant combinations, and in all cases differed than when feeding on its glasshouse prey T. vaporariorum reared on tobacco (Nicotiana tabacum). The results are discussed in the light of the current debate on methods for conducting host range testing as part of an environmental risk assessment. Handling Editor: Dirk Babendreier     

Relative contribution of rainfall and coconut hybrids to the abundance and composition of the Auchenorrhyncha community as potential vectors of phytoplasmas in the state of Sergipe,Brazil

相似文献