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Plants under attack by aboveground herbivores emit complex blends of volatile organic compounds (VOCs). Specific compounds in these blends are used by parasitic wasps to find their hosts. Belowground induction causes shifts in the composition of aboveground induced VOC blends, which affect the preference of parasitic wasps. To identify which of the many volatiles in the complex VOC blends may explain parasitoid preference poses a challenge to ecologists. Here, we present a case study in which we use a novel bioinformatics approach to identify biologically relevant differences between VOC blends of feral cabbage (Brassica oleracea L.). The plants were induced aboveground or belowground with jasmonic acid (JA) and shoot feeding caterpillars (Pieris brassicae or P. rapae). We used Partial Least Squares--Discriminant Analysis (PLSDA) to integrate and visualize the relation between plant-emitted VOCs and the preference of female Cotesia glomerata. Overall, female wasps preferred JA-induced plants over controls, but they strongly preferred aboveground JA-induced plants over belowground JA-induced plants. PLSDA revealed that the emission of several monoterpenes was enhanced similarly in all JA-treated plants, whereas homoterpenes and sesquiterpenes increased exclusively in aboveground JA-induced plants. Wasps may use the ratio between these two classes of terpenes to discriminate between aboveground and belowground induced plants. Additionally, it shows that aboveground applied JA induces different VOC biosynthetic pathways than JA applied to the root. Our bioinformatic approach, thus, successfully identified which VOCs matched the preferences of the wasps in the various choice tests. Additionally, the analysis generated novel hypotheses about the role of JA as a signaling compound in aboveground and belowground induced responses in plants.

The sweetpotato whitefly, Bemisia tabaci, is a cryptic species complex composed of more than 24 different biotypes around the world. The Q biotype of B. tabaci, which is thought to have originated in the Mediterranean Basin, is now a widespread and serious agricultural pest. In this study, the genetic differences among Q biotype populations from Mediterranean countries and China were investigated. Based on their mt COI gene sequences, the Q biotype populations could be divided into two groups, which were labelled as MedBasin 1 and MedBasin 2. MedBasin 1 is indigenous to the western Mediterranean area while MedBasin 2 is indigenous to the eastern Mediterranean area. Genetic variation was greater in the MedBasin 1 populations than in the MedBasin 2 populations. Unlike the introductions into the USA, which involved both Medbasin1 and MedBasin2 populations, all B. tabaci Q biotype populations in China belonged to MedBasin 1. Wolbachia detection in eight representative Q biotype populations from China, Egypt and Syria indicated that all of the populations were infested with Wolbachia, and the infection rate of the Chinese populations (42.5%) were not significantly different from that of Egypt and Syria (51.4%). Phylogenetic analysis indicated that the evolution of the Wolbachia populations was not closely linked with the evolution of their B. tabaci hosts.

Bemisia tabaci is a species complex, of which the B and Q biotypes are globally distributed. B. tabaci feeds on more than 600 plant species including cotton, which is one of the main crops in Pakistan. In this study, the biotypes/haplotypes of B. tabaci populations collected from cotton plants in Pakistan, China, and Egypt were identified, and their phylogenetic relationships were investigated. None of the populations from Pakistan or Egypt belonged to the B or Q biotype: all 16 samples from Pakistan belonged to haplotype “PCG-1” and it is a group of unresolved populations all from Pakistan, while all three populations from Egypt belonged to unresolved haplotype “ECG.” The three populations from China belonged to the B biotype. Phylogenetic analysis indicated that the PCG-1, ECG, and B biotypes clustered into different clades even though they share the same cotton plant species as their host. The association between the outbreaks of cotton leaf curl disease and the occurrence of the PCG haplotype of B. tabaci in Pakistan is discussed.

Bemisia tabaci (Gennadius) is a species complex, and its two most damaging biotypes B and Q are globally distributed pests. Despite increasing biological and economic impacts, little is known about the evolutionary mechanisms that favor their competition with native populations. Here, we investigated the genetic mutations in the P450 gene of the invasive B, Q biotypes and the native Cv population. Four mutations associated with chemical resistance, Pro-Leu, Ala-Ser, Ser-Phe and Trp-Leu, were found in the cytochrome P450 CYP6C and CYP9F genes of the B and Q biotypes. Bioassay results also revealed that both the B and Q biotypes have about 12–47 times more resistance to acephate, beta-cypermethrin, methomyl, and 5–7 times more resistance to imidacloprid insecticide than Cv population. Our results provide a molecular approach for better understanding and monitoring the pesticide resistances of invasive and native B. tabaci populations in China.

The sweet potato whitefly, Bemisia tabaci , is a complex species, and many of its biotypes are important agricultural pests. The B and Q biotypes are invasive and coexist with the native Cv biotype on vegetable and ornamental crops in China. In this study, these three biotypes were identified based on their morphological characteristics, RAPD–PCR analysis, and DNA sequences of the COI gene. The anterior and posterior wax fringes of the B, Q, and Cv biotypes significantly differed from each other. Based on this morphological characteristic, the three biotypes can easily be distinguished in greenhouses and fields. Genomic DNA RAPD–PCR band patterns also revealed differences between these biotypes using the H 16 primer. The B biotype has three bright DNA bands between 250 and 600 bp, the Q biotype only has one bright band at ∼300 bp, while the Cv biotype has no band between 250 and 500 bp. Both the Cv and Q biotypes have two bright bands at ∼750 and 1000 bp while the B biotype has only one band at ∼1000 bp. Based on the COI gene, the genetic identity between B and Cv, B and Q, and Q and CV was 85.8%, 94.7%, and 86.0%, respectively. The MP tree indicated that the phylogenetic relationship between the B and Q biotypes is much closer than that between the B and Cv or the Q and Cv biotypes. The uses of the morphological, RAPD–PCR, and DNA sequencing methods in biotype identification of B. tabaci are discussed.

Summary 1Plant species employ several direct and indirect defence strategies to protect themselves against insect herbivores. Most studies, however, have focused on shoot-induced responses. Much less is known about interactions between below- and above-ground herbivores and how these may affect their respective parasitoids. 2Here, we quantify the impact of below-ground induced responses vs. that of above-ground induced responses in a feral Brassica on the performance of Pieris brassicae and its endoparasitoid Cotesia glomerata. Jasmonic acid (JA) was applied to induce the plants above- or below-ground. The glucosinolate, sugar and amino acid levels of the leaves were analysed. 3Pieris brassicae larvae grew significantly slower on shoot JA-induced (SJA) plants than on root JA-induced (RJA) and control plants, which were treated with acidic water. On RJA and control plants they showed similar developmental trajectories. Pupal masses, survival till eclosion and egg load, however, were similar on all plants. 4The development of C. glomerata larvae on SJA plants was significantly longer than that on RJA and control plants. In contrast, the parasitoid's pupal stage lasted longer in hosts feeding on control plants. The total developmental times eventually were similar in all groups. However, the masses of male and female C. glomerata adults that developed hosts on control and RJA plants were significantly larger than those from hosts on SJA plants. JA application increased total glucosinolate contents and decreased the sugars and total amino acids levels independent of whether JA was applied. However, the trajectories of herbivore-induced glucosinolate levels differed between RJA and SJA plants. 5These results show that the differential effects of above- and below-ground-induced responses on herbivores also affect higher trophic levels in a nonlinear fashion via differential changes in host plant quality. In particular, the indirect effects that below-ground herbivores have on the performance of above-ground parasitoids may exceed the direct effects of plant chemistry on herbivore performance. Consequently, above-ground and below-ground interactions mediated by induced plant responses have the potential to mediate insect community structure and function in complex ways.

Trichogramma evanescens West. (Hymenoptera: Trichogrammatidae) and Copidosoma desantisi Annecke & Mynhardt (Hymenoptera: Encyrtidae) are potential parasitoids of the potato tuber moth (PTM), Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) in Egypt. Discrimination of a parasitized host from an unparasitized host would prevent wasting of time, eggs and reduce competition with conspecifics or heterospecifics. Therefore, we evaluated interspecific host discrimination, multiparasitism and intrinsic competition between the two wasp species. In a choice test, females of T. evanescens showed high interspecific host discrimination only when they were offered 2-day-old C. desantisi parasitized and unparasitized PTM eggs. In contrast, C. desantisi showed high host discrimination and preferred unparasitized eggs to PTM eggs harboring 2-h- or 2-day-old T. evanescens’ eggs. We also evaluated the effect of different introduction sequences on the efficacy of the two wasps. Dissection data indicated t...

We evaluated the potential for using infective juveniles of the entomopathogenic nematode Steinernema feltiae to control the sweetpotato whitefly Bemisia tabaci B biotype on cucumber, hibiscus, and collard, under greenhouse conditions. The effects of four adjuvants (PVA, glycerol, Triton X-100, and horticultural spraying oil) on the efficiency of Steinernema feltiae in B. tabaci control were also assessed because they might increase nematode survival by reducing desiccation. The mortality of B. tabaci nymphs increased by 18, 18, and 20% on collard, hibiscus, and cucumber plants when S. feltiae concentration increased from 5000 to 15,000 infective juveniles/mL. When treated with S. feltiae (10000 infective juveniles/mL), second instar nymphs suffered greater mortality than the other instars of B. tabaci, regardless of host plant species. Mortality of B. tabaci nymphs was higher on hibiscus than on collard and cucumber plants. The use of adjuvants greatly increased infection of B. tabaci by S. feltiae. The ...

The search time of Encarsia bimaculata Heraty et Polaszek was examined and recorded by using filter paper discs in Petri dish arenas impregnated with Bemisia tabaci (Gennadius) honeydew or its component carbohydrates. Our data show that E. bimaculata used honeydew as a contact kairomone to locate its host. Females responded quantitatively to the honeydew and the search time in the treated patches increased. This increase was concentration-dependent with regard to the amount of honeydew applied, but it levelled off 0.05 g/ml onwards. The response of E. bimaculata to honeydew decreased with increasing time after application and was significantly reduced 8 days after treatment. The parasitoid females were also arrested in patches treated with glucose, fructose, trehalulose and trehalose; trehalose elicited the highest response in the parasitoids. However, sucrose and low concentrations of melezitose did not elicit a significant effect. Glucose, sucrose, fructose, trehalose and trehalulose increased the longevity of the parasitoid females by a factor of 8.4, 8.1, 6.3, 6.1 and 4.2, respectively. Melezitose and 0.15 g/ml natural honeydew, however, had no effect on parasitoid lifespan. The effects of aqueous spray of honeydew sugars on egg to adult survivorship and parasitization of B. tabaci by E. bimaculata significantly differed when compared with controls only in cases where mixtures of glucose + fructose and trehalose and fructose + trehalose were applied.

The host instar preferences of Encarsia bimaculata and Eretmocerus sp. nr. furuhashii parasitizing Bemisia tabaci and their development on four host plants, collard, eggplant, cucumber and tomato, were studied in the laboratory. Both of the parasitoids accepted all nymphal stages of B. tabaci, but E. bimaculata preferred third and fourth instars while Er. sp. nr. furuhashii preferred second and third instars under both choice and no choice conditions. Regardless of host stage parasitized, adults of parasitoids emerged only from fourth instars. When given the simultaneous choice of all instars, E. bimaculata reduced parasitization of first and second instars (3.73 and 4.76%, respectively) while increasing parasitization of third and fourth instars (5.44 and 6.93%, respectively), in contrast Er. sp. nr. furuhashii increased its parasitization of second and third instar nymphs (1.27 and 3.17%, respectively) and decreased that of first and fourth instars (7.0 and 3.06%, respectively). Host plants did...

Nymphal developmental periods and mortality of Bemisia tabaci when exposed to two parasitoids Encarsia bimaculata and Eretmocerus sp. nr. furuhashii at different nymphal stages were studied in the laboratory. Developmental periods of various nymphal instars were significantly delayed among instars when parasitized by E. bimaculata and Eretmocerus sp. nr. furuhashii. Developmental periods of 1st–4th nymphal instars when originally parasitized by E. bimaculata were 20.13, 19.19, 18.65 and 17.93 days, respectively. Developmental periods were protracted when instars were parasitized by Er. sp. nr. furushashii with values of 23.16, 21.37, 20.76 and 20.31 days. However, averaged developmental periods of B. tabaci immatures without parasitism were 14.10 days. Mortalities of B. tabaci immatures were significantly different among instars when parasitized by E. bimaculata or Er. sp. nr. furuhashii. Mortality was highest at the 3rd instar and lowest at the 1st instar when parasitized by E. bimaculata, whereas when p...

Eretmocerus sp. nr. furuhashii (Hymenoptera: Aphelinidae) is an indigenous parasitoid of Bemisia tabaci (Gennadius)(Hemiptera: Aleyrodidae) from southern China; the effects of constant temperatures on the life history of E. sp. nr. furuhashii were examined in the laboratory. The developmental period ranged from 39.2 days at 20°C to 12.40 days at 32°C. A total of 263.4 degree-days were required to complete development with a lower developmental threshold temperature of 11.1°C. Of the eggs produced, 59.3% completed development at 20°C with completion increasing to 71.5% at 26°C. Adult female longevity was 10.8 days at 20°C and 5.2 days at 32°C while the mean daily offspring reproduced per female was highest at 29°C with 5.9 offspring. Adult oviposition peaked three days after emergence at 26, 29 and 32°C, and four days post-emergence at 20°C and 23°C. The total numbers of offspring produced per female ranged from 25.7 individuals at 32°C to 41.1 individuals at 20°C. The sex ratio had a female bias and ranged from 0.72 at 17°C to 0.51 at 35°C. The intrinsic rate of increase was 0.1727 at 29°C followed with 0.1606 at 32°C. Results indicated that E. sp. nr. furuhashii reaches its maximum biological potential at temperatures ranging from 26°C to 32°C.

The developmental, survivorship and reproductive biology of Eretmocerus sp. nr furuhashii Rose & Zolnerowich parasitizing Bemisia tabaci (Gennadius) biotype B on tomato, cucumber, eggplant and collard at 26±0.5°C was studied. The mean longevity ranged from 6.5 days on tomato to 8.1 days on collard. The mean lifetime fecundities on tomato, cucumber, eggplant and collard were 35.4, 37.3, 41.4 and 46.4 eggs, whereas the mean lifetime fertility was 20.2, 22.7, 28.3 and 33.6 offspring, respectively. Developmental time was longest on cucumber (17.1 days) and shortest on collard (15.9 days). Survival rates varied significantly across host plants. Sex ratio (♀:♂) varied from 1.71 to 1.93 across the four hosts. The intrinsic rate of increase (rm) was highest (0.157) on collard and lowest on tomato (0.133). Mean generation time (R0) ranged from 14.7 to 20.9 days. All the data demonstrated that the reproductive success and overall performance of E. sp. nr furuhashii increased as the density of leaf hairs declined. As leaf hairs play a key role in determining efficacy, it is unlikely that effective biological control of B. tabaci using E. sp. nr furuhashii will be achieved on non-glabrous crop varieties.

Field populations or strains of Propylaea japonica collected from four places in southern China (Guangzhou, Nanning, Guilin, and Yuxi) were tested for susceptibility to four insecticides (abamectin, imidacloprid, beta-cypermethrin, and chlorpyrifos) by the Petri-dish Potter tower method and compared with an insecticide-susceptible strain. Concentrations that proved lethal for 50% of the tested individuals (LC50) were estimated by probit analysis, and resistance factors (RF) were calculated at the LC50 level, which ranged from 1.6 to 10.1, depending on the insecticide. In addition, the Guangzhou strain formed the original population for imidacloprid resistance selection. After selection for 20 generations, the resistance had increased 39.3-fold. Fitness analysis in terms of such traits as fecundity, days to maturity, and survival showed that although both resistant and susceptible populations developed at comparable rates, the resistant strain was less fecund (it laid fewer eggs and a smaller proportion of those eggs hatched and resulted in adults), attaining a fitness score of only 0.56 relative to the susceptible strain. These observations suggest that it is possible to detect strains of P. japonica highly resistant to insecticides under laboratory conditions, and that resistance to imidacloprid carries considerable fitness costs to P. japonica. The study served to expand our understanding of the impact of imidacloprid resistance on biological parameters of P. japonica in more detail and to facilitate the deployment of natural enemies resistant to insecticides in integrated pest management.

Facultative bacterial endosymbionts are associated with many arthropods and are primarily transmitted vertically from mother to offspring. However, phylogenetic affiliations suggest that horizontal transmission must also occur. Such horizontal transfer can have important biological and agricultural consequences when endosymbionts increase host fitness. So far horizontal transmission is considered rare and has been difficult to document. Here, we use fluorescence in situ hybridization (FISH) and multi locus sequence typing (MLST) to reveal a potentially common pathway of horizontal transmission of endosymbionts via parasitoids of insects. We illustrate that the mouthparts and ovipositors of an aphelinid parasitoid become contaminated with Wolbachia when this wasp feeds on or probes Wolbachia-infected Bemisia tabaci AsiaII7, and non-lethal probing of uninfected B. tabaci AsiaII7 nymphs by parasitoids carrying Wolbachia resulted in newly and stably infected B. tabaci matrilines. After they were exposed to infected whitefly, the parasitoids were able to transmit Wolbachia efficiently for the following 48 h. Whitefly infected with Wolbachia by parasitoids had increased survival and reduced development times. Overall, our study provides evidence for the horizontal transmission of Wolbachia between insect hosts by parasitic wasps, and the enhanced survival and reproductive abilities of insect hosts may adversely affect biological control programs., Author Summary Vertically-transmitted facultative bacterial endosymbionts are common in invertebrates, and affect traits as diverse as the mode of sexual reproduction, speciation, and susceptibility to pathogens. Horizontal transmission of endosymbionts is thought to be infrequent in most species, and not to contribute to their spread through populations. Here we demonstrate that parasitoid wasps can act as vectors, transmitting the endosymbiont Wolbachia between whitefly hosts at a high rate. The ovipositors and mandibles of parasitoids can be contaminated with Wolbachia when probing infected whitefly. If these parasitoids then probe Wolbachia-free hosts and the whitefly survive, it will result in a stably infected line with increased fitness. Such vector-borne transmission may explain why endosymbionts are so widely distributed, and why genetically similar symbionts are often found in phylogenetically distant organisms.

The ladybird Propylaea japonica (Thunberg) is one of most important natural enemies of aphids in China. This species is threatened by the extensive use of insecticides but genomics-based information on the molecular mechanisms underlying insecticide resistance is limited. Hence, we analyzed the transcriptome and expression profile data of P. japonica in order to gain a deeper understanding of insecticide resistance in ladybirds. We performed de novo assembly of a transcriptome using Illumina's Solexa sequencing technology and short reads. A total of 27,243,552 reads were generated. These were assembled into 81,458 contigs and 33,647 unigenes (6,862 clusters and 26,785 singletons). Of the unigenes, 23,965 (71.22%) have putative homologues in the non-redundant (nr) protein database from NCBI, using BLASTX, with a cut-off E-value of 10(-5). We examined COG, GO and KEGG annotations to better understand the functions of these unigenes. Digital gene expression (DGE) libraries showed differences in gene expression profiles between two insecticide resistant strains. When compared with an insecticide susceptible profile, a total of 4,692 genes were significantly up- or down- regulated in a moderately resistant strain. Among these genes, 125 putative insecticide resistance genes were identified. To confirm the DGE results, 16 selected genes were validated using quantitative real time PCR (qRT-PCR). This study is the first to report genetic information on P. japonica and has greatly enriched the sequence data for ladybirds. The large number of gene sequences produced from the transcriptome and DGE sequencing will greatly improve our understanding of this important insect, at the molecular level, and could contribute to the in-depth research into insecticide resistance mechanisms.

Whitefly Bemisia tabaci is a globally distributed and most destructive pest to agriculture. Owing to increasing chemical resistance, a long-lasting strategy to manage this pest must involve biological control. Herbivore-induced plant volatiles (HIPVs) usually play a profoundly important role in the foraging behaviour of natural enemies. Here, the effects of HIPVs from Chinese broccoli on the foraging behaviour of two dominant natural enemy species of B. tabaci in China, Encarsia formosa and Serangium japonicum, were investigated using a four-arm olfactometer, and exogenous jasmonic acid (JA) was used to induce plant volatiles to mimic the damage of the herbivore pest.The parasitoid E. formosa was found to be more attracted by the volatiles from JA-induced broccoli than those from control plants. The residence times of E. formosa in the final-choice areas closed to volatiles from shoot JA (SJA)- and root JA (RJA)-induced plants were 119.8 ± 35.2 s and 99.8 ± 34.7 s respectively in the dual-choice experiments, and 123.8 ± 32.0 s and 102.3 ± 28.7 s respectively in the three-choice experiment. All are significantly longer than those spent in the final-choice area closed to volatiles from control plants (CON). JA-induced volatiles were also only a little more attractive to the predator S. japonicum. However, there was no significant difference between each of the two natural enemies in residence time spent in the final-choice areas closed to SJA, RJA or CON volatiles in both the dual- and three-choice experiments. Furthermore, the number of times that the parasitoid or predator entered the SJA, RJA and CON final-choice areas was not significantly different in any of the experiments.The present results indicate that RJA- and SJA-induced plant volatiles have higher efficiencies in attracting the natural enemies of whitefly B. tabaci. The attractive efficiencies varied according to the plant volatiles that JA induced, and also depended on the natural enemy species. The parasitoid E. formosa seems to be more sensitive to and attracted by the induced volatiles than the predator S. japonicum.

Bemisia tabaci is a cryptic species complex. In Pakistan, members of the complex, MEAM1 and AsiaII 1, are the predominant species infesting cotton. The biology of the two on cotton, collard, cucumber and tomato was studied.In all cases there were significant interactions between species and host. MEAM1 developmental periods did not differ significantly across hosts, whereas AsiaII 1 developed more slowly on vegetables than on cotton. MEAM1 survival was highest on tomato (53.5 ± 1.1%), while AsiaII 1 survived best on cotton (67.3 ± 11.6%). MEAM1 longevity and fecundity were highest on tomato (14.7 ± 1.7 days and 82.4 ± 9.9 eggs), while AsiaII 1 longevity and fecundity were highest on cotton (23.7 ± 2.5 days and 135.2 ± 13.6 eggs). The MEAM1 intrinsic rates of increase (r(m)) on cotton and vegetable were similar (0.08-0.10), whereas the AsiaII 1 r(m) on cotton (0.15) was higher than on vegetables (0.11-0.13). The biology of MEAM1 from Pakistan was compared with published studies; it had a consistently slower rate of development, lower percentage survival, lower adult longevity, longer generation time, lower net reproductive rate and lower r(m).MEAM1 performed similarly across all hosts, whereas AsiaII 1 performed better on cotton. The comparison between the Pakistani MEAM1 with published studies suggests that the invasive MEAM1 may have higher performance.

Plants employ both direct and indirect defenses to protect themselves from attacks by herbivores and pathogens. To date most aboveground and belowground interaction studies have focused on interactions between plants and leaf-chewing herbivores, while the plant defence on the performance of phloem-feeding insects, induced by above- and belowground interaction, has been less explored. Here, jasmonic acid (JA) was used to mimic herbivore-induced responses in Chinese broccoli ( Brassica oleracea var. alboglabra ) roots (RJA) and shoots (SJA). The effects of JA-induced plant defenses on the performance of the phloem-feeding whitefly, Bemisia tabaci , and its aphelinid parasitoid Encarsia formosa were investigated. The results indicated that SJA induction has a much larger negative effect on B. tabaci than RJA: nymphs develop slower and have a lower survivorship. Also, females live shorter and have a lower fecundity on SJA plants compared to those on RJA and untreated control (CON) plants. The intrinsic rate of increase ( r m ) of B. tabaci on SJA plants was 0.089, which was significantly lower than those on CON and RJA plants (0.115 and 0.104, respectively). The parasitoid E. formosa , on the other hand, shows a significantly faster development when parasitizing whitefly hosts feeding on SJA plants, whereas parasitism rate, longevity and fecundity were similar to those on RJA and CON plants. The current study reveals that plants induced with exogenous JA vary in both their resistance to whitefly and suitability for parasitoids, depending on the organ to which the JA was applied. Root and shoot JA applications also have contrasting effects on the phloem-feeding insect B. tabaci and its parasitoid, that is, SJA induction leads to more negative effects on whitefly performance than RJA induction, but its parasitoid performs better on hosts reared on SJA plants. These results show that top-down and bottom-up processes governing herbivore populations on Chinese broccoli are working in concert to increase plant resistance when plants are induced by SJA application.

Bemisia tabaci (Hemiptera: Aleyrodidae) is a globally distributed pest composed of at least 34 morphologically indistinguishable cryptic species. At least seven species of endosymbiont have been found infecting some or all members of the complex. The origin(s) of the associations between specific endosymbionts and their whitefly hosts is unknown. Infection is normally vertical, but horizontal transmission does occur and is one way for new infections to be introduced into individuals. The relationships between the different members of the cryptic species complex and the endosymbionts have not been well explored. In this study, the phylogenies of different cryptic species of the host with those of their endosymbionts were compared. Of particular interest was whether there was evidence for both coevolution and horizontal transmission. Congruence was observed for the primary endosymbiont, Portiera aleyrodidarum, and partial incongruence in the case of two secondary endosymbionts, Arsenophonus and Cardinium and incongruence for a third, Wolbachia. The patterns observed for the primary endosymbiont supported cospeciation with the host while the patterns for the secondary endosymbionts, and especially Wolbachia showed evidence of host shifts and extinctions through horizontal transmission rather than cospeciation. Of particular note is the observation of several very recent host shift events in China between exotic invader and indigenous members of the complex. These shifts were from indigenous members of the complex to the invader as well as from the invader to indigenous relatives.

Brevipalpus obovatus Donnadieu is an important pest mite on tea plants in South China. In the current study, predatory mites of B. obovatus in the tea gardens of Guangzhou were extensively surveyed. In total, 13 species of predatory mites (four families with seven genera) were recorded. The population proportion of Amblyseius hainanensis Wu et Qian was the highest (68.6 %), followed by that of Anystis baccarum (L.) (8.4 %) and A. theae Wu (6.3 %). The effects of starvation time, habitat size and pest population density on the predatory efficiency of the most dominant species, A. hainanensis, feeding on B. obovatus were assessed. In addition, the effectiveness of artificial rainfall in reducing B. obovatus populations was evaluated. After starvation for 48 h, the predatory efficiency of A. hainanensis was significantly higher than those that had been starved for 24 or 72 h when 30-50 B. obovatus eggs were made available. The predation of A. hainanensis on B. obovatus also increased with increasing prey density. The number of prey attacked by A. hainanensis in a 3.2 cm(2) habitat was significantly higher than in a 6.3 cm(2) habitat. The average predation of A. hainanensis was 31.7 eggs per day when offered 100 B. obovatus eggs on a tea leaf. This decreased to 17.8 eggs per day when four A. hainanensis shared 100 B. obovatus eggs. B. obovatus populations can be reduced by artificial rainfall, with the reduction affected by rainfall intensity. With an intensity of 40 mm in 15 min, 90.2 % mortality of B. obovatus occurred; lower mortalities were recorded (13.3 and 29.8 %) when the intensity was 2 or 4 mm in 15 min. Combination of the predatory mite A. hainanensis and artificial rainfall for the integrated pest management of B. obovatus is discussed.

Background The whitefly Bemisia tabaci is cryptic species complex composed of numerous species. Individual species from the complex harbor a diversity of bacterial endosymbionts including Wolbachia. However, while Wolbachia is known to have a number of different roles, its role in B. tabaci is unclear. Here, the antibiotic rifampicin is used to selectively eliminate Wolbachia from B. tabaci so as to enable its roles in whitefly development and reproduction to be explored. The indirect effects of Wolbachia elimination on the biology of Encarsia bimaculata, a dominant parasitoid of B. tabaci in South China, were also investigated. Methodology/Principal Finding qRT-PCR and FISH were used to show that after 48 h exposure to 1.0 mg/ml rifampicin, Wolbachia was completely inactivated from B. tabaci Mediterranean (MED) without any significant impact on either the primary symbiont, Portiera aleyrodidarum or any of the other secondary endosymbionts present. For B. tabaci MED, Wolbachia was shown to be associated with decreased juvenile development time, increased likelihood that nymphs completed development, increased adult life span and increased percentage of female progeny. Inactivation was associated with a significant decrease in the body size of the 4th instar which leads us to speculate as to whether Wolbachia may have a nutrient supplementation role. The reduction in nymph body size has consequences for its parasitoid, E. bimaculata. The elimination of Wolbachia lead to a marked increase in the proportion of parasitoid eggs that completed their development, but the reduced size of the whitefly host was also associated with a significant reduction in the size of the emerging parasitoid adult and this was in turn associated with a marked reduction in adult parasitoid longevity. Conclusions/Significance Wolbachia increases the fitness of the whitefly host and provides some protection against parasitization. These observations add to our understanding of the roles played by bacterial endosymbionts.

BACKGROUND:Thecottonwhitefly,Bemisiatabaci(Gennadius),isacrypticspeciescomplex,andmembersofthecomplexhave become serious pests in Pakistan because of their feeding and their ability to transmit cotton leaf curl virus (CLCuV). Here, an analysis was made of the identity of B. tabaci collected from cotton and a range of non-cotton hosts in the cotton-growing zones in Punjab and Sindh, the main cotton-producing provincesof Pakistan, using a portion of the mitochondrial cytochrome oxidase 1 gene. Thegeographic distribution of the differentmembers of thecomplex was thencompared with the incidence of CLCuD. RESULTS: Using the Dinsdale nomenclature, the results revealed three putative species, Asia 1, Asia II 1 and Middle East-Asia Minor 1. Asia II 1 (also referred to in the literature as biotypes K, P, PCG-1, PK1, SY and ZHJ2) was only recorded from Punjab cotton plants, whereas Asia 1 (also referred to in the literature as biotypes H, M, NA and PCG-2) was found in both Sindh and Punjab. Middle East-Asia Minor 1 (commonly known as biotype B and B2) was found only in Sindh. Moreover, Asia II 1 was associated with high incidences of CLCuD, whereas regions where Middle East-Asia Minor 1 was present had a lower incidence. PhylogeneticanalysisshowedthattheMiddle East-AsiaMinor1population in Sindh formedadistinctgeneticsubgroup within the putative species, suggesting that the Sindh province of Pakistan may form part of its home range. So far, no individuals from the putative species Mediterranean (commonly known as biotypes Q, J and L) have been found in Pakistan. CONCLUSIONS: The capacity to manage pests and disease effectively relies on knowledge of the identity of the agents causing the damage. In the case of CLCuD in Pakistan, this knowledge has been obscured to some extent because of the inconsistent approach to identifying and distinguishing the different B.tabaci associated with CLCuD. The situation has now been clarified, and a strong association between disease incidence and vector identity and abundance has been shown. Given this advance, futureresearchcannowfocusonfactorsthatinfluencethecapacityofdifferentvectorspeciestotransmitthevirusesthatcause CLCuD, the reason for differences in vector abundance and the lack of geographic overlap between the cryptic vector species. This knowledge will contribute to the development of improved methods with which to manage the disease in Pakistan. c � 2010 Society of Chemical Industry

Recently, Davis et al. [1] claimed that ‘“non-native” species have been vilified for…generally polluting “natural” environments’. They further assert that ‘a pervasive bias against alien species…has been embraced by the public, conservationists, land managers and policy-makers, as well as by scientists’. They postulate that eradication attempts are mostly a waste of time and money, that many introductions are ecologically beneficial and that the alarm raised about invasive organisms has been exacerbated by unsubstantiated nativism.

BACKGROUND: Destruxins (dtxs) are the mycotoxin produced by certain entomopathogenic fungi, such as Metarhizium anisopliae, Aschersonia sp, Alternaria brassicae and Ophiosphaerella herpotrichae. It can affect a wide variety of biological processes in insects, including innate immune, Ca(2+) channel in cells, and apoptosis in a dose-dependent manner. Dtxs have been used as biological control agent for a long time, however, their molecular mechanism of action is still unknown. PRINCIPAL FINDINGS: In this study, both digital gene expression (DGE) and two-dimensional electrophoresis (2-DE) approaches were adopted to examine the effects of dtx A on Plutella xyllostella (L.) larvae. By using DGE and 2-DE analyses, 1584 genes and 42 protein points were identified as being up- or down regulated at least 2-fold in response to dtx A. Firstly, injection of dtx A to larvae accelerated the increase of peptidoglycan recognition protein (PGRP), which could activate the Toll signal pathway inducing production of antibacterial substances such as cecropin and gloverin. Dtx A also stimulated prophenoloxidase (proPO) system which plays an important role in innate immunity and leads to melanization of external organisms. Secondly, dtx A suppressed the expression of genes related to the Toll pathway, and induced expression of serine proteinase inhibitors (serpins), especially the serpin 2 that blocked process of the proPO system. Finally, other physiological process like xenobiotics detoxification, apoptosis, calcium signaling pathway and insect hormone biosynthesis, were also mediated in response to dtx A toxicity. CONCLUSIONS: Transcript and protein profiling analyses will provide an insight into the potential molecular mechanism of action in P. xylostella larvae in response to dtx A.