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As predators, the macronutrients spiders extract from their prey play important roles in their mating and reproduction. Previous studies of macronutrients on spider mating and reproduction focus on protein, the potential impact of prey lipid content on spider mating and reproduction remains largely unexplored. Here, we tested the influence of prey varying in lipid content on female mating, sexual cannibalism, reproduction, and offspring fitness in the wolf spider Pardosa pseudoannulata. We acquired 2 groups of fruit fly Drosophila melanogaster that differed significantly in lipid but not protein content by supplementing cultural media with a high or low dose of sucrose on which the fruit flies were reared (HL: high lipid and LL: low lipid). Subadult (i.e., 1 molt before adult) female spiders that fed HL flies matured with significantly higher lipid content than those fed LL flies. We found that the mated females fed with HL flies significantly shortened pre-oviposition time and resulted in a significantly higher fecundity. However, there was no significant difference in female spiders varying in lipid content on other behaviors and traits, including the latency to courtship, courtship duration, mating, copulation duration, sexual cannibalism, offspring body size, and survival. Hence, our results suggest that the lipid content of prey may be a limiting factor for female reproduction, but not for other behavioral traits in the wolf spiders P. pseudoannulata.

Henosepilachna vigintioctopunctata is an emerging horticultural pest of Solanaceae plants in Asia. Here, we employed transcriptome sequencing of three female and three male H. vigintioctopunctata libraries to identify sex-related genes. We recorded 281 599 294 bp of clean reads, and de novo assembly generated 85 206 unigenes, with N50 of 1 311 bp and average length of 763 bp. We found 5 002 genes highly expressed in males and 2 179 genes highly expressed in females. Expression profiles of six unigenes specific to females, six unigenes specific to males, and ten unigenes common to both sexes were verified using semi-quantitive RT-PCR; results showed expression levels of these 22 unigenes were relatively consistent with the transcriptome analysis. Using all unigenes as references, we identified 6 657 putative simple sequence repeats. The transcriptome sequences and gene expression profiles of female and male H. vigintioctopunctata help explore genetic mechanisms of sexual dimorphism.

MEAM1 (Middle East-Asia Minor 1, "B" biotype) and MED (Mediterranean, "Q" biotype) are the two most destructive cryptic species of the Bemisia tabaci complex on the planet. Our previous studies have shown that MEAM1 outcompetes MED on cabbage; the underlying mechanism is unknown. In the Brassicaceae family, the glucosinolate-myrosinase defense system plays a crucial role in deterring feeding, inhibiting growth, and causing acute toxicity against a wide range of generalist herbivores. In the present study, we first compared the survival of MEAM1 and MED exposed to sinigrin (a glucosinolate) and myrosinase (an enzyme that degrades glucosinolates); we found that survival of both species was high in response to sinigrin alone but was near zero in response to sinigrin + myrosinase. We then used electropenetrography (electrical penetration graphs, EPG) to assess the feeding behaviors of MEAM1 and MED whiteflies on cabbage. The EPG results revealed that the mean duration of each potential drop (pd, indicating an intracellular puncture) was substantially longer for MED than MEAM1 on cabbage, indicating that the exposure to the toxic hydrolysates of glucosinolate and myrosinase is greater for MED than for MEAM1. We therefore conclude that differences in penetrating behaviors may help explain the different effects of cabbage on MEAM1 and MED whitefly species.

Two cryptic species of the Bemisia tabaci species complex, MEAM1 (Middle East-Asia Minor 1) and MED (Mediterranean), are highly destructive herbivores. Attack by herbivorous insects often induces defense responses in plants, including the accumulation of toxic secondary metabolites, the synthesis of herbivore-induced plant volatiles (HIPVs) and defensive proteins, and the release of volatile organic compounds that attract natural enemies. These defense responses, which often differ depending on the herbivore, may affect the preference and performance of later-arriving con- and heterospecific whiteflies that attack the same plant. In the present study, we found that MEAM1 whiteflies preferred settling and ovipositing on non-infested and MED-infested cabbage over MEAM1-infested cabbage plants, but that MED whiteflies showed no significant difference in settling or oviposition preference among non-infested, MEAM1-infested, and MED-infested plants. MEAM1 infestation increased the contents of total phenols and flavonoids in cabbage, which coincided with the increased expression of the following genes in the phenylpropanoid biosynthesis pathway: PAL2, C4H, and 4CL1. Soluble protein contents were also markedly higher in the MEAM1-infested cabbage plants than in the non-infested and MED-infested cabbage plants. Overall, these results demonstrate that previous infestation by MEAM1 and MED whiteflies induced defense responses in cabbage plants that had different effects on the host preference and performance of later-arriving con- and heterospecific whiteflies. Phenolic compounds may be the key factors influencing host choice by MEAM1 and MED whiteflies on cabbage plants.

Many damaging agricultural pests can, in addition to their direct feeding damage, acquire and transmit plant pathogens. Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) is considered a ‘supervector’ of disease-causing plant pathogens and viruses. One of the most damaging of these is Tomato yellow leaf curl virus (TYLCV), a circulatively transmitted begomovirus than can extensively damage field and greenhouse crops. Because sustained feeding periods are necessary to acquire and transmit circulatively transmitted viruses, pesticides that, in addition to their direct lethality, suppress feeding in surviving individuals may be particularly effective in decreasing viral transmission. We assessed the impact of sulfoxaflor, a sulfoximine insecticide, on the settling preference, feeding, and viral transmission of TYLCV-carrying B. tabaci on tomato. We found that viruliferous B. tabaci avoided both settling and feeding on sulfoxaflor-treated plants, and that sulfoxaflor virtually eliminated the transmission of TYLCV by B. tabaci. The antifeedant properties of sulfoxaflor have previously been reported in other pest systems; our results document similar effects on viruliferous B. tabaci and demonstrate that this pesticide can reduce TYLCV transmission by surviving individuals.

Pesticides primarily affect target organisms via direct toxicity, but may also alter the feeding behaviors of surviving individuals in ways that alter their effect on host plants. The latter impact is especially important when pests can transmit plant pathogens. The Mediterranean (MED) population of the sweetpotato whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) transmits Tomato yellow leaf curl virus (TYLCV), a pathogen that can be economically devastating in field and greenhouse cropping systems. We first assessed the impact of sublethal (LC15) and label concentrations of flupyradifurone, a butenolide-derived insecticide, on the feeding behavior of TYLCV-infected MED on tomato. We next measured the effect of flupyradifurone on plant TYLCV load, vector transmission efficiency, and MED survival. Both the LC15 and label flupyradifurone concentrations dramatically altered MED feeding and caused the near cessation of both salivation and phloem ingestion (necessary for viral transmission and acquisition, respectively). Both concentrations also significantly reduced plant TYLCV load, and the label rate of flupyradifurone sharply decreased TYLCV transmission while killing >99% of MED. As the first report of pesticide-induced changes in the feeding behavior of viruliferous Bemisia, our findings highlight the potential importance of chemically driven feeding cessation in the control of TYLCV and other Bemisia-transmitted plant pathogens.

Prey vary dramatically in quality, and maternal diet is generally assumed to substantially influence offspring survivorship, growth, and reproduction in spiders. Numerous studies that have tested this hypothesis have focused exclusively on parental generation or have considered relatively few fitness components of juvenile offspring. However, maternal diet may have a substantial effect on fitness performance beyond juvenile offspring. Here, we investigated the influence of one-time maternal feeding on multiple offspring fitness components, including the survival rate and growth of juvenile offspring as well as the mating and reproductive success of adult offspring in Hylyphantes graminicola, a sheetweb spider with an extremely short lifespan (∼1 month). We fed field-collected adult female spiders two different diets only once immediately before oviposition: midges (Tendipes sp.) only (MO) or flies (Drosophila melanogaster) only (FO). Juvenile offspring of MO females had significantly higher survival rate, faster growth, and larger male size at maturity than FO offspring. Although maternal diet did not significantly influence mating behavior or fecundity of female offspring overall, those of MO females laid eggs earlier and their eggs also hatched earlier and had a higher hatching rate than those of FO females. Intriguingly, one-time maternal feeding was sufficient to have such an influence on offspring fitness even beyond juvenile offspring in H. graminicola. This one-time maternal effect may be widespread in other spiders and other invertebrates with a short lifespan. This article has an associated First Person interview with the first author of the paper., Summary: A single meal immediately before oviposition is sufficient to influence offspring survival, growth, and daughters' reproduction in the sheetweb spider Hylyphantes graminicola.

Prey proteins and lipids greatly impact predator life-history traits. However, life-history plasticity offers predators the opportunity to tune the life-history traits in response to the limited macronutrients to allocate among traits. A fast-growing predator species with a strict maturation time may be more likely to consume nutritionally imbalanced prey. Here, we tested this hypothesis by examining the effect of the protein-to-lipid ratio in prey on a small sheet web-building spider

Prey proteins and lipids greatly impact predator life-history traits. However, life-history plasticity offers predators the opportunity to tune the life-history traits in response to the limited macronutrients to allocate among traits. A fast-growing predator species with a strict maturation time may be more likely to consume nutritionally imbalanced prey. Here, we tested this hypothesis by examining the effect of the protein-to-lipid ratio in prey on a small sheet web-building spider, Hylyphantes graminicola, with a short life span, using adult Drosophila melanogaster as the prey. By manipulating the macronutrient content of the prey to generate three prey types with different protein-to-lipid ratios (i.e. high, intermediate and low), we demonstrated that the majority of the spiders that consumed only these flies could reach full maturity. However, juvenile spiders that consumed high-lipid (low protein-to-lipid ratio) flies had a higher rate of mortality than those consuming medium-protein and high-protein flies. The prey protein-to-lipid ratio had no significant effects on the developmental duration and size at maturity. Although the prey protein-to-lipid ratio had no significant influence on mating behaviour and female fecundity, females reared on high-lipid flies exhibited a significant delay in oviposition compared with those reared on high-protein flies. We conclude that high-lipid prey has negative effects on the survival and reproductive function of H. graminicola Our study thus provides clear evidence that low plasticity with fast development to a certain size means a high nutritional requirement for protein at a cost of lower survival and prolonged time to egg laying when prey have low protein-to-lipid content in H. graminicola.

Material and/or genetic benefits are hypothesized to be the main drivers of female mate choice. Research on female mate choice has mainly focused on polyandrous species and has seldom considered monandrous species. Given the absence of postcopulatory mate choice in monandrous females, we predicted that precopulatory mate choice is important for monandrous species. Using the wolf spider Pardosa astrigera as a model monandrous species, we compared mating, reproductive output and offspring fitness between females with preferred mates (mates that were accepted on the first exposure) and females with nonpreferred mates (mates that were rejected on the first exposure but were induced to mate on the second exposure). Our results showed that the mating duration, latency to egg laying and to egg hatching, fecundity and egg hatching rate did not differ significantly between females with preferred versus nonpreferred mates. In contrast, female and male development time was significantly shorter and female carapace width was significantly greater for offspring of females with preferred versus nonpreferred mates. In addition, survival from egg hatching to maturity was twice as high for offspring of females with preferred mates. These results indicate that female mate choice by the monandrous P. astrigera provides genetic rather than material benefits.

Variations in species morphology and life‐history traits strongly correlate with geographic and climatic characteristics. Most studies on morphological variations in animals focus on ectotherms distributed on a large geographic scale across latitudinal and/or altitudinal gradient. However, the morphological variations of spiders living in the same habitats across different seasons have not been reported. In this study, we used the wolf spider, Pardosa astrigera, as a model to determine seasonal differences in adult body size, melanism, fecundity, and egg diameter both in the overwintering and the first generation for 2010 and 2016. The results showed that in 2010, both females and males of the overwintering generation were significantly darker than the first generation. Moreover, the overwintering females were markedly larger and produced more and bigger eggs than the first generation in both 2010 and 2016. Considering the overwintering P. astrigera experiencing low temperature and/or desiccation stress, these results suggest that substantially darker and larger body of the overwintering generation is adaptive to adverse conditions.

Offspring born to related parents often have lower fitness than those born to unrelated parents, a phenomenon termed inbreeding depression. While many species have been shown to rely on pre- and/or postcopulatory mate choice to avoid inbreeding, such research has focused largely on polyandrous rather than monandrous species. The absence of postcopulatory mate choice in monandrous species suggests that precopulatory mate choice should play a more important role in inbreeding avoidance. We used a monandrous wolf spider, Pardosa astrigera , as a model system to investigate whether (1) male spiders respond differently to sibling and nonsibling females; (2) female spiders respond differently to sibling versus nonsibling males; and (3) inbreeding affects females and their offspring. Male courtship behaviour was similar for sibling and nonsibling females; although females were less likely to mate with siblings, over half did mate successfully with them. Sibling-mated females produced fewer offspring from the first egg sac and fewer total offspring, but inbred offspring survived longer in a range of environments than their outbred counterparts. This suggests that the fitness costs of reduced fecundity in sibling-mated females may be offset by higher offspring survivorship. Our results highlight the importance of considering both parent and offspring fitness when addressing the costs of inbreeding, and are the first to document the impact of inbreeding on sexual behaviour and reproductive fitness in a monandrous spider.

In order to identify suitable Trichogramma strains for mass production and successful control of key lepidopteran pests in paddy fields in the Greater Mekong Subregion, the effects of high temperatures on wasp life history traits were compared among three strains of Trichogramma chilonis Ishii and two strains of Trichogramma ostriniae Pang et Chen, collected from paddy fields in the region. At a rearing temperature of 25 °C, life history traits differed significantly among the five strains tested and the three T. chilonis strains and a T. ostriniae strain were of high performance. When female wasps were exposed to higher temperatures commonly encountered in the region, negative effects were observed on key life history parameters of adult females and their offspring at 34 °C, which became even more serious at 37 °C. In particular, the two T. ostriniae strains were not able to successfully develop to adulthood at all at 37 °C while for the T. chilonis strains adult emergence was significantly reduced. In addition, the emerged offspring females lived only around one day and no parasitism was observed. When the three T. chilonis strains were exposed to 37 °C for 4 to 12 h at prepupal and pupal stages, reflecting heat shocks that the released Trichogramma may experience in the field, adult emergence was significantly reduced after an exposure time of 12 h. In summary, the three T. chilonis strains show a relatively high potential for incorporation in a biological control program in the target region. Our results also highlight that tests at both rearing and field temperatures are necessary in selection of potential Trichogramma strains for an inundative release program where there is significant difference between rearing and field temperatures.

The B and Q putative species of Bemisia tabaci are among the most invasive pests in the world. In China, Q is displacing B. Although this displacement is often attributed to the higher resistance of Q to insecticides, a higher tolerance of Q to low-quality host plants may also be important. In this study, we first determined the contents of main secondary insect-resistant compounds (total phenol and flavonoids) and nutrients (total amino acid, free protein, total nitrogen, phosphorus, and potassium) in four genotypes pepper (Capsicum annuum). We then conducted host choice and feeding behavior (EPG) experiments with B and Q on the four pepper genotypes. Zhongjiao4 was found to be the high-quality genotype (it had low levels of insect-resistance substances and high levels of nutrients), and Zhonghuahong was found to be the low-quality genotype (it had high levels of resistant compound and low levels of nutrients). EPG data indicated that both B and Q females fed more efficiently on high-quality Zhongjiao4 than on the other three pepper genotypes. In terms of settling and oviposition, however, B preferred the low-quality Zhonghuahong, and Q showed no preference among the four genotypes. We suggest that the lack of correlation between the results for feeding efficiency and settling/oviposition might be explained by repellent plant volatiles whose effects differ depending on pepper genotype and whitefly species.

The performance of herbivorous insects is greatly affected by host chemical defenses and nutritional quality. Some herbivores have developed the ability to manipulate plant defenses via signaling pathways. It is currently unclear, however, whether a herbivore can benefit by simultaneously reducing plant defenses and enhancing plant nutritional quality. Here, we show that the better performance of the whitefly Bemisia tabaci Middle East-Asia Minor 1 (MEAM1; formerly the “B” biotype) than Mediterranean (MED; formerly the “Q” biotype) on cabbage is associated with a suppression of glucosinolate (GS) content and an increase in amino acid supply in MEAM1-infested cabbage compared with MED-infested cabbage. MEAM1 had higher survival, higher fecundity, higher intrinsic rate of increase (rm), a longer life span, and a shorter developmental time than MED on cabbage plants. Amino acid content was higher in cabbage infested with MEAM1 than MED. Although infestation by either biotype decreased the levels of total GS, aliphatic GS, glucoiberin, sinigrin, glucobrassicin, and 4OH-glucobrassicin, and the expression of related genes in cabbage, MED infestation increased the levels of 4ME-glucobrassicin, neoglucobrassicin, progoitrin, and glucoraphanin. The GS content and expression of GS-related genes were higher in cabbage infested with MED than with MEAM1. Our results suggest that MEAM1 performs better than MED on cabbage by manipulating host defenses and nutritional quality.

A low-dose gamma radiation phytosanitary treatment against the oriental fruit fly, Bactrocera dorsalis Hendel, was developed for guava fruits. The measure for efficacy of the treatment is preventing adult emergence from late third instars that were reared in the fruit of guava, Psidium guajava L. The dose–response tests with 1-, 2-, 3-, 7-d-old larvae in guava were initiated to determine the most tolerant stages, the late-aged third instars. No adult emerged from a total of 100,684 late-aged third instars irradiated at the dose of 97–116 Gy, resulting in an efficacy of 99.9970% at the 95% confidence level. The minimum dose for 100% preventing adult emergence from 2-, 5-, 7-d-old pupae (1800 pupae in each dose) reared in artificial diets was 100, 500, and 1750 Gy, respectively. Quality determinations on ‘Taiwan’ guavas were conducted at 1, 3 and 7 days after gamma radiation at doses of 200, 400, 600, 800, 1,200, 2000 and 6000 Gy. The guavas could tolerate radiation dose up to 600–800 Gy as there were no significant changes in organoleptic characteristics (≤800 Gy), the chemical and nutritional contents (sugar, sucrose, total sugar, titratable acid, vitamin C, and soluble solid) (≤600 Gy). Therefore, a dose of 116 Gy, which give the disinfestations efficacy of 99.9968% for the late-aged larvae in guavas and 100% mortality of 2-d-old pupae, is suggested as the minimum absorbed dose for phytosanitary irradiation treatment of B. dorsalis in fruits.

Lactation is a mammalian attribute, and the few known nonmammal examples have distinctly different modalities. We document here milk provisioning in a jumping spider, which compares functionally and behaviorally to lactation in mammals. The spiderlings ingest nutritious milk droplets secreted from the mother’s epigastric furrow until the subadult stage. Milk is indispensable for offspring survival in the early stages and complements their foraging in later stages. Maternal care, as for some long-lived vertebrates, continues after the offspring reach maturity. Furthermore, a female-biased adult sex ratio is acquired only when the mother is present. These findings demonstrate that mammal-like milk provisioning and parental care for sexually mature offspring have also evolved in invertebrates, encouraging a reevaluation of their occurrence across the animal kingdom, especially in invertebrates.

In nature, male wolf spiders may encounter silk of conspecific females, males, and/or both. It is generally accepted that males are able to discriminate maturity, sex, and mating status through silk-mediated chemical information of females. However, whether males can discriminate silk by chemical cues among virgin females of different post-maturation ages and between female silk with and without previously being occupied by other males remains largely unexplored. Given that female sexual receptivity increases in post-maturation, males are predicted to prefer old over young virgin females, and are able to discriminate silk of females which have and have not been previously being occupied by other males. In this study, we used the monandrous wolf spider, Pardosa astrigera, to test this prediction experimentally. When males were exposed to the silk of virgin females of different post-maturation ages (1-, 3-, and 6-day-old females), we found no significant differences in male courtship latency and courtship intensity to female silk across the different ages. However, males displayed significantly higher courtship intensity to the silk of females without being previously occupied by other males than to the silk of females with being previously occupied by other males. When males were directly exposed to virgin females, significantly higher courtship intensity was detected in males in response to 6-day-old females compared with 1-day-old ones. Thus, our results suggest that P. astrigera males can discriminate females using chemical cues from silk that has been previously occupied by other males and to older females with higher sexual receptivity, whereas they invest less to silk cues from virgin females regardless of their post-maturation ages.

The sweetpotato whitefly Bemisia tabaci is a highly destructive agricultural and ornamental crop pest. It damages host plants through both phloem feeding and vectoring plant pathogens. Introductions of B. tabaci are difficult to quarantine and eradicate because of its high reproductive rates, broad host plant range, and insecticide resistance. A total of 791 Gb of raw DNA sequence from whole genome shotgun sequencing, and 13 BAC pooling libraries were generated by Illumina sequencing using different combinations of mate-pair and pair-end libraries. Assembly gave a final genome with a scaffold N50 of 437 kb, and a total length of 658 Mb. Annotation of repetitive elements and coding regions resulted in 265.0 Mb TEs (40.3%) and 20 786 protein-coding genes with putative gene family expansions, respectively. Phylogenetic analysis based on orthologs across 14 arthropod taxa suggested that MED/Q is clustered into a hemipteran clade containing A. pisum and is a sister lineage to a clade containing both R. prolixus and N. lugens. Genome completeness, as estimated using the CEGMA and Benchmarking Universal Single-Copy Orthologs pipelines, reached 96% and 79%. These MED/Q genomic resources lay a foundation for future ‘pan-genomic’ comparisons of invasive vs. noninvasive, invasive vs. invasive, and native vs. exotic Bemisia, which, in return, will open up new avenues of investigation into whitefly biology, evolution, and management.

Bradysia odoriphaga is frequently subjected to heat shock during the summer in China. Although the effects of heat shock on insect ecology and physiology have been widely explored, the effects of heat shock on the life history parameters of Bradysia odoriphaga are largely unknown. In the present study, we investigated the effects of heat shock on B. odoriphaga survival and reproduction as well as on offspring development and sex ratio. We exposed adult B. odoriphaga to 31, 33, 35, or 37 °C for different durations (from 0 to 120 min). The results showed that the survival of both sexes declined with the increase in temperature and exposure time, especially at 33, 35, and 37 °C. Longevity was markedly greater for males than females across all treatments. Fecundity generally declined as temperature and exposure time increased, and no eggs hatched when females were exposed to 37 °C for >75 min. The development of offspring larvae was significantly delayed when the parent female and male had been exposed to ≥31 °C for ≥30 min. In addition, the sex ratio of F1 progeny derived from heat-shocked parental adults was increasingly skewed to female as exposure time and temperature treatment increased. Overall, the results indicate that heat shock negatively influences B. odoriphaga.

Plant defense responses can greatly affect plant viruses and their herbivore vectors. The current article reports on plant defense responses involving jasmonic acid (JA), salicylic acid (SA), and proteinase inhibitor (PI) in the three-way interaction between tomato plants, tomato yellow leaf curl virus, and the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). The results showed that feeding by viruliferous B. tabaci increases the longevity and fecundity of nonviruliferous B. tabaci that subsequently feed on the same plant. Feeding by nonviruliferous B. tabaci alone suppressed plant defense responses involving JA and PI but induced responses involving SA. Feeding by viruliferous B. tabaci increased the suppression of plant defenses involving JA and PI but did not increase responses involving SA. These results indicate that the interactive effects of tomato yellow leaf curl virus and B. tabaci on plants increase vector fitness and virus transmission by reducing plant defense.

B and Q putative species of Bemisia tabaci are two of the most invasive pests in the world. In China, Q is displacing B, but the underlying mechanism has been poorly explored. The difference in tolerance to host plants between B and Q may shed some light on the displacement. In the present study, two types of resistance (antixenosis or antibiosis) of cabbage and pepper against B and Q putative species were characterized based on demographic parameters (host selection, fecundity, etc.) and feeding behavior [as determined by electrical penetration graph (EPG)]. Female longevity, fecundity, and nymph survival were substantially higher on cabbage than on pepper for B, but were similar on the two hosts for Q. B nymphs suffered high mortality on pepper, suggesting a high level of antibiosis against B in pepper. Both B and Q preferred to settle and oviposit on cabbage rather than on pepper, indicating a high level of antixenosis against B and Q in pepper. With regard to feeding behavior, EPG data indicated that both B and Q whiteflies fed more efficiently on cabbage than on pepper. Overall, both B and Q preferred cabbage to pepper, and both performed better on cabbage than on pepper, but the negative effects of pepper were greater on B than on Q. Our results demonstrate that Q is more tolerant of a low suitability host than B, which may partially explain why Q has displaced B in China.

In a mating system in which females are monandrous and males are polygynous, females may incur a risk by mating with males with possible sperm depletion following consecutive matings. Here, we examined the effects of male mating history on male mating success and female reproductive fitness in the wolf spider Pardosa pseudoannulata by performing mating trials and sperm counting experiments. Results showed that male mating history had a significant negative impact on subsequent copulation success but had little effect on courtship duration and courtship intensity. In addition, neither male courtship intensity nor morphological measurements of males and females had significant effects on male mating success. Furthermore, male mating history had no obvious impact on the fecundity of inseminated females, with no significant differences observed in the oviposition rate of females, the numbers and the carapace width of the second-instar spiderlings between treatments. Results showed that the number of sperm decreased significantly after mating but could be replenished, with no significant differences observed between groups in which males had rested for 7 d. These findings suggest that polygynous male spiders may recharge their sperm during the mating season, but how females differentiate the mating status of males remains unknown.

Bacterial symbionts infect most insect species, including important pests such as whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), and often exert important effects on host ecology. The facultative symbiont Hamiltonella is found at high frequencies in the B. tabaciMED (type: Mediterranean—MED) in China. The prevalence of this symbiont in natural populations suggests beneficial effects of infection or manipulation of host reproduction. To date, however, no empirical studies on the biological role of Hamiltonella on the host B. tabaci have been reported. Here, we investigated the effects of Hamiltonella infection on the sex ratio and several fitness parameters in B. tabaci MED by comparing Hamiltonella-infected whiteflies with Hamiltonella-free ones. We found that Hamiltonella-infected whiteflies produced significantly more eggs, exhibited significantly higher nymphal survival, faster development times, and larger adult body size in comparison with Hamiltonella-free whiteflies, while ...

B and Q are two putative species of the Bemisia tabaci complex (Hemiptera: Aleyrodidae), and are among the most invasive and destructive pests of crops and horticultural plants worldwide. In China, Q predominates and is displacing B. Although researchers have proposed that the higher capacity of Q to utilize host plants plays an important role in its replacement of B, there are few relevant field surveys and experimental studies. The difference in host assessment between B and Q in multiple-choice rather than in no-choice situations may be essential to understanding the displacement. Here, we compared settling and oviposition preferences, and adult and nymph performance, for the putative species B and Q of the B. tabaci complex on three common host species: poinsettia [Euphorbia pulcherrima Wild. ex Klotsch (Euphorbiaceae)], cotton [Gossypium hirsutum L. (Malvaceae)], and cabbage [Brassica oleracea L. (Brassicaceae)]. Although the preferred hosts for settling and oviposition were the same as those that supported maximum fitness (adult longevity, fecundity, and nymph survivorship), these hosts differed between B and Q. When given a choice, B preferred to settle and oviposit on cabbage over poinsettia and cotton, whereas Q preferred to settle and oviposit on poinsettia and cotton over cabbage. In a no-choice experiment, adult longevity, fecundity, and nymphal survival for B were greater on cabbage than on poinsettia and cotton, but the opposite was true for Q.

Interspecific competition between herbivores is widely recognized as an important determinant of community structure. Although researchers have identified a number of factors capable of altering competitive interactions, few studies have addressed the influence of neighboring plant species. If adaptation to/ epigenetic effects of an herbivore’s natal host plant alter its performance on other host plants, then interspecific herbivore interactions may play out differently in heterogeneous and homogenous plant communities. We tested the impact of natal host plants on interactions between the Middle-east Asia Minor 1 (MEAM1) and Mediterranean (MED) cryptic species of the whitefly Bemisia tabaci by rearing the offspring of a cabbage-derived MEAM1 population and a poinsettia-derived MED population together on three different host plants: cotton, poinsettia, and cabbage. We found that MED excluded MEAM1 on poinsettia and that MEAM1 excluded MED on cabbage, results consistent with previous research. MED also excluded MEAM1 when reared together on cotton, however, a result at odds with multiple otherwise-similar studies that reared both species on the same natal plant. Our work provides evidence that natal plants affect competitive interactions on another plant species, and highlights the potential importance of neighboring plant species on herbivore community composition.

The performance of herbivorous insects is greatly affected by host chemical defenses and nutritional quality. Some herbivores have developed the ability to manipulate plant defenses via signaling pathways. It is currently unclear, however, whether a herbivore can benefit by simultaneously reducing plant defenses and enhancing plant nutritional quality. Here, we show that the better performance of the whitefly Bemisia tabaci Middle East‐Asia Minor 1 (MEAM1; formerly the “B” biotype) than Mediterranean (MED; formerly the “Q” biotype) on cabbage is associated with a suppression of glucosinolate (GS) content and an increase in amino acid supply in MEAM1‐infested cabbage compared with MED‐infested cabbage. MEAM1 had higher survival, higher fecundity, higher intrinsic rate of increase (r m), a longer life span, and a shorter developmental time than MED on cabbage plants. Amino acid content was higher in cabbage infested with MEAM1 than MED. Although infestation by either biotype decreased the levels of total GS, aliphatic GS, glucoiberin, sinigrin, glucobrassicin, and 4OH‐glucobrassicin, and the expression of related genes in cabbage, MED infestation increased the levels of 4ME‐glucobrassicin, neoglucobrassicin, progoitrin, and glucoraphanin. The GS content and expression of GS‐related genes were higher in cabbage infested with MED than with MEAM1. Our results suggest that MEAM1 performs better than MED on cabbage by manipulating host defenses and nutritional quality.

Host selection is central to understanding the evolution of the interaction between herbivorous insects and host plants. Most studies on host selection of herbivorous insects are focused on the optimal oviposition theory which posits that the herbivores preferentially oviposit on plants that provide optimal conditions for offspring development (preference–performance hypothesis). However, the positive correlation between female oviposition preference and offspring performance is not always observed. Here, we determined the relationship between whitefly settling and oviposition preference and nymph performance of B and Q putative species of Bemisia tabaci on three host plants, cotton Gossypium hirsutum L., tomato Lycopersicum esculentum Mill, and poinsettia Euphorbia pulcherrima Wild. We further investigated whether nutritional and defensive chemistry of the three host species shaped whitefly settling and oviposition preference of both putative species. Foliar chemistry differed significantly among the three host species. Compared to cotton and tomato foliage, poinsettia foliage was 8 % lower in nitrogen, 60 % higher in carbohydrate, and 90 % higher in phenolic compounds, respectively. When given a choice, B and Q putative species of B. tabaci preferred settling on nutritionally superior tomato, whereas both putative species preferentially oviposited on nutritionally inferior poinsettia. Nymph survivorship of B and Q putative species was substantially reduced and nymph developmental duration (egg-to-adult) was markedly prolonged on poinsettia relative to those reared on cotton and tomato. Therefore, our results are consistent with the optimal foraging theory, rather than the optimal oviposition theory. Females of B and Q putative species of B. tabaci preferentially ovipositing on poinsettia may be a trade-off between nymph performance and the avoidance of natural enemy.

The cloning, expression in vitro, and characterization of two aminopeptidase Ns (APN5s and APN2s) isolated from the midgut of Cry1Ac-resistant (R) and susceptible (S) strains of Plutella xylostella larvae are presented in this paper. The deduced amino acid sequences of APN5s included C-terminal GPI-modification sites, the gluzincin aminopeptidase motif GATEN, and three N-glycosylated sites; those of APN2s had no GPI-modification sites, had gluzincin aminopeptidase motif GAMEN, and had four N-glycosylated sites. O-glycosylated sites were not predicted for either APN. Because APN2R and APN2S cDNAs contained the same nucleotides, only full-length cDNAs encoding APN5R and APN5S were expressed in Trichoplusia ni cells. Far-Western blotting showed that the expressed receptor APN5 bound to the Cry1Ac toxin. An enzyme-specific activity experiment also showed that APN5 genes were expressed in T. ni cells. ELISA revealed no differences in the binding of expression proteins from the resistant and susceptible strain with Cry1Ac. © 2011 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:60–70 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/jbt.20401

In China, Bemisia tabaci Q (commonly known as biotype Q) has rapidly displaced B (commonly known as biotype B) in the past 6 years. The mechanisms underlying such phenomenon have been studied extensively in recent years; however, we have not come to a definitive conclusion yet. In the present study, the differences in host suitability between B and Q whitefly adults to five host plants (cabbage, cotton, cucumber, poinsettia, and tomato) were evaluated based on their respective feeding behaviors using a direct-current electrical penetration graph (DC-EPG) system. Pair-wise comparisons of B. tabaci B and Q feeding on each of the five host plants clearly indicate that Q feeds better than B on tomato, cotton and poinsettia, while B feeds better than Q on cabbage and cucumber. The EPG parameters related to both phloem and non-phloem phases confirm that cabbage and cucumber are best suited to B, while tomato, cotton, and poinsettia are best suited to Q. Our present results support the contention that host suitability and adult feeding behavior contribute to the competitive displacement of biotype B by biotype Q. The discrepancy between field (previous studies) and laboratory results (this study), however, suggests that 1) whitefly displacement is apparently contributed by multiple factors; and 2) factor(s) other than the host plant suitability may play a vital role in dictating the whitefly biotypes in the field.

Females of many species mate multiply, yet some taxon females mate with only one male, also known as monandry. Although the underlying mechanism behind female monandry is poorly understood relative to female polyandry, there are two contrasting hypotheses, male control and female control, for the maintenance of monandry. Since females generally benefit from multiple mating for material and/or genetic benefits, cases of monandry may reflect male manipulation on female remating at the expense of female fitness (male control). Alternatively, monandry may be favored by females, if females maximize their fitness by mating once (female control). Here, we tested two hypotheses by manipulating the number of mating (repeated mating and polyandry) on female fitness in a largely monandrous wolf spider, Pardosa astrigera. We allowed females to be inseminated once, twice with the same males (repeated mating) or with two males (polyandry) and determined female fitness consequences. The number of female mating, regardless of a single mating, repeated mating, or polyandry, had no significant effects on female fecundity, fertility, and survival and size of their spiderlings. However, the fitness cost of female multiple mating may to some extent be underestimated under laboratory conditions. In addition, female survival was adversely affected by induced multiple mating. Therefore, our results suggest that monandry of the wolf spider (P. astrigera) may be under the control of females, rather than under the control of males.

The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), causes severe crop losses to many crops. The worst of these losses are often associated with the invasion and establishment of biotypes B and Q of this pest. Previous research in 2007 showed that biotype Q occurred with other biotypes in most field populations in China. To determine the current status of the biotype composition in the field, an extensive survey covering mainly eastern parts of China was conducted in 2009. Using polymerase chain reaction primers specific for the mitochondrial cytochrome oxidase I of biotypes B and Q and gene sequencing, we determined the biotypes composition in 61 whitefly populations and their distribution across 19 provinces in China. Our research revealed that only biotypes B and Q have been found in the field in 2009 in China. Among them, biotype Q was dominant in 44 locations (100.0%) and biotype B was dominant in 17 locations (100.0%). The current survey indicates that biotype Q has rapidly displaced biotype B in most locations in China.

The chemoreceptors distributed on forelegs and palps of male wolf spiders are known to be involved in intersexual chemical communication, yet their distribution pattern and relative importance are supposed. This study employed scanning electron microscopy (SEM) to determine chemoreceptor morphology and distribution pattern on male forelegs and palps of the wolf spider Pardosa astrigera. We also performed behavioral assays to determine their relative importance in intersexual chemical communication. Although the fine structure of the chemoreceptors distributed on male forelegs and palps did not differ greatly, the chemoreceptors were more widely distributed on palps relative to forelegs. When the chemoreceptors of palps were chemically ablated with zinc sulfate, male courtship latency was significantly prolonged and courtship intensity significantly suppressed as compared to those of the forelegs-ablated and/or control ones. Therefore, we conclude that the contact chemoreceptors are mostly distributed on male palps, thereby males locating their mates through dragline-mediated female pheromone.

Although the effects of male mating history on female reproductive output and longevity have been studied in insects, few such studies have been carried out in spiders. In a mating system in which females are monandrous while males are polygynous, females may incur the risk by mating with successful males that have experienced consecutive matings and suffer from the possible depletion of sperm and/or associated ejaculates. Here, we examine the effects of male mating history on male courtship and copulation duration, female reproductive fitness, and female adult longevity of the wolf spider, Pardosa astrigera. Results indicated that male mating frequency had little effect on their subsequent copulation success, and of 35 males tested, about half of the males were able to copulate with five virgin females successively at an interval of 24 h. Male mating history had little effect on their courtship duration. However, male mating history significantly affected male copulation duration, female adult longevity, and reproductive output. Males that mated more frequently copulated longer and more likely failed to cause their mates to produce a clutch, although there was no significant difference in the number of eggs laid and the number of eggs hatched regardless of the first clutch or the second one. Multiple mating of male P. astrigera resulted in significant reduction in female adult longevity. Our results indicate that monandrous females mating with multiple-mated males may incur substantial fitness costs.

The copulation duration of male wolf spider Pardosa astrigera, was significantly influenced by environmental temperature, as had been found in some insect species. Therefore, temperature during male courtship and copulation may influence the amount of sperm and seminal fluids transferred during copulation, which in turn could influence female fitness. In order to test this hypothesis, we subjected pairs of male and female P. astrigera to five temperature groups from 16 to 32 °C at an interval of 4 °C, and investigated whether and to what extent the various temperatures during male courtship and copulation influenced female reproductive output and female adult longevity under controlled laboratory conditions. With the increase of copulation temperature, females were more likely to lay egg sacs. The total egg sacs and lifetime fecundity of female were positively influenced by copulation temperature, whereas female lifetime spiderlings and adult longevity were independent of copulation temperature.

Spiders possess a suit of characteristics, which play important roles in the fields of sensory modalities and sexual selection. Although the effects of temperature on spider prey-hunting, web-building, sexual signaling and habitat selection are well-documented, the effects of environmental temperature on spider courtship and copulatory behaviours are largely unexplored. In order to determine the effects of temperature on the sexual behaviours of the wolf spider Pardosa astrigera, we subjected pairs of male and female to five temperatures from 16 to 32 °C at an interval of 4 °C in a controlled laboratory conditions. Results indicated that in males most behavioural parameters, except the number of hematodochal expansions, were significantly influenced by environmental temperature. Male P. astrigera courtship latency, courtship duration, and copulatory duration declined gradually with increasing temperature within the range of 16–28 °C, whereas the number of pedipalp insertions and frequencies of both pedipalp insertions and hematodochal expansions increased gradually with temperature.

It has been previously reported that TYLCV can be transmitted from viruliferous males to non-viruliferous females and from viruliferous females to non-viruliferous males, but not between insects of the same sex; female whiteflies transmit TYLCV-Is with higher efficiency than males through symptoms recognition and viral DNA identification in tomato test plants (one insect per plant, with 48 h AAP and 48 h IAP). However, it remains unclear whether non-infected female and male could obtain same virus from TYLCV-infected tomato plants, and whether TYLCV-infected female and male could transmit same virus to non-viruliferous tomato plants. To address this issue, quantitative real-time PCR were applied to detect TYLCV content in adults or tomato plant. The acquisition and transmission experiments showed that both female and male can acquire and transmit the virus and no acquisition capability difference was observed between newly emerged female and male, however, female demonstrated superior transmission capability than male. Moreover, gene expressions profilings of GroEL and Hamiltonella in non-viruliferous and viruliferous female was all higher than that in male. These results further indicated that sex is an important factor affecting TYLCV transmission efficiency in B. tabaci.