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Mirid bugs (Hemiptera: Miridae) are an important group of insect pests on many agricultural crops, including cotton, legumes, cereals, vegetables, and fruits (Wheeler, 2001). The adults and nymphs feed via piercing and sucking mouthparts on the terminal meristems, young flower buds, fruits (including cotton bolls), and other tissues, often causing the formation of bushy plants, the abscission of flower buds and fruits, and the malformation of mature fruits (Wheeler, 2001). These injuries greatly reduce crop yield and quality, causing serious economic losses in years of high infestation levels. Unlike many other common piercing/sucking insects (e.g., aphids, planthoppers, whiteflies) that are vascular feeders, mirid bugs are mostly considered ‘lacerate-and-flush’ feeders (Miles, 1972; Backus, 1988). More specifically, mirid bugs use their stylets to first lacerate the plant cells, simultaneously secreting a watery saliva into the ruptured cellular matter, and then ingest the resulting lacerated/macerated ‘soup’ (Backus et al., 2007). However, certain species – e.g., Helopeltis clavifer (Walker) – move their stylets very little while probing and use the watery saliva itself to macerate plant tissue, a strategy that is termed ‘macerate-and-flush’ feeding (Miles, 1987; Miles & Taylor, 1994). As both feeding strategies of mirid bugs are apparently related to the presence of digestive enzymes in their saliva, knowledge of the extra-oral digestion of mirid bugs is important for fully understanding the interactions between mirid bugs and their host plants (CelorioMancera et al., 2008). Among the various digestive enzymes in the salivary glands of mirid bugs, polygalacturonase (PG) is the most important in the induction of visible plant injury. This enzyme catalyzes the hydrolysis of the a-1,4-glycosidic linkages in polygalacturonic (pectic) acid in the cell walls. Strong & Kruitwagen (1968) determined the presence of PG in the salivary glands of Lygus hesperus Knight, and Strong (1970) further found that the plant injury caused by L. hesperus was mainly due to the activity of PG, rather than tomechanical damage caused by stylet probing. Shackel et al. (2005) injected a crude and partially purified PG solution into alfalfa (Medicago sativa L.) florets and cotton (Gossypium hirsutum L.) flowers and observed damage similar to that caused by Lygus feeding, whereas the control plant injected with a solution lacking PG showed no damage. Meanwhile, Celorio-Mancera et al. (2008) compared the damage of an enzymatically active PG and a mutant inactive PG in alfalfa florets and found that the former elicited Lygus damage symptoms, whereas the latter did not. These two recent studies support the results of previous studies (Strong & Kruitwagen, 1968; Strong, 1970) and highlight the significance of PG proteins in the formation of plant symptoms caused bymirid bug feeding. In China, the mirid bug Apolygus lucorum (Meyer-D€ ur) is a common polyphagous pest (Cao & Wan, 1983; Lu & Wu, 2008). Since the late 1990s, with the wide-scale adoption of transgenic Bt (Bacillus thuringiensis Berliner) cotton and the associated reduction of insecticide use in this crop, A. lucorum population levels have drastically increased, resulting in high infestations in such crops as cotton, local Chinese dates, cherries, grapes, apples, and pears (Lu et al., 2010; Lu &Wu, 2011). Although A. lucorum causes the same damage symptoms as other common mirid bug species (e.g., Lygus spp.) (Lu & Wu, 2008), the role of its salivary gland digestive enzymes in the formation of plant damage symptoms has not been determined. In addition, although the micropressure probe system is suitable for simulating mirid bug feeding on transplanted plants in the laboratory (Shackel et al., 2005), it requires a specialized micropressure probe system which is not suitable for assay*Correspondence: E-mail: yhlu@ippcaas.cn

The adoption of Bt transgenic cotton has practically eliminated lepidopteran pests from this crop and has produced a secondary pest problem, with pierce-sucking insects such as the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae). The future of cotton genetic pest management is threatened by these insects and their development of resistance to chemical insecticides. Lygus lineolaris is also a pest of more than 100 other crops. The development of transcriptome data for this insect should be transformative in essentially all aspects of research on plant bug biology and the development of control strategies. The first 454 tarnished plant bug whole body (WB) and gut (G) transcriptomes were constructed (half plate for each). A total of 116 163 527 bases were obtained, representing 262 555 WB and 229 919 G reads (SRA048217) of which 232 058 (SRS280903) and 168 069 (SRS280894) reads, respectively, were available for assembly. The average read length was 233.1 and 208.5 bp for WB and G, respectively. The whole body and gut reads were assembled together (WB-G) to produce the most complete transcriptome possible from our sequencing effort and resulted in 6 970 contigs with an average length of 393 bp. The gut transcriptome alone was assembled into 3 549 contigs with an average length of 349 bp. The smallest contig was 55 bp and the largest was 3 466 bp, and there were 62 484 sequences that could not be assembled (singletons) among both transcriptomes. Overall transcriptome analysis was organized according to the Gene Ontology consortium, enzyme commission, and InerPro using the Blast2GO® program. We further characterized metabolic systems and messages associated with development.

Interactions between plants and their herbivores are often multidimensional, complicating interpretation of herbivore-impact studies. A previous study, directed toward understanding variation in incidences of flower bud abscission among cotton plants attacked by Lygus plant bugs, revealed an unanticipated correlation between levels of phosphorus nutrition and the propensity of plants to abscise developing flower buds. Here, we further investigate the relationship between phosphorus nutrition and cotton [Gossypium hirsutum Tod. (Malvaceae)] plant responses to herbivory by tarnished plant bugs, Lygus hesperus Knight (Hemiptera: Miridae). Complementary experimental approaches and survey data both suggest that levels of phosphorus nutrition falling within the normal range of variation can influence the manner by which plants respond to herbivory. In particular, higher levels of phosphorus nutrition resulted in elevated bud abscission rates when buds were damaged. Interestingly, increased levels of abscission under high-phosphorus regimes did not translate into a decrease in overall cotton lint yield, suggesting that the ‘phosphorus effect' may ultimately reflect how environmentally contingent differences in the allocation of vegetative vs. reproductive investments can provide parallel pathways to equal yields.

In recent years, RNA interference (RNAi) has been validated as a viable approach for functional genetic studies in non-model organisms. In this report we demonstrate the efficacy of RNAi in the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Miridae: Hemiptera). A L. lineolaris inhibitor of apoptosis gene (LlIAP) has been identified and cloned. The translated sequence encodes a 381 amino acid protein similar to other insect IAPs and contains two conserved baculovirus inhibitor of apoptosis protein repeat (BIR) domains. Microinjection of double stranded RNA (dsRNA) corresponding to two disparate portions of the gene resulted in decreased LlIAP mRNA quantities relative to controls. Both nymphs and adult specimens injected with IAP dsRNA exhibited significantly reduced lifespan compared with those injected with non-insect dsRNA (eGFP). Thus, RNAi-mediated knockdown of LlIAP expression has been correlated with a lethal phenotype in adults and nymphs.

An experiment that involved 79 named cultivars and advanced selections of Fragaria x ananassa L., 46 Fragaria virginiana Duch. clones, and 12 F. virginiana backcross selections, and eight Fragaria virginiana x Fragaria chiloensis (L.) Duch. (all Rosaceae) selections, was conducted to detect variation in strawberry genotypes for resistance to tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Heteroptera: Miridae). The F. virginiana genotypes were shown to be more resistant than the cultivars and advanced selections in both 2001 and 2002. Within the group of cultivars and advanced selections, several June-bearing and dayneutral genotypes were more resistant than others. There were fewer plant bugs on F. virginiana than on the cultivars and hybrids. Insect numbers were consistently correlated with percentage of damaged fruits and damage severity, but total numbers of flowers and fruits were only correlated with insect numbers, percentage fruit damage, and damage severity in 1 of the 2 years. Our results suggest that strawberry cultivars, highly resistant to tarnished plant bug, can be bred, if the trait is introgressed from F. virginiana selections.

A series of bioassays were conducted to determine the response of adult western tarnished plant bugs, Lygus hesperus Knight (Heteroptera: Miridae), to artificial diets containing potassium chloride (KCl). We first examined the feeding behavior of L. hesperus by direct observation in a no-choice diet feeding arena. We observed a total of 22 Lygus feeding events lasting an average of 411 ± 64 s on the control artificial diet and only three feeding events lasting an average of 11 ± 3 s on the KCl-treated diet. We then conducted several multiple diet choice bioassays to determine the feeding response of L. hesperus when exposed simultaneously to five artificial diet treatments containing different amounts of KCl. For the first bioassay, we used standard clear parafilm diet packets and for the second bioassay we used dark green parafilm diet packets to hold the various diet treatments. Regardless of the diet packet color, L. hesperus overwhelmingly selected the 0% KCl diet treatment over diets containing 3, 6, 9, or 12% KCl. The third and fourth multiple diet choice bioassays were identical to the first bioassay, except that concentrations of the KCl-treated diets were reduced. Lygus hesperus consistently selected the control diet over all diets containing more than 0.5% KCl. However, when the concentration of KCl in the diet was reduced to ≤0.4%, there were no significant differences in feeding activity exhibited by L. hesperus. Finally, to determine if the addition of KCl to the diet influenced their upwind response, we examined the responses of L. hesperus that were simultaneously exposed to a control artificial diet and a diet containing 12% KCl in a Y-tube olfactometer bioassay. Of the 95 adults tested, 47 selected the arm containing the normal diet and 48 selected the arm containing KCl-treated diet, indicating that dietary constituents did not preferentially attract or repel L. hesperus. The results from these studies strongly suggest that KCl negatively affects L. hesperus feeding behavior by functioning as a strong gustatory deterrent when concentrations exceed 0.5%. Visual and volatile cues appeared to have no role in mediating orientation or feeding behavior under these test conditions.

Insect populations vary in the proportion of individuals exhibiting a particular ‘state’ (e.g., developmental stage, sex, egg load, or nutritional status). Because an insect’s developmental state often determines both its size and its behavior, it is likely that this will also affect the probability of being sampled. We propose that a comprehensive approach to pest management must consider the interaction between the structure of a pest population (i.e., the relative number of individuals in each state) and any statedependent sampling bias. To illustrate the usefulness of this method we sampled populations of the western tarnished pest bug, Lygus hesperus Knight (Heteroptera: Miridae), in cotton fields. Our sampling technique utilized large cages to measure the absolute densities of each L. hesperus stage and adult sex within a population. This technique allowed us to document a wide range of absolute stage structures and sex ratios across 10 L. hesperus populations in California. Using a combination of cage samples and sweep net samples, we quantified the state-dependent sampling bias by calculating the efficiency of sweep sampling as a function of L. hesperus developmental stage and sex. We found that the efficiency of sweep nets increased steadily with each successive developmental stage (i.e., nymphal instar) of L. hesperus. We also found that sweep nets are slightly more efficient in capturing male vs. female L. hesperus adults. Since other studies have documented that the stage and sex of L. hesperus can affect feeding impact on cotton flower buds, our results suggest that accurate predictions of Lygus damage will need to incorporate stage and sex-dependent sampling biases.

Effects of mowing frequency on ground cover composition and on numbers of predators, parasitoids, and select phytophagous arthropods in the ground cover of three reduced-insecticide pear orchards were determined. Concurrent samples taken in the tree canopy (with beating trays) and in the herbicide strips on the orchard floor (with pitfall traps) tested whether counts of natural enemies in these two habitats were also affected by mowing regime. A reduction in frequency of mowing from two to three times per month (= control) to once per month or once per growing season led to increased cover of grasses, broadleaf plants, and broadleaf plants in flower. Sweep net samples of natural enemies in the ground cover were dominated numerically by spiders (Araneae), parasitic Hymenoptera, and predatory Heteroptera, with lesser numbers of other taxa (Syrphidae, Neuroptera, Coccinellidae). Predators and parasitoids showed substantial increases in numbers associated with decreased mowing frequency. Sweep net counts of aphids, Lygus spp. (Heteroptera: Miridae), and leafhoppers/planthoppers, all potential prey of predators, also increased significantly with decreased mowing frequency. In the pitfall samples, only the European earwig (Forficula auricularia L.) (Dermaptera: Forficulidae) exhibited a change in counts associated with mowing treatment; numbers of earwigs in pitfall traps declined as mowing frequency decreased. For the beat tray samples, mean tray counts for most natural enemy taxa were higher in the less frequently mowed plots, but significantly (P < 0.05) so only for two taxa: spiders and a predatory mirid, Deraeocoris brevis (Uhler) (Heteroptera: Miridae). It remains to be determined whether biological control of pests in the tree canopy can be enhanced by manipulating mowing frequency. Questions raised by this study include whether there is extensive movement by natural enemies between the ground cover and tree canopy, and whether plot size affects the likelihood of showing that mowing frequency influences predator densities in the tree canopy.

A vacuum apparatus was used in a test bench environment to determine the effects of two operational parameters on vacuuming efficacy for an insect pest. Nymphs and adults of tarnished plant bug, Lygus lineolaris P. de. B. (Hemiptera: Miridae), marked with fluorescent powder, were positioned on strawberry plants according to three height classes. Three speeds of inlet passage (i.e., 2, 4 and 6 km h -1 ) and two heights (passage at 2/3 and 3/3 of the canopy) of inlet relative to the top canopy of the plants were investigated. After vacuuming the marked insects remaining on the plants were then found using a UV light and the class height of their position on the plant and the substrate (i.e., soil, leaf, stem or fruit/flower) were noted. The efficacy of the vacuum was optimal when the inlet was passed at 4 km h -1 with the inlet at a height of 2/3 of the strawberry canopy. Nymphs were usually vacuumed more efficiently than adults. Most (64.5%) individuals that were not vacuumed did not change position after inlet passage. Most (85.9%) individuals that changed position after inlet passage experienced vertical, mostly downward, movements.

Lygus bugs (Heteroptera: Miridae) are mostly phytophagous insects which can be pests on a number of agronomic crops (Snodgrass et al., 1984). The tarnished plant bug, Lygus lineolaris (Palisot de Beau-vois), is a polyphagous insect with nearly 400 known hosts of which at least 130 are economically-important crops in the U.S. and Canada (Young, 1986). The polyphagous nature of L. lineolaris is apparent in its life cycle in which adults move from one host plant to the next according to the sequential occurrence of suitable hosts during the growing season (Cleveland, 1982). Although it is known that females release an attractant for males which facilitates mating (Scales, 1968; Graham, 1987), the pheromone has not yet been identified. The small size of L. lineolaris and its antennae is a significant obstacle to biochemical studies of olfaction of this insect.

In no-choice tests Leiophron uniformis (Gahan) from the Southwestern United States readily attacked their reported hosts, Lygus hesperus Knight, L. lineolaris (Palisot de Beauvois), L. elisus Van Duzee, and a previously unreported host, L. desertinus Knight. Only 6.7% of the L. lineolaris attacked were successfully parasitized compared to 84–87% parasitization of the other species. Such low parasitism of L. lineolaris was obtained with both laboratory-reared and field-collected parasitoids. Two factors caused the low rate of parasitism of L. lineolaris. (1) This host successfully encapsulates most of the L. uniformis eggs oviposited in them. This is the first time such an immune response to a parasitoid has been demonstrated in the Heteroptera. (2) Female L. uniformis oviposit less frequently into L. lineolaris than into other hosts. Resume Etude de l'encapsulation de Leiophron uniformis par Lygus lineolaris et de ses relations avec le comportement d'acceptation de l'hote L'aptitude du braconide Leiophron uniformis a parasiter les larves de quatre especes nuisibles importantes de Lygus a ete examinee. Les especes de Lygus signalees comme hotes de L. uniformis: L. hesperus, L. lineolaris, L. elisus, et un hote jamais signale, L. desertinus ont ete exposees separement a des femelles de braconide. Les larves des quatre especes sont fortement attaquees. Seules 6,7% des larves de L. lineolaris attaquees ont ete parasitees avec succes, contre 84 a 87% pour les trois autres especes. Ce faible taux de parasitisme de L. lineolaris etait le resultat aussi bien des attaques de parasitoides recoltes dans la nature qu'eleves au laboratoire. Les larves de L. hesperus et L. lineolaris attaquees par les femelles de L. uniformis ont ete dissequees. Seuls 12,8% des larves de L. lineolaris contenaient des indices de pontes contre 83,7% pour celles de L. hesperus. 66,7% des oeufs trouves dans L. lineolaris etaient encapsules. C'est la premiere fois qu'une telle reponse immunologique a ete observee chez un heteroptere. Le faible nombre d'oeufs pondus par la femelle du braconide montre qu'elle est capable de detecter l'inadequation de L. lineolaris comme hote et d'eviter de gaspiller ses oeufs en utilisant peu les larves attaquees.

The digestibility of raw starches by the amylases in the digestive system of Lygus disponsi and the effect of CI−or NO3− on the digestion were investigated. Raw potato starch was only little digested by the amylases, while raw wheat starch was digested fairly well and raw corn starch moderately. The promoting effect of CI− or NO3− on the digestion of the raw starch was nil in potato, pronounced in corn and moderate in wheat. In the shaking incubation, the promoting effect of NO3− on the digestion of raw wheat starch showed a tendency to be negative. When the insoluble starches were cooked, their digestibility was improved and about equal among wheat, corn and potato. The promoting effect of CI− or NO3− on the digestion of the cooked insoluble starches exceeded those of the raw insoluble starches and the cooked soluble starch. The possibility of starch digestion by L. dispons***i and the significance of the promoting effect of CI− and NO3− on the digestion were discussed. ZUSAMMENFASSUNG DIE VERDAULICHKEIT ROHER STARKEN DURCH DIE AMYLASEN IM VERDAUUNGSSYSTEM DER WANZE LYGUS DISPONSI UND DIE WIRKUNG VON CI− UND NO3− AUF DIE VERDAUUNG Die Verdaulichkeit roher Starke durch die Amylasen im Verdauungssystem der Wanze L. disponsi und die Wirkung von CI− und NO3− auf die Verdauung wurde untersucht. Rohe Kartoffelstarke wurde durch die Amylasen nur wenig verdaut, aber rohe Weizen- und Maisstarken ziemlich gut, beziehungsweise leidlich. Die fordernde Wirkung von CI− und NO3− auf die Verdauung der rohen Starken war null bei der Kartoffel, ausgepragt beim Mais und mittelmassig beim Weizen. Im Falle der Schuttel-Inkubation zeigte die fordernde Wirkung von NO3− auf die Verdauung roher Weizenstarke eine Neigung negativ zu werden. Wenn unlosliche Starke gekocht wurde, wurde ihre Verdaulichkeit verbessert, und fur alle der Weizen-, Mais- und Kartoffelstarken zwar im gleichen Masse. Die fordernde Wirkung von CI− und NO3− auf die Verdauung der gekochten unloslichen Starke ging uber diejenige der rohen unloslichen Starke und der gekochten loslichen Starke hinaus. Die Moglichkeit der Starkeverdauung durch L. disponsi und die Bedeutung der fordernde Wirkung von CI− und NO3− auf Verdauung wurden erortert.