Eight polymorphic microsatellite markers developed in the green leaf bug,Lygus lucorum Meyer‐Dür (Hemiptera: Miridae)

We developed eight polymorphic microsatellite markers for the green leaf bug, Lygus lucorum Meyer‐Dür. The number of observed alleles per locus in 48 individuals ranged from three to 13, whereas the observed and expected heterozygosities ranged from 0.133 to 0.810 and from 0.236 to 0.886, respectively. Cross‐species amplifications were conducted both within and between generas, and the amplification results indicated that these primers enriched for L. lucorum Meyer‐Dür are species‐specific.     

Effect of different isolates of Beauveria bassiana on field populations of Lygus hesperus

Lygus hesperus (Knight) (Hemiptera: Miridae) is a particularly damaging pest of many crops in the Western United States. Current control tactics are chemically based and there is some concern over resistance building up in populations. Based on previous laboratory studies conducted in California and Mississippi, USA, two new isolates of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (Deuteromycotina: Hyphomycetes) were selected for field-testing against L. hesperus in California. Alfalfa plots were treated with one of three isolates of B. bassiana (a commercial isolate, an isolate from CA (WTPB2) or an isolate from MS (TPB3)) or the chemical pesticide Warrior T. More than 75% of the adults collected from plots 3 days after application with B. bassiana were infected but no differences in percentage infection occurred among fungal treatments. In addition, approximately 30% of the insects collected from control plots or plots treated with Warrior T were also infected. PCR analysis using SSR markers revealed that the isolate causing most of the infections in fungus treated plots was the isolate applied. A mix of infections was found in control plots and plots treated with Warrior T. Despite high levels of infection, no significant reductions of adult populations occurred until 10–14 days after application when plots treated with Warrior T or B. bassiana had about half the numbers of adult L. hesperus as the control plots.     

Identification of endo- and exo-polygalacturonase activity in Lygus hesperus (Knight) salivary glands

Polygalacturonase (PG) activity found in the salivary gland apparatus of the western tarnished plant bug (WTPB, Lygus hesperus Knight) has been thought to be the main chemical cause of the damage inflicted by this mirid when feeding on its plant hosts. Early viscosity and thermal stability studies of the PG activity in L. hesperus protein extracts were difficult to interpret. Thus, it has been suggested that one or more PG protein(s) with different hydrolytic modes of action are produced by this mirid. In order to understand the quantitative complexity of the WTPB salivary PG activity, PG purification from a protein extract from salivary glands excised from L. hesperus insects was performed using affinity and ion exchange chromatography. To elucidate the qualitative complexity of the purified PGs, the digestion products generated by the PGs were separated using high performance anion exchange chromatography with pulsed amperometric detection. At least five PG proteins were detected; these differing in terms of their glycosylation, mass-to-charge ratios, and/or molecular mass. The characterization of the products generated by these PGs showed that endo- and exo-acting PGs are produced by WTPB. Although none of the PGs was purified to homogeneity, the present work provides biochemical evidence of a multiplicity of PGs that degrade the pectin component of the plant tissue in different fashions. The implications of these findings affect the understanding of WTPB feeding damage and, potentially, help identify ways to control this important crop pest. Arch. Insect Biochem. Physiol. 2008. © 2008 Wiley-Liss, Inc.     

熊蜂气管内寄生螨布赫纳蝗螨的生物学特性观察

对新疆与河北地区野生明亮熊蜂及小峰熊蜂蜂王内寄生螨布赫纳蝗螨Locustacarus buchneri的生物学特性进行了初步观察。结果表明： 该螨对两种熊蜂的寄生率分别为10.43%和8.3%,寄生部位为气管与气囊。室内饲养至30天的蜂王体内寄生螨量明显高于饲养至60天的蜂王。未被螨寄生的蜂王与被寄生者比较,前者体重显著高于后者,但二者间产卵始期、产卵率、食卵率和存活率差异不显著。     

Vacuuming tarnished plant bug on strawberry: a bench study of operational parameters versus insect behavior

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 lineolarisP. 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^–1with 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.     

A survey of Lygus parasitoids in Sweden

Lygus spp. (tarnished plant bugs) are generalist herbivores and occur as pests on a wide range of crops. In the development of conservation biological control strategies for Lygus spp. in Sweden, more information is needed on the impact of different natural enemies. In this study, we determined the occurrence and the degree of parasitism on adults and nymphs of the most common Lygus species in alfalfa, barley, red clover and oilseed rape in Uppsala in Central Sweden and in Umeå in Northern Sweden. Nymphs and adults of Lygus spp. were collected by sweep netting for estimation of their parasitism level (by dissection) and identification of parasitoid species (from reared Lygus specimens). The dominant Lygus species in both locations was L. rugulipennis (75–99%). Parasitism by Phasia obesa (Tachnidae) on overwintering Lygus adults was recorded in almost every field sampled at both locations. The parasitism level was low at overwintering sites but increased in arable fields during summer. Lygus nymphs collected in Umeå were parasitised by Peristenus pallipes (Braconidae) and in Uppsala by P. relictus, P. pallipes and P. varisae. The hyperparasite Mesochorus globulator (Ichneumonidae) was recorded in Umeå.     

不同寄主植物对绿盲蝽成虫形态发育的影响

本文探讨了桃树、枣树、茶树及棉花4种不同寄主植物对绿盲蝽成虫形态发育的影响。通过田间采集4种寄主上绿盲蝽成虫,从体长、体宽、口针长、头宽和体重等指标比较不同寄主植物绿盲蝽的差异。结果表明,棉花绿盲蝽雌雄虫的体长、体宽、口针长、头宽均显著大于其他3种寄主植物。在体重上,雌虫和雄虫均表现出棉花＞茶树＞枣树＞桃树的规律,而且棉花绿盲蝽显著高于桃树绿盲蝽。试验表明,不同寄主植物对绿盲蝽成虫的形态发育有明显影响。在这4种寄主中,棉花极显著利于绿盲蝽成虫的形态发育。     

Influence of the surrounding landscape on crop colonization by a polyphagous insect pest

Landscape composition plays an important, but poorly understood, role in the population dynamics of agricultural pest species with broad host ranges including both crops and weeds. One such pest, the generalist plant bug Lygus hesperus Knight (Hemiptera: Miridae), is a key cotton pest that feeds on various hosts differing in quality in California's San Joaquin Valley (USA). We investigated the effects of 15 common crops and uncultivated agricultural land on L. hesperus populations, by correlating the densities of L. hesperus in focal cotton fields with the areas of the 16 crops in surrounding rings. Insect counts were provided by private pest‐control advisors, and spatial data were obtained from Kern County records. We first calculated Spearman's partial correlation coefficients on an annual basis for each crop separately, and then performed a meta‐analysis of these correlations across years to describe the overall effect of a particular crop on L. hesperus after the effects of the 15 other crops are removed. Consistent with studies conducted in other areas, L. hesperus density was positively correlated with safflower, and negatively with cotton. Lygus hesperus density was also correlated with several other crops that are often not considered in pest management, including grape, oat, and onion (positive correlations), and almond, pistachio, and potato (negative correlations). Lygus hesperus density was also found to be negatively correlated with alfalfa and positively correlated with uncultivated habitats, a relationship that receives mixed support in the literature. Several other crops tested were not significantly correlated with L. hesperus densities in focal cotton fields, suggesting a neutral role for them in L. hesperus dynamics. The improved understanding of the effects of a greater variety of crops on L. hesperus population dynamics will be useful in the design of agricultural landscapes for enhanced management of this important polyphagous pest.