Assessment of trap plants to regulate numbers of the European tarnished plant bug, Lygus rugulipennis, on late-season strawberries

Various species of plants in the family Asteraceae were shown to be hosts for the European tarnished plant bug Lygus rugulipennis and one, Matricaria recutita, was chosen as a potential trap plant for adults of this capsid species on their migration into fields of late-season strawberries from other host plants in July. There was a delay in the build-up of populations of nymphs of L. rugulipennis on strawberries surrounded by a barrier strip of M. recutita compared to those without a barrier, but overall there were no consistent reductions in populations of the pest. Numbers of L. rugulipennis on the trap plant were small until late August. In a similar experiment using an alternative trap plant, Medicago sativa, no significant reductions in the numbers of L. rugulipennis were found on strawberries with the trap barrier, despite large numbers of the pest insect being found on this trap plant.Although predatory arthropods such as spiders, Orius spp., and nabids, and hymenopterous parasitoids were found on the trap plants, there was no indication that they became more numerous on the strawberry plots inside these barriers than on those without surrounding trap plants.     

The phenology of Lygus rugulipennis, the European tarnished plant bug, on late-season strawberries, and control with insecticides

The phenology of Lygus rugulipennis, the European tarnished plant bug, was studied in fields of strawberries producing late-season (July to September) crops. Adults invaded fields in small numbers, mainly in July. Large numbers of nymphs were found in late July and early August; these matured into adults from late August. Adults formed the overwintering population; some remained in strawberry fields but left in spring to feed on other host plants. All the insecticides tested, i.e. malathion, chlorpyrifos, heptenophos, cypermethrin, bifenthrin and trichlorfon, gave good short-term control of nymphs.     

绿盲蝽为害对枣树叶片光合作用及叶绿素荧光特性的影响

【目的】探讨绿盲蝽Apolygus lucorum(Meyer-Dür)为害对枣树叶片光合作用的影响及其机制。【方法】以一年生冬枣Zizyphus jujuba cv.Dongzao和酸枣Ziziphus jujuba var.spinosa树叶片为试材,测定了绿盲蝽为害1,3,5和7 d时枣树叶片光合速率、气体交换、叶绿素荧光参数和叶绿素含量的变化。【结果】绿盲蝽为害3,5和7 d时冬枣叶片的净光合速率(net photosynthesis rate,Pn)较对照分别降低了55.83%,55.42%和59.61%;而酸枣叶片净光合速率仅在5和7 d时较对照分别降低了26.66%和27.34%。冬枣叶片的气孔导度被绿盲蝽为害3,5和7 d时较对照明显降低。冬枣叶片光合速率的下降与气孔导度(stomatal conductance,Gs)和总叶绿素含量的下降呈显著正相关,而酸枣叶片光合速率的下降仅与叶绿素含量显著正相关。绿盲蝽为害后冬枣和酸枣叶片的快速荧光诱导曲线受到显著影响。冬枣叶片的最大光化学效率(maximum photochemical efficiency,Fv/Fm)在绿盲蝽为害不同时间时相对于对照明显降低,而酸枣叶片没有受到明显的影响。绿盲蝽为害不同时间对冬枣和酸枣叶片的光系统Ⅱ放氧复合体(oxygen-evolving complex,OEC)以及光反应活性中心均造成了伤害,但酸枣受到的伤害程度明显低于冬枣。绿盲蝽为害5和7 d后冬枣叶片的光系统Ⅱ的电子传递活性降低,而酸枣叶片光系统Ⅱ的电子传递活性没有受到显著影响。绿盲蝽为害导致冬枣和酸枣叶片的电子传递的量子产额较对照明显降低,酸枣叶片中的降低幅度低于冬枣。【结论】绿盲蝽为害造成枣树叶片净光合速率明显降低,不同品种存在明显差异,冬枣叶片Pn降低程度明显高于酸枣。绿盲蝽为害后枣树叶片净光合速率的下降与叶绿素含量降低呈显著正相关。绿盲蝽为害影响了枣树叶片PSⅡ的结构和功能,导致供体侧的OEC受到伤害,光合作用PSⅡ反应中心失活,PSⅡ反应中心关闭程度增加,电子传递活性受到了抑制,其中酸枣叶片PSⅡ受到的影响明显低于冬枣叶片。     

A false‐positive food chain error associated with a generic predator gut content ELISA

Conventional prey‐specific gut content ELISA (enzyme‐linked immunosorbent assay) and PCR (polymerase chain reaction) assays are useful for identifying predators of insect pests in nature. However, these assays are prone to yielding certain types of food chain errors. For instance, it is possible that prey remains can pass through the food chain as the result of a secondary predator (hyperpredator) consuming a primary predator that had previously consumed the pest. If so, the pest‐specific assay will falsely identify the secondary predator as the organism providing the biological control services to the ecosystem. Recently, a generic gut content ELISA was designed to detect protein‐marked prey remains. That assay proved to be less costly, more versatile, and more reliable at detecting primary predation events than a prey‐specific PCR assay. This study examines the chances of obtaining a ‘false positive’ food chain error with the generic ELISA. Data revealed that the ELISA was 100% accurate at detecting protein‐marked Lygus hesperus Knight (Hemiptera: Miridae) remains in the guts of two (true) primary predators, Hippodamia convergens Guérin‐Méneville (Coleoptera: Coccinellidae) and Collops vittatus (Say) (Coleoptera: Melyridae). However, there was also a high frequency (70%) false positives associated with hyperpredators, Zelus renardii Kolenati (Hemiptera: Reduviidae), that consumed a primary predator that possessed protein‐marked L. hesperus in its gut. These findings serve to alert researchers that the generic ELISA, like the PCR assay, is susceptible to food chain errors.     

Host preferences of introduced and native parasites (Hymenoptera: Braconidae) of phytophagous plant bugs (Hemiptera: Miridae) in alfalfa-grass fields in the northeastern USA

During an eight-year field study at two widely-separated locations (NJ & DE, USA), seven species of phytophagous mirid plant bugs were found in alfalfa and alfalfa-grass fields grown for animal forage. Five species of parasites were reared from these mirids. Two parasite species introduced from Europe killed significantly higher proportions of nymphs of the two important mirid pests of alfalfa than did native parasites. The introduced Peristenus digoneutis Loan parasitized an average of 31% of first and second generation tarnished plant bugs, Lygus lineolaris, a native insect; and the introduced Peristenus conradi parasitized 22% of first generation alfalfa plant bugs, Adelphocoris lineolatus, an introduced species. In addition, Peristenus pallipes significantly parasitized nymphs of Trigonotylus caelestialium (43%) and Leptopterna dolabrata (37%); both mirids are immigrant species. Because the parasite P. pallipes significantly attacked only these two non-native mirids, and is present in Europe, it also may be an accidental introduction to North America. A native wasp, Leiophron uniformis, heavily parasitized (49%) the native garden fleahopper, Halticus bractatus. A third native species, P. pseudopallipes, occasionally parasitized a few Lygus lineolaris in alfalfa at one location. Two other mirids, Stenotus binotatus and Megaloceroea recticornis, both accidently-introduced grass-feeding species, were not parasitized by native or introduced species. It is noteworthy that the effective host ranges of all the parasites in alfalfa-grass fields were limited: four of the five parasite species significantly parasitized only one of the seven mirid species, and the other parasite significantly parasitized only two mirids. Activity of the four common parasites was correlated with the mirids' host plant: three species principally parasitized alfalfa-feeding mirids, and one species principally parasitized grass-feeding mirids.     

Stage-dependent feeding behavior by western tarnished plant bugs influences flower bud abscission in cotton

Unexplained variability in the relationship between the number of herbivores in a field and the amount of crop damage can arise if there is a large amount of variation among herbivore individuals in the amount of feeding damage each generates. In California, populations of the western tarnished plant bug, Lygus hesperus Knight (Heteroptera: Miridae), produce highly variable levels of damage to cotton plants (Gossypium hirsutum L.) (Malvaceae), even when found at low densities. Because L. hesperus populations are also highly variable in their overall stage structure, we hypothesize that differences in crop damage might result from varying impact by each L. hesperus stage on cotton flower buds (termed squares). Laboratory measurements of L. hesperus mouth‐parts and distance to anther sacs, a preferred feeding site, revealed that 1st?3rd instar L. hesperus nymphs will not be able to feed on anther sacs of larger squares (over 8 mm in length) but will be able to feed on squares that are most sensitive to L. hesperus damage (<7 mm). Because even the 1st instars can feed on the most sensitive ‘pinhead’ squares, size constraints do not rule out damaging effects from the youngest L. hesperus. Laboratory observations revealed that later developmental stages, and adults, spend more time feeding on cotton squares relative to 2nd and 3rd instars. In addition, a field experiment revealed no effect of 2nd instars on square retention (relative to control cages) but did reveal a significant decrease in square retention generated by adult L. hesperus (4th instar L. hesperus resulted in an intermediate level of square retention). In a final study we sampled L. hesperus stage structure and density across 38 cotton fields. Multiple regression revealed that the densities of 1st?3rd instars of L. hesperus are not correlated with anther sac damage or square retention. However, in 2 years 4th and 5th instars were positively correlated with anther sac damage and negatively correlated with square retention. In the a third year, adult L. hesperus showed correlations in the same direction, across fields and across sites within fields. Overall, these results suggest that the adults and the largest nymphs of L. hesperus (4th and 5th instars) are particularly damaging to cotton squares, with the 1st?3rd instars of L. hesperus causing little damage to plants.     

Optimal concentration of Beauveria bassiana vectored by bumble bees in relation to pest and bee mortality in greenhouse tomato and sweet pepper

Greenhouse cage trials were conducted to determine the optimal concentration of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) (BotaniGard 22WP^® formulation) as vectored by the bumble bee, Bombus impatiens (Cresson) (Hymenoptera: Apidae) pollinator for control of greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) on greenhouse tomato, tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae) and green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae) on greenhouse sweet pepper. Three inoculum concentrations of B. bassiana: low, 9 × 10⁹; middle, 6.24 × 10¹⁰; and high, 2 × 10¹¹ conidia g^?1 of inoculum and two controls (one with bees and heat-inactivated inoculum, and the other which contained only the host plants and pest species) were tested in a completely randomized block design. Beauveria bassiana killed 18, 54 and 56% of the adult T. vaporariorum and 33, 70 and 67% of the adult L. lineolaris, respectively, at the low, middle and high concentrations; but no infection from B. bassiana occurred in each of the control treatments. Internal infection rates after surface sterilization of the pest insects were 11, 34 and 35% for adult T. vaporariorum, 29, 54 and 58% for adult L. lineolaris, 22, 34 and 30% for nymphal M. persicae and 17, 29 and 32% for nymphal T. vaporariorum, respectively, at the low, middle and high concentrations. Significantly more bumble bees died at the high concentration of B. bassiana (42–45%) than at the other concentrations (9–15%) and the controls (5–7%). Spores of B. bassiana were collected throughout the plant canopy with the greatest numbers sampled from the top third of the canopy [ca. 1,200 colony forming units (CFU) per cm^?2]. The middle concentration was selected as the optimal concentration because it provided the best pest control with the least impact on the bees.     

绿盲蝽气味结合蛋白AlucOBP7的表达及气味结合特性

气味结合蛋白(odorant binding proteins, OBPs) 在昆虫嗅觉识别中起着重要的作用, 尤其是在运输外界脂溶性气味分子通过嗅觉感器淋巴液到达嗅觉受体(olfactory receptors, ORs)的过程中发挥关键作用。明确OBPs在昆虫同外界进行信息交流过程中的作用有利于阐明昆虫嗅觉识别的机制, 同时可为利用干扰昆虫嗅觉识别来进行害虫防治奠定理论基础。本研究克隆了一个绿盲蝽Apolygus lucorum (Meyer-Dür)气味结合蛋白AlucOBP7基因（GenBank登录号: JQ675724）, 并进行了原核表达, 以1-NPN为荧光探针采用荧光竞争结合实验研究了AlucOBP7蛋白和10种棉花挥发物及 6种性信息素类似物的结合能力。结果表明： 在10种棉花挥发物中, AlucOBP7能够和2 己酮及水杨酸甲酯有效结合, 结合常数分别为55.13 μmol/L和28.26 μmol/L。在6种盲蝽性信息素类似物中, 4-氧代-反-2-己烯醛和AlucOBP7 具有较强的结合能力, 结合常数为23.14 μmol/L。丁酸乙酯、 丁酸丁酯及己酸己酯也能够和AlucOBP7 有效结合, 但结合能力中等, 结合常数分别为30.58, 39.26和35.81 μmol/L。初步推测, AlucOBP7 可能是绿盲蝽性信息素结合蛋白(pheromone binding proteins, PBPs), 并在感受性信息素和植物挥发物的过程中发挥双重功能。     

The mitochondrial genome of the plant bug Apolygus lucorum （Hemiptera： Miridae）＂ Presently known as the smallest in Heteroptera

The complete mitochondrial （mt） genome of the plant bug, Apolygus lucorum, an important cotton pest, has been sequenced and annotated in this study. The entire circular genome is 14 768 bp in size and represents the smallest in presently known heteropteran mt genomes. The mt genome is encoding for two ribosomal RNA （rRNA） genes, 22 transfer RNA （tRNA） genes, 13 protein coding genes and a control region, and the order, content, codon usage and base organization show similarity to a great extent to the hypothetical ancestral model. All protein coding genes use standard initiation codons ATN. Conventional stop codons TAA and TAG have been assigned to the most protein coding genes; however, COIII, ND4 and ND5 genes show incomplete terminator signal （T）. All tRNA genes possess the typical clover leaf structure, but the dihydrouridine arm of tRNAser（A6N） only forms a simple loop. Secondary structure models of rRNA genes are generally in accordance with the former models, although some differences exist in certain parts. Three intergenic spacers have never been found in sequenced mt genomes of Heteroptera. The phylogenetic study based on protein coding genes is largely congruent with previous phylogenetic work. Both Bayesian inference and maximum likelihood analyses highly support the sister relationship ofA. lucorum and Lygus lineolaris, and Miridae presents a sister position to Anthocoridae.