辽宁省潜叶蝇（双翅目：潜蝇科）及其寄生蜂的种类与多度调查

辽宁省是东北地区重要的“菜篮子”生产基地。蔬菜易受到潜叶蝇的为害,导致蔬菜产业的健康发展受到威胁。为了更好防控蔬菜上的潜叶蝇,本研究对辽宁省潜叶蝇和寄生蜂进行本底资源调查。以辽宁省潜叶蝇及其天敌寄生蜂的种类和多样性为切入点进行田间调查,采用随机取样法,于2016-2020年调查辽宁省蔬菜、花卉以及杂草上潜叶蝇及其寄生蜂的种类和多样性,并基于形态特征与COI基因序列对潜叶蝇和寄生蜂的种类进行鉴定。结果显示,辽宁省共鉴定出5种潜叶蝇,包括本地种豌豆彩潜蝇Phytomyza horticola和葱斑潜蝇Liriomyza chinensis,入侵种美洲斑潜蝇L. sativae、三叶草斑潜蝇L. trifolii和番茄斑潜蝇L. bryoniae;其中发生最为优势的种类为豌豆彩潜蝇,其嗜好十字花科和菊科植物;寄主谱最广的是美洲斑潜蝇,发现危害7科17种植物。共发现潜叶蝇的寄生蜂41种,从发生数量来看,以姬小蜂科最多（7 816头,占比78.84%）,其次是金小蜂科（1 533头,占比15.46%）、茧蜂科（549头,占比5.54%）和瘿蜂科（16头,占比0.16%）;姬小蜂科的多样性指数和丰富度指数均最高,瘿蜂科均匀度指数最高;豌豆潜蝇姬小蜂Diglyphus isaea（4 385头）是优势种,占寄生蜂总数的44.23%。本研究填补了辽宁省潜叶蝇及其天敌寄生蜂的种类及多度调查的空白,为该省份潜叶蝇的防治和天敌寄生蜂的深入研究奠定了理论基础,同时建议加强对辽宁省的豌豆彩潜蝇和美洲斑潜蝇的防治,发挥当地优势寄生蜂如豌豆潜蝇姬小蜂对潜叶蝇的生物防控作用。     

Host Range Assessment of Helicotylenchus pseudorobustus (Tylenchida: Hoplolaimidae) on Pasture Species

The host status of 15 commonly occurring pasture species for Helicotylenchus pseudorobustus was tested in a greenhouse trial. Only tall fescue, with and without Neotyphodium endophyte infection, was a good host (Pf/Pi = final/initial population > 1). Inoculation survival was tested in a second trial, which showed that only 10% of the H. pseudorobustus nematodes survived the first 7 days after inoculation. When the Pf/Pi was adjusted to account for a 10% survival, all of the grass and clover hosts tested had a Pf/Pi > 1. Both trials showed a positive correlation between increased numbers of H. pseudorobustus and free-living nematodes.     

Biosteres longicaudatus: Developmental dependence on host (Anastrepha suspensa) physiology

Larvae of Anastrepha suspensa that were in the first day of the third instar were parasitized by females of the solitary endoparasitoid, Biosteres longicaudatus. At the end of the 6-hr oviposition period, larvae were ligated posterior to the ring gland so that some larvae had parasitoids anterior to the ligature while in others, the parasitoids were in the abdomen, posterior to the ligature. Ninety-two percent of the parasitoids anterior to the ligature hatched to the first through third instars. Parasitoids posterior to the ligature had a 75% egg hatch to the first instar only. No larval molts to the second or subsequent instars occurred in these parasitoids. Upon parabiosis to 3-day-old, unparasitized host pupae, the ligated larvae pupated and 97% of the first-instar parasitoids in these parabiosed larval abdomens molted to the second instar. Newly laid parasitoid eggs transplanted to 3-day-old pupal hosts had less than one-third of the egg hatch of those transplanted to first-day third-instar hosts. The data implicate the physiological state of the host (vis-a-vis pupation and associated events) as being an important factor in the development of the endoparasitoid.     

Meloidogyne petuniae n. sp. (Nemata: Meloidogynidae), a Root-knot Nematode Parasitic on Petunia in Brazil

Meloidogyne petuniae n. sp. is described and illustrated from specimens parasitic on petunia (Petunia hybrida L.) in Brasilia, Brazil. The perineal pattern of the female is elongate to ovoid with a high, squarish arch and widely spaced, coarse striae. The stylet of the female is 12.9-16.5 µm long and has three small, rounded knobs that are distinctly set off from the shaft. Each knob is marked by a deep longitudinal indentation posteriorly and anteriorly. In SEM the base of the shaft appears to be divided into six distinct ridges. The excretory pore opens about 15.4-53.6 µm from the head end. Males are approximately 0.8-2.2 mm long. Most specimens have a high and narrow head cap, but in some the head cap is narrow and low. The stylet of the male is 21.1-26.0 µm long and has small, rounded knobs, set off from the shaft, but not indented as in the female. Second-stage juveniles are 353-464 µm long; the labial disc is fused with the medial lips to form a dumbbell-shaped head cap; the medial lips are indented posteriorly; and the head region is marked with one to two irregular annulations. The stylet is 9.2-10.8 µm long and has rounded, posteriorly sloping knobs. The tail is slender, approximately 46.4-57.2 µm long, and has a short hyaline terminus, 10.3-13.5 µm long. The somatic chromosome number is 2n = 41 and the esterase phenotype is VS1-S1, with S1 being a weak band. The malate dehydrogenase phenotype is N1, which is unique for this species. Petunia, tomato, tobacco, pea, and bean are good hosts; pepper, watermelon, and sweet corn are poor hosts; and peanut, cotton, and soybean are non-hosts. Galls produced by this species are smaller on petunia than on tomato.     

Detection of the solanum fruit fly, Bactrocera latifrons (Hendel) in Tanzania (Dipt., Tephritidae)

Abstract:  The presence of the Solanum fruit fly, Bactrocera latifrons , in Africa is reported for the first time, based on trapped and reared specimens in Tanzania. Two new host records, Solanum aethiopicum and Solanum macrocarpon , are reported.     

Pristionchus uniformis,should I stay or should I go? Recent host range expansion in a European nematode

Pristionchus pacificus has been developed as a model system in evolutionary developmental biology, evolutionary ecology, and population genetics. This species has a well-known ecological association with scarab beetles. Generally, Pristionchus nematodes have a necromenic association with their beetle hosts. Arrested dauer larvae invade the insect and wait for the host's death to resume development. Only one Pristionchus species is known to frequently associate with a non-scarab beetle. Pristionchus uniformis has been isolated from the chrysomelid Leptinotarsa decemlineata, also known as the Colorado potato beetle, in Europe and North America, but is also found on scarab beetles. This unusual pattern of association with two unrelated groups of beetles on two continents requires the involvement of geographical and host range expansion events. Here, we characterized a collection of 81 P. uniformis isolates from North America and Europe and from both scarab beetles and L. decemlineata. We used population genetic and phylogenetic analyses of the mitochondrial gene nd2 to reconstruct the genetic history of P. uniformis and its beetle association. Olfactory tests on beetles chemical extracts showed that P. uniformis has a unique chemoattractive profile toward its beetle hosts. Our results provide evidence for host range expansion through host-switching events in Europe where P. uniformis was originally associated with scarab beetles and the nematode's subsequent invasion of North America.     

Are three colonies of Neostromboceros albicomus,a candidate biological control agent for Lygodium microphyllum,the same host biotype?

Three colonies of Neostromboceros albicomus, a candidate biological control agent of Lygodium microphyllum, were barcoded using the D2 expansion domain, to determine which of two biotypes they represented. The first colony, collected in 2005 and 2007, was used for the initial host range testing. Colonies collected in 2012 and 2014 are currently being used to finalise this testing. All three colonies were collected in Trat Province, Thailand and all three populations show identical sequences to the N. albicomus biotype which prefers L. microphyllum as its host plant. The N. albicomus biotype that uses L. flexuosum as its host plant differs by a single nucleotide, a difference which may reflect cryptic speciation.