Native plant diversity increases herbivory to non-natives

There is often an inverse relationship between the diversity of a plant community and the invasibility of that community by non-native plants. Native herbivores that colonize novel plants may contribute to diversity–invasibility relationships by limiting the relative success of non-native plants. Here, we show that, in large collections of non-native oak trees at sites across the USA, non-native oaks introduced to regions with greater oak species richness accumulated greater leaf damage than in regions with low oak richness. Underlying this trend was the ability of herbivores to exploit non-native plants that were close relatives to their native host. In diverse oak communities, non-native trees were on average more closely related to native trees and received greater leaf damage than those in depauperate oak communities. Because insect herbivores colonize non-native plants that are similar to their native hosts, in communities with greater native plant diversity, non-natives experience greater herbivory.     

Divergence of ovipositor length and egg shape in a brood parasitic bitterling fish through the use of different mussel hosts

Bitterling fishes deposit their eggs on the gills of living mussels using a long ovipositor. We examined whether ovipositor length (OL) and egg shape correlated with differences in host mussel species in the family Unionidae among populations of the tabira bitterling (Acheilognathus tabira) in Japan. Bitterling populations that use mussels in the sub-family Anodontinae possessed longer ovipositors and more elongated eggs than those using mussels of Unioninae, as expected from the difference in host size between the sub-families (anodontine mussels are larger than unionine mussels). Based on a robust phylogeny of A. tabira populations, we demonstrated that the evolution of both OL and egg shape were correlated with host differences, but not with each other, suggesting that these traits have been selected for independently. Our study demonstrates how adaptive traits for brood parasitism may diverge with host shift due to different host availability and/or interspecific competition for hosts.     

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。     

Seasonal host alternation by the andromeda lace bug,Stephanitis takeyai (Heteroptera: Tingidae) between its two main host-plant species

I studied the seasonal occurrence of the andromeda lace bug,Stephanitis takeyai, on its two main host-plant species. In a secondary forest in Kyoto, this bug altered its hosts seasonally, i.e., from an evergreen shrub,Pieris japonica, in winter to a deciduous shrub,Lyonia elliptica, in summer. In contrast, in Nara park where fewL. elliptica were available, the bug exploited onlyP. japonica. Thus, seasonal host alternation by this bug is not obligate. A comparison of adult longevity and fecundity on the two host-plant species demonstrated the higher quality ofL. elliptica as a food resource. Corresponding to this difference in host quality, there was a dramatic difference in the seasonal population growth in the two study sites. In Nara, the population size at the beginning of the 2nd generation was almost the same as in the overwintered generation, whereas in Kyoto the population size in the 2nd generation was approximately one hundred times as large as in the overwintered generation. Thus seasonal host alternation is adaptive for the bug. In a previous study, I reported that overwintering as eggs in living leaves of their hosts is likely to be common among all the related species of this bug. Thus, this trait can be considered to be a phylogenetic constraint to the group. I speculate that host alternation by this bug has been derived because it is more adaptive from autoecy on an evergreen plant, similar to the pattern currently found in Nara, and that this bug can not only exploit deciduous host due to a phylogenetic constraint.     

菌寄生属研究进展

菌寄生属通常寄生于其他真菌子实体上,是子囊菌的重要类群之一,在生物医药和工农业等方面具有经济重要性。简述了菌寄生属在资源与分类、系统发育和寄主专化性等方面的研究现状及进展。已有的分子系统学研究表明,菌寄生属是多谱系类群,形成多个分支,各分支与其无性型特征和寄主种类有关。今后需进一步澄清属种概念,建立稳定的有性阶段-无性阶段对应关系,在全面了解其物种多样性和地理分布特点基础上,深入探讨种间系统发育关系。     

Ecological impacts of invading species: Do parasites of the cane toad imperil Australian frogs?

Parasite transfer to native fauna is a potentially catastrophic impact of invasive species. Introduced cane toads in Australia frequently host the nematode lungworm Rhabdias pseudosphaerocephala, which reduces viability of metamorph toads. If native frogs are vulnerable to this South American parasite, cane toad invasion may affect native species via this route; but if the native taxa are not vulnerable, we may be able to exploit the parasites for managing toads. Our laboratory experiments show that infective larvae can penetrate the body of all seven species of Australian frogs (five hylids: Cyclorana longipes, Litoria caerulea, Litoria dahlii, Litoria nasuta, Litoria rothii, one myobatrachid: Opisthodon ornatus, and one limnodynastid: Limnodynastes convexiusculus) we tested, but most did not host the adult worms at the end of the trials, and none showed major impairment of growth, survival or locomotor performance. One native tree‐frog (L. caerulea) retained high infection levels with few ill effects, suggesting that we might be able to use this taxon as a reservoir species to build up local parasite densities for toad management. However, the interspecific variation in lungworm retention suggests that generalizations about parasite effects on native frogs will be elusive.     

Is parasitoid virulence against multiple hosts adaptive or constrained by phylogeny? A study of Leptopilina spp. (Hymenoptera: Figitidae)/Drosophila (Diptera: Drosophilidae) interactions

Summary. Some insects can develop immune resistance to koinobiont parasitoids. Reciprocally, adaptation to host immunology is critical for parasitoid success. Phylogenetic inertia and correlations between virulence against different hosts can act as constraints preventing these adaptations. Insights on these constraints may be obtained from the analysis of patterns of variations in the interactions at the species or genus level. Multivariate phylogenetic comparative methods were applied to virulence traits of 13 parasitoid strains of Leptopilina spp. (Hymenoptera: Figitidae) on five host strains of the Drosophila melanogaster species subgroup (Diptera Drosophilidae). Independent contrasts of virulence were calculated and principal component analysis (PCA) was performed on the independent contrasts to estimate the dimensionality of the interactions. Most of the variation of virulence was associated with the first component of the PCA (62.2%). But a significant proportion was explained by the second and third components, suggesting specific interactions. Strain–strain reciprocal specificity was observed in several pairs of host–parasitoid species. Significant phylogenetic inertia was observed on parasitoid virulence, but only at the genus level and only against hosts of intermediate resistance (phylogenetic R² between 0.62 and 0.85). Some parts of the interaction matrix exhibited specific interactions and others were fixed due to ancestral non-specific virulence (or avirulence). The results were interpreted viewing virulence as a threshold trait determined by underlying liability. When liability is far from the threshold, virulence is fixed. When liability is close to the threshold, virulence varies specifically and reciprocal adaptations can take place. These phylogenetic constraints may lead to a scenario of escape and radiation coevolution in the host–parasitoid system.     

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.     

Induction of host‐plant preference in Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae)

The coconut hispine beetle, Brontispa longissima, is a serious invasive pest of coconut palm (Cocos nucifera) in Southeast Asia and the Pacific region. Recently, however, it has been reported that on Ishigaki Island, Japan, where C. nucifera is rare, the endemic palm Satakentia liukiuensis serves as a regular host. To explore this phenomenon, we examined the preferences of the beetle for the two palm hosts by choice tests and measurements of feeding amount using four different groups: naïve adults obtained from a colony reared on C. nucifera (NC); naïve adults from a colony reared on S. liukiuensis (NS); wild adults collected on C. nucifera on Ishigaki Island (WC); and wild adults collected on S. liukiuensis on Ishigaki Island (WS). Both NC and NS consumed significantly more C. nucifera leaves than S. liukiuensis leaves and were observed more often on the leaves of C. nucifera. These results suggest that B. longissima has an innate preference for C. nucifera. In contrast, field‐collected adults (WC, WS) initially showed preferences for the species on which they were collected, but after exposure to the other host plant for 2 weeks, their preferences for that host increased. These results suggest that the feeding experience of B. longissima adults affected their subsequent host preferences. This flexible host preference may have facilitated the beetle’s successful establishment in novel Japanese habitats where the original host plant was rare.     

Seasonality and host utilization of the invasive fruit fly, Bactrocera invadens (Dipt., Tephritidae) in central Tanzania

Abstract:  The temporal occurrence of the invasive and economically important pest fruit fly, Bactrocera invadens was studied in three agro-ecological areas of Morogoro Region, central Tanzania, during 2004–2005. Weekly and monthly trappings were carried out with methyl eugenol, protein bait and synthetic food attractant. Bactrocera invadens was permanently present at low and mid-altitudes (380–520 m a.s.l.) with peak periods coinciding with the fruiting season of mango ( Mangifera indica ) and guava ( Psidium guajava ). At high altitude (1650 m a.s.l.) its incidence was only temporal and apparently the result of dispersal from lower altitudes after the mango fruiting season. Rearing results showed mango, loquat ( Eriobotrya japonica ), guava and grapefruit ( Citrus  ×  paradisi ) to be the favoured commercial host fruits. Other Citrus species, cucurbits, papaya ( Carica papaya ) and avocado ( Persea americana ) were less favoured.