Cleome hassleriana plants fully support the development and reproduction of Nesidiocoris tenuis

BioControl - Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) is a zoophytophagous predator that feeds on plants as well as prey. Several non-crop host plant species have been used to maintain...     

Development of a multiplex method to discriminate between Neochrysocharis formosa (Hymenoptera: Eulophidae) reproductive modes

A multiplex polymerase chain reaction (PCR) method was applied to differentiate thelytokous and arrhenotokous strains of Neochrysocharis formosa (Westwood). Alignment of strain first internal transcribed spacer regions revealed high nucleotide variability and the strain-specific primer sequence used. Strains were easily differentiated after gel electrophoresis of multiplex PCR products because arrhenotokous specimens produced a 500-bp fragment as well as the 800-bp fragment common to both strains. This method successfully distinguished N. formosa strains regardless of collection site across Japan; thus, it is probably suitable for similar applications in Turkey, Italy, and elsewhere.     

Correction to: Cleome hassleriana plants fully support the development and reproduction of Nesidiocoris tenuis

BioControl - A correction to this paper has been published: https://doi.org/10.1007/s10526-021-10089-4     

Control of Myzus persicae and Lipaphis erysimi (Hemiptera: Aphididae) by adults and larvae of a flightless strain of Harmonia axyridis (Coleoptera: Coccinellidae) on non-heading Brassica cultivars in the greenhouse

The green peach aphid [Myzus persicae (Sulzer)] and turnip aphid [Lipaphis erysimi (Kaltenbach)] are economically important pests with a worldwide distribution. We have evaluated the efficacy of releasing adults and larvae of a flightless strain of the multicolored Asian lady beetle (Harmonia axyridis Pallas) as a control measure against these aphids on plants of non-heading Brassica cultivars. Both adults and larvae of H. axyridis were observed to be effective biocontrol agents, markedly decreasing the numbers of aphids. The residence duration of adults was longer than that of larvae. The proportion of non-marketable plants damaged by aphids was lower in plots into which either adults or adults and larvae of H. axyridis had been released. These results suggest that both adults and larvae of this flightless strain of H. axyridis are effective in controlling aphids on plants of non-heading Brassica cultivars.     

Gene flow between sexual and asexual strains of parasitic wasps: a possible case of sympatric speciation caused by a parthenogenesis-inducing bacterium

Sympatric speciation is strictly defined as the emergence of two species from a population in which mating has been random with respect to the place of birth of the mating partners. Mathematical models have shown that sympatric speciation is possible, but very few examples have been documented in nature. In this article, we demonstrate that arrhenotokous and thelytokous strains of a parasitic wasp, Neochrysocharis formosa, speciated sympatrically through infection by a symbiotic bacterium Rickettsia for the following reasons: First, Rickettsia infection was detected in all of the thelytokous strains collected throughout Japan. Second, the arrhenotokous and thelytokous strains have been collected sympatrically. Third, crossing experiments between the two strains did not result in fertilized offspring. In addition, the two strains were genetically isolated at the nuclear and mitochondrial genes. Fourth, the two strains showed a sister relationship in nuclear 28S rRNA gene. Finally, thelytokous females treated with antibiotics produced Rickettsia-free male offspring of the same reproductive form as arrhenotokous females indicating that the thelytokous strain could have speciated sympatrically from an individual of the arrhenotokous strain.     

Predation of a biological control agent,Nesidiocoris tenuis (Hemiptera: Miridae), by the spider Leucauge blanda in greenhouse eggplant crops

Nesidiocoris tenuis (Hemiptera: Miridae) is used widely around the world as a biological control agent. In Kochi Prefecture, Japan, at the end of each greenhouse eggplant crop production period, the N. tenuis populations that have developed are collected and transferred to ‘natural-enemy-rearing greenhouses’ so that farmers can use the bug in the next production period. However, spider numbers have been increasing at the end of the production periods and it is becoming difficult to collect N. tenuis in some greenhouses. Therefore, we constructed specific primers for N. tenuis mtDNA to test whether the species was being preyed upon by the predominant spider species, Leucauge blanda. In polymerase chain reactions, these primers amplified a 148-bp fragment of the mitochondrial cytochrome oxidase subunit I gene of N. tenuis but not of any of the 13 other arthropod species tested that occurred in eggplant greenhouses. In a laboratory experiment, the rates of detection of N. tenuis DNA in the spiders after the end of a period of feeding on the bug were 90% at 0?h, 60% at 24?h, and 0% at 72?h. In a greenhouse field experiment, the rate of detection of N. tenuis DNA in the spider was 95%. These results suggest that L. blanda is responsible for the observed suppression of N. tenuis populations in greenhouse eggplant crops.     

A new cytogenetic mechanism for bacterial endosymbiont-induced parthenogenesis in Hymenoptera

Vertically transmitted endosymbiotic bacteria, such as Wolbachia, Cardinium and Rickettsia, modify host reproduction in several ways to facilitate their own spread. One such modification results in parthenogenesis induction, where males, which are unable to transmit the bacteria, are not produced. In Hymenoptera, the mechanism of diploidization due to Wolbachia infection, known as gamete duplication, is a post-meiotic modification. During gamete duplication, the meiotic mechanism is normal, but in the first mitosis the anaphase is aborted. The two haploid sets of chromosomes do not separate and thus result in a single nucleus containing two identical sets of haploid chromosomes. Here, we outline an alternative cytogenetic mechanism for bacterial endosymbiont-induced parthenogenesis in Hymenoptera. During female gamete formation in Rickettsia-infected Neochrysocharis formosa (Westwood) parasitoids, meiotic cells undergo only a single equational division followed by the expulsion of a single polar body. This absence of meiotic recombination and reduction corresponds well with a non-segregation pattern in the offspring of heterozygous females. We conclude that diploidy in N. formosa is maintained through a functionally apomictic cloning mechanism that differs entirely from the mechanism induced by Wolbachia.