CABI

About: CABI is a nonprofit organization based out in Wallingford, United Kingdom. It is known for research contribution in the topics: Population & Introduced species. The organization has 789 authors who have published 1759 publications receiving 73843 citations. The organization is also known as: Centre for Biosciences and Agriculture International.

Factors influencing the occurrence of fall armyworm parasitoids in Zambia

Abstract: Invasive alien species have environmental, economic and social impacts, disproportionally threatening livelihood and food security of smallholder farmers in low- and medium-income countries. Fall armyworm (FAW) (Spodoptera frugiperda), an invasive insect pest from the Americas, causes considerable losses on maize to smallholder farmers in Africa since 2016. The increased use of pesticides to control FAW in Africa raises concerns for health and environmental risks resulting in a growing interest in research on biological control options for smallholder farmers. In order to evaluate the occurrence of local natural enemies attacking FAW, we collected on a weekly basis FAW eggs and larvae during a maize crop cycle in the rainy season of 2018–2019 at four locations in the Lusaka and Central provinces in Zambia. A total of 4373 larvae and 162 egg masses were collected. For each location and date of collection, crop stage, the number of plants checked and amount of damage were recorded to analyse which factors best explain the occurrence of the natural enemy species on maize. Overall parasitism rates from local natural enemies at each location varied between 8.45% and 33.11%. We identified 12 different egg-larval, larval and larval-pupal parasitoid species. Location, maize growth stage, pest density and larval stage significantly affected parasitoid species occurrence. Our findings indicate that there is potential for increasing local populations of natural enemies of FAW through conservation biological control programmes and develop safe and practical control methods for smallholder farmers.

Identification of active components from volatiles of Chinese bayberry, Myrica rubra attractive to Drosophila suzukii

Abstract: Drosophila suzukii (Diptera: Drosophilidae) is native to Southeast Asia and now has become a severe pest of several soft fruits in Europe and the Americas. It causes considerable damage to Chinese bayberry, Myrica rubra, in China. In the present study, we employed gas chromatograph–electroantennographic detection (GC–EAD) together with behavioural bioassays and trapping experiments to identify volatile semiochemicals emitted by Chinese bayberry attracting D. suzukii. Electrophysiological experiments revealed the presence of six EAD-active compounds from ripe bayberry fruits, including methyl (E)-3-hexenoate, methyl (E)-2-hexenoate, ethyl (E)-2-hexenoate, α-ylangene, α-humulene and an unidentified compound that elicited consistent antennal response. In two-choice bioassays, bayberry fruits attracted all responding flies, and significantly more flies responded to the volatile extract of bayberry fruits. Four EAD-active compounds were attractive to mated female D. suzukii at lower doses (0.01 and 0.1 µg), but showed repellency at higher doses (10 and 100 µg). Mixtures of these four compounds at different ratios attracted D. suzukii flies at all test doses (0.1, 1 and 10 µg). Both male and female flies were trapped by a mixture of synthetic methyl (E)-3-hexenoate, methyl (E)-2-hexenoate, ethyl (E)-2-hexenoate and α-humulene in a ratio of 1:1.3:1:6.4 in the field trapping experiment. Significantly more males than females were captured in the trap baited with the synthetic blend, and the percentages of D. suzukii captured out of all flies by the traps baited with lure were higher than that baited with blank control. Our findings may provide insights into the olfactory responses of D. suzukii to specific host plant volatiles, and contribute to further development of an effective lure for monitoring D. suzukii in the field.

Reduced insecticide susceptibility of the wheat aphid Sitobion miscanthi after infection by the secondary bacterial symbiont Hamiltonella defensa

Abstract: Background Bacterial symbionts in insects, especially aphids, have a major influence on host adaptation. We previously showed that infection with the secondary symbiont Hamiltonella defensa increases the fitness of the wheat aphid Sitobion miscanthi, yielding increases in fitness parameters such as adult weight and offspring number. However, whether H. defensa affects the sensitivity of host aphids to insecticides remains unknown. Results We tested the effects of H. defensa on host aphid susceptibility to the insecticides chlorpyrifos methyl, imidacloprid, cyantraniliprole and acetamiprid. Our results showed that compared with Hamiltonella-free aphid clones, Hamiltonella-infected aphid clones exhibited lower sensitivity to most of the tested insecticides at low concentrations. Quantitative polymerase chain reaction showed that the density of H. defensa in the infected clones was slightly decreased at 24 h but then sharply increased until the late stage after treatment with the different insecticides. H. defensa in the host aphids was detected by fluorescence in situ hybridization and was localized to the aphid hindgut. Levels of the detoxification enzymes acetylcholinesterase, glutathione transferase and carboxylesterase were significantly higher in Hamiltonella-infected clones than in Hamiltonella-free clones. Conclusions The findings indicated that infection with H. defensa reduced aphid susceptibility to the investigated insecticides at low concentrations, potentially by increasing detoxification enzyme activity in the host. Therefore, symbiont-mediated insecticide resistance should be taken into account when performing resistance-monitoring studies. Studies of symbiont-mediated insecticide resistance may enhance our understanding of the emergence of insecticide resistance in agricultural systems. © 2020 Society of Chemical Industry.

Whole-Genome Sequence of the Orchid Anthracnose Pathogen Colletotrichum orchidophilum

Abstract: Colletotrichum orchidophilum is a plant-pathogenic fungus infecting a wide range of plant species belonging to the family Orchidaceae. In addition to its economic impact, C. orchidophilum has been used in recent years in evolutionary studies because it represents the closest related species to the C. acutatum species complex. Here, we present the first-draft whole-genome sequence of C. orchidophilum IMI 309357, providing a resource for future research on anthracnose of Orchidaceae and other hosts.

Presence of a 20 bp insertion/deletion in the ITS1 region of Verticillium lecanii

Abstract: Polymerase chain reaction (PCR) amplification of the complete ribosomal RNA internally transcribed spacer (ITS) region of 36 isolates of Verticillium lecanii and related species gave a single 620 bp product in 31 isolates. Five isolates received as V. lecanii, however, gave a single product of 600 bp. Restriction fragment analysis of the PCR products from all isolates gave consistent patterns for the 31 isolates with a 620 bp product. The five isolates with the 600 bp product showed only minor discrepancies to these, generally related to the size of only one restriction fragment. The total ITS region was sequenced from 10 typical 620 bp isolates and one 600 bp isolate. Sequence variation between the isolates varied from 0 to 14.5%, and the 20 bp size discrepancy was found to relate to an insertion or deletion in the centre of the ITS1 region.