Browsing by Author "Zaviezo T."

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    Assessment of fitness traits of pure and mixed crosses of Mastrus ridens populations to improve classical biological control of codling moth
    (2022) Sandanayaka W.R.M.; Davis V.A.; Page-Weir N.E.M.; Chhagan A.; Jenkins H.K.; Blin A.; Zaviezo T.
    © 2022Populations of natural enemies in classical biological control programs often undergo recurring bottlenecks during importation and rearing, which can result in lower genetic variability and fitness. Enriching colonies with wild individuals, multiple importations or combining populations from different origins may help reduce this problem. Mastrus ridens (Hymenoptera: Ichneumonidae), a gregarious idiobiont ectoparasitoid of codling moth (Cydia pomonella) larvae was introduced to New Zealand from laboratory colonies dating to the 1990s. To improve populations for release, individuals from a most recent collection were imported from Chile (CL). Tests were conducted to measure genetic diversity of the parental populations (F0) and fitness traits of pure and mixed combinations of NZ and CL populations for F0 and the F1 generations. Results showed several effects depending on the population origin. CL females and males in the F0 generation lived longer than NZ females and males. Offspring from a CL mother lived longer than those from a NZ mother, and F0 and F1 females from a CL mother parasitized more larvae than females from a NZ mother. Genetic diversity estimates of F0 CL and NZ populations were 24% and 17% heterozygosity, respectively, and the NZ population had a larger proportion of diploid males than the CL population. Thus, no improvement in reproductive output resulted by mixing NZ and CL populations, as hypothesized, but a maternal effect was found in this species. This study shows the importance of understanding and tracking imported populations' genetic diversity and fitness traits in classical biological control programs.
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    First report of the rhodesgrass mealybug Antonina graminis (Maskell, 1897) (Hemiptera: Coccomorpha: Pseudococcidae) in Chile, with key to genera of Pseudococcidae
    (Springer Science and Business Media Deutschland GmbH, 2021) Amouroux P.; Zaviezo T.
    © 2021, African Association of Insect Scientists.The rhodesgrass mealybug, Antonina graminis (Maskell, 1897), is reported for the first time from Chile, in the northern region of Tarapacá. This legless mealybug is widely distributed in tropical and subtropical regions around the world, and yet mentioned in the neighbouring countries. It feeds on a large variety of grasses (Poaceae), and can be considered as pest. The species identification was based on morphological and molecular data using the 28S gene as barcode marker. Of the five sites sampled, A. graminis was found in only one, indicating it may correspond to a recent introduction. Thus, it would be important to survey more closely its distribution within the country. A key to the genera of Pseudococcidae from Chile is provided, including relevant genera considered as pest, and not established in the country. This key is of direct interest to stakeholders in Chile, such as national phytosanitary services, and farm advisors.
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    Intraspecific variation in biocontrol traits in Mastrus ridens (Hymenoptera: Ichneumonidae) laboratory populations
    (Springer Science and Business Media B.V., 2021) Zaviezo T.; Romero A.; Calleja F.; Calvo C.; Osorio R.; Casanoves F.; Irles P.
    © 2021, International Organization for Biological Control (IOBC).Breeding natural enemies to generate populations with improved characteristics is an attractive idea, particularly nowadays with the increase in use of biological control and the availability of modern molecular and genetic tools. A first step in the process is to characterize traits which can be important for biological control and their intraspecific variation. In this study we characterized fecundity, longevity and dispersal-related traits of four endogamic and three exogamic laboratory populations (lines) of Mastrus ridens, an important parasitoid of the codling moth (Cydia pomonella (L.)). We found that several traits were positively correlated and that there was variability among lines and between endogamic and exogamic lines. Exogamic lines presented a better combination of trait values than endogamic lines. The absence of trade-offs among the traits studied in M. ridens would be advantageous for a breeding program. Nevertheless, it would be important not to lose genetic variability in the process, because of the presence of complementary sex determination (CSD) and negative effects of inbreeding on other traits. The results of this study could be useful for the selection of M. ridens lines with better traits and as preliminary information for breeding programs.
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    The positive association between natural vegetation, native coccinellids and functional diversity of aphidophagous coccinellid communities in alfalfa
    (Blackwell Publishing Ltd, 2021) Grez A.A.; Oberti R.; Zaviezo T.; Casanoves F.; Pliscoff P.
    © 2021 The Royal Entomological SocietyA greater taxonomic and functional diversity of natural enemies in agroecosystems is frequently positively associated with more effective pest control, due to the complementarity of species or traits. But this diversity has declined with landscape homogenisation and loss of natural covers, particularly losing native species, which play an important role in pest suppression within crops. We evaluated the effect of landscape on coccinellid communities and aphids, and the relative contribution of coccinellids and aphids in shaping taxonomic and functional diversity of coccinellid communities in alfalfa fields. We characterised the landscape at 1 km radius surrounding 17 alfalfa fields, and the taxonomic and functional diversity of coccinellid communities collected throughout the season in alfalfa. Functional diversity indices considered four traits: body size, habitat specialisation, ubiquity and temporal variability. We found a positive association among native coccinellids in alfalfa and the amount of natural cover in the landscape, while aphids positively associated with agricultural cover. Also, we found a positive association among functional and taxonomic diversity indices with native coccinellids, and a negative association with exotics, demonstrating the contribution of native coccinellids in adding taxonomic and functional diversity to the aphidophagous communities in alfalfa fields. Aphids also associated positively with some functional and taxonomic diversity indices. Our results highlight the need to promote appropriate management practices in agricultural landscapes in order to conserve native coccinellid species in alfalfa, maintain a diversified species pool and their potential for aphid pest suppression.