Evaluating potential olive orchard sugar food sources for the olive fly parasitoid Psyttalia concolor

Olive fruit fly Bactrocera oleae (Rossi) (Diptera: Tephritidae) is a major olive pest in the Mediterranean basin where increasing insecticide resistance has enhanced damage and necessitates more reliance on other control strategies, such as biological control. Provision of floral resources has been reported to improve the effectiveness of natural enemies. Here, we tested the effect of six plant nectars and two honeydew sources on the survival of Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae), a parasitoid wasp used in the biological control of olive fruit fly. Our results showed a positive effect on survival associated with nectars of Anchusa azurea Mill., Rosmarinus officinalis L., Lavatera cretica L. and Calamintha nepeta (L.) Savi, while honeydew proved to be a valuable alternative food source. When offering flowers directly to insects, Anchusa azurea, Lavatera cretica, and Foeniculum vulgare L. were found to be the most beneficial species, indicating also that P. concolor feeds predominantly on shallow corollas

Reproductive strategies and food sources used by Acerophagus n. sp. near coccois, a new successful parasitoid of the invasive mealybug Phenacoccus peruvianus

Phenacoccus peruvianus Granara de Willink (Hemiptera: Pseudococcidae) is a new invasive mealybug that causes important damages in ornamental plants in urban landscapes and nurseries in Southern Europe. Recently, a new species of genus Acerophagus Smith (Hymenoptera: Encyrtidae) has been recorded as the main parasitoid of P. peruvianus in Spain, displacing the native parasitoid Leptomastix epona Walker (Hymenoptera: Encyrtidae). In this work, we have determined some traits of the reproductive and feeding strategies of Acerophagus sp.: fecundity, immature developmental time, host instar suitability, and preference when parasitizing P. peruvianus, and the effect of natural occurring sugar sources on adult longevity. Acerophagus sp. egg load reached its maximum when it was 5 days old. Second and third nymphal instars and adults were suitable for parasitism and immature development (efficient encapsulation was low). Immature development lasted between 20 and 22 days. Acerophagus sp. developed as a solitary parasitoid in the second instar and as a gregarious parasitoid in older instars (2-4 parasitoids per host). All the emerged offspring were females. Acerophagus sp. always preferred older instars when different host instars were available. Finally, adults lived more than 20 days when fed on honey, but they lived fewer than 3 days when fed on naturally occurring sugar sources (host honeydew and host plant flowers, Bougainvillea glabra). The consequences of these characteristics on biological control and parasitoid rearing are discussed.This research was supported by one predoctoral grant [FPU (A. Beltra)] and a postdoctoral fellowship [Juan de la Cierva (A. Tena)] from the Spanish Ministry of Economy and Competitiveness. English corrections were funded by the Universitat Politecnica de Valencia, Spain.Beltrà Ivars, A.; Tena Barreda, A.; Soto Sánchez, AI. (2013). 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Relative Prevalence of Grapevine Leafroll-Associated Virus Species in Wine Grape-Growing Regions of California

<div><p>Some diseases manifest as one characteristic set of symptoms to the host, but can be caused by multiple pathogens. Control treatments based on plant symptoms can make it difficult to effectively manage such diseases, as the biology of the underlying pathogens can vary. Grapevine leafroll disease affects grapes worldwide, and is associated with several viral species in the family <i>Closteroviridae</i>. Whereas some of the viruses associated with this disease are transmitted by insect vectors, others are only graft-transmissible. In three regions of California, we surveyed vineyards containing diseased vines and screened symptomatic plants for all known viral species associated with grapevine leafroll disease. Relative incidence of each virus species differed among the three regions regions, particularly in relation to species with known vectors compared with those only known to be graft-transmitted. In one region, the pathogen population was dominated by species not known to have an insect vector. In contrast, populations in the other surveyed regions were dominated by virus species that are vector-transmissible. Our survey did not detect viruses associated with grapevine leafroll disease at some sites with characteristic disease symptoms. This could be explained either by undescribed genetic diversity among these viruses that prevented detection with available molecular tools at the time the survey was performed, or a misidentification of visual symptoms that may have had other underlying causes. Based on the differences in relative prevalence of each virus species among regions and among vineyards within regions, we expect that region and site-specific management strategies are needed for effective disease control.</p></div