Landscape Simplification Increases Bactrocera Oleae Abundance In Olive Groves: Populations Dynamics In Different Land Uses.

Bactrocera oleae is the main pest in olive groves and its management requires a sustainable perspective to reduce the use of chemical products. Landscape context is being considered as an important driver of pest reduction but results on B. oleae show inconsistency to date. Most of landscape-pest control studies focus on the dynamics of the pests within the focal crop, ignoring these dynamics in other land uses. Here we present a study in which we analyze the seasonal population dynamics of the olive pest B. oleae in the most important land uses of a typical olive landscape in Portugal. We found that B. oleae is present in all the land uses and the dynamics are very similar to those in the olive groves. However, the presence of these land uses in the landscape did not display any increase of B.oleae abundance within the olives groves. In contrast, a landscape mainly composed by olive groves increased the abundance of this pest. Importantly, more diverse landscapes surrounding olive groves reduce the abundance of the olive fly. Based on these findings, we can conclude that B. oleae is present in all the land uses of the studied landscape but that this presence does not imply an increase of B. oleae in olive groves. Indeed, other land uses can promote landscape diversification which is a driver of the reduction of B. oleae populations in olive groves. We thus encourage olive stakeholders to increase landscape diversification around their farms by promoting/restoring other crops/habitats.

Aydın İli Zeytin Alanlarında Zeytin Sineği (Bactrocera oleae (Gmelin)) (Diptera: Tephritidae)’ nin Populasyon Değişimleri ve Zararı

Emergence period of Olive fly (Bactrocera oleae (Gmelin)) (Diptera: Tephritidae) and its population changes and damage on the fruits were studied in three olive orchards in Umurlu, Dalama and Çakmar districts in Aydın province. During the study, one McPhail trap with 2 per cent diammonium phosphate liquid (McPhail), one yellow visual trap with pheromone capsule on (YVTP), and three yellow visual traps mounted an eppendorf capsule within pure ammonium acetate (AA) were placed in each olive orchards. Studies were conducted between 2009-2011 years, and the traps were counted weekly. As a result of population monitoring, first flies were seen on the traps in mid-October and continued during the season till mid-December when its emergence ended. The population levels were too low during the study. However, as the population peaked, the higher population level was determined on YVTP with 307.0 individual/trap in olive orchard in Umurlu district in October 30, 2009. On the other hand, it was counted 70,0 individual/trap in McPhail and 51.3 individual/trap in avarage in AA. The damage on the fruit was the highest in Umurlu with 17.2 per cent in 2009. The population levels in Dalama and Çakmar were 45.0 and 3.0 individual/trap in pheromone traps, and 8.0 and 1.0 individual/trap in avarage in AA, respectively. The damages on the fruits were 8.9 and 3.7 per cent in Dalama and Çakmar, respectively. The population level and damage were appeared in a very low levels in the following years of the study.

Yeasts Associated with the Olive Fruit Fly Bactrocera oleae (Rossi) (Diptera: Tephritidae) Lead to New Attractants

The olive fruit fly (Bactrocera oleae Rossi) is the primary insect pest in all olive-growing regions worldwide. New integrated pest management (IPM) techniques are needed for B. oleae to mitigate reliance on pesticides used for its control which can result in negative environmental impacts. More effective lures for monitoring olive flies would help to know when and where direct chemical applications are required. The aim of this research was to find new, more effective methods for B. oleae detection and monitoring. Twelve insect-associated yeasts were selected and tested as living cultures in McPhail traps for the attraction of olive flies. Certain yeasts were more attractive than others to B. oleae; specifically, Kuraishia capsulata, Lachancea thermotolerans, Peterozyma xylosa, Scheffersomyces ergatensis, and Nakazawae ernobii, than the industry-standard dried torula yeast (Cyberlindnera jadinii; syn. Candida utilis). The attractiveness of dry, inactive (i.e., non-living) formulations of these five yeasts was also tested in the field. Inactive formulations of K. capsulata, P. xylosa, N. ernobii, and L. thermotolerans were significantly more attractive to B. oleae than commercially available torula yeast. Green lacewing, Chrysoperla comanche (Stephens) (Neuroptera: Chrysopidae), adults were incidentally caught in traps baited with the live yeast cultures. This is the first field study that compares olive fly attraction to yeast species other than torula yeast. Commercialization of yeasts that are more attractive than the torula standard would improve monitoring and associated control of the olive fruit fly.

Effects of climatic changes on olive fly, Bactrocera oleae (Rossi) population dynamic with respect to the efficacy of its larval parasitoid in Egyptian olive trees

Background The potential effects of two parameters of climatic change conditions (temperature and relative humidity) on the population dynamics of the olive fly across the two ecological areas in Egypt were studied. The olive trees in El-Behera Governorate are more affected by the olive fly compared to the olive trees in the orchard of El-Fayoum Governorate. In this study, the character of climate change in influencing the dynamics of insect population and associated parasites was discussed at the regional level. Results The results exhibited that the olive trees in the coast governorate were more susceptible to the olive fly than the inner governorate. The parasitism percentage was recorded 41.7 and 46.4% at the beginning of the seasons 2016 and 2017, respectively in El-Fayoum Governorate. In El-Behera Governorate, the maximum parasitism percentage was recorded 49.5% (2016 season), while the 2017 season, the parasitism percentage was recorded 50.4%. The majority of the ordinary parasite was Psyttalia concolor in the two regions. Conclusion The study clarifies that there is a positive correlation between B. oleae abundance and the effects of temperature and its parasitoid, Psyttalia concolor. Further, there is no significance found between the olive fly and relative humidity and its parasitoid populations.

Horizontal transfer and finalization of a reliable detection method for the olive fruit fly endosymbiont, Candidatus Erwinia dacicola

Background The olive fly, Bactrocera oleae, is the most important insect pest in olive production, causing economic damage to olive crops worldwide. In addition to extensive research on B. oleae control methods, scientists have devoted much effort in the last century to understanding olive fly endosymbiosis with a bacterium eventually identified as Candidatus Erwinia dacicola. This bacterium plays a relevant role in olive fly fitness. It is vertically transmitted, and it benefits both larvae and adults in wild populations; however, the endosymbiont is not present in lab colonies, probably due to the antibiotics and preservatives required for the preparation of artificial diets. Endosymbiont transfer from wild B. oleae populations to laboratory-reared ones allows olive fly mass-rearing, thus producing more competitive flies for future Sterile Insect Technique (SIT) applications. Results We tested the hypothesis that Ca. E. dacicola might be transmitted from wild, naturally symbiotic adults to laboratory-reared flies. Several trials have been performed with different contamination sources of Ca. E. dacicola, such as ripe olives and gelled water contaminated by wild flies, wax domes containing eggs laid by wild females, cages dirtied by faeces dropped by wild flies and matings between lab and wild adults. PCR-DGGE, performed with the primer set 63F-GC/518R, demonstrated that the transfer of the endosymbiont from wild flies to lab-reared ones occurred only in the case of cohabitation. Conclusions Cohabitation of symbiotic wild flies and non-symbiotic lab flies allows the transfer of Ca. E. dacicola through adults. Moreover, PCR-DGGE performed with the primer set 63F-GC/518R was shown to be a consistent method for screening Ca. E. dacicola, also showing the potential to distinguish between the two haplotypes (htA and htB). This study represents the first successful attempt at horizontal transfer of Ca. E. dacicola and the first step in acquiring a better understanding of the endosymbiont physiology and its relationship with the olive fly. Our research also represents a starting point for the development of a laboratory symbiotic olive fly colony, improving perspectives for future applications of the Sterile Insect Technique.

Study of some demographic parameters of Bactrocera (Dacus oleae); Test of a new food attractant in a trapping method

This study focuses on the observation of changes in the demographic parameters of olive fly over time in two regions, Mitidja and Mezghana region, the method consists in identifying certain biotic and abiotic factors that can play a role on the variations of these parameters; on the other hand we tested new food attractiveness in a trapping method. The Results showed that the demographic parameters (emergence, parasitism and mortality) are influenced by the year and by the region factor with a very high emergence rate above 50%; On the other hand, the rate of parasitism remains low with a maximum value of 33.23% recorded in Mezghenna, regarding nymphal mortality the maximum value is recorded in Chebacheb with 26.44%. Furthermore, the study of the efficiency of nitrogen fertiliser (Urea 46 unit) on the catches of adults showed us that the best concentration of attraction is 6%; on the other hand, the yellow color of the traps positively influences the catches of Bactroceraoleae.