Laboratory evaluation of the effects of different concentrations of calcined kaolin applied on orange fruits on the behaviour of Ceratitis capitata

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera Tephritidae), is one of the most devastating agricultural pests worldwide. The kaolin particle film has been demonstrated to effectively control C. capitata on several crops although several studies have proved that kaolin treatments may alter the agroecosystem entomofauna, and specifically in citrus crops. The aim of this work was to study, under laboratory conditions, the efficacy of different kaolin particle film concentrations (1.5%, 2.5%, 3%, 5% and 6% w/v) applied on orange fruits cv “Valencia Late” to optimize its use against C. capitata in citrus groves. We assessed the effect of different kaolin particle film concentrations on the fruit acceptance, repellence, behavioural response, and efficacy fruit infestation. Through all the specific approaches, the 2.5% kaolin treatments applied in two layers successfully reduced the fruit infestation by C. capitata. This processed kaolin treatment should offer efficacy in real field conditions as satisfactory as conventional pesticides towards high populations.info:eu-repo/semantics/publishedVersio

Analysis of pesticide residues in honeybee (Apis mellifera L.) and in corbicular pollen. Exposure in citrus orchard with an integrated pest management system

In the last years, the honeybee population is facing growing threats such as expansion of pathogens, incorrect use of phytosanitary products and environmental contaminants, loss or fragmentation of habitat, invasive species and climate change. The citrus cropping by Integrated Pest Management (IPM) in Spain combines strategies to reduce pest populations preventing environmental problems and reducing levels of damage by using chemicals only when it is strictly necessary. The goal of this study is to develop a simple analytical method to evaluate pesticide residue levels in honeybees and corbicular pollen when honeybees are exposed to plant protection products (PPPs) used in integrated pest management citrus orchards. The proposed method is based in an ultrasound assisted extraction procedure followed by a dispersive solid phase extraction (d-SPE) clean-up with alumina and LC-MS/MS pesticides determination. The method was validated in samples of honeybee and corbicular pollen for 10 pesticides commonly used in citrus orchards under IPM. This procedure was compared with QuEChERS methodologies for these matrices. The developed method was applied to determine pesticides in both matrices in a two -year study in citrus orchards.info:eu-repo/semantics/acceptedVersio

Evaluation of residue levels of imidacloprid and thiamethoxam after foliar application to the citrus varieties Lane Late, Valencia Late, Rohde Summer, and Nules

Neonicotinoids are used to protect citrus trees against pests. Dissipation and persistence of neonicotinoids in pollen and nectar of citrus trees after foliar applications and their potential exposure to pollinators have not been well characterized. Field studies were conducted using three orange and one mandarin varieties to compare the imidacloprid and thiamethoxam residue levels and their decline in pollen and nectar after treatments in pre-bloom close to flowering period and their persistence 1 yr after treatment. The possible risk to honeybees was assessed. In nectar, thiamethoxam and imidacloprid residues were between 61 and 99% lower than in pollen, depending on the citrus variety or/and the days after treatment when applied close to blooming. At the end of the flowering period, imidacloprid in pollen and nectar was not detected in the mandarin variety after treatment in pre-bloom, whereas for thiamethoxam, no residues were detected in nectar but 10 ng/g was detected in pollen. There were no quantifiable levels of residues for either neonicotinoids in pollen or nectar during the flowering period of the following year. Neonicotinoid residue levels and their decline in nectar and pollen in citrus depended on the timing of applications relative to flowering and on the citrus variety. The absence of neonicotinoid residues 1 yr out after foliar applications in all varieties assayed demonstrated that none of the neonicotinoids tested were persistent. The results could be different in other citrus varieties, and therefore, also the exposure assessment for managed pollinators.info:eu-repo/semantics/acceptedVersio

Tendencias estacionales y anuales en las poblaciones de campo de la mosca mediterránea de la fruta, Ceratitis capitata, en cítricos del Mediterráneo: comparación de dos áreas geográficas en el este de España

[EN] Seasonal and annual trends in Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) populations were analyzed to determine the factors that influence population fluctuations in the field. Adult flies were monitored along 2003-07 in two citrus areas in eastern Spain with similar climate, Valencia and Tarragona. Adults were present throughout the study period, even in winter. The initial annual population increase was related to previous winter and spring temperatures. Captures started to increase in April-May and usually reached a peak in July. This peak corresponded to the maximum capture period in Valencia, but not in Tarragona, where there was usually a second peak in autumn, with capture levels similar to the first peak. Gravid females were found throughout the year, even in overwintering populations of medfly. The availability of other host fruit species in the vicinity of the citrus groves may explain the differences in annual abundance and distribution of captures between the two areas studied.[ES] Se analizó la evolución estacional de las poblaciones de Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) para determinar los factores que influencian sus fluctuaciones poblacionales en campo. Se muestreó la población de adultos entre 2003 y 2007 en dos áreas citrícolas del este de España con clima similar, Valencia y Tarragona. Se encontraron adultos a lo largo de todo el periodo de estudio, incluso en invierno. El primer incremento anual de la población estuvo relacionado con las temperaturas previas del invierno y la primavera. Las capturas comenzaron a incrementarse en abril-mayo y generalmente alcanzaron un máximo en julio. Este máximo correspondió al máximo periodo de capturas en Valencia, pero no en Tarragona, donde hubo generalmente un segundo máximo en otoño, con niveles de captura similares al primer máximo. Se encontraron hembras grávidas a lo largo de todo el año, incluso en las poblaciones invernantes de mosca de la fruta. La disponibilidad de otras especies de frutales hospedantes cercanas a las parcelas de cítricos puede explicar las diferencias en abundancia anual y distribución estacional de capturas entre las dos áreas estudiadas.We would like to thank Rafel Monfort for his help with the field work. This research was funded by a project from the Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), of Spain’s Ministerio de Educación y Ciencia (Project RTA03- 103-C6). We thank also Alejandro Tena for useful comments on early drafts of the manuscript.Martinez-Ferrer, MT.; Navarro Campos, C.; Campos Rivela, JM.; Marzal Moreno, C.; Fibla, JM.; Bargues Desolmes, L.; García Mari, F. (2010). Seasonal and annual trends in field populations of Mediterranean fruit fly, Ceratitis capitata, in Mediterranean citrus groves: comparison of two geographic areas in eastern Spain. Spanish Journal of Agricultural Research. 8(3):757-765. https://doi.org/10.5424/sjar/2010083-1275S7577658

Effectiveness of the parasitoid Anisopteromalus calandrae (Hymenoptera : Pteromalidae) in the control of Sitophilus zeamais and Rhyzopertha dominica in paddy rice

Altres ajuts: acords transformatius de la UABRice is an important cereal crop in Spain that is frequently attacked by pests that cause significant quantitative and qualitative losses. Among them, the maize weevil, Sitophilus zeamais, is the key pest, and the lesser grain borer, Rhyzopertha dominica, is a serious pest found later in the season. The cosmopolitan ectoparasitoid, Anisopteromalus calandrae, which attacks late-instar larvae of coleopterans that develop inside grain kernels, has been reported as an efficient natural enemy. In this study, we evaluated whether the control efficacy of this parasitoid on S. zeamais was affected by the presence of the alternative host, R. dominica. Our laboratory experiment demonstrated the parasitoid preference for S. zeamais larvae when mixed with R. dominica larvae at different proportions. This preference for the maize weevil larvae allowed us to maintain a similar control efficacy of S. zeamais when it was offered alone than when it was offered together with R. dominica larvae. In our second experiment, done in 500 kg bags of paddy rice, similar results were obtained, since the presence of R. dominica larvae did not alter the control efficacy of A. calandrae on S. zeamais larvae. Therefore, our results confirmed a good perspective for implementing the use of this natural enemy as a control tool in big bags of paddy rice

Population dynamics and seasonal trend of California red scale ("Aonidiella aurantii" Maskell) in citrus in Northern Spain

The California red scale, Aonidiella aurantii (Maskell), was detected in citrus in Catalonia, Northern Spain, in 2000, and has since spread slowly and irregularly southwards, with foci of infestation currently found in southern Tarragona citrus-growing areas. Since Catalonia is the northern citrus growing area in Spain, between 2002 and 2009, the A. aurantii biological cycle (male flights and seasonal history) was studied in two citrus groves and compared with other regions and countries. Population dynamics showed that 4 male flights occur (including that of the overwintering generation) in May, mid June-mid July, August and in October, the most abundant being in August (over 60% of males captured throughout the year). The thermal constant estimated between male flights, using 11.7 ºC as the lower threshold temperature, was 611.8 ± 35.5 DD. Three peaks of sensitive instar were also observed, in early June, late July-early August, and late September. The number of crawlers captured reached a maximum on 27 May (± 1.85 days), 24.8 ± 2.5 days (184.2 ± 18.1 DD) after the first male flight. The male flight abundance showed there was a relationship only between two consecutive generations, revealing the rapid shifts in population abundance. We estimated when the first sensitive instar peak occurred through a non-destructive method, based on the peak of males captured during the first flight

Development of a PCR-based method for the screening of potential predators of the African citrus psyllid Trioza erytreae (Del Guercio)

Trioza erytreae is one of the vectors of Huanglongbing (HLB), the main global citrus groves threat. Since its recent detection in the north-western Iberian Peninsula (Spain and Portugal), its contention and eradication have been a priority to prevent its spread. For the biological control of T. erytreae, it is important to understand the role that each potential natural enemy could have. With the aim to determine which predators have incorporated T. erytreae into their diet, a PCR-based method has been developed for the specific detection of T. erytreae in their gut contents. For this, a pair of specific primers was designed from the mitochondrial cytochrome c oxidase subunit I (COI) region. Specificity of this pair of primers was studied and feeding trials with two predator species were conducted to determine the decay rates of T. erytreae within their gut. None of the non-target species was amplified, showing the high specificity of these T. erytreae primers. Feeding trials showed 4.8h and 4.5h half-life time detections of T. erytreae ingested by Chrysoperla carnea and Cryptolaemus montrouzieri, respectively. Finally, field-collected generalist predators of T. erytreae-infested citrus trees from the Canary Islands and Galicia (Spain), were analysed by conventional PCR for the presence of T. erytreae in their guts. Results showed that a wide range of predator taxa ingested the target prey, like the families Coccinellidae, Anthocoridae, Chrysopidae, Hemerobiidae, Forficulidae, Miridae, Syrphidae, Formicidae, Erythraeidae and the order Araneae, with detection percentages ranging from 20 to 100%. These results confirm that most of the analysed generalist predators found in citrus trees could be potential candidates for the biological control of T. erytreae in future biological control programs of this HLB vector.info:eu-repo/semantics/acceptedVersio

Releases of the parasitoid Anisopteromalus calandrae (Hymenoptera: Pteromalidae) can control Sitophilus zeamais (Coleoptera: Curculionidae) in big bags of paddy rice

Sitophilus zeamais is a key pest in stored rice in Spain and other Mediterranean countries. Today, it is mostly controlled with a few pesticides, such as pyrethroids or phosphine. Apart from the problem of pesticide resistance, this can lead to the accumulation of toxic residues in the stored rice. Therefore, alternative control methods are needed. Biological control with the parasitoid Anisopteromalus calandrae is a feasible and sustainable alternative since it is very effective at limiting the growth of the weevil population. In this study, we evaluated the dispersal capacity and effectiveness of this parasitoid in controlling S. zeamais larvae located deep in 500 kg bags of paddy rice during two seasons, summer and autumn. The parasitoid was easily able to reach the bottom of the bags (1 m) in both seasons. At the released parasitoid-to-host ratio, the parasitoid was also able to limit weevil population growth by around 60% compared to the control treatment, based on the released parasitoid-to-host ratio, indicating that it offers an effective alternative control method.info:eu-repo/semantics/acceptedVersio

Neonicotinoid contamination in wildflowers collected from citrus orchards in a northwestern Mediterranean Region (Spain) after tree foliar treatments

Ground-cover vegetation attracts and harbors beneficial insects to the agrosystem, playing an important role in conservation biological control. Integrated pest management (IPM) program guidelines recommend the implantation of sowed or resident wild covers in perennial crops. Given the high-quality fruit requirements, even in IPM programs, insecticides can be required in citrus crops. This study presents, over a year, the levels of neonicotinoids (thiamethoxam and imidacloprid) in not-target ground-cover wildflowers growing spontaneously in citrus orchards after foliar treatment of citrus trees. The presence and persistence of these neonicotinoids in different wildflower species were studied. Concentrations of thiamethoxam and imidacloprid in whole wildflowers ranged from < method quantification limit (MQL) to 52.9 ng g−1 and from < MQL to 98.6 ng g−1, respectively. Thiamethoxam was more frequently detected than imidacloprid. Thiamethoxam and imidacloprid were detected up to 336 and 230 days after treatment, respectively. The highest detection frequencies (100%) and highest thiamethoxam and imidacloprid mean concentrations (26.0 ± 7.3 ng g−1 and 11.0 ± 10.6 ng g−1, respectively) occurred in wildflowers collected 9 days after the treatments. Since application, a clear decrease in the concentration of both compounds and differences in the accumulation depending on wildflower species were observed. Cross contamination was detected, indicating a transport from adjacent treated plots. Maintaining a cover crop in citrus orchards may lead to detrimental effects on non-target arthropods if these neonicotinoid compounds are used for pest control since they can entail a chronic exposure during at least 230 days for imidacloprid and 336 days for thiamethoxam.info:eu-repo/semantics/publishedVersio

Efficacy of Selected Insecticides for Chemical Control of the African Citrus Psyllid, Trioza erytreae (Psylloidea: Triozidae)

The recent spread of the African citrus psyllid, Trioza erytreae, one of the vectors of the devastating citrus disease, Huanglongbing (HLB), to parts of mainland Europe has created considerable concern. In this study, we show the efficacy of several insecticides with varying modes of action on different developmental stages of T. erytreae. In laboratory trials, spinetoram caused the highest mortality in T. erytreae eggs (between 80 and 90%), while dimethoate, lambda cyhalothrin, spinetoram, cyantraniliprole, and paraffin oil showed over 90% mortality on nymphs. Dimethoate, spinetoram and paraffin oil also demonstrated high efficacy against adults. In winter field conditions, dimethoate showed the best results to control T. erytreae nymph populations, and lambda cyhalothrin showed persistent egg control. Our results support the use of different insecticides to control T. erytreae for adults in winter, and for egg and nymph populations in spring and summer.info:eu-repo/semantics/publishedVersio