António Mexia

Biological Control of Thrips (Thysanoptera) by Orius laevigatus (Heteroptera: Anthocoridae) in Organically-Grown Strawberries

ABSTRACT In Portugal, strawberries are a key crop for the organic farming market. In 1990 and 1991 Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), the western flower thrips (WFT), was a major pest of strawberries in the Algarve. In 1993, the predator Orius laevigatus (Fieber) (Heteroptera: Anthocoridae), a common naturally occurring species in Portugal, was experimentally released in strawberry plantings. Numbers of thrips per flower were lower in cages where the Orius were released. In one of the cages where O. laevigatus was released there was also an appreciable growth of the composit weed Chamaemelum mixtum (L.). The later produced large amounts of pollen and there was a lower thrips populations and a higher Orius population in this plot, which happened after the weed flowering. It is not clear if this thrips reduction was caused by the increase of O. laevigatus, as a result of feeding on the weed pollen, or by a similar transfer of thrips to the Compositae also attracted by their pol...

Seasonality of the Mediterranean Fruit Fly (Diptera: Tephritidae) on Terceira and Sao Jorge Islands, Azores, Portugal

Population dynamics studies are very important for any area-wide control program as they provide detailed knowledge about the relationship of Medfly [Ceratitis capitata (Wiedemann)] life cycle with host availability and abundance. The main goal of this study is to analyse seasonality of C. capitata in Terceira and Sao Jorge Islands (Azores archipelago) using field and laboratory data collected during (2010–2014) CABMEDMAC (MAC/3/A163) project. The results from Sao Jorge Island indicate significantly lower male/female ratio than on Terceira Island. This is an important finding specially regarding when stablishing the scenario parameters for a sterile insect technique application in each island. The population dynamics of C. capitata are generally linked with host fruit availability and abundance. However, on Terceira Island fruit infestation levels are not synchronized with the trap counts. For example, there was Medfly infestations in some fruits [e.g., Solanum mauritianum (Scop.)] while in the nearby traps there were no captures at the same time. From this perspective, it is important to denote the importance of wild invasive plants, on the population dynamics of C. capitata, as well important to consider the possibility of having different densities of traps according to the characteristics of each area in order to improve the network of traps surveillance’s sensitivity on Terceira Island.

Western Flower Thrips Response to Color

The color preferences of western flower thrips (WFT) were studied to help use sticky traps efficiently. White, yellow and blue traps were tested. Bright blue and dark blue traps were the most attractive. The Horiver-Tr® trap captured more WFT than these blue traps but not significantly more than the dark blue trap. The bright yellow trap was not the most appropriate for use.

Spatial regression analysis of Ceratitis capitata Wiedemann (Diptera: Tephritidae) on Terceira Island, Azores

The fruit fly Ceratitis capitata Wiedemann is one of the most important threats to the trade of fresh fruits in the world due to its ability to survive in a wide range of hosts and climatic conditions. The main goal of this study is to evaluate if there is any significant relationship between the abundance of wild adults of C. capitata and the spatial characteristics of the location. The ordinary least squares estimation model calculated for each gender cannot provide a satisfactory general explanation for abundance of both genders of wild adults, yet it might generate some hypotheses about wild adult females of C. capitata fruit-seeking behaviour. Results from geographically weighted regression analysis can provide a satisfactory general explanation for abundance of both genders of wild adults. Both methods suggest that males are more dispersed than females, and because of that they might play an important role in scouting the surroundings for additional fruit hosts. The presence of some host-plants, even in places offering less protection (like pasture areas), provides an ecological corridor that supports the spread of wild adults of C. capitata.

Insecticidal efficacy and persistence of a co-occluded binary mixture of Helicoverpa armigera nucleopolyhedrovirus (HearNPV) variants in protected and field-grown tomato crops on the Iberian Peninsula

BACKGROUND A binary co-occluded mixture (HearSP1B:LB6) of Helicoverpa armigera single nucleopolyhedrovirus (HearNPV) variants was previously found to be highly pathogenic under laboratory conditions. The insecticidal efficacy and persistence of this mixture were determined in greenhouse and field-grown tomato crops in Spain and Portugal. RESULTS Concentrations of 10(9) -10(11) occlusion bodies (OBs) L(-1) of HearSP1B:LB6 resulted in 89-100% mortality of larvae on treated tomato plants in growth chambers. In protected tomato crops, application of 10(10) OBs L(-1) of HearSP1B:LB6 was as effective as Bacillus thuringiensis (Bt) and spinosad in reducing the percentage of damaged fruits, and resulted in higher larval mortality than the Bt treatment. In open-field tomato crops, virus treatments were as effective in reducing the percentage of damaged fruit as spinosad, Bt and chlorpyrifos treatments. The persistence of the insecticides on tomato plants was negatively correlated with solar radiation in both field and greenhouse settings. Residual insecticidal activity of OBs on protected tomato crops at 6 days post-application was 55 and 35% higher than that of Bt and spinosad respectively. On field-grown tomato, OB persistence was significantly lower than with spinosad or chlorpyrifos. CONCLUSION The efficacy and persistence of HearSP1B:LB6 OBs were comparable with those of commercial insecticides in both field and greenhouse tomato crops. Future studies should focus on reducing application rates to determine insecticidal efficacy at lower OB concentrations.

Are wild flowers and insect honeydews potential food resources for adults of the olive moth, Prays oleae?

The use of non-crop resources by natural enemies and their potentialities to enhance their effectiveness as pest control agents is increasing as a method for conservation biological control. Nevertheless, the effect of consumption of non-crop resources by pests has been generally overlooked being this knowledge crucial to favor natural enemies but not pests. In the present work, insect honeydews and flowers suitability as food resources for the olive tree key-pest Prays oleae were analyzed under laboratory conditions. The selected honeydews were excreted by Saissetia oleae and Euphyllura olivina, two olive pests, and the selected plants were seven abundant species in the olive grove agroecosystem that bloom simultaneously with the flight period of the anthophagous generation of P. oleae. In this work, some of these resources were identified as potential food sources for P. oleae. Despite the general findings, which indicate that honeydews have less nutritional value for insects than nectar, P. oleae reached the best survival and reproduction performance with the insects’ honeydews. Several of the tested flowers were identified as potential food resources for P. oleae, being Malva sylvestris the one that originated the best performance. Moreover, our results suggest that P. oleae females are synovigenic and emerge with nutritional reserves for reproduction. We highly recommend accomplishing further research before establishing these resources in biological control methods in order to confirm their effect on pests in fields.

Validation of a geographic weighted regression analysis as a tool for area-wide integrated pest management programs for Ceratitis capitata Wiedemann (Diptera: Tephritidae) on Terceira Island, Azores

ABSTRACT Extrapolation from quantitative sampling to the surrounding areas is an essential feature of many aspects of real world applications in pest management decision-making. However, these decisions are only as good as the accuracy of the methods that provided the information. The problem of estimating Mediterranean fruit fly population densities from trap grids is a specific case. The efficiency of three methods to estimate fruit flies trapped per day values for non-sampled areas in Terceira Island is evaluated, the inverse distance weighted, ordinary Kriging and the geographic weighted regression (GWR). Each method has its own specificities and merits. The results demonstrate that the GWR method is capable of estimating hotspots for the next season and can be used to identify ecological corridors over a non-sampled area. The high spatial heterogeneity and topographical conditions present on Terceira Island may explain why a more mathematically complex method is more reliable than simpler methods for use in possible future wide-area control program for medfly.

Biological Control of Western Flower Thrips with Orius laevigatus (Heteroptera: Anthocoridae) in Organic Strawberries in Portugal

In Portugal, strawberries are a key crop for the organic farming market. In 1990 and 1991 western flower thrips (WFT) were a major pest of strawberries in the Algarve. In 1992 and 1993 WFT populations were considerably lower and not economically important. In 1993 there was a maximum of 4.3 thrips per strawberry flower. The predator Orius laevigatus (Fieber), which is a common, naturally occurring species in Portugal, was experimentally released in strawberry plantings. Although numbers of thrips per flower were lower in cages where they were released, these numbers were not significantly different from numbers of thrips in cages without the predator. In one cage where O. laevigatus was released, there was an appreciable growth of the weed Chamaemelum mixtum (L.). The latter produced large amounts of pollen and it is not clear if the lower thrips populations in this case, which happened after the weed flowering, were caused by an increase of O. laevigatus, as a result of feeding on the pollen, or by a thrips transfer to the Compositae weeds attracted by the pollen.

Wild flower resources and insect honeydew are potential food items for Elasmus flabellatus

Adult parasitoids need non-host food such as nectar or honeydew for survival and reproduction. In a conservation biological control strategy, the knowledge about non-host feeding of parasitoid species is a key factor to successfully increase their action. The nutritional behavior of Elasmus flabellatus (Fonscolombe) (Hymenoptera: Eulophidae), a major parasitoid of the olive moth, Prays oleae (Bernard) (Lepidoptera: Praydidae), is completely unknown. Survival experiments were performed on two secondary olive pest honeydews and eight common flowering plant species in order to analyze their suitability as potential food sources for E. flabellatus females. Abdomen and gut dissections were carried out to verify the pollen consumption and the egg production. Floral architecture and insect morphology were described. Cox’s proportional hazard regression models were used to analyze the differences between parasitoid survivals. Honeydews secreted by Saissetia oleae (Olivier) (Hemiptera: Coccidae) and Euphyllura olivina (Costa) (Hemiptera: Psyllidae) resulted in the best performance followed by the flowers of Malva sylvestris L. (Malvaceae), Daucus carota L. (Apiaceae), and the Cichorioideae Tolpis barbata (L.) and Andryala integrifolia L. Theoretical flower resources accessibility were assessed and related with the survival results. E. flabellatus females did not consume pollen and did not produce eggs, suggesting that the species is synovigenic and requires additional foods for egg production. In sustainable pest control programs, this novel knowledge is a promising opportunity for improving suitable food resources of E. flabellatus in the field.

Usefulness of Plant Derived Products to Protect Rice Against Fungi in Western Europe

The ethnopharmacobotanical usages of aromatic plants, from the Mediterranean region, as spices, for human or animal health applications, among other purposes, are well-known. However, natural products from plant origin can also play a role as natural chemical substances for crop and food protection leading to an increased interest on the plants auto protective capacity against pathogenic agents. Search on plant derived bioactive products, which could be less toxic to the environment and more biologically selective than synthetic compounds are of major importance, for rural and agro-industrial economic sectors. Naturally occurring biologically active compounds from plant extracts and essential oils are examples of GRAS compounds, that are of increased importance due to restrictions on pesticides and to environmental and food safety concerns. Rice is a staple food for over half of the world population being one of the cheapest sources of food energy and protein. This crop cereal raises interest in Europe. It is cultivated in the south of Europe for centuries, being Italy the major rice producer and Portugal the main rice consumer. Fungi infection and the inherent occurrence of mycotoxins can be responsible for serious economic losses and public health risks. Knowledge about the origin of the growth of toxigenic fungi is a prerequisite to the establishment of mycotoxins control programs. Rice samples collected in Portuguese farms or from factories were analyzed for fungal infection. Several fungi taxa were isolated (Absidia, Alternaria, Aspergillus, Bipolaris, Botrytis, Chaetomium, Curvularia, Cunninghamella, Epicoccum, Fusarium, Geotrichum, Helicoma, Nigrospora, Penicillium, Pyricularia, Rhizopus, Scytalidium, Stemphylium, Sordaria, Trichoconiella, Trichoderma, Trichothecium, and Ulocladium), some of them being potentially mycotoxigenic. The knowledge on the plant synthesis of substances potentially useful to control microbial infections, led to evaluate the bioactivity of extracts, and essential oils of a set of aromatic plants against fungi affecting rice. We enhance the good results achieved with Cuminum cyminum , Laurus nobilis , Mentha pulegium, Origanum vulgare, and Satureja montana both with extracts and essential oils against Aspergillus candidus , Aspergillus flavus, Aspergillus niger, Botrytis cinerea, Cladosporium cucumerinum, Fusarium culmorum and Penicillium sp.