Rosa Vercher

Citrus Pest Management in the Northern Mediterranean Basin (Spain, Italy and Greece)

Main management options for Arthropod pests of citrus and species recently introduced in the northern Mediterranean regions are reviewed. Available control strategies are discussed, incuding visual inspections practices, insect trapping methods and parasitoids or parasites release in augmentative or classical biological control. IPM practices and side effects of pesticides are also reviewed.

Recruitment of native parasitoid species by the invading leafminer Phyllocnistis citrella (Lepidoptera: Gracillariidae) on citrus in Spain.

Abstract The parasitoid assemblage associated with the citrus leafminer Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) was studied in citrus orchards in eastern Spain over a 7-yr period (1995–2001) after the leafminer’s introduction in 1994. In total, 11,587 adult native parasitoids were collected. To evaluate parasitism, 93,846 live immature stages of the citrus leafminer were observed, of which 21,460 (22.9%) were found to be parasitized. The parasitoid complex recruited around P. citrella was typical for invader hosts: lower species richness, generalized habits, idiobiont strategy, and low to moderate rates of parasitism. Two of the 10 species reared from the citrus leafminer, Pnigalio sp. and Cirrospilus brevis Zhu, LaSalle and Huang, accounted for >90% of the parasitoids. Native parasitoids moved onto the invading host rapidly, except for C. brevis, which required 3 yr to become common and widespread. In other leafminer species from plants in the vicinity of citrus orchards, the proportion of P. citrella parasitoids was higher in woody (69.7%) than in herbaceous plants (22.2%). The high population levels reached by the new pest, associated with a negative density dependence response of the parasitoids at these high population levels, suggest that the native parasitoid assemblage exerted only a limited role in regulating the population of the new host.

Density and Structure of Saissetia oleae (Hemiptera: Coccidae) Populations on Citrus and Olives: Relative Importance of the Two Annual Generations

Abstract Saissetia oleae (Olivier) (Hemiptera: Coccidae) populations were studied and compared in citrus (Citrus spp.) and olive (Olea europaea L.) groves to determine the number of generations, crawler emergence periods and changes in population density during the year. Ten citrus and four olive groves were sampled regularly between March 2003 and December 2005 in eastern Spain, covering an area of 10,000 km2. Each sample consisted of 16 branches and 64 leaves. Saissetia oleae populations presented a similar trend in both crops during the three years of study. Populations peaked in July, when crawlers emerged after the egg-laying period, and decreased during several months due to mortality of first instars in summer. A second crawler emergence period, with lower numbers and more variability from year to year, occurred between October and March. Populations did not increase during this period, probably because most eggs and crawlers perished during the winter and also because females that gave rise to this fall-winter generation were half as big and fecund as spring females. No differences were found between the size of mature females that had developed on citrus and on olives during the spring. Considering this population pattern, the best seasonal period to apply pesticides to control S. oleae would be at the end of July, when populations are synchronous, all crawlers have already emerged, and first instars predominate.

Factors influencing adult female oviposition in the citrus leafminer Phyllocnistis citrella

1 The citrus leafminer (CLM) Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) is a serious pest in most citrus‐growing regions of the world. The influence of leaf length, citrus species or variety, leaf colour tone and temperature on CLM oviposition was studied from field observations and laboratory experiments. The spatial distribution of eggs on leaves was also examined. Field data were obtained from 1100 samples collected in eastern Spain for 7 years.

SBO in Water Detoxification: Photo-Fenton Processes at Mild Conditions

The implementation of a photo-Fenton process at mild acidic conditions is a potential environmental application for SBOs. The Fenton reagent (sacrificial amounts of hydrogen peroxide and catalytic iron salts) has been demonstrated as an efficient method for the removal of toxic xenobiotics that is enhanced upon irradiation; sunlight can be used for this purpose. In order to avoid precipitation of iron at pH above 3, several strategies have been tested. One of them involves formation of photoactive iron complexes. Humic substances have been employed for this purpose, due to their ability to complex iron. Because of its similar chemical properties, SBO are candidates for this purpose. Experiments carried out with different pollutants have shown that SBO are not good photocatalysts because of the strong screen effect associated to their color, while they are useful to drive a photo-Fenton at milder pH, as they are good complexing agents for iron. Doehlert matrixes have been employed to determine that the pH range for efficient photo-Fenton can be extended to values of ca. 5 and that optimal SBO concentration is approximately 20 mg/L. Finally, SBO have demonstrated to be non toxic, scarcely biodegradable and relatively resistant to oxidizing conditions.