Aleixandre Beltrà

Molecular and morphological characterisation of Pseudococcidae surveyed on crops and ornamental plants in Spain.

Mealybugs (Hemiptera: Pseudococcidae) are common invasive pests in Europe, causing major problems on crops and ornamental plants. However, very few data are available concerning the mealybug fauna of southern Europe. This lack of data and the difficulty of identifying mealybugs morphologically by traditional techniques currently limit the perspectives for efficient specific pest management. The aim of this study was to provide multi-criterion characterization of mealybugs surveyed in eastern Spain in order to facilitate their routine identification through DNA sequencing or the use of derived species-specific molecular tools. We characterised 33 mealybug populations infesting crops and ornamental plants in eastern Spain, using a combination of molecular and morphological techniques, including the sequencing of the universal barcode DNA region cytochrome c oxidase subunit I (COI). This characterisation has led to the identification of ten species and provides sequence data for three previously unsequenced species, contributing to the phylogenetic knowledge of the family Pseudococcidae. In addition, the intraspecific variations found in the populations of five mealybug species provide insight into their invasion history.

Guiding Classical Biological Control of an Invasive Mealybug Using Integrative Taxonomy

Delottococcus aberiae De Lotto (Hemiptera: Pseudococcidae) is a mealybug of Southern African origin that has recently been introduced into Eastern Spain. It causes severe distortions on young citrus fruits and represents a growing threat to Mediterranean citrus production. So far, biological control has proven unsatisfactory due to the absence of efficient natural enemies in Spain. Hence, the management of this pest currently relies only on chemical control. The introduction of natural enemies of D. aberiae from the native area of the pest represents a sustainable and economically viable alternative to reduce the risks linked to pesticide applications. Since biological control of mealybugs has been traditionally challenged by taxonomic misidentification, an intensive survey of Delottococcus spp. and their associated parasitoids in South Africa was required as a first step towards a classical biological control programme. Combining morphological and molecular characterization (integrative taxonomy) a total of nine mealybug species were identified in this study, including three species of Delottococcus. Different populations of D. aberiae were found on wild olive trees, in citrus orchards and on plants of Chrysanthemoides monilifera, showing intra-specific divergences according to their host plants. Interestingly, the invasive mealybug populations from Spanish orchards clustered together with the population on citrus from Limpopo Province (South Africa), sharing COI haplotypes. This result pointed to an optimum location to collect natural enemies against the invasive mealybug. A total of 14 parasitoid species were recovered from Delottococcus spp. and identified to genus and species level, by integrating morphological and molecular data. A parasitoid belonging to the genus Anagyrus, collected from D. aberiae in citrus orchards in Limpopo, is proposed here as a good biological control agent to be introduced into Spain.

New records of mealybugs (Hemiptera: Pseudococcidae) from Spain

Five mealybug (Hemiptera: Pseudococcidae) species were identified as new records for Spain: Phenacoccus madeirensis (Green), Phenacoccus solani Ferris, Dysmicoccus boninsis (Kuwana), Hypogeococcus pungens Granara de Willink and Ferrisia malvastra (McDaniel).

Fortuitous biological control of the invasive mealybug Phenacoccus peruvianus in Southern Europe

Phenacoccus peruvianus Granara de Willink (Hemiptera: Pseudococcidae) is a Neotropical invasive mealybug that has rapidly spread throughout Mediterranean Basin. It has established itself as the principal pest of several ornamental plants, causing considerable problems in nurseries and urban landscapes. The aim of this study was to determine the natural enemy complex of this pest and report the feasibility of its biological control. Six urban green spaces were surveyed in eastern Spain from 2008 to 2010. The most abundant natural enemies of P. peruvianus were found to be the primary parasitoids Acerophagus n. sp. near coccois and Leptomastix epona Walker (Hymenoptera: Encyrtidae). Phenacoccus peruvianus populations were lower during the second and third year of the survey, coinciding with an increase of the parasitoid Acerophagus sp., which displaced the native L. epona. Differential female offspring and resource preemption are discussed as the main reasons for this displacement.

Molecular evidence for ongoing complementarity and horizontal gene transfer in endosymbiotic systems of mealybugs

Intracellular bacterial supply of essential amino acids is common among sap-feeding insects, thus complementing the scarcity of nitrogenous compounds in plant phloem. This is also the role of the two mealybug endosymbiotic systems whose genomes have been sequenced. In the nested endosymbiotic system from Planococcus citri (Pseudococcinae), “Candidatus Tremblaya princeps” and “Candidatus Moranella endobia” cooperate to synthesize essential amino acids, while in Phenacoccus avenae (Phenacoccinae) this function is performed by its single endosymbiont “Candidatus Tremblaya phenacola.” However, little is known regarding the evolution of essential amino acid supplementation strategies in other mealybug systems. To address this knowledge gap, we screened for the presence of six selected loci involved in essential amino acid biosynthesis in five additional mealybug species. We found evidence of ongoing complementarity among endosymbionts from insects of subfamily Pseudococcinae, as well as horizontal gene transfer affecting endosymbionts from insects of family Phenacoccinae, providing a more comprehensive picture of the evolutionary history of these endosymbiotic systems. Additionally, we report two diagnostic motifs to help identify invasive mealybug species.

Predation rate and performance of three ladybirds against the green peach aphid Myzus persicae in sweet pepper

Myzus persicae (Sulzer) (Hemiptera: Aphididae) is one of the most common and harmful pest species attacking sweet pepper. Here, we compared the predation rate and performance of Adalia bipunctata (L.), Hippodamia variegata (Goeze), and Scymnus interruptus Goeze (Coleoptera: Coccinellidae) fed on M. persicae infesting sweet pepper. In the laboratory, when offered 150 aphids daily, A. bipunctata was the most voracious species (predation per adult female of 122.7 aphids per 24 h) followed by H. variegata (87.7) and S. interruptus (27.3). When offered 50 aphids, 92% of the S. interruptus larvae developed to adults, 48% of H. variegata, and only 7% of A. bipunctata. In greenhouse experiments, A. bipunctata completely eradicated the aphid population within 2 days following release, whereas H. variegata and S. interruptus initially reduced the aphid population; however, in the long‐term, the infestation was not controlled. Adults of A. bipunctata remained on the plants even in the absence of prey but they laid almost no eggs. Very few adults of H. variegata and S. interruptus were recorded on the plants despite the presence of prey, yet egg laying was observed. Overall, A. bipunctata had an immediate impact on the aphids and is more suitable for curative releases. However, it showed limited potential to establish in the crop. Due to their capacity to complete development with low prey availability, the potential of H. variegata and S. interruptus for preventative releases against aphids in greenhouse crops should be studied further.

Association between ants (Hymenoptera: Formicidae) and the vine mealybug (Hemiptera: Pseudococcidae) in table‐grape vineyards in Eastern Spain

BACKGROUND The vine mealybug, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) is a key pest of grapevine in the Mediterranean Basin. Some honeydew collecting ant species are known to increase mealybug populations in other grape-growing regions. However, there is scarce information on either the ant species present in Mediterranean vineyards or their impact on mealybugs. We conducted a study in four commercial vineyards in Eastern Spain in order to i) identify the ant species foraging on the vine canopies, ii) study the association among ant activity, vine mealybug abundance and fruit damage, and iii) test a novel method for ant management, distracting ants from guarding vine mealybugs by providing sugar dispensers. RESULTS We recorded three ant species native to the Mediterranean foraging on the vine canopies: Lasius grandis (Forel), Pheidole pallidula (Nylander) and Plagiolepis schmitzii (Forel). The mean percentage of damaged fruits per vine was positively correlated with the number of vine mealybugs captured in traps placed at the trunk. We detected a positive but weak relationship between ant activity, vine mealybug abundance and fruit damage. The provisioning of sugar dispensers reduced the number of ants foraging on the vines by 23.4% although this reduction was not statistically significant. Vine mealybug abundance was significantly reduced (72%) after sugar provisioning. CONCLUSION Our results suggest that the ant species native to vineyards in eastern Spain induce population increases of the vine mealybug. Moreover, the provisioning of sugars can be a valuable tool for ant management and mealybug control.