Mealybugs (Hemiptera: Pseudococcidae) are major pests of a wide range of crops and ornamental plants worldwide. Their high degree of morphological similarity makes them difficult to identify and limits their study and management. We aimed to identify a set of markers for the
Scale insects are frequent invaders. With 129 established species, they numerically represent one of the major group of insects alien to Europe. Scales are usually small insects with wingless females. Due to this small size and concealment, many species, mainly belonging to the families Diaspididae, Pseudococcidae and Pseudococcidae, have been accidentally introduced to Europe, mostly originating from tropical regions and essentially from Asia. Th e trade of fruit trees and ornamentals appears to be the usual pathway of introduction. At present, alien scales represent an important component of the European entomofauna, accounting for about 30% of the total scale fauna.
Epitrix species (Coleoptera: Chrysomelidae) feed mostly on plants from the family Solanaceae and some of them are major pests of potato crops. All Epitrix species are morphologically highly similar, which makes them difficult to identify and limits their study and management. Identification of species is mostly based on the observation of the genitalia and requires a high level of expertise. Here, we propose a tool to reliably identify all developmental stages of the most economically important Epitrix species feeding on potato in Europe and North America (Epitrix cucumeris, Epitrix similaris, Epitrix tuberis, Epitrix subcrinita and Epitrix hirtipennis). We first sequenced two DNA markers (mitochondrial cytochrome c oxidase I (COI) and nuclear internal transcribed spacer 2 (ITS2)) to test their effectiveness in differentiating among six Epitrix species (126 specimens). Morphospecies of Epitrix were well-differentiated by both DNA barcodes and no mitochondrial introgression was detected. Then, we developed an RFLP-based diagnostic method and showed that unambiguous species discrimination can be achieved by using the sole restriction enzyme TaqI on COI polymerase chain reaction products. The tool proposed here should improve our knowledge about Epitrix species biology, distribution and host range, three capacities that are particularly important in the detection and management of these pest species. Specifically, this tool should help prevent the introduction of E. tuberis and E. subcrinita in Europe and limit the spread of the recently introduced E. cucumeris and E. similaris, with minimal disruption to Solanaceae trade.
Pseudococcidae (mealybugs) is a large taxonomic group, including a number of agronomic pests. Taxonomic identification of mealybug species is a recurrent problem and represents a major barrier to the establishment of adequate pest management strategies. We combined molecular analysis of three DNA markers (28S-D2, cytochrome oxidase I and internal transcribed spacer 2) with morphological examination, for the identification of 176 specimens collected from 40 mealybug populations infesting various crops and ornamental plants in Egypt and France. This combination of DNA and morphological analyses led to the identification of 17 species: seven in Egypt (Planococcus citri (Risso), Planococcus ficus (Signoret), Maconellicoccus hirsutus (Green), Ferrisia virgata (Cockerell), Phenacoccus solenopsis Tinsley, Phenacoccus parvus Morrison and Saccharicoccus sacchari (Cockerell)) and 11 in France (Planococcus citri, Pseudococcus viburni Signoret, Pseudococcus longispinus (Targioni-Tozzetti), Pseudococcus comstocki (Kuwana), Rhizoecus amorphophalli Betrem, Trionymus bambusae (Green), Balanococcus diminutus (Leonardi), Phenacoccus madeirensis Green, Planococcus vovae (Nasonov), Dysmicoccus brevipes (Cockerell) and Phenacoccus aceris Signoret), Pl. citri being found in both countries. We also found genetic variation between populations considered to belong to the same species, justifying further investigation of the possible occurrence of complexes of cryptic taxa.
Bruchidius atrolineatus (Pic) is present in crops of Vigna unguiculata towards the end of the dry season at the beginning of September when pods start to form. Females lay many eggs on most available green pods. However, this oviposition behaviour results in an important egg mortality. During September, pods gradually reach maturity whilst new pods are formed. Females therefore have at their disposal a growing number of differently mature pods. Confronted with such a situation, B. atrolineatus females show an opportunist behaviour and lay most of their eggs on the most abundant stage, i.e. the most easily discovered stage (ripening green pods in mid-September or dry pods towards the end of September). However, they also lay eggs on other phenological stages no matter how abundant they are. B. atrolineatus females therefore show a certain behavioural plasticity enabling them to reproduce on all stages of pods whose maturity, chemistry and texture may differ. Larvae can develop either in maturing or dry seeds. The number of eggs laid from mid September is lower and lower whatever the phenological stage attacked. This decrease would be due to a reduction of the first generation adult bruchids and of the reproductive potential of females.Callosobruchus maculatus appears in crops at the same time as B. atrolineatus, but oviposits preferentially on dry pods. Eggs are observed during the whole period of study, but the numbers laid are always low. With the increase in pod number, eggs are dispersed among the different substrates available. However, the average number of eggs laid on the pods remains constant. Despite the high mortality due to the oviposition behaviour of B. atrolineatus and to other factors (impact of hymenopterous parasitoids), these two bruchids cause important losses to seeds of V. unguiculata. Control methods against these pests should be envisaged .in the field before harvesting.
Mealybugs (Hemiptera: Pseudococcidae) are pests constraining the international trade of Brazilian table grapes. They damage grapes by transmitting viruses and toxins, causing defoliation, chlorosis, and vigor losses and favoring the development of sooty mold. Difficulties in mealybug identification remain an obstacle to the adequate management of these pests. In this study, our primary aim was to identify the principal mealybug species infesting the major table grape-producing regions in Brazil, by morphological and molecular characterization. Our secondary aim was to develop a rapid identification kit based on species-specific Polymerase Chain Reactions, to facilitate the routine identification of the most common pest species. We surveyed 40 sites infested with mealybugs and identified 17 species: Dysmicoccus brevipes (Cockerell), Dysmicoccus sylvarum Williams and Granara de Willink, Dysmicoccus texensis (Tinsley), Ferrisia cristinae Kaydan and Gullan, Ferrisia meridionalis Williams, Ferrisia terani Williams and Granara de Willink, Phenacoccus baccharidis Williams, Phenacoccus parvus Morrison, Phenacoccus solenopsis Tinsley, Planococcus citri (Risso), Pseudococcus viburni (Signoret), Pseudococcus cryptus Hempel, four taxa closely related each of to Pseudococcus viburni, Pseudococcus sociabilis Hambleton, Pseudococcus maritimus (Ehrhorn) and Pseudococcus meridionalis Prado, and one specimen from the genus Pseudococcus Westwood. The PCR method developed effectively identified five mealybug species of economic interest on grape in Brazil: D. brevipes, Pl. citri, Ps. viburni, Ph. solenopsis and Planococcus ficus (Signoret). Nevertheless, it is not possible to assure that this procedure is reliable for taxa that have not been sampled already and might be very closely related to the target species.
Mealybugs are major pests of grapevines worldwide. They cause economic losses by lowering the cosmetic value of fruits, reducing yields, transmitting viruses and resulting in the quarantine or rejection of produce in international trade. Knowledge of the species present in a vineyard is important for the adjustment of management strategies. We surveyed and accurately characterized the mealybugs infesting vineyards in one of the main production areas of Chile; 164 mealybugs were sampled from 26 vineyards in four regions of Chile and identified by DNA sequencing for two markers (cytochrome oxidase I and internal transcribed spacer 2) and morphological examination. Pseudococcus viburni (Signoret) was the most common species, followed by Pseudococcus meridionalis Prado and Pseudococcus cribata González. Molecular variability at the COI and ITS2 loci was observed in both P. viburni and P. cribata. A comparison of haplotypes of P. viburni worldwide provides support for a recent hypothesis that this species is native to South America, a finding with direct consequences for management. Neither Pseudococcus longispinus (Targioni & Tozzetti) nor Planococcus ficus Signoret were found.
Around 2004, a new type of injury was noticed in potato tubers harvested in the north of Portugal. Two North American flea beetles, Epitrix cucumeris and Epitrix similariswere later identified. The second species seems to be responsible for the characteristic type of tuber injury observed. The main morphological characters enabling the two species to be distinguished are presented.
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