Haralabos Tsolakis

Integrative taxonomy demonstrates the unexpected synonymy between two predatory mite species: Cydnodromus idaeus and C. picanus (Acari : Phytoseiidae)

Species of the mite family Phytoseiidae are well known as predators of mite pests all over the world. Their identification is thus of great interest for biological control. The specimens examined in this study belong to the species Cydnodromus idaeus (described from Brazil) and C. picanus (described from Chile). They were collected together on the same plant in Argentina. These species are mainly differentiated by the presence/absence of the dorsal solenostomes (gland openings) gd2. Some morphometric differences were observed between the Argentinian specimens and the type material of C. idaeus and C. picanus; however, they were not sufficient to support a species separation. Morphological and molecular analyses with two mtDNA (12S rRNA, CytB) and a nuclear DNA (ITS) marker showed no difference between Argentinian specimens with and without the solenostome gd2. Also, molecular differentiation between these latter specimens, C. picanus and C. idaeus, was very low, suggesting that all these individuals belong to the same species. Biological experiments confirm these results, as 75% of the progeny resulting from females with gd2 had gd2 present whereas all the descendants resulting from the females without gd2 had gd2 present too. The presence/absence of this solenostome seems thus to be variable within a species and cannot be used diagnostically. We conclude that all specimens from Argentina belong to C. idaeus and that C. picanus is a junior synonym of C. idaeus. The present results were unexpected as the presence/absence of solenostomes is used in Phytoseiidae identification keys and as one of a suite of diagnostic characters for discriminating between species. The consequences of these findings for the taxonomy of Phytoseiidae are discussed.

Distribution of Phytoseiid Mites (Parasitiformes, Phytoseiidae) on Hazelnut at Two Different Altitudes in Sicily (Italy)

Abstract Phytoseiid mites associated with hazelnut in Sicily were sampled during 1991–1993. Two orchards at two different altitudes (500 and 1,000 m above sea level) were taken into account. No chemicals had been applied in the two fields for at least 7 yr and the agricultural practices were limited (spring tillage and removal of dead branches). Thirteen species, out of a total of 19, were collected at the lower altitude and 14 at the higher; eight of these species [ Kampimodromus aberrans (Oudemans), Typhlodromus intercalaris Livshitz & Kuznetsov, Amblydromella crypta (Athias-Henriot), Typhlodromus rhenanoides Athias-Henriot, Amblyseius andersoni (Chant), Euseius stipulatus (Athias-Henriot), Paraseiulus erevanicus Wainstein & Arutunjan, Phytoseius finitimus Ribaga sensu Denmark] were common to both fields. As far as the distribution of phytoseiids was concerned, we took into consideration their presence on three different sites of the plants: trunk, low branches, and high branches. On the whole the population of phytoseiid mites was uniformly distributed on the plant from October through April, although as far as the single species were concerned, some were uniformly distributed on the plant and some showed a preference toward a particular part of the plant. K. aberrans showed a preference toward high and low branches at 1,000 m above sea level (asl), whereas T. intercalaris showed such a preference in both sites. However, at 500 m asl, A. crypta preferred the trunk, whereas T. rhenanoides was uniformely distributed on the plant in both sites.

Effects of Neem oil (Azadirachta indica A. Juss) on Tetranychus urticae Koch (Acariformes, Tetranychidae) in laboratory tests

The effects of a commercial neem oil titolated in azadirachtin at 10,000 ppm on the phytophagous mite Tetranychus urticae Koch were investigated in laboratory trials. The material provoked a high mortality on the post embryonic developmental stages of the mite when citrus leaves were used as substrate, while mortality was lower (40%) on bean leaves. Neem oil caused a high mortality of young females (100%) and also a remarkable reduction of the oviposition rate in contaminated females (from 10.9 to 93.5%). The two choice-tests, carried out in order to evaluate the repellent effect of the material, showed that neem oil has long term repellent properties.

Overwintering of phytoseiid mites (Parasitiformes, Phytoseiidae) on hazelnut (Corylus avellana) in Sicily (Italy)

A study was conducted on the overwintering of predatory mites on hazelnut at two different altitudes (500 and 1000 m a.s.1.). The most common species encountered during two successive winters were Kampimodromus aberrans, Typhlodromus intercalaris and Typhlodromus cryptus. At both altitudes, all three species overwintered predominantly as non-ovipositing female. At 500 m a.s.l., the first young stages of K. aberrans appeared in the second half of April, while no young stages were found until May at 1000 m a.s.l. A few males and young stages of T. intercalaris were found at 500 m a.s.1., no young stages were found at 1000 m a.s.l. Compared to T. intercalaris, more males and young stages of T. cryptus could be observed at 500 m a.s.l. — at 1000 m a.s.l., only a few males were collected and young stages were completely absent. The calyces of the insemination apparatus of overwintering females of the three species were usually found empty. Ten percent of the females at 500 m a.s.l. showed remnants of spermatophores and only few females had an intact spermatophore inside. At the higher altitude the situation was similar, but the number of females containing spermatophores or their remnants was smaller.

On the identity of Neoseiulus fallacis (Garman 1948) (Parasitiformes, Phytoseiidae): redescription of the species and description of the new species Neoseiulus garmani

ABSTRACT Neoseiulus fallacis (Garman) is a broadly commercialised phytoseiid mite used in Integrated Pest Management (IPM) programmes especially in northern and southern America. However, its taxonomic status was, until now, equivocal because no redescription based on type material had ever been made. The authors redescribe N. fallacis from type material in Garman’s collection, designating the lectotype and paralectotypes for the species. Moreover, a new species of the fallacis complex, discovered among the fallacis type material, is described and named N. garmani sp. nov. in honour of Philip Garman.