LA SISTEMATICA DEI PHYTOSEIIDAE: CENNI STORICI, SITUAZIONE ATTUALE E PROSPETTIVE DI SVILUPPO

La sistematica della famiglia Phytoseiidae ha una lunga e controversa storia. Tra le cause principali di queste controversie possiamo ricordare le piccole dimensioni di questi acari e le conseguenti difficoltà di individuare caratteri morfologici universalmente validi da adoperare in una classificazione sistematica che rispecchi anche la filogenesi. Viene riportato in seguito un excursus storico della sistematica di questi piccoli predatori focalizzando l’attenzione alle due più importanti teorie di organizzazione dei taxa nell’ambito della famiglia che si sono delineate nel tempo e attualmente vengono adottate dai diversi sistematici. L’autore ha cercato di individuare i punti deboli di entrambe, fornendo infine alcune indicazioni sull’indirizzo futuro della classificazione dei Phytoseiidae.Systematics of the Phytoseiidae: historical review, current situation and future prospects The systematics of the family Phytoseiidae has a long and controversial history. These disputes were due mainly to the small size of these mites and to the difficulty in identifying valid morphological features for a systematic classification that also reflects the phylogeny. The author reports here an historical overview of the systematics of these predators, focusing on the two main theories on organization of taxa within this family. The author has tried to identify the weaknesses of both theories, providing some cues for the future of Phytoseiidae systematics

Osservazioni sulla dinamica di popolazione di due cicaline ampelofaghe nella Sicilia occidentale

Observations on population dynamics of leafhoppers in Western Sicily vineyards From 2007 to 2009 field observations were carried out in two vineyards (organically and conventionally managed) in Menfi (Agrigento province, Sicily). Population dynamics of two leafhoppers, Jacobiasca lybica (cotton leafhopper) and Zygina rhamni were followed by chromotropic traps and leaf observation in field. Both species were constantly present in vineyards. Z. rhamni did not register statistical differences between the two fields, while J. lybica was mostly present in the conventionally managed field. In this vineyard for two consecutive years (2007 and 2008) J. lybica population exceeded the intervention threshold. On the other hand, in the organically managed vineyard the cotton leafhopper population remained below the intervention threshold for all the observation period

Control of Bactrocera oleae by low environmental impact methods: NPC methodology to evaluate the efficacy of lure-and-kill method and copper hydroxide treatments

The NonParametric Combination (NPC) methodology is proposed to verify the influence of the lure-and-kill method, using Ecotraps (Vioryl SA), on the distribution of Bactrocera oleae (Rossi) (Diptera Tephritidae) infestation in olive groves, and the integration of this method with copper hydroxide sprayings. This approach does not require the verification of any rigid assumption as many parametric methods do. Results of field trials indicate a strict relationship among the efficiency of the lure-and-kill method on time, dimension of the field, and population density of the olive fly. Moreover, the lure-and-kill method alone seems insufficient to provide an efficient control of the olive fly population in small olive groves. However, when this method is integrated with two copper hydroxide sprayings, the infestation of drupes is maintained below the damage threshold

Predation of Typhlodromus longilaterus Athias-Henriot (Parasitiformes, Phytoseiidae) females on eggs and juveniles of the tetranychid mites Tetranychus urticae (Koch) and Panonychus citri (McGregor) (Acariformes, Tetranychidae)

Typhlodromus longilaterus is a generalist phytoseiid mite described by Athias-Henriot in 1957 and commonly found in Israel on spontaneous herbaceous plants. As very little is known about this species, the present study reports preliminary results on the predation capacity of phytoseiid females on eggs and juveniles of two tetranychid mites very common in the Mediterranean area, Tetranychus urticae and Panonychus citri. After 24 hours the phytoseiid females preyed on 15% of offered eggs of both tetranychids, while the prey ratio was higher on T. urticae eggs after this period (33.4% and 33.5% vs 20.8% and 16.2% after 2 and 3 days for T. urticae and P. citri respectively). The phytoseiid showed its preference also for nymphs of T. urticae preying on 44-50% of nymphs offered, while the predation range was lower on nymphs of P. citri (from 30.3 to 36.3%)

Evaluation of infestation by Lobesia botrana (Dennis et Schiffermüller) (Lepidoptera, Tortricidae) and its relation to territorial differences and cultivar susceptibility

A three year study (2008-2010) was carried out in two organically managed vineyards in western Sicily to verify both the influence of different cultivars and microclimatic conditions on grape moth infestation and on mould infections of grapes. Observations were done on two autochthonous cultivars (Inzolia and Catarratto) and four international ones (Chardonnay, Cabernet Sauvignon, Syrah and Merlot). Results showed a different degree of infested grapes among the different cultivars in both farms but also a different level of infestation between the two farms for the same cultivar. Chardonnay was the most infested cultivar by the grape moth larvae, while Merlot was the less infested one. Botrytis cinerea was almost absent on the majority of the cultivars, while the sour bunch rot was always present. This disease was sometimes present on all infested grapes. On the other hand, Aspergillus was present at very low levels on the majority of the cultivars

Valutazione dell’infestazione di Lobesia botrana (dennis et Schiffermüller) in funzione alle differenze territoriali e alla suscettibilità varietale

A three years study (2008-2010) was carried out in two organic managed vineyards in western Sicily in order to verify both the influence of different cultivars and microclimatic conditions on grape moth infestation and on mould infections of grapes. Observations were done on two autochtonous (Inzolia and Catarratto) and four international (Chardonnay, Cabernet Sauvignon, Syrah and Merlot) cultivars. Results showed a different degree of infested grapes among the different cultivars in both farms but also a different level of infestation between the two farms for a same cultivar. Chardonnay was the most infested cultivar by the grape moth larvae, while Merlot was the less infested. Botrytis cinerea was almost absent on the majority of the cultivars, while the sour bunch rot was always present. This disease sometimes was present on all infested grapes. On the other hand Aspergillus was present in very low levels on the majority of the cultivars

Effect of pollens and preys on various biological parameters of the generalist mite Cydnodromus californicus

The generalist phytoseiid mite Cydnodromus californicus (McGregor) (Mesostigmata Phytoseiidae) is considered a very important biocontrol agent of the spider mite Tetranychus urticae Koch both in greenhouses and field. Its capacity to feed alternative foods allows the increase of the population in field, even when the primary prey is not available. To investigate the effect of various alternative food substances present in the Mediterranean agroecosystems on the biological parameters of C. californicus, laboratory trials were carried out using 17 pollens and 3 preys. As it was expected, T. urticae was the best food for both the postembryonic development and the oviposition rate (100% of attained adulthoods and 2.65 eggs/female/day were laid). Good results were obtained also with pollens of Carpobrotus edulis (L.) and Scrophularia peregrina L.: on both pollens, 84% of eggs reached the adulthood and the oviposition rate was 2.00 and 1.81 eggs/female/day for the two pollens respectively. Interesting results were obtained with the alternative prey Petrobia hartii (Ewing), very common on Oxalis spp., a weed widespread in Mediterranean orchards (72% of attained adulthoods and 0.57 eggs/female/day). On the other hand, the effect of Mentha piperita L. was not positive on the juvenile development (only 28% of eggs reached the adulthood), while it was positive on the oviposition rate (1.12 eggs/female/day)

On the perception of leaf morphology and visible light by Tetranychus urticae Koch (Acariformes, Tetranychidae)

The two-spotted spider mite Tetranychus urticae is one of the most polyphagous and most damaging pests worldwide. The behaviour of the mite differs on its various host plants and this could influence crop defence strategies. We investigated the perception of leaf morphology by T. urticae in relation to the effects of visible light on the selection of sites on which females prefer to live and feed. Mite females chose the shaded surface when smooth and glabrous lemon leaves were offered as a surface for living and feeding, showing a photophobic behaviour. However, they clearly preferred the abaxial surface of bean leaves regardless of the presence or absence of visible light. As no differences were found regarding the food quality between the adaxial and abaxial leaf surfaces, mite behaviour seems to be related firstly to the perception of leaf morphology and secondly to visible light. As regards the first factor, T. urticae prefers the abaxial surface of leaves with a complicated architecture, i.e. veins in relief, on which they can easily build their dense web, and this factor has priority in comparison to the negative effect of the visible radiations. The second factor is important on smooth and glabrous leaves, these being unsuitable for building the complicated characteristic webs of T. urticae