Antonio Masetti

Parasitic hymenoptera fauna on agromyzidae (diptera) colonizing weeds in ecological compensation areas in northern Italian agroecosystems.

Abstract Parasitoids (Hymenoptera) associated with agromyzid leafminers (Diptera: Agromyzidae) were studied in three rural farms located in northern Italy. The parasitoids were reared from mined foliage of weeds growing in field margins. We reared 998 Hymenoptera specimens, representing five families, 23 genera, and 53 species, from leafminers infesting weeds. Eulophidae was the most abundant family (67.64%), followed by Braconidae (28.86%), Eucoilinae (1.40%), Tetracampidae (1.40%), and Pteromalidae (0.7%). Braconids was the most species rich family, accounting for 28 species; eulophids were represented by 19 species, pteromalids by four species, and eucoilins and tetracampids by one species each. The dominant parasitoid was the eulophid Pediobius metallicus (Nees), representing 18.17% of the total, followed by Diglyphus isaea (Walker) (12.73%), and Neochrysocharis formosa (Westwood) (10.82%). The most abundant braconid parasitoid was Dacnusa maculipes Thomson (9.62%). More than 80% of parasitoids were recovered from 10 plant species: Cirsium arvense (L.) Scopoli, Plantago lanceolata L., Sonchus asper (L.) Hill, Papaver rhoeas L., Picris echioides L., Lactuca serriola L., Myagrum perfoliatum L., Ranunculus velutinus Tenore, Arctium lappa L., and Medicago sativa L. The retention and the management of wild plants within field margins can be crucial tools to enhance the populations of biological control agents of agromyzids and to conserve rare parasitic wasp species.

Spatial Patterns and Sampling Plan for Liriomyza huidobrensis (Diptera: Agromyzidae) and Related Parasitoids on Lettuce

Abstract Field experiments were carried out in 2000 and 2001 in northern Italy, with the aim of developing a composite sampling strategy for estimating populations of Liriomyza huidobrensis (Blanchard) larvae and mines on lettuce. Larval parasitoid populations also were sampled to estimate the contribution of these beneficials to pest control. Covariance analysis and parallelism test indicated that there were not significant differences in the coefficient of Taylor’s power law between treatments (untreated versus treated) and between seasons (2000 versus 2001) for both pest and parasitoid stages. The slope of each regression was significantly >1 for L. huidobrensis mines and larvae, and endoparasitoid and ectoparasitoid larvae, indicating a clumped distribution of both pest and parasitoids. Constant precision level stoplines for mines and larvae of L. huidobrensis and for endoparasitoid and ectoparasitoid larvae were calculated, by using the common a and b derived from Taylor’s power law. Wilson and Room binomial sampling was used to estimate the mean number of L. huidobrensis mines or live larvae from the ratio of leaves with mines. In this way, it is possible to estimate the mean density of L. huidobrensis by counting the leaves with mines, an index parameter easy to obtain in field sampling. Validation of the presence-absence sampling plan by using field data collected in 2002 and 2003 seasons, showed that the Wilson and Room model fits very well empirical data. Statistical analysis does not show any significant difference between observed and predicted data.

Faunistic Study of the Agromyzidae (Diptera) on Weeds of Marginal Areas in Northern Italy Agroecosystems

Abstract Extensive surveys of weedy plant species among hedgerows of different complexity and floristical composition were conducted with the aim to evaluate the role of weeds as reservoirs of agromyzids and to study the trophic relationships between these Diptera and noncrop plants. Field samplings were carried out weekly collecting foliage infested by leafminers from the representative weedy plants in three sites located in Bologna province, Italy. During 1998–1999, a total of 646 agromyzid specimens were reared, representing eight genera and 24 species. The most abundant species were Chromatomyia horticola (Goureau), Phytomyza lappae Goureau, Phytomyza ranunculi Schrank, Phytomyza plantaginis Robineau-Desvoidy, Liriomyza trifolii (Burgess), and Ophiomyia pulicaria (Meigen). C. horticola was the dominant species accounting for 35.76% of adults reared. Agromyzids mined 25 plant species belonging to nine families. The Asteraceae, in particular Cirsium arvense (L.) Scopoli and Sonchus asper (L.) Hill, were the most important sources of leafminers considering both species richness and population densities. Shannon–Weaver (H′), Simpson (D), and Berger–Parker (d) indices all pointed out that agromyzid species diversity was higher in the site characterized by the highest floristic richness, the highest complexity of ecological net and nonintensive agriculture. Most of the weeds sampled proved to be reservoirs for noneconomically important agromyzids in open-field crops in Italy.

The Influence of Vegetation and Landscape Structural Connectivity on Butterflies (Lepidoptera: Papilionoidea and Hesperiidae), Carabids (Coleoptera: Carabidae), Syrphids (Diptera: Syrphidae), and Sawflies (Hymenoptera: Symphyta) in Northern Italy Farmland

ABSTRACT Landscape structure as well as local vegetation influence biodiversity in agroecosystems. A study was performed to evaluate the effect of floristic diversity, vegetation patterns, and landscape structural connectivity on butterflies (Lepidoptera: Papilionoidea and Hesperiidae), carabids (Coleoptera: Carabidae), syrphids (Diptera: Syrphidae), and sawflies (Hymenoptera: Symphyta). Vegetation analysis and insect samplings were carried out in nine sites within an intensively farmed landscape in northern Italy. Plant species richness and the percentage of tree, shrub, and herb cover were determined by means of the phytosociological method of Braun-Blanquet. Landscape structural connectivity was measured as the total length of hedgerow network (LHN) in a radius of 500 m around the center of each sampling transect. Butterflies species richness and abundance were positively associated both to herb cover and to plant species richness, but responded negatively to tree and shrub cover. Shrub cover was strictly correlated to both species richness and activity density of carabids. The species richness of syrphids was positively influenced by herb cover and plant richness, whereas their abundance was dependent on ligneous vegetation and LHN. Rarefaction analysis revealed that sawfly sampling was not robust and no relationship could be drawn with either vegetation parameters or structural connectivity. The specific responses of each insect group to the environmental factors should be considered in order to refine and optimize landscape management interventions targeting specific conservation endpoints.

Area‐wide monitoring of potato tuberworm (Phthorimaea operculella) by pheromone trapping in Northern Italy: phenology, spatial distribution and relationships between catches and tuber damage

The potato tuberworm (PTW) Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) is key pest of potato in tropical and subtropical regions. From 2002 onward, PTW has emerged as a problem in the Bologna province, the main potato production area in Northern Italy. Field investigations were performed to study the temporal and spatial dynamics of PTW. Adult moths were monitored using pheromone‐baited traps over 3 years (2009–2011). Traps were georeferenced and catches were analyzed by geostatistical maps. Each year, the percentage of damaged tubers at harvest was assessed. Pheromone trapping, integrated with temperature‐dependent developmental times, showed that PTW completed two generations throughout the potato‐growing season; the remaining generations developed in the noncrop season. Maps showed a clumped distribution of PTW at the landscape scale. The hot spots of infestation corresponded to the areas most intensively cropped with potato. Trap catches from hilling to harvesting were linearly and positively correlated with the percentage of damage in 2 out of 3 years and in the pooled data set. The present study demonstrated the widening of PTW areal to Northern Italy. In this area, georeferenced pheromone traps were validated as a useful monitoring technique for describing the phenology and distribution of PTW, thus providing crucial knowledge for the rational management of this pest.

Lethal and Sub-lethal Effects of Four Insecticides on the Aphidophagous Coccinellid Adalia bipunctata (Coleoptera: Coccinellidae)

Abstract Conventional insecticide assays, which measure the effects of insecticide exposure on short-term mortality, overlook important traits, including persistence of toxicity or sub-lethal effects. Therefore, such approaches are especially inadequate for prediction of the overall impact of insecticides on beneficial arthropods. In this study, the side effects of four modern insecticides (chlorantraniliprole, emamectin benzoate, spinosad, and spirotetramat) on Adalia bipunctata (L.) (Coleoptera: Coccinellidae) were evaluated under laboratory conditions by exposition on treated potted plants. In addition to investigation of acute toxicity and persistence of harmful activity in both larvae and adults of A. bipunctata, demographic parameters were evaluated, to provide a comprehensive picture of the nontarget effects of these products. Field doses of the four insecticides caused detrimental effects to A. bipunctata; but in different ways. Overall, spinosad showed the best toxicological profile among the products tested. Emamectin benzoate could be considered a low-risk insecticide, but had high persistence. Chlorantraniliprole exhibited lethal effects on early instar larvae and adults, along with a long-lasting activity, instead spirotetramat showed a low impact on larval and adult mortality and can be considered a short-lived insecticide. However, demographic analysis demonstrated that chlorantraniliprole and spirotetramat caused sub-lethal effects. Our findings highlight that sole assessment of mortality can lead to underestimation of the full impact of pesticides on nontarget insects. Demographic analysis was demonstrated to be a sensitive method for detection of the sub-lethal effects of insecticides on A. bipunctata, and this approach should be considered for evaluation of insecticide selectivity.

Evaluation of the potential exposure of butterflies to genetically modified maize pollen in protected areas in Italy: Exposure of butterflies to maize pollen

Environmental impacts of genetically modified crops are mandatorily assessed during their premarket phase. One of the areas of concern is the possible impact on nontarget organisms. Crops expressing Cry toxins might affect Lepidoptera larvae living outside cultivated fields, through pollen deposition on wild plants, which constitute their food source. While pollen toxicity varies among different events, possible exposure of nontarget species depends on the agro‐environmental conditions. This study was conducted in two protected areas in Italy, characterized by different climatic conditions, where many Lepidoptera species thrive in proximity to maize cultivations. To estimate the possible exposure in absence of the actual stressor (e.g., Cry1‐expressing maize plants), we conducted a two‐year field survey of butterflies and weeds. Indicator species were selected—Aglais (Inachis) io in the Northern site and Vanessa cardui in the Southern site—and their phenology was investigated. Pollen dispersal from maize fields was measured by collection in Petri dishes. Duration and frequency of exposure was defined by the overlap between pollen emission and presence of larvae on host plants. Different risk scenarios are expected in the two regions: highest exposure is foreseen for A. io in the Northern site, while minimal exposure is estimated for V. cardui in the Southern site. In the latter case, locally grown maize cultivars flower in mid‐summer in coincidence with an aestivation period for several butterfly species due to hot and dry conditions. Moreover, host plants of V. cardui are at the end of their life cycle thus limiting food availability.

Response of the European Ladybird Adalia bipunctata and the Invasive Harmonia axyridis to a Neonicotinoid and a Reduced-Risk Insecticide

Abstract The spread of the multicolored Asian lady beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) in Europe coincided with the decline of the native Adalia bipunctata (L.) (Coleoptera: Coccinellidae). Both species are predators of aphids in orchards, and differential susceptibility to insecticides used to control fruit pests may contribute to explain the competitive advantage of the invasive over the native species. In this study, the insecticidal activity of imidacloprid and spinetoram was tested on third instars and adults of both ladybird species under laboratory conditions. Insects were exposed to insecticide residues on potted peach plants that were sprayed with the maximum recommended field doses (100 mg/liter for imidacloprid and 66.67 mg/liter for spinetoram). Mortality was scored after short (2 d for both stages) and long (7 and 10 d for adults and larvae, respectively) exposure periods.The susceptibility to the insecticides was very similar for H. axyridis and A. bipunctata. Imidacloprid caused a significant increase in the mortality of both stages of the two species for every exposure period. On the other hand, when exposed to spinetoram residues, larvae and adults of both ladybirds did not show higher mortality than controls after short and long exposure periods. The pest suppression provided by ladybirds, which could be severely hampered by the applications of nonselective pesticides, might be enhanced by the adoption of reduced-risk insecticides, selective for these beneficial insects.

Long term changes in the communities of native ladybirds in Northern Italy: impact of the invasive species Harmonia axyridis (Pallas)

Since the mid-2000s, the exotic coccinellid species Harmonia axyridis (Pallas) has established itself in Northern Italy, raising serious concerns about possible repercussions on native ladybirds. In this study we compared the ladybird assemblages in 2015–2016 with those sampled in 1995–1996, before the arrival of H. axyridis. Surveys were carried out in the same sites and with the same methods for both periods. Aphidophagous ladybirds were sampled in hedgerows and herbaceous habitats at field margins by mechanical knockdown and sweeping net, respectively. The changes in the structure of ladybird communities after the arrival of H. axyridis were significantly different between arboreal and herbaceous habitats. Harmonia axyridis is currently the dominant species in shrubs and trees, and all the native ladybird species taken together account for only approximately one third of the total individuals sampled in 2015–2016. On the other hand, the relative abundance of the exotic species in herbaceous habitats was low, and it has had a negligible relevance on the structure of ladybird communities on grasslands. Among native species, Adalia bipunctata (L.), whose ecological niche largely overlaps with that of H. axyridis, suffered the largest decline between 1995–1996 and 2015–2016. The co-occurrence of H. axyridis invasion and the regression of A. bipunctata suggest a direct impact of the exotic species, because no other major modifications occurred in the studied areas between sampling periods.