Autocontamination trap with entomopathogenic fungi: a possible strategy in the control of Rhynchophorus ferrugineus (Olivier) (Coleoptera Curculionidae)

An experimental autocontamination trap was devised to infect Rhynchophorus ferrugineus (Olivier), the Red Palm Weevil, adults with entomopathogenic fungi. The aim was to develop an autocontamination device to support integrated R. ferrugineus control programs. In laboratory bioassays, the delivery system successfully attracted, infected and released weevil adults after they contacted cereal substrata inoculated with indigenous strains of Beauveria bassiana (Balsamo- Crivelli) Vuillemin and Metarhizium anisopliae (Metchnikoff) Sorokin. Tests carried out with the experimental traps showed that M. anisopliae was the more virulent pathogen, causing 75% cumulative mortality in adults, while B. bassiana gave a 45% cumulative mortality. Infectivity of M. anisopliae was not affected by different cereal substrata, i.e. wheat and rice, since curculionid cumulative mortality (95%) and treatment efficiency (95% Abbott) were very high on both of them and Red Palm Weevil LT50 was reached within the same time (15 days). Conidial persistence and germinability of M. anisopliae grown on the rice substratum were examined in field conditions inside traps located in sunny and shady positions in spring, summer and autumn. The results showed that the traps preserved fungal inoculum stability longer in spring and summer than in autumn. No significant difference in M. anisopliae conidial persistence was found between sunny and shady traps during the various seasons

Metarhizium anisopliae biopesticides and fungus isolates: control efficacy against Rhynchophorus ferrugineus (Olivier) (Coleoptera Dryophthoridae) on different contamination substrata.

The lack of biological insecticides based on Metarhizium anisopliae (Metsch.) Sorokin registered in Italy for the control of the Red Palm Weevil (RPW), Rhynchophorus ferrugineus (Olivier), prompted studies to evaluate the efficacy of two commercial products, Met52® and BioStormTM and of their fungal isolates, M. anisopliae (Man52) and (ManBS) respectively, against the adults. The virulence of the M. anisopliae strains (Man52) and (ManBS) was compared with that of an indigenous M. anisopliae (Man08/I05) strain obtained from R. ferrugineus specimens collected in the wild and that showed to be very virulent against the RPW in previous studies. In both tests the sublethal effects of the treatments on female reproductive potential were examined in relation to the infective substratum. Laboratory results indicated that the commercial formulations mixed directly into the soil were not active in transmitting the infection to RPW adults and in reducing female fecundity and fertility. Diversely the fungal M. anisopliae (ManBS), (Man52) and (Man08/I05) strains inoculated on a rice substratum caused over 80% mortality of the phytophagous. In particular, M. anisopliae (ManBS) and the M. anisopliae (Man08/I05) produced the highest mortality (100%), with LT50 e LT90 reached in 3 and 6 days respectively. M. anisopliae (Met52) strain instead led to 85% mortality of RPW specimens in 28-days but it took longer to reach LT50 (6 days) and LT90 (12 days). The reproductive potential of females infected with the fungal strains was also significantly reduced with respect to the control. This study indicates the possibility of using also M. anisopliae strains in use against other insects of agricultural importance, for the control of R. ferrugineus although their effectiveness is conditioned by the formulations and/or methods employed against the RPW

Effects of cryopreservation and freeze-drying on proteases enzymatic activity of entomopathogenic strains of Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metchnikoff) Sorokin.

Beauveria bassiana and Metarhizium anisopliae are fungal species known for their entomopathogenic activity; they represent an important alternative to chemical control of many pest insects and appropriate preservation methods are thus necessary to maintain their properties over time. In the present study the effects of cryopreservation and freeze­drying were investigated on virulence determinants such as proteases and specifically on subtilisin-type Pr 1 and Pr 2 that seem to play a predominant role in insect fungal penetration. Three Metharizium anisopliae strains (M 13/ I05, M 13/ I12 and M 13/ I33) and three Beauveria bassiana strains (B 13/ I03, B 13/ I57 and B 13/ I63) were tested. Data obtained from our experiments show that the decrease of Pr 1 and Pr 2 enzymatic activity in B. bassiana and M. anisopliae strains 7 months after storage does not affect their entomopathogenic ability against larvae of Tenebrio molitor compared to the fresh cultures before storage. The role of Pr 1 and Pr 2 as predominant factors in the entomopathogenicity of both fungal species is discussed. No significant differences were found in any strain tested for morphological features using both preservation methods

ACLEESCF. SP. FOVEATUS(COLEOPTERA CURCULIONIDAE), AN EXOTIC PESTOF FICUS CARICAIN ITALY: A SUSTAINABLE APPROACH TO DEFENCE BASEDON ALUMINOSILICATE MINERALS AS HOST PLANT MASKING SOLIDS

The exceptionally frequent entries of alien pest are a major source of concern for the farmers who haveto protect their crops from unknown insects, often without natural enemies in the new areas. A new pestbelonging to the Molytinae family (Coleoptera: Curculionidae), tribe Hylobiini, reported as Acleessp. cf.foveatusVoss, was recently introduced in Italy. The species is responsible for severe damages in many Italianfig nurseries and orchards, particularly in the Italian Central Northern regions, i.e. Tuscany, Ligury andLatium. Currently, no active ingredients are registered against this insect on fig crops. An innovative and eco-friendly approach for controlling this exotic weevil infestation was investigated, by using montmorillonite-based clays, either in their native state or containing copper(II) species, and clinoptilolite zeolites, in order tocheck the perception of the adults’ weevil towards the different solid materials and, subsequently, to evaluatethe capability of these innovative products to act as masking agent with respect to the host plant and/or asrepellent upon contact. The formulations containing copper(II)-exchanged clay and clinoptilolite zeoliteshowed preliminary promising results in terms of efficacy and environmental sustainability

Cuticle-degrading protease and toxins as virulence markers of Beauveria bassiana (Balsamo) Vuillemin

Beauveria bassiana is one of the most known entomopathogenic fungal species and its entomopathogenic mechanism involves several bioactive metabolites, mainly cuticle-degrading enzymes and toxic molecules, which are predicted to play a key role as virulence factors. In this study six Beauveria bassiana strains (B 13/I03, B 13/I11, B 13/I49, B 13/I57, B 13/I63, and B 13/I64) were assayed against Tenebrio molitor larvae. Enzymatic activity of total proteases and specifically Pr 1 and Pr 2, as well as the production of toxic compounds were investigated in each fungal strain. Toxins were detected both in vitro—in medium filtrates and mycelia—and in vivo—in Tenebrio molitor larvae infected by the fungal strains tested. B 13/I11 and B 13/I63 strains showed the most significant entomopathogenic activity against Tenebrio molitor larvae (cumulative mortality rate 100 and 97%, respectively; average survival time 5.85 and 6.74 days, respectively). A widely variable and fungal strain-dependent enzymatic activity of total proteases, Pr 1 and Pr 2 was found. Beauvericin, beauvericin A and bassianolide resulted the most prevalent toxins detected in the substrates analyzed. It has been found that an increase of beauvericin content in vivo resulted significantly correlated to a decrease of Tenebrio molitor larvae average survival time in entomopathogenic bioassay (inverse correlation). The involvement of beauvericin in B. bassiana entomopathogenic process is confirmed; in vitro analysis of cuticle degrading proteases activity and toxins production in relation to the methods adopted resulted insufficient for a rapid screening to determine the virulence of B. bassiana strains against Tenebrio molitor larvae

Can we manage alien invasive insects without altering native soil faunal communities? A field trial on Popillia japonica

Biological and integrated pest control are key assets to environmentally friendly management of cropland. Use of entomopathogens against target pests is common, yet the effects of such released organisms on native, non-target invertebrates are currently poorly known. This is particularly true for relatively inconspicuous components of agroecosystems such as soil biological biota. Popillia japonica, a polyphagous alien invasive scarab beetle native to Japan, is now present in Europe where huge efforts are being conducted to control the pest and slow its spread. In particular, entomopathogenic nematodes and fungi have been used for larval control. Here we test the effects of those agents on both P. japonica larvae and non-target soil biota by comparing soil arthropod assemblages before and after treatment of field plots in an irrigated perennial meadow.Application of an indigenous strain of the nematode Heterorhabditis bacteriophora resulted in significant reduction in numbers of P. japonica larvae. In contrast, an indigenous strain of the entomopathogenic fungus Metarhizium robertsii failed to provide significant control. We found no evident effect on non-target edaphic arthropods under either treatment in comparison to untreated control plots. Some taxa, namely Collembola and Acarina, showed a disproportionate increase in treated plots, suggesting that some changes may occur in the long term, at least in particular arthropod groups. Our results suggest the selected strain of H. bacteriophora is an excellent candidate for managing P. japonica larvae with minimal adverse impact on non-target species and ecosystem functioning

First assessment of entomopathogenic fungi and nematodes in hot springs in central Italy and first record of Pristionchus uniformis for the country

Geothermal soils in Central Italy are characterized by high temperatures (up to 60°C), low pH values, and sparse vegetation. The biodiversity of entomopathogenic soil fungi and nematodes has never been assessed in these areas. Soil samples (N = 12) separated from each other by at least 100 meters were collected in the areas of Le Biancane Natural Park (Grosseto) and Sasso Pisano (Pisa). The Galleria bait method was used to assess the presence of entomopathogenic fungi and nematodes. A total of nine species of fungi and one nematode were isolated and molecularly identified. All these species came from samples collected in the immediate surroundings of geothermal spring, apart from one Beauveria pseudobassiana collected at about 16 meters from the nearest spring. Moreover, Pristionchus uniformis previously reported only from North America and few European countries is recorded for the first time in Italy.&nbsp