Edison Pasqualini

Apple and peach fruit volatiles and the apple constituent butyl hexanoate attract female oriental fruit moth, Cydia molesta, in the laboratory

Volatiles emitted from immature and mature peach and apple fruits were all attractive to mated female oriental fruit moth, Cydia molesta (Busck), in a dual choice arena. Females did not discriminate between odours emitted by these two major host plants. The same natural blends were behaviourally ineffective for virgin females. A major component of apple fruit volatiles, butyl hexanoate, also attracted female C. molesta. Mated females were attracted to two medium dosages, while virgin females responded positively to the lowest of the five dosages tested. The time course of the captures of the moths shows a diurnal activity cycle known from the field. The possible implications of a semiochemical which attracts females are discussed in the context of previous findings that gravid females may immigrate from peaches into apple orchards particularly in the later phase of the season.

Toxicity of emamectin benzoate to Cydia pomonella (L.) and Cydia molesta (Busck) (Lepidoptera: Tortricidae): laboratory and field tests.

BACKGROUND Emamectin benzoate is a novel macrocyclic lactone insecticide derived from naturally occurring avermectin molecules isolated by fermentation from the soil microorganism Streptomyces avermitilis Kim & Goodfellow. The present study aims to evaluate the toxicity of emamectin benzoate to codling moth, Cydia pomonella (L.), and oriental fruit moth, C. molesta (Busck), under laboratory and semi-field conditions. RESULTS Dose response bioassays showed that emamectin benzoate had a high level of intrinsic toxicity to early-stage larvae of both species, and that contact activity might contribute significantly to mortality. In the semi-field trials, residual toxicity lasted for more than 1 week. Ovicidal activity was recorded only for C. pomonella (approximately 30%), irrespective of the concentrations tested. Field trials confirmed the efficacy of emamectin benzoate on codling moth when applied at 7 day intervals. Fruit damage, both from the first and second generations, was comparable with that on treatment with chlorpyrifos-ethyl, used as a chemical reference. CONCLUSION Emamectin benzoate may be considered a valuable tool for the control of codling moth as a component of an IPM programme. Its collective advantages are: high efficacy, lack of cross-resistance with currently used products, control of secondary pests such as oriental fruit moth and selective toxicity that spares beneficials.

Effects of the fungicides mancozed and dithianon on mortality and reproduction of the predatory miteAmblyseius andersoni

Laboratory studies using commercial formulations of mancozeb and dithianon at concentrations equivalent to recommended field rates of 200 and 80 g/hl, respectively, were conducted to evaluate toxic effects of these fungicides on the predatory miteAmblyseius andersoni Chant. In short-term tests where females were placed on apple-leaf disks and sprayed with mancozeb, no mortality of adults was observed; however, there was a 34% decrease in fecundity, a 7.1% decrease in egg hatch, and mortality of larvae and protonymphs was 6.7%. In long-term tests, a significant reduction in fecundity was also observed. A decrease in hatch that was dependent on age at time of treatment was found when eggs were treated directly with mancozeb. No effects on mite mortality or reproduction were observed in short-term tests with dithianon. These results suggest that dithianon might be considered as a potential alternative to mancozeb for scab control.

The biological efficacy of pear ester on the activity of Granulosis virus for codling moth

Ethyl (E,Z)-2,4-decadienoate (pear ester) is an adult and larval kairomonal attractant for Cydia pomonella (L.) (Lepidoptera: Tortricidae). The possibility of using a microencapsulated formulation of pear ester (DA-MEC, a.i. 5%, Trécé Inc.) to interfere with the host location behaviour was evaluated. Laboratory leaf disc bioassays and field efficacy trials were carried out on apple to determine the potential of improving the insecticidal performance of the granulovirus of C. pomonella (CpGV) by co-mixing with pear ester in a sprayable formulation. In laboratory bioassays, adding DA-MEC at low doses of CpGV insecticide increased the larval mortality as a function of time. The field tests performed revealed a significant effect of the blank DA-MEC formulation in reducing fruit injury compared to an unsprayed control.

Efficacy baselines of seven insecticides against larvae of Pandemis heparana (Lepidoptera: Tortricidae)

A diet-incorporation larval bioassay was used to evaluate the response of the leafroller Pandemis heparana (Denis and Schiffermüller) to seven insecticides: tebufenozide (Mimic 23% a.i., Bayer), methoxyfenozide (Prodigy 23% a.i., Bayer), flufenoxuron (Cascade 50 DC 4.7% a.i., BASF), lufenuron (Match 5.32% a.i., Syngenta), indoxacarb (Steward WG 30% a.i., Du Pont), abamectine (Vertimec EC 1.9% a.i., Syngenta) and spinosad (Laser 44.2% a.i., Dow Agro Science). Both neonate and 12-day-old (third to fourth instar) larvae were used in the bioassay. The obtained efficacy baselines were compared with the response of the pest exposed to leaves treated with the same insecticides. The persistence of field-aged leaf residues of the seven insecticides was bioassayed on neonate larvae. Given the obtained LC50 values in the diet-incorporation bioassays larval age was not always a significant factor affecting the response of P. heparana larvae. Differences in LC50 values between neonate and 12-day-old larvae were not statistically significant for abamectine, tebufenozide and methoxyfenozide. Young larvae seemed to be more susceptible than older larvae to spinosad, indoxacarb and lufenuron, while flufenoxuron was more effective against 12-day-old than neonate larvae. When the larvae were exposed to the insecticides on treated leaves, all the tested compounds were less effective on older larvae than on neonates. When applied at the recommended field rates, all seven insecticides can be considered highly effective against both neonate and 12-day-old larvae of P. heparana because their security index (SI = recommended field rate/LC90) always exceeded the threshold value of 1. The high persistence of insect growth inhibitors (IGIs) and moulting accelerating compounds (MACs) in the field compensates for their relatively low SI values. For this reason and given their activity against Cydia pomonella, IGIs and MACs are the most interesting insecticides for spring treatments for the combined control of both species, P. heparana and C. pomonella.

Bioassay approaches to observing behavioural responses of adult female Cydia molesta to host plant odour

Abstract:  Three different olfactometers were evaluated in order to develop a bioassay procedure testing for the olfactory responses of Cydia molesta. Females were tested individually using a linear and a Y‐tube olfactometer, and in groups using a dual‐choice arena. Room temperature, relative humidity, light intensity, airflow, age of the moths and odour source were kept constant during experiments. The odour source tested was a green shoot of peach excised 10 min before experiments started. Cydia molesta females showed a significant response to this plant odour in all olfactometers. A number of qualitative aspects were found to be in favour of the dual choice arena as a tool for screening potentially attractive odour sources. It allowed for a differentiation of the response of mated and virgin females. Experimental conditions allowed the circadian rhythm of insects to be mimicked. Manipulation of individuals is reduced and flight is not precluded.

Cacopsylla pyri L. (Hom., Psyllidae) and its predators relationship in Italy's Emilia-Romagna region

Abstract: Sampling techniques for Cacopsylla pyri adults and its predators (Anthocoris nemoralis, Coccinellidae spp. and Chrysopidae spp.) were comparatively studied over autumn–winter 2000 in three pear orchards of Ferrara Province in northern Italys Emilia‐Romagna Region. Bating tray (or frappage), yellow sticky traps and corrugated cardboard traps were employed for insect monitoring while water pan traps were used for the phenological timing of leaf fall. The beating tray provided a more representative sampling method to evaluate the population dynamics and density of C. pyri and its predators than the yellow sticky traps; the corrugated cardboard proved a reliable tool to assess the predator population dynamic in overwintering refuges. Along with climate (temperature) and plant physiological (leaf fall) data, the results reported provide useful information for the scheduling of winter treatments, also in case to control the spread of the mycoplasma‐like organism (pear decline) in spring.

Probing behaviour of Cacopsylla pyri on a resistant pear selection

European pear psylla Cacopsylla pyri L. (Hemiptera Psyllidae) is one of the worst pests of pear (Pyrus communis L.) in Europe. We investigated probing behaviour in adults and nymphs of C. pyri by full EPG on a psylla‐resistant pear selection, NY 10353. Concerning stylet probing behaviour on the plant surface, the results showed no significant differences between the resistant selection and the susceptible cultivar Bartlett, and no differences were also detected for epidermis and mesophyll resistance in the same conditions. For mesophyll/phloem, no differences were found in adults. However, in nymphs, weak resistance factors (longer stylet penetration and mesophyll salivation) were detected in the resistant selection. In phloem, EPG data indicate strong resistance factors in NY 10353, especially for nymphs and summer‐form adults (longer time before the first phloem ingestion and a lower duration of each phloem ingestion event). No prolonged (>10 min) phloem ingestion was performed by nymphs and adults in the resistant selection. The results support the hypothesis that NY 10353 resistance factors are located in the phloem sap and cause high C. pyri nymph mortality: this could be useful as a basis for further investigations of resistance mechanisms at the metabolic, chemical and genetic levels.

Preliminary Resistance Screening on Abamectin in Pear Psylla (Hemiptera: Psyllidae) in Northern Italy

Abstract In northern Italy (Emilia-Romagna region), integrated pest management has been used for several years against pear psylla, Cacopsylla pyri L. (Hemiptera: Psyllidae), a relevant pest of pear (Pyrus spp.) trees. After the outlawing of amitraz in 2005, the most common active ingredient involved is abamectin, a mixture of avermectin B1a and avermectin B1b. After the development of C. pyri resistance to azinphos methyl in southern France, we evaluated, by topical application, the different sensitivities to abamectin on C. pyri populations collected in orchards from Emilia-Romagna, where different field strategies were used, with alternative success in terms of pest management. The LC50 values ranged between 1.61 and 28.37 mg/liter, and they revealed variations more related to collection time than to field strategies. The failure of abamectin treatments against C. pyri in some Emilia-Romagna locations is probably unrelated to resistance development, but rather it is related to incorrect pest defense management, which could interfere with pest parasitoids and predators.

Survey of Susceptibility to Abamectin of Pear Psylla (Hemiptera: Psyllidae) in Northern Italy

ABSTRACT The pear psylla, Cacopsylla pyri L. (Hemiptera: Psyllidae), is a relevant pest of pear, Pyrus communis L., trees in Emilia-Romagna region (northern Italy). The susceptibility to the insecticide abamectin was evaluated at different times of the year on C. pyri populations undergoing different control strategies within conventional, integrated, and organic farms. The tests performed were the egg spray and the topic and dip bioassay on adults. The larval mortality was evaluated by dip bioassay on treated leaves. The activity of P450-dependent monooxygenases, a relevant enzyme system involved in insecticide resistance of C. pyri, was also determined in adults by 7-ethoxycoumarin O-deethylation (ECOD assay). Tests on treated eggs and on larvae showed no significant differences in LC50 and LC90, although these values were always lower in individuals collected from organic farms in comparison with all other farms. Tests on overwintering adults revealed differences among populations, probably more related to collection time than to field pest control strategies. Unexpectedly, the ECOD assay on adults showed a slightly higher cytochrome P450 monooxygenase activity in the population undergoing organic control in comparison to others. Our results indicate that egg spray is the most reliable bioassay to verify data of open-field applications. Apparently, no resistance to abamectin has yet been developed by C. pyri in Emilia-Romagna.