Gérald Chouinard

Progress in plum curculio management: a review

The plum curculio, Conotrachelus nenuphar Herbst (Coleoptera: Curculionidae), is a key pest of apple orchards of North America. In absence of chemical treatments, up to 85% damage is caused to the fruit at harvest. In spite of its importance, plum curculio is one of the least known pest of apple orchards. This paper reviews research advances that were made since 1992 to implement sound IPM programmes against this pest. These advances include behavioral studies, trapping methods, attractants, entomogenous nematodes and treatments of peripheral zones, with special reference to apple orchards. Plum curculio management achieved through peripheral-zone treatments have been successful in commercial situations.

Prey Selection by the Lady Beetle Harmonia axyridis : The Influence of Prey Mobility and Prey Species

The influence of prey mobility and species on prey selection by the coccinellid Harmonia axyridis Pallas was determined under laboratory conditions for two prey species, Hyaliodes vitripennis (Say) and Tetranychus urticae Koch. Prey selection was influenced by prey mobility. In the presence of active prey, the coccinellid selected T. urticae while in presence of immobilized prey, H. vitripennis was preferred. Harmonia axyridis searching time was longer in the presence of active H. vitripennis than in the presence of active T. urticae. Moreover, the coccinellid capture rate was lower for active H. vitripennis caused by effective defensive mechanisms. Prey suitability was affected by prey mobility and species. Immobilized H. vitripennis were the most profitable prey, i.e. induced a shorter developmental time and no mortality. However, active H. vitripennis were not a suitable food source for H. axyridis. Our results suggested that three factors are involved in prey selection by H. axyridis: (i) prey mobility; (ii) prey defensive mechanisms; and (iii) prey species.

Evolving ecosystems approaches to fruit insect pest management

Abstract Ecological studies of agroecosystems have demonstrated both significant environmental problems associated with the intensive physical and chemical control of highly simplified crop production systems, and the largely untapped opportunities for knowledge-intensive bioecological design and management of more complex systems. Barriers for change often over-emphasise economics and lack of appropriate knowledge and technology. Equally important are lack of awareness, particularly of long-term and global implications of current practices, lack of vision, disempowerment and feelings of isolation, and inconsistencies between professed values and actual practices. To address these barriers and to facilitate change, an overlapping three-stage – efficiency, substitution, redesign (ESR) – evolutionary approach to pest control has been developed.

Spatial distribution and movements of plum curculio adults within caged apple trees.

In the spring of 1987 and 1988, 65Zn labeled plum curculios, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), were released within two field cages, each containing four dwarf apple trees. The cages were surveyed regularly between ‘pink’ and 22 d after ‘fruit set’ stages, and the location of labeled insects and substrates occupied were recorded. Labeled beetles first appeared in trees between ‘pink’ stage and beginning of bloom, and the number within trees gradually increased until ‘petal fall’ stage. Between ‘full bloom’ and 22 d after ‘fruit set’ stages, adults were found on the ground in 54% of the observations. At ‘petal fall’ stage, the main host structures occupied were spurs, twigs, and flowers or fruit. Height in the trees, rate of movement (cm/h), and occurrence on the ground, spurs, flowers or fruits, and leaves and new annual growth, were related to the product of air temperature and relative humidity. Most dispersal from tree to tree occurred between ‘full bloom’ and ‘fruit set’ stages. Highest occurrence in trees was observed between 1800 and 0000 h. In the daytime, labeled adults tended to leave host structures except spurs, which were used as resting sites, mostly by females. Females occurred significantly higher in the tree canopy than males, although egg‐laying was most frequent at mid‐level. During bloom, up to 30% of plum curculios were found to rest simultaneously at the base of tree trunks, prior to their gradual invasion of trees. This behavior should be taken into account in the development of an effective shelter trap for monitoring this insect, and in the design of integrated control strategies.

Peripheral‐zone treatments for plum curculio management: validation in commercial apple orchards

Peripheral applications of organophosphate insecticides were evaluated as an alternative strategy for controlling adult plum curculio, Conotrachelus nenuphar Herbst (Coleoptera: Curculionidae) in four commercial orchards in Quebec, Canada. Each orchard was partitioned into a reference and an experimental plot to compare the classical full plot treatment with a peripheral treatment alternative. The experimental plots were divided into five zones, i.e. central, North, South, West and East. Peripheral zones were defined as the first five rows of apple trees (or 20 m wide). Plum curculio adults were monitored weekly by limb tapping. Fresh oviposition scars were evaluated by examining 20 fruitlets per tree on each outermost tree in the peripheral zone and 20 fruit on 25 trees in the central zone. Azinphosmethyl treatments were carried out in the zones where more than 1% fruitlets bore fresh ovipositional scars. Fruit damage was mostly (92%) found in the peripheral zones. Plum curculio damage at harvest varied from 0.0 to 0.7% and from 0.0 to 0.8% in the experimental and reference plots respectively. Total insect damage on fruit at harvest varied from 1.3 to 3.8% in the experimental plots, and from 0.4 to 5.0% in the reference plots. In 1991, there were no significant differences between population indices of the spotted tentiform leafminer, the apple aphid, leafroller species and cicadellids in the peripheral versus central zones. In the experimental plots, populations of woolly apple aphid, two‐spotted spider mite and apple rust mite were significantly higher in peripheral zones than in the central zones. In 1992, there were no significant differences between population indices of peripheral versus central zones for both experimental and reference plots. All localities and years pooled, peripheral zones of experimental plots received 1.22 insecticide treatments, against 1.29 for reference plots. However, central zones of experimental plots received 0.38 insecticide treatments, against 1.13 for reference plots. Assuming a 20 m peripheral zone and a 10 ha square orchard, the percent reduction in insecticides would be ca. 75%.

Cyclic behavior of plum curculio,Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), within caged dwarf apple trees in spring

From 12 to 19 May 1987, during “Morspur” apple bloom, 21 radioactively labeled (65Zn) adult plum curculios, Conotrachelus nenuphar (Herbst), were released within a field cage containing four dwarf apple trees and located three times a day. A technique was developed for quickly obtaining (x, y, z)coordinates of location for adults foraging within apple trees. Cyclic patterns of behavior were detected using spectral analysis procedures. Over 70% of plum curculios exhibited diel periodicity with respect to activity and rate of movement, 36% exhibited such periodicity with respect to presence in the trees, and 27% with respect to movements from the center to the periphery of the canopy. Presence in fruit clusters, height in the trees, and movements along east-west and north-south axes showed little or no periodicity. Factors triggering cyclic behavior and practical implications of the results are discussed.

A meridic diet for the rearing of Hyaliodes vitripennis (Hemiptera: Miridae), a predator of mites in apple orchards

Abstract We compared biological parameters of the mite predator Hyaliodes vitripennis (Hemiptera: Miridae) reared on live Tetranychus urticae Koch versus two artificial diets used in rearing generalist predators: Coleomegilla maculata lengi Timberlake (Coleoptera: Coccinellidae) and Chrysoperla rufilabris Burmeister (Neuroptera: Chrysopidae). Both coccinellid and chrysopid diet resulted in lower mortality and increased longevity of H. vitripennis, but daily fecundity was greater with the former. The phagostimulant β-sistosterol had the greatest impact on H. vitripennis mortality (lowest) and nymphal weight gain (highest) when added to the coccinellid diet. These results demonstrate that H. vitripennis could be reared on an artificial diet, and suggests that β-sistosterol has phagostimulant properties for this predator.

Electroantennogram technique for Conotrachelus nenuphar (Coleoptera: Curculionidae).

ABSTRACT Reliable electroantennogram (EAG) responses were obtained from the plum curculio, Conotrachelus nenuphar (Herbst), by using a whole body mount with glass electrodes filled with KCl-saturated AgCl solution that penetrated the antennal club (recording electrode) and the membrane attached to the cervical sclerite between the thorax and the head (indifferent electrode). Known attractive odor sources including extracts of headspace collections of ‘Stanley’ plum and ‘Empire’ apple tissues and a synthetic source of racemic grandisoic acid were used to verify the sensitivity of the technique. The amplitude of responses was significantly greater for females than males among all candidate stimuli evaluated. The recorded amplitudes for all odor stimuli evaluated were significantly greater than the methylene chloride solvent control. The development of this EAG technique will facilitate use of a coupled gas chromatographic-electroantennographic detection system to aid in detection of novel, biologically and behaviorally active volatile sources that can be subsequently evaluated in behavioral trials and ultimately lead to more powerful attractants for use in monitoring and management programs for plum curculios in commercial fruit orchards.

Occurrence of Grapholita molesta (Lepidoptera: Tortricidae) in major apple-growing areas of southern Quebec.

Oriental fruit moth (Grapholita molesta (Busck) (Lepidoptera: Tortricidae)) adult males were captured by pheromone traps in 10 of 24 orchards monitored in southern Quebec from 2003 to 2005. Twelve, 22, and 133 oriental fruit moths were captured in 2003, 2004, and 2005, respectively. One oriental fruit moth larva was collected in each of two orchards in 2004. This is the first record of this species in Quebec apple orchards.

Evaluating electrophysiological and behavioral responses to volatiles for improvement of odor-baited trap tree management of Conotrachelus nenuphar (Coleoptera: Curculionidae).

ABSTRACT Plum curculio, Conotrachelus nenuphar (Herbst), one of the most important pests of apple in eastern and central North America, is usually managed in New England apple orchards by multiple full-block insecticide applications. Efforts to reduce insecticide inputs against plum curculio include using an “attract and kill” approach: odor-baited trap trees deployed in the perimeter row of apple orchards. The standard approach is based on baiting apple trees with two olfactory stimuli, the fruit volatile benzaldehyde and the aggregation pheromone of plum curculio, grandisoic acid. We attempted to improve attraction, aggregation, and retention of adult plum curculios within specific baited trap tree canopies within apple orchards using an additional host plant volatile found to be highly stimulating in electroantennogram studies, trans-2-hexenal. We also attempted to increase aggregation using increased release rates of grandisoic acid. We found that trans-2-hexenal did not provide increased aggregation when deployed as an additional attractant within trap trees or when conversely deployed as a “push” component or repellent in perimeter trees lateral to the baited trap tree. Although increasing the release rate of grandisoic acid 5× actually appeared to increase overall aggregation within trap trees, it was not significantly different than that obtained using the standard dose. Therefore, we believe that the standard olfactory stimuli are sufficient to provide aggregation within trap trees, but that other means should be used to manage them after their arrival.