Key Pest Of Apples Research Articles

Toward the Integration of an Attract-and-Kill Approach with Entomopathogenic Nematodes to Control Multiple Life Stages of Plum Curculio (Coleoptera: Curculionidae).

Efforts to reduce insecticide inputs against plum curculio, Conotrachelus nenuphar, a key pest of apples in eastern North America, include perimeter-row insecticide sprays applied after the whole-orchard petal fall spray to manage dispersing adults and, more recently, insecticide sprays confined to odor-baited trap trees. Entomopathogenic nematodes (EPNs) are virulent to ground-dwelling stages of C. nenuphar, and may be applied to the ground underneath trap-tree canopies. Here, we (1) compared the efficacy of the odor-baited trap tree approach with grower-prescribed (=grower standard) sprays to manage C. nenuphar populations over a six-year period in seven commercial apple orchards in New England; and (2) assessed the performance of the EPN Steinernema riobrave at suppressing ground-dwelling stages of C. nenuphar. In addition, the performance of S. riobrave was compared against that of S. carpocapsae and S. feltiae in one year. Across the six years, percent fruit injury on trap tree plots averaged 11.3% on odor-baited trap trees and 1.4% on unbaited trees in grower standard plots, highlighting the ability of trap trees to aggregate C. nenuphar activity and subsequent injury. Mean percentage injury on fruit sampled from interior trees, the strongest measure of treatment performance, in trap tree plots did not differ significantly from that recorded on interior trees in grower standard spray plots (0.95 vs. 0.68%, respectively). Steinernema riobrave consistently reduced C. nenuphar populations as indicated by the significantly lower number of adult C. nenuphar that emerged from the soil, when compared to water control. Steinernema carpocapsae and S. riobrave performed similarly well, and both EPN species outperformed S. feltiae. Our combined findings indicate that an IPM approach that targets multiple life stages of C. nenuphar has the potential to manage this pest more sustainably in a reduced-spray environment.

Potential of entomopathogenic nematodes against the pupal stage of the apple maggot Rhagoletis pomonella (Walsh) (Diptera: Tephritidae).

The apple maggot, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), is considered a key pest of apples and is native to the eastern United States. The virulence of seven different species of entomopathogenic nematodes (EPN) was assessed against pupae of R. pomonella under laboratory conditions. Nematode species and strains included Steinernema carpocapsae (ALL strain), Steinernema feltiae (SN strain), Steinernema riobrave (355 strain), Steinernema glaseri (VS strain), Heterorhabditis bacteriophora (VS strain), Heterorhabditis indica (HOM1 strain), and Heterorhabditis megidis (UK211 strain). We conducted three bioassays: (i) short-term exposure cup bioassay (7 d), (ii) long-term cup bioassay (30 d), and (iii) pot bioassay (30 d). In the short-term exposure bioassay, all nematode strains (applied at 54 infective juvenile nematodes (IJs) cm−2) significantly reduced (range: 42.9-73.8%) insect survival relative to the control, but no differences were observed among the treatments. For the long-term exposure bioassay, using the same EPN application rate as the short exposure assay, all treatments reduced adult R. pomonella emergence compared with the control. Steinernema riobrave was the most virulent (28.3% survival), and S. glaseri and H. megidis were the least virulent (53.3% survival). In the pot experiment, S. riobrave and S. carpocapsae (applied at 27 IJs cm−2) had the highest virulence (23.3 and 31.7% survival of R. pomonella, respectively), while H. bacteriophora was the least effective (68.33% survival). Our results indicate that S. riobrave, S. carpocapsae, and S. feltiae have substantial potential to attack R. pomonella pupae, and their field application under the tree canopy (prior to adult emergence) in the spring when temperatures are conducive might be a good option for successful IPM of apple maggot fly.

Intra-annual continuous reproduction of the apple pest Microtus lusitanicus: Implications for management

The Lusitanian pine vole (Microtus lusitanicus) is a key pest of apple in Asturias (NW Spain). The sustainable management of populations of this vole requires a deep knowledge of relevant aspects of its biology and ecology. To improve our knowledge on the breeding characteristics of M. lusitanicus, we analysed a sample of 700 individuals collected monthly in apple orchards during two years. The continuous occurrence of immature specimens and pregnant females during the whole study period indicates that M. lusitanicus can breed continuously throughout the year in apple orchards in Asturias. The relatively mild weather conditions in winter and the presence of a permanent grass cover throughout the year seem to be favourable conditions for continuous breeding of the vole. Nevertheless, some data (decrease in the size of testes and seminal vesicle of mature males in winter, lower percentage of pregnant females in December and of non-mature specimens in March) suggest that reproduction activity decreases slightly in winter. Mean litter size was relatively low in comparison with that reported for other Microtus species. The balanced adult sex-ratio and the relatively small testis size are congruent with a monogamous mating system. Nevertheless, the frequent coexistence of matures with two or more other adult voles of the opposite sex, and even the cohabitation of one male with two pregnant females, suggest that monogamy was facultative in our population. This study adds significantly to the current knowledge on the biology of this vole pest and can help in the design and implementation of sustainable and efficient management plans. As a first step, control practices should be deseasonalized and applied throughout the year.

Inclusion of Specialist and Generalist Stimuli in Attract-and-Kill Programs: Their Relative Efficacy in Apple Maggot Fly (Diptera: Tephritidae) Pest Management.

Investigating the chemical ecology of agricultural systems continues to be a salient part of integrated pest management programs. Apple maggot fly, a key pest of apple in eastern North America, is a visual specialist with attraction to host fruit-mimicking cues. These cues have been incorporated into red spherical traps used for both monitoring and behaviorally based management. Incorporating generalist or specialist olfactory cues can potentially increase the overall success of this management system. The primary aim of this study was to evaluate the attractiveness of a generalist olfactory cue, ammonium carbonate, and the specialist olfactory cue, a five-component apple volatile blend, when included as a component of a red attracticidal sphere system. Secondly, we assessed how critical it was to maintain minimal deviation from the optimal, full-round specialist visual stimulus provided by red spheres. Finally, attracticidal spheres were deployed with specialist olfactory cues in commercial apple orchards to evaluate their potential for effective management of apple maggot. Ammonium carbonate did not increase residency, feeding time, or mortality in the laboratory-based trials. Field deployment of specialist olfactory cues increased apple maggot captures on red spheres, while the generalist cue did not. Apple maggot tolerated some deviation from the optimal visual stimulus without reducing captures on red spheres. Attracticidal spheres hung in perimeter trees in orchards resulted in acceptable and statistically identical levels of control compared with standard insecticide programs used by growers. Overall, our study contributes valuable information for developing a reliable attract-and-kill system for apple maggot.

Integration of Insecticidal, Phagostimulatory, and Visual Elements of an Attract and Kill System for Apple Maggot Fly (Diptera: Tephritidae)

The apple maggot fly, Rhagoletis pomonella (Walsh), is a key pest of apple in eastern North America that has been historically controlled with organophosphate insecticide applications. Here we report on progress toward development of an effective and maintenance-free attracticidal sphere system for this pest species. In our studies, we evaluated lethality of spinosad in combination with a feeding stimulant (sucrose) to replace a Tangletrap sticky coating as the killing agent of a sphere-based behavioral control system. Spinosad was incorporated into cylindrical and contoured controlled-release caps that were fixed atop visually stimulating sphere bases. For both cap styles, spinosad at or near 1.0% (a.i.) proved to be a relatively durable fly-killing agent, providing approximately equal to 85% mortality after simulated rainfall exposure reflective of average season-long precipitation levels experienced during the primary period of risk of apple maggot injury to fruit in the northeastern United States. In field trials, we assessed the impact of color degradation of contoured controlled-release caps on visual responsiveness of apple maggot fly and found that it had no significant impact on captures. In commercial orchard trials designed to evaluate the potential of attracticidal spheres with contoured caps for direct control of apple maggot, a perimeter-based deployment provided protection comparable to plots receiving 1-2 whole-plot insecticide applications.

Availability and Location of Cocooning Sites for Diapausing Codling Moth Larvae (Cydia pomonella(L.)) (Lepidoptera: Tortricidae) on Mature and Young Apple Trees

Mature larvae of the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), a key pest of apples and pears, leave infested fruit and spin cocoons in which they transform to pupae. These larvae may either immediately transform to pupae from which moths emerge two to three weeks later, or they overwinter in a state of diapause (Headlee 1929; Steiner 1929; Cutright 1937; Gould & Geissler 1941; Yothers & Carlson 1941; MacLellan 1960; Geier 1963; Wearing & Skilling 1975a,b; Howell 1994; Lacey et al. 2006).

Characterization of Microencapsulated Pear Ester, (2E,4Z)-Ethyl-2,4-decadienoate, a Kairomonal Spray Adjuvant against Neonate Codling Moth Larvae

Codling moth (CM), Cydia pomonella (Lepidoptera: Tortricidae), is the key pest of apples, pears, and walnuts worldwide. The pear-derived kairomone, ethyl (2E,4Z)-2,4-decadienoate, the pear ester (PE), evokes attraction and arrestment of CM larvae. Microencapsulated PE formulation (PE-MEC) enhances the control efficacy of insecticides when used as a spray adjuvant. Characterization of the microencapsulated kairomone, including microcapsule size, concentrations, emission rates, and larval response, was performed. Microcapsule diameter ranged from 2 to 14 mum, with 68% of capsules being 2-3 mum, and the concentration of microcapsules averaged 25.9 x 10(4) capsules per mL of field spray solution. Headspace collections showed emission of PE was related to PE-MEC concentration and was best described as first-order power decay. Neonate larvae responded to PE-MEC applications aged through 14 days. These results demonstrated that application of PE-MEC concurrent with insecticides may increase neonate foliar wandering, thereby disrupting host location and enhancing mortality by prolonging its exposure to insecticide.

The intrinsic toxicity of several neonicotinoids to Lygus lineolaris and Hyaliodes vitripennis, a phytophagous and a predacious mirid

The tarnished plant bug Lygus lineolaris (Palisot de Beauvois) is a key pest of apples in eastern Canada and, currently, chemical control is the only way to manage this pest. Hyaliodes vitripennis (Say) is a univoltine indigenous predacious mirid and an integral part of biological control programs for apples in certain regions of Quebec. In worst-case laboratory conditions, thiamethoxam, thiacloprid and acetamiprid were exceptionally toxic to this predacious mirid. The adults were more susceptible than the nymphs. However, the residual toxicity of these neonicotinoids to L lineolaris in orchards was very short-lived. Because of the short residual toxicity, neonicotinoids should be applied when L lineolaris is at maximum abundance and well before eggs of H vitripennis hatch in late June.

Ecology and management of plum curculio, Conotrachelus nenuphar [Coleoptera :Curculionidae], in apple orchards

Plum curculio (Conotrachelus nenuphar) is a native pest of pome and stone fruit in eastern North America. It is a key pest of apple (Malus pumila) orchards in Quebec. In spring, adults disperse primarily from woodland overwintering sites to apple orchards. Before fruit set, the beetles are mainly nocturnal. As fruits become available for oviposition, adults extend their activity to the daytime. Full grown larvae found in dropped apples in June (June drop) enter the soil to pupate. The summer brood emerges in August, feeds on the remaining fruit throughout the fall and then disperses to suitable overwintering sites. Little is known of its community and host plant relationships, dispersal behavior, factors influencing its mode of locomotion, choice of food sources, overwintering sites, micro-habitat selection, orientation, and action threshold. Commercially available biocontrol agents are not effective, and convenient and reliable monitoring techniques for the timing of sprays have not been developed. However, recent field and insectary studies on the behavior and activity of plum curculio adults may allow us to improve the efficiency of control strategies. These findings are presented here, together with their implications for control of the plum curculio by modifying its habitat, and by better timing and location of sprays and other interventions. This paper also includes brief reviews of biological controls, insect growth regulators, and genetic controls for plum curculio.

Evaluation of extended‐season mating disruption of the Oriental fruit moth Grapholita molesta (Busck) (Lep., Tortricidae) in apples

Abstract: Oriental fruit moth Grapholita molesta (Busck) (Lep., Tortricidae) has recently become a key pest of apples throughout the eastern USA. Pheromone‐mediated mating disruption of Oriental fruit moth was successfully used in North Carolina apple orchards in the past few years. However, low levels of late‐season fruit damage occurred in some orchards treated in late May with hand‐applied pheromone dispensers because of inadequate dispenser longevity. To investigate alternative pheromone application schedules for extended mating disruption control, the following pheromone treatments were compared with conventional insecticides in Henderson County (NC) in 2002: late May application of hand‐applied dispensers; late June application of hand‐applied dispensers; late May application of hand‐applied dispensers supplemented with a late August application of sprayable pheromone dispensers; late May application of hand‐applied dispensers which have a longer activity period; and conventional insecticides as a control. All treatments were sprayed with an insecticide at petal fall in late April for thinning and for control of the first generation Oriental fruit moth adults. Pheromone trap catches were significantly reduced in all mating disruption blocks compared with conventional insecticide blocks. Among pheromone treatments, the highest trap captures were recorded in the delayed hand‐applied dispenser treatment in June before treatment. However, the mean percentage fruit damage did not vary with timing of application of hand‐applied dispensers and the type of pheromone dispenser used. Clearly, the combination of each mating disruption treatment with insecticide application against first generation Oriental fruit moth was as effective as the conventional insecticide treatment under moderate population pressure.