Toxicity and residual activity of methoxyfenozide and tebufenozide to codling moth (Lepidoptera: Tortricidae) and oriental fruit moth (Lepidoptera: Tortricidae)

A series of studies were conducted to examine the residual activity and toxicity of the ecdysone agonists tebufenozide and methoxyfenozide to codling moth, Cydia pomonella (L.), and oriental fruit moth, Grapholita molesta (Busck), in North Carolina apple systems. Methoxyfenozide exhibited greater activity than tebufenozide against codling moth eggs in dose-response bioassays, with a 4.5- and 5.3-fold lower LC50 value to eggs laid on fruit treated before or after oviposition, respectively. Oriental fruit moth eggs were 57- and 12-fold less sensitive to methoxyfenozide than were codling moth eggs on fruit treated before and after oviposition, respectively. Methoxyfenozide was effective in reducing larval entries of both codling moth and oriental fruit moth in field residual activity bioassays, exhibiting activity for at least 28 d after application. Residue breakdown on fruit was approximately 80% at 28 d after treatment for both methoxyfenozide and tebufenozide, with the most rapid residue decline (60%) occurring during the first 14 d after application. Two applications of methoxyfenozide applied at 14-d intervals provided better canopy coverage and higher residue levels than one application. Spray volume (683 versus 2,057 liters/ha) did not affect the efficacy of methoxyfenozide. Leaf and fruit expansion during the season was measured to determine potential plant-growth dilution effects on residual activity. There was very little increase in leaf area after mid May, but increase in fruit surface area over the season was described by a second order polynomial regression. Implications for codling moth and oriental fruit moth management programs are discussed.     

Male oriental fruit moth response to a combined pheromone-based attracticide formulation targeting both oriental fruit moth and codling moth (Lepidoptera: Tortricidae)

Combined attracticide formulations targeting Oriental fruit moth, Grapholita molesta (Busck), and codling moth, Cydia pomonella (L.), were tested in a field trapping experiment. Capture of male codling moths in traps baited with the combined formulation was reduced compared with traps baited with the codling moth formulation alone, whereas capture of male Oriental fruit moth was increased compared with traps baited with the Oriental fruit moth formulation alone. Subsequent wind tunnel experiments showed that a single locus of the mixed attracticide formulation or close parallel presentation of the two formulations enhanced source contact by male Oriental fruit moths but did not influence earlier behaviors. However, the two formulations presented in a serial arrangement to Oriental fruit moth males in the wind tunnel resulted in enhanced lock-on, upwind flight, and source contact behaviors. In addition, male Oriental fruit moths remained on mixed pheromone droplets of the paste matrix longer than on droplets of the Oriental fruit moth formulation alone. The increased time spent on the mixed droplet was correlated with a more rapid poisoning and a greater proportion of poisoned males compared with males exposed to the Oriental fruit moth attracticide alone. These results demonstrate that a combined attracticide formulation will have different effects on each of the targeted species. It is anticipated that, due to decreased attractiveness, a combined formulation would be less effective against the codling moth. However, a mixed formulation, due to increased attractiveness and toxicity, could be more effective against the Oriental fruit moth under field conditions.     

Monitoring oriental fruit moth and codling moth (Lepidoptera: Tortricidae) with combinations of pheromones and kairomones

Experiments were conducted in North and South America during 2012–2013 to evaluate the use of lure combinations of sex pheromones (PH), host plant volatiles (HPVs) and food baits in traps to capture the oriental fruit moth, Grapholita molesta (Busck), and codling moth, Cydia pomonella (L.), in pome and stone fruit orchards treated with sex pheromones. The combination of the sex pheromone of both species (PH combo lure) significantly increased G. molesta and marginally decreased C. pomonella captures as compared with captures of each species with either of their sex pheromones alone. The addition of a HPV combination lure [(E,Z)‐2,4‐ethyl decadienoate plus (E)‐β‐ocimene] or acetic acid used alone or together did not significantly increase the catch of either species in traps with the PH combo lure. The Ajar trap baited with terpinyl acetate and brown sugar (TAS bait) caught significantly more G. molesta than the delta trap baited with PH combo plus acetic acid in California during 2012. The addition of a PH combo lure to an Ajar trap significantly increased catches of G. molesta compared to the use of the TAS bait or PH combo lure alone in 2013. Female G. molesta were caught in TAS‐baited Ajar traps at similar levels with or without the use of additional lures. Ajar traps baited with the TAS bait alone or with (E)‐β‐ocimene and/or PH combo lures caught significantly fewer C. pomonella than delta traps with sex pheromone alone. Ajar traps with 6.4‐mm screened flaps caught similar numbers of total and female G. molesta as similarly baited open Ajar traps, and with a significant reduction in the catch of non‐targets. Broader testing of HPV and PH combo lures for G. molesta in either delta or screened or open Ajar traps is warranted.     

Baseline monitoring of codling moth (Lepidoptera: Tortricidae) larval response to benzoylhydrazine insecticides

A diet-incorporation larval bioassay was developed to measure the response of codling moth, Cydia pomonella (L.), to the benzoylhydrazine insecticides tebufenozide and methoxyfenozide. The bioassay tested neonates and third, fourth, and fifth instars from a laboratory colony and neonates and fourth instars from a pooled population collected from five certified-organic apple orchards. Bioassays were scored after 6 and 14 d. No differences between the laboratory and field population were found for either insecticide. Significant differences were found in the response of third and fifth instars between the 6 and 14 d bioassays, primarily due to a high proportion of moribund larvae in the shorter assay. Larval age had a significant effect in bioassays and was more pronounced in 6- versus 14-d tests. Fifth instars were significantly less susceptible to both insecticides than other stages, while responses of third and fourth instars were similar. The response of neonates was significantly different from third and fourth instars to tebufenozide but not with methoxyfenozide in the 14-d test. Field bioassays excluded the use of fifth instars and were scored after 14 d. LC50s estimated for 18 field-collected populations varied five- and ninefold for tebufenozide and methoxyfenozide, respectively. The responses of all but six field-collected populations were significantly different from the laboratory strain. Five of these six populations were collected from orchards with no history of organophosphate insecticide use. The LC50 for methoxyfenozide of one field-collected population reared in the laboratory for three generations declined fourfold, but was still significantly different from the laboratory population. These data suggest that transforming current codling moth management programs in Washington from a reliance on organophosphate insecticides to benzoylhydrazines may be difficult.     

Susceptibility of Oriental fruit moth (Lepidoptera: Tortricidae) larvae to selected reduced-risk insecticides

To determine their baseline susceptibility to chlorantraniliprole, spinetoram, spinosad, and acetamiprid, oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), neonates were placed on diet cubes containing a range of concentrations of each insecticide. Mortality was assessed after 96 h. Two populations-a long-term laboratory colony from Rutgers University and a colony established in 2007 from a southwestern Illinois (Calhoun County) field population-were tested. We used probit and logit analyses to compare the responses of Calhoun colony neonates from parents reared on 'Gala' apples (Malus spp.) with those of Calhoun colony neonates from parents reared on lima bean, Phaseolus lunatus L., diet. We also compared the responses of Calhoun colony neonates with those of Rutgers colony neonates (all from parents reared on apples). LC50s (ppm in diet) for Calhoun colony progeny of adults reared on apples were 0.08, 0.06, 0.41, and 0.30, respectively, for chlorantraniliprole, spinetoram, acetamiprid, and spinosad. Parental food source (apples versus lima bean diet) did not consistently influence the concentration-mortality relationships for neonates. Based on LC50s and toxicity ratio tests, Calhoun colony neonates were slightly but significantly less susceptible to spinetoram and acetamiprid than were Rutgers colony neonates. Similarly, LC90s and toxicity ratio tests indicated that Calhoun colony neonates were slightly but significantly less susceptible to chlorantraniliprole as well. However, toxicity ratios (Calhoun/Rutgers) were low in all instances, and the highest ratio was 1.73 at LC90 for chlorantraniliprole. Overall, the two colonies responded similarly to these insecticides. Results reported here provide baseline data for future monitoring of resistance development.     

Direct and correlated responses to artificial selection on flight activity in the oriental fruit moth (Lepidoptera: Tortricidae)

The ability of a sufficient number of individuals to disperse is crucial for long‐term survival of populations. However, dispersal is often energetically costly, and thus is expected to trade‐off against other life‐history traits. In insect pest species, the occurrence of individuals with high flight activity challenges management practices. We performed artificial selection on flight activity and measured correlated responses to selection in the oriental fruit moth, Grapholita (= Cydia) molesta, a widely distributed and expanding lepidopteran pest of fruit crops. Both sexes rapidly responded to the imposed regime of divergent selection, indicating an adaptive potential of flight activity in this species. Upward‐selected moths died sooner than downward‐selected ones, providing evidence for a cost of flight activity to adult survival, reputedly associated with enhanced metabolic rates. Oppositely‐selected females had similar total reproductive output, disproving a trade‐off between dispersal and reproduction, although females with higher flight activity laid their eggs sooner. The ratio of body weight to forewing surface (forewing loading) did not significantly differ between selected lines. The present study contributes to the understanding of dispersal evolution, and also provides new insights into life‐history theory as well as important baseline data for the improvement of pest management practices. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 879–889.     

Entomopathogenic nematodes for control of diapausing codling moth (Lepidoptera: Tortricidae) in fruit bins

Fruit bins infested with diapausing larvae of codling moth larvae, Cydia pomonella (L.), are a source of reinfestation of orchards and may jeopardize the success of mating disruption programs and other control strategies. Bins are not routinely treated for control of overwintering codling moth before placing them in orchards. Entomopathogenic nematodes provide a noninsecticidal alternative to methyl bromide that could be applied at the time bins are submerged in dump tanks at the packing house for flotation of fruit. Diapausing codling moth larvae in miniature fruit bins were highly susceptible to infective juveniles of Steinernema carpocapsae (Weiser). Immersion of bins in suspensions of S. carpocapsae ranging from 5 to 100 infective juveniles per milliliter of water resulted in 68-100% mortality. Immersion times of 1 or 5 min in suspensions with 5 infective juveniles of S. carpocapsae per milliliter of water, with and without Tween 80 (0.01%), yielded essentially the same mortality of codling moth larvae. Highest mortalities in codling moth larvae (88%) after treatment of bins in suspensions of 5 infective juveniles of S. carpocapsae per milliliter of water were observed after incubation for 24 h at 25 degrees C and 70% RH. Lowest mortalities (37%) were observed after incubation at 15 degrees C and 35% RH. Comparative tests conducted with Heterorhabditis marelatus Liu & Berry, Steinernema kraussei (Steiner), and S. carpocapsae with 5 infective juveniles per milliliter of water resulted in 21.7, 53.9, and 68.7% mortality, respectively. The use of miniature fruit bins as described in this article provides an effective means of assessing nematode efficacy without the cumbersome size of commercial bins.     

Susceptibility of male oriental fruit moth (Lepidoptera: Tortricidae) populations from New Jersey apple orchards to azinphosmethyl

Toxicological responses to azinphosmethyl of male Oriental fruit moth, Grapholita molesta (Busck), from five commercial orchards in which control failures had occurred were examined for azinphosmethyl resistance and for potential resistance mechanisms by using topical pheromone trap bioassay and compared with a reference population that had no history of control failure and had received little selection pressure. The 1998 field survey indicated moderate level of resistance to azinphosmethyl (2.7-4.1-fold); slopes of regressions lines (2.47-2.76) indicate genetically heterogeneous populations. An approximate twofold decline was observed between the fourth flight of 1998 and the first flight of 1999, suggesting the presence of unstable resistance in moths collected from these study sites. The 1999 field surveys indicated lower levels of tolerance to azinphosmethyl. The resistance ratios ranged from 1.17 to 1.86 during the first flight of 1999 and 1.24-2.64 during the fourth flight of 1999. Steep slopes of the concentration-response lines during 1999 season indicated the presence of genetically homogeneous populations with some exceptions. A 1.5-2.0-fold increase was observed between the first and fourth flights of 1999, indicating that resistance can build up during the growing season. S,S,S,-tri-n-butyl phosphorotrithioate (DEF), but not piperonyl butoxide, significantly enhanced the toxicity of azinphosmethyl, suggesting that enhanced metabolism by esterases is involved in the tolerance of azinphosmethyl in moths collected from these study sties.     

Correlated insecticide cross-resistance in azinphosmethyl resistant codling moth (Lepidoptera: Tortricidae)

Resistance to several classes of insecticides was correlated with azinphosmethyl resistance in codling moth, Cydia pomonella (L.), in California. In tests of laboratory and field populations, cross-resistance was positively correlated with azinphosmethyl and two organophosphates (diazinon, phosmet), a carbamate (carbaryl), a chlorinated hydrocarbon (DDT), and two pyrethroids (esfenvalerate and fenpropathrin). Additionally, negatively correlated cross-resistance was identified between azinphosmethyl and two other organophosphates, chlorpyrifos and methyl parathion. Patterns of resistance observed in laboratory colonies were confirmed with field bioassays. In bioassays of field populations, azinphosmethyl resistance was observed to increase from 1991 to 1993, although levels of resistance remained < 13-fold. Because orchards with azinphosmethyl resistance have had difficulties with suppression of codling moth, and cross-resistance was found for all tested classes of insecticides, strategies for managing resistance will need to be developed so as to protect current and future control tactics. The two insecticides with negatively correlated cross-resistance are discussed as potential tools for resistance management.     

Comparative survival rates of oriental fruit moth (Lepidoptera: Tortricidae) larvae on shoots and fruit of apple and peach

Studies were designed to examine the effects of host plants on oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), survival. G. molesta larval survival in the orchard was comparable between apple (Malus spp.) and peach (Prunus spp.) shoots, indicating that both host species can harbor large larval populations during the early season. G. molesta larvae used multiple shoots for feeding and development on peaches but usually only damaged single shoots in apple. Survival differences were present between peach and apple fruit, but this survival was affected by fruit maturity level. Generally, larval survival higher was in ripening peach fruit than in green, immature apple fruit. Larval survival varied among several apple cultivars, indicating that cultivar-level variability needs to be considered. These host-associated effects may impact efforts to predictively model G. molesta populations in commercial orchards where multiple host plant species, or different cultivars of the same species are often grown in proximity. Thus, host-associated dynamics should be included into future population models that underlie management programs.     

Ionizing irradiation quarantine treatment against oriental fruit moth (Lepidoptera: Tortricidae) in ambient and hypoxic atmospheres

Oriental fruit moth, Grapholita molesta (Busck), is a pest of many rosaceous temperate fruits, including pomes, Malus spp., and stone fruits, Prunus spp., in much of the world. However, some areas are free of the pest, and shipments of fruit hosts from infested to noninfested areas may be regulated. Current quarantine treatments for oriental fruit moth include methyl bromide fumigation and cold storage for several weeks. Methyl bromide use is being restricted because it is a stratospheric ozone-depleting substance, and alternatives are sought. Cold is not tolerated by many hosts of oriental fruit moth. The objective of this research was to develop irradiation quarantine treatments against the pest under ambient and hypoxic storage conditions because some hosts of oriental fruit moth are stored in hypoxic atmospheres, and hypoxia is known to lessen the effects of irradiation. In ambient atmospheres, no adults emerged from 58,779 fifth instars (the most radiotolerant stage present in fruit) irradiated with a target dose of 200 Gy (195-232 Gy measured). In atmospheres flushed with nitrogen, 5.3% of adults emerged from 44,050 fifth instars irradiated with a target dose of 200 Gy (194-230 Gy measured), but they died at a faster rate than control adults and without laying eggs. A dose of 232 Gy (the maximum recorded when 200 Gy was targeted) is recommended to disinfest any fruit of oriental fruit moth under ambient and hypoxic atmospheres.     

Radiation biology and inherited sterility in false codling moth (Lepidoptera: Tortricidae)

False codling moth, Cryptophlebia leucotreta (Meyrick), male and female mature pupae and newly emerged adults were treated with increasing doses of gamma radiation and either inbred or out-crossed with fertile counterparts. For newly emerged adults, there was no significant relationship between dose of radiation and insect fecundity when untreated females were mated to treated males (N female by T male). However, fecundity of treated females mated to either untreated (T female by N male) or treated males (T female by T male) declined as the dose of radiation increased. A similar trend was observed when mature pupae were treated. The dose at which 100% sterility was achieved in treated females mated to untreated males (T female by N male) for both adults and pupae was 200 Gy. In contrast, newly emerged adult males treated with 350 Gy still had a residual fertility of 5.2% when mated to untreated females, and newly emerged adult males that were treated as pupae had a residual fertility of 3.3%. Inherited effects resulting from irradiation of parental (P1) males with selected doses of radiation were recorded for the F1 generation. Decreased F1 fecundity and fertility, increased F1 mortality during development, and a significant shift in the F1 sex ratio in favor of males was observed when increasing doses of radiation were applied to the P1 males.     

Sublethal exposure to methoxyfenozide-treated surfaces reduces the attractiveness and responsiveness in adult oriental fruit moth (Lepidoptera: Tortricidae)

The chemical communication (female attractiveness and male responsiveness) of adult oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), exposed to surfaces treated with the ecdysteroid agonist methoxyfenozide for 48 h were investigated in two laboratory wind tunnel assays. The recapture assay examined the ability of treated males to orient to a single cage of treated females, and the data gathered were mean percentage of males recaptured per treatment. The male sexual behavior assay examined some specific orientation behaviors (associated with sexual excitability) of treated males when they were given a choice of two competing pheromone sources (cages of treated females), and the data gathered were mean time males spent in upwind plume orientations and at source contact (female cage) per treatment. Data from the recapture assay suggests that exposure to methoxyfenozide impacts male responsiveness more than female attractiveness. In contrast, data from the sexual behavior assay strongly revealed that exposure to methoxyfenozide-treated surfaces does negatively impact both the ability of calling females to attract males and of aroused males to display sustained upwind flight behavior and time spent at the female cages.     

Variability in the efficacy of sex pheromone lures for monitoring oriental fruit moth (Lepidoptera: Tortricidae)

Studies were conducted in Chile and the United States to compare the attractiveness of various commercial sex pheromone lures and two experimental lures for oriental fruit moth, Grapholita molesta (Busck), in peach orchards treated with or without sex pheromone dispensers. The experimental lures contained the three‐component sex pheromone blend of G. molesta: Z‐8‐dodecenyl acetate, E‐8‐dodecenyl acetate and Z‐8‐dodecenol (Z8‐12:OH), and the sex pheromone of codling moth, Cydia pomonella (L.), (E,E)‐8,10‐dodecadien‐1‐ol, (codlemone). Commercial lures varied in their substrate, initial loading and blend ratio of components. Significant differences in male catches were found among commercial lures in orchards treated with or without sex pheromone dispensers. Experimental lures with the addition of codlemone significantly increased the catches of G. molesta using lures loaded with 0%, 1% or 5% Z8‐12:OH in the G. molesta blend compared with the same ratio of components in just the G. molesta blend. The experimental lures were significantly more attractive than all commercial lures in the untreated orchard. However, moth catch with the experimental lures in the sex pheromone‐treated orchard was only intermediate among all of the lures tested. These findings highlight the need to develop more effective and standardized lures that can be used in trap‐based monitoring programme for this important pest.     

Factors affecting entomopathogenic nematodes (Steinernematidae) for control of overwintering codling moth (Lepidoptera: Tortricidae) in fruit bins

Fruit bins infested with diapausing codling moth larvae, Cydia pomonella (L.), are a potential source of reinfestation of orchards and may jeopardize the success of mating disruption programs and other control strategies. Entomopathogenic nematodes (EPNs) were tested as a potential means of control that could be applied at the time bins are submerged in dump tanks. Diapausing cocooned codling moth larvae in miniature fruit bins were highly susceptible to infective juveniles (IJs) of Steinernema carpocapsae (Weiser) and Steinernema feltiae (Filipjev) in a series of experiments. Cocooned larvae are significantly more susceptible to infection than are pupae. Experimental treatment of bins in suspensions of laboratory produced S. feltiae ranging from 10 to 100 IJs/ml of water with wetting agent (Silwet L77) resulted in 51-92% mortality. The use of adjuvants to increase penetration of hibernacula and retard desiccation of S. feltiae in fruit bins resulted in improved efficacy. The combination of a wetting agent (Silwet L77) and humectant (Stockosorb) with 10 S. feltiae IJs/ml in low and high humidity resulted in 92-95% mortality of cocooned codling moth larvae versus 46-57% mortality at the same IJ concentration without adjuvants. Immersion of infested bins in suspensions of commercially produced nematodes ranging from 10 to 50 IJs/ml water with wetting agent in an experimental packing line resulted in mortality in cocooned codling moth larvae of 45-87 and 56 - 85% for S. feltiae and S. carpocapsae, respectively. Our results indicate that EPNs provide an alternative nonchemical means of control that could be applied at the time bins are submerged in dump tanks at the packing house for flotation of fruit.     

Effects of orchard host plants (apple and peach) on development of oriental fruit moth (Lepidoptera: Tortricidae)

Studies were designed to examine the effects of host plants (apple, Malus domestica Borkh., and peach, Prunus persica L.) on the development of oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae). Oriental fruit moth larvae developed faster on peach than on apple, both on fruit as well as on growing terminal shoots. On fruit, these differences were shown to cause significant changes in both the rate (approximately 20-60 degree-days earlier emergence on peach than on apple) and patterns of adult emergence among several cultivars of peaches and apples. Slopes of female emergence plots varied by host in 2003, with emergence occurring over a longer period on peach cultivars than on apple cultivars (with one exception). Slopes of male emergence curves did not differ by cultivar in 2003. These host-driven effects could impact the efficacy of traditional pest management approaches and probably complicate efforts to predictively model G. molesta populations in mixed cultivar orchards. Such developmental effects may help to explain previously observed differences in patterns of pheromone trap captures in peach versus apple orchards. Host-associated effects should be incorporated into future models to develop more realistic predictive tools and thus improve integrated pest management efforts.     

Integrated control of oriental fruit moth (Lepidoptera: Tortricidae) in peach orchards using insecticide and mating disruption

The efficacy of an integrated and a conventional oriental fruit moth, Grapholita molesta (Busck), control program was compared using 4-ha blocks of peach at three Niagara Peninsula farms during 1997-1999. In the integrated program, chlorpyrifos was used to control first-generation larvae and mating disruption using Isomate M100 pheromone dispensers was used to control the second and third generations. In the conventional program, chlorpyrifos was used to control first-generation larvae and pyrethroids were used to control larvae of the later generations. The average release rate of pheromone was 23.7-26.4 mg/ha/h over a period of 86-91 d. The pheromone treatment reduced the capture of moths in pheromone-baited traps on average by 98%, suggesting a high level of disruption. The integrated program provided control of oriental fruit moth similar to the control provided by a conventional program. The mean percentage of peach shoots infested with first- and second-generation larvae, and fruit infested with third-generation larvae was not significantly greater in the integrated-program blocks during the 3-yr study. The elimination of insecticide sprays from the integrated-program blocks did not result in an increase in damage caused by plant bugs. The incidence of damage caused by other pests was negligible in both the integrated and conventional blocks.     

Postharvest methyl bromide fumigation of Japanese plums to control codling moth (Lepidoptera: Tortricidae)

Postharvest chamber fumigation with 48 mgL^?1 (3.0 lbs./1000 ft³) methyl bromide (MB) for 2 h at pulp temperature (T) ≥ 21 °C and chamber load ≤50% is used to control codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), in fresh nectarine, Prunus persica (L.) var. nucipersica, and French plum, P. domestica (L.), exports from California USA to Japan. Fumigations were conducted to verify that control of C. pomonella is expected following an analogous fumigation of fresh Japanese plums, P. salicina (Lindl.). A kinetic model, based on temporal measurement of MB levels in chamber headspace and how calculated exposures varied across the fumigation trials, showed that fresh Japanese plums and French plums sorb MB at a statistically equivalent rate, which resulted in an MB exposure ca. 20% higher than that observed for fresh nectarines. Importantly, results from commercial-scale fumigations indicate that pallet shrouds do not influence the efficacy of MB toward C. pomonella eggs, as their presence did not affect the rate of MB sorption, evidence that supports the use of pallet shrouds to safeguard against the potential for post-fumigation infestation in this export scenario, and beyond. Results are discussed in the context of graduation toward optimized quarantine fumigation schedules, which will promote more strategic technical and economic Quarantine Pre-shipment (QPS) uses of MB.     

梨小食心虫对LED光的趋性及影响因素的研究

为了明确梨小食心虫Grapholita molesta Busck对LED光的趋性及果园利用LED光诱捕梨小食心虫的效果,为开发基于梨小食心虫趋光行为的新防治手段提供依据。本研究通过室内观察梨小食心虫成虫对不同波长的4种LED光及白光的趋性及暗适应时间、性别、日龄和光照强度对趋光性的影响,进一步调查了LED光对田间梨小食心虫成虫的诱捕效果。结果表明:在室内条件下,梨小食心虫成虫对520 nm的绿光趋性最强。1⁵日龄成虫中,以3日龄成虫趋光性最强,且雌虫趋光性显著高于雄虫。在暗适应0.55日龄成虫中,以3日龄成虫趋光性最强,且雌虫趋光性显著高于雄虫。在暗适应0.5³.0 h范围内,梨小食心虫成虫的趋光性表现为"抛物线形",以暗适应2.0 h时趋光性最强,并显著高于其它暗适应处理时间。在550、650、750、850 lx光照强度下,以650 lx光强时的趋光性最强。田间诱捕结果表明,不同颜色的LED灯对梨小食心虫的诱捕效果均不理想,不适于梨小食心虫的防治。     

Monitoring oriental fruit moth (Lepidoptera: Tortricidae) with sticky traps baited with terpinyl acetate and sex pheromone

Studies in Argentina and Chile during 2010–2011 evaluated a new trap (Ajar) for monitoring the oriental fruit moth, Grapholita molesta (Busck). The Ajar trap was delta‐shaped with a jar filled with a terpinyl acetate plus brown sugar bait attached to the bottom centre of the trap. The screened lid of the jar was inserted inside the trap, and moths were caught on a sticky insert surrounding the lid. The Ajar trap was evaluated with and without the addition of a sex pheromone lure and compared with delta traps left unbaited or baited with a sex pheromone lure and a bucket trap filled with the same liquid bait. Studies were conducted in a sex pheromone‐treated orchard in Argentina and an untreated orchard in Chile. In Chile, the Ajar trap without the sex pheromone lure caught significantly fewer males, females and total moths than the bucket trap, and fewer males and more females than the sex pheromone‐baited delta trap. Total moth catch did not differ between the Ajar trap without a sex pheromone lure and the sex pheromone‐baited trap. Adding a sex pheromone lure to the Ajar trap significantly increased total moth catches to levels not different from those in the bucket trap. However, the Ajar trap with the sex pheromone lure caught significantly more males and fewer females than the bucket trap. In Argentina, the Ajar trap with or without the addition of a sex pheromone lure caught similar numbers of both sexes and total moths as the bucket trap. The sex pheromone‐baited delta trap caught <4% of the number of moths as these three traps. The bucket trap in both studies caught significantly more non‐targets than the delta and Ajar traps. Moth catches in the Ajar trap declined significantly after 2–3 weeks when the bait was not replaced.