Field Cage Trials Research Articles

Quantitative trait loci increasing acylsugars in tomato breeding lines and their impacts on silverleaf whiteflies

Solanum pennellii LA716, a wild relative of tomato, produces acylsugars, an insect resistance compound with activity against many tomato insect pests. Breeding of cultivated tomato using S. pennellii LA716 as a donor parent has led to the development of the elite acylsugar-producing tomato breeding line CU071026. CU071026 contains five introgressed S. pennellii genomic regions, and produces acylsugars at moderate levels that are effective against insect pests. A BC1F1 population was created by crossing the F1 CU071026 × S. pennellii LA716 with CU071026 as the recurrent parent; this BC1F1 population was used to identify additional regions of the S. pennellii genome important for further improvement of acylsugar production. This population was genotyped with 94 markers in the segregating regions and phenotyped for level of acylsugar production. Using QTLNetwork 2.1 for the detection of quantitative trait loci (QTL) and epistatic interactions, this study identified five QTL for total acylsugar level. Additionally, two epistatic interactions between QTL were found to control significant levels of total acylsugar production. Two of the QTL identified were further evaluated in silverleaf whitefly (Bemisia tabaci) field cage trials using acylsugar breeding lines that differ for the presence/absence of these QTL. While high levels of silverleaf whitefly resistance were observed in all acylsugar breeding lines, lines containing the additional QTL on either chromosomes 6 or 10 had increased levels of total acylsugar production and reduced incidence of whitefly. Acylsugar lines containing the chromosome 6 QTL also had increased density of the type IV glandular trichomes which produce and exude acylsugars.

Mate Choice by Lekking Males: Evidence from the Mediterranean Fruit Fly from Field Cage Trials (Diptera: Tephritidae)

Abstract The Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann), exhibits a lek mating system characterized by intense female choice apparently based on male courtship performance. However, recent observations showed that receptive females are aggressive toward one another and compete for access to displaying males, suggesting that the traditional view that sexual competition in the medfly is restricted exclusively to males may not be accurate. The current study further examines the accepted view of the medfly mating system by investigating the possibility that males discriminate among potential mates on the basis of female age. In field cage trials, we scored matings for males presented with virgin females of different ages. Young females were mated more frequently than old females, and additional tests revealed that this pattern did not reflect age-dependent variation among virgin females in mating propensity or response to male signaling. Although the experimental environment was artificial in simultaneously providing males with young and old virgin females, the existence of nonrandom mating nonetheless was unexpected given the accepted view that, given limited mating opportunities, male medflies will copulate indiscriminately with available females. Fecundity, fertility, egg-to-pupal yield, and longevity were compared among females of different ages to assess the potential reproductive benefits gained by males via age discrimination among potential mates. Young females (10–15 d old) had significantly higher fecundity, fertility, and egg-to-pupal yield than old females (35–40 d old), and consequently male choice for young females appears to confer substantial fitness benefits.

Ginger root oil increases mating competitiveness of sterile Mediterranean fruit fly (Diptera:Tephritidae) in Western Australia

AbstractThe exposure of sterile male Mediterranean fruit fly, Ceratitis capitata (Wiedemann) to the aroma of essential oil derived from ginger root Zingiber officinale Roscoe (GRO) has been shown in field cage trials to increase their mating success. This field cage study compared the mating performance of mass reared sterile Mediterranean fruit fly males prepared for ground release programmes under four different post‐irradiation systems, two of which involved exposure of the flies to GRO aroma. In the first system, irradiated pupae were placed into non‐vented 5‐L paper tubs, individually aromatized by 20 μl of GRO (4 ml/m3) for 96–120 h until the adults were 2–3 days old. In the second system, irradiated pupae were placed in vented 5‐L paper tubs, exposed for 24 h in a GRO aromatized room (0.5 ml/m3) when the adults were 3 days old and contained until required for mating tests at 5 days old. The third and fourth systems were the same as the first two systems respectively, except that the flies were not exposed to GRO aroma. Significant differences in mating success were found among treatments. The exposure of 2 to 3‐day old flies to GRO aroma improved mating performance slightly compared with equivalent non‐exposed flies, but it was still below the minimum value accepted under international standards, while 27% of unexposed 5‐day‐old sterile males mated and had competitiveness (Fried value 0.38) slightly above this minimum level. GRO exposed 5‐day‐old flies had the highest mating percentage (67%) and a level of competitiveness (Fried value 1.81) based on induced sterility above that of wild flies (Fried value 1). The results indicate that the effectiveness of sterile male ground release programmes can be increased significantly by releasing 5‐day‐old sterile males that have been exposed to GRO in an entirely aromatized adult fly holding room.

Comparative evaluation of two olive fruit fly parasitoids under varying abiotic conditions

Psyttalia lounsburyi (Silvestri) and P. humilis (Silvestri) (Hymenoptera: Braconidae) were evaluated in California for their potential to control the invasive olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae). Psyttalia lounsburyi is a specialist on B. oleae while P. humilis also attacks other tephritid species. Field cage trials, conducted from 2006 to 2009, were used to compare P. lounsburyi and two populations of P. humilis (Kenya and Namibia) in California’s interior valley and coastal regions. Both parasitoid species reproduced on B. oleae in all trials. Under similar abiotic conditions, offspring production per female was higher in P. humilis than in P. lounsburyi, suggesting that host specificity by P. lounsburyi does not confer a higher efficiency on B. oleae in cultivated olives. Two abiotic factors were shown to impact parasitoid efficiency. First, adult parasitoid survival was poor during periods of high summer temperatures, common to the olive production areas in California’s interior valleys. Second, parasitism levels were lower on B. oleae larvae feeding in larger Ascolano cv. fruit than in smaller Manzanillo cv. fruit. Results are discussed relative to biological control of B. oleae in commercial olives and the usefulness of natural enemies specialized to attack fruit flies in wild olives compared with the larger cultivated olive fruit.

Inheritance of Soybean Aphid Resistance from PI 71506

Resistance to the soybean aphid (Aphis glycines Matsumura) was characterized in segregating populations from crosses of soybean [Glycine max (L.) Merr.] accession PI 71506 to susceptible cultivars, and compared to Rag1 resistance from the cultivar ‘Dowling.’ Two susceptible adapted cultivars were crossed with PI 71506 or Dowling. In no-choice greenhouse assays, resistance corresponded to a single dominant gene model for both the PI 71506-derived and Dowling-derived populations. Segregation of aphid resistance in SD1111RR × PI 71506 F2:3 populations in aphid field-cage trials also fit a single-gene model, as did segregation of aphid resistance in the F2:5 generation. However, other genetic effects may also contribute to aphid resistance from PI 71506. Comparison with Rag1 resistance from Dowling indicated that PI 71506 resistance was weaker than that associated with Rag1, but antixenosis resistance from PI 71506 was effective against an Ohio aphid biotype that has overcome Rag1 resistance.

Economic injury levels for southern green stink bugs (Hemiptera: Pentatomidae) in R7 growth stage soybeans

Stink bugs, primarily southern green stink bug, Nezara viridula (Hemiptera: Pentatomidae), are a major pest complex of soybeans ( Glycine max) throughout the southern United States. Densities sometimes peak during late R6 and R7 soybean growth stages when soybeans are approaching physiology maturity and the rate of injury from stink bugs is reduced. Field cage trials were conducted from 2005 to 2008 to examine the type and extent of soybean damage caused by southern green stink bugs during the R7 growth stage. The yield response was variable, but overall was not significant. The impact of southern green stink bugs on quality was more consistent. Test weight decreased, and heat damage and total damage increased as stink bug density increased. Based on these data, three economic injury models were developed using different assumptions. The model that assumes no yield loss, does not predict economic injury within the range of stink bug densities tested. However, if the statistically non-significant yield losses are accepted as real, then the models suggest that the southern green stink bug economic injury level and action threshold for soybeans during R7 stage is generally between nine and 15 stink bugs per row m.

Risk posed by the invasive defoliator Uraba lugens to New Zealand native flora

The risk posed to New Zealand native flora by the recently-established pest of Australian origin Uraba lugens Walker (Lepidoptera: Nolidae) (gum leaf skeletonizer) was assessed. Weed biological control host range testing methods were applied to identify those New Zealand plant species potentially at risk. Native plants tested were primarily in the Myrtaceae, the family that contains all the Australian hosts of U. lugens. 2 Experimental methods included no-choice larval feeding assays and field cage and laboratory oviposition trials. Difficulty in ascertaining reliable oviposition preference data from cage oviposition trials limited the confidence with which the invader's field host range could be predicted. 3 Field surveys of plants attacked by U. lugens in the infested area supported the initial predictions but only some of the at-risk native Myrtaceae were present in the area. 4 The risk to native New Zealand plants is presented in terms of two mechanisms: development of self-sustaining populations and temporary spill-over of solitary larvae. Development of self-sustaining populations of the pest within native forests is deemed to be highly improbable. 5 Temporary spill-over impacts are most likely in urban areas within mixed species plantings or boundaries between native/exotic forests and coinciding with the mobile larval life stages. Spill-over impacts from U. lugens have only been recorded to date on Metrosideros excelsa.

Determination of host status of citrus fruits against the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae)

Abstract The Mediterranean fruit fly (Medfly), Ceratitis capitata (Wiedemann) is a pest of citrus in parts of Western Australia. Three citrus cultivars: Valencia oranges, Eureka lemons and Imperial mandarins, as well as non‐citrus control fruits, were examined for attractiveness and suitability to Medfly in the field and in the laboratory using choice and no‐choice experiments. Oranges were more susceptible to Medfly than mandarins and lemons. Punctures in the skin had a significant impact on the degree of infestation in both citrus and non‐citrus control fruit. Artificial infestation and larval survivorship were used to investigate the suitability of each cultivar to Medfly under laboratory conditions. Oranges and mandarins were suitable for the development of Medfly, but lemons were a poor host. When each cultivar was in season, field cage trials demonstrated that infestation occurred in oranges and mandarins but not in lemons.

Exposing Entire Adult Holding Rooms Containing Sterile Male Mediterranean Fruit Flies to OrangE Oil Increases the Mating Success of Those Males in Field-cage Trials

A previous study demonstrated that exposing entire rooms holding mass-reared males of the Mediterranean fruit fly, Ceratitis capitata (Wied.), to the aroma of ginger root oil increased mating success relative to that observed for non-exposed males. Here, we followed the same experimental protocol to test whether the aroma of orange oil similarly enhanced male mating performance. Working at an eclosion facility in California, we exposed trailers (132 m3) containing ≈ 14 million C. capitata males from a genetic sexing (tsl, temperature sensitive lethal) strain to orange oil aroma for 24 h and compared mating success of non-exposed or ginger root oil-exposed tsl males in field-cage trials (in which tsl males competed against males from a standard, bisexual strain for females from this same standard strain). Both orange oil- and ginger root oil-exposed tsl males achieved a significantly greater proportion of the total matings than non-exposed (to any aroma) tsl males. No difference in relative mating success was observed between orange oil- and ginger root oil-exposed tsl males. As orange oil is considerably less expensive than ginger root oil, its use could reduce costs substantially.

Exposure to the Ripe Fruit of Tropical Almond Enhances the Mating Success of Male Bactrocera dorsalis (Diptera: Tephritidae)

Exposure to the Ripe Fruit of Tropical Almond Enhances the Mating Success of Male Bactrocera dorsalis (Diptera: Tephritidae)

Monarch Butterfly Oviposition on Swallow-Worts (<I>Vincetoxicum</I> spp.)

As black swallow-wort, Vincetoxicum nigrum L. Moench, and pale swallow-wort, V. rossicum (Kleopow) Barbar., spread throughout the northeastern United States and southern Canada, there is concern about the impact of these invasive plants on populations of the native North American monarch butterfly Danaus plexippus L. Recent laboratory studies in New York and Ontario, Canada, have found little or no oviposition by monarch butterflies on the two Vincetoxicum species. In Rhode Island, we found 10.5-21.7% oviposition on Vincetoxicum species relative to common milkweed Asclepias syriaca L. in choice tests and 11.9-20.3% in no-choice tests in 2 yr of laboratory testing. These results were supported by field cage trials where monarchs given a choice between V. nigrum and A. syriaca laid 24.5% of their eggs on V. nigrum. In surveys of three pasture fields in Rhode Island where relative coverage of A. syriaca exceeded that of V. nigrum by a 0.77:0.23 ratio, 15.4% of monarch eggs were found on V. nigrum plants. In V. nigrum stands with very little A. syriaca (6.25 stems/ha), monarch egg density on V. nigrum was found to be over five times greater than in the three mixed pasture fields. In none of our laboratory or field evaluations was there any survival of monarch larvae on Vincetoxicum species. It seems that in Rhode Island, Vincetoxicum species serve as an oviposition sink for monarch butterflies. These findings suggest that East Coast butterflies may differ in host selection from those in central New York and southern Ontario, Canada.

Sterile Insect Technique and Mediterranean Fruit Fly (Diptera: Tephritidae): Assessing the Utility of Aromatherapy in a Hawaiian Coffee Field

The sterile insect technique (SIT) is widely used in integrated programs against tephritid fruit fly pests, particularly the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Unfortunately, the mass-rearing procedures inherent to the SIT often lead to a reduction in the mating ability of the released males. One potential solution involves the prerelease exposure of males to particular attractants. In particular, exposure of male Mediterranean fruit flies to ginger, Zingiber officinale Roscoe, root oil (GRO) has been shown to increase mating success in laboratory and field cage trials. Here, we describe a field experiment that compares the level of egg sterility observed in two Hawaiian coffee, Coffea arabica L., plots, with GRO-exposed, sterile males released in one (treated) plot and nonexposed, sterile males released in the other (control) plot. Once per week in both plots over a 13-wk period, sterile males were released, trap captures were scored to estimate relative abundance of sterile and wild males, and coffee berries were collected and dissected in the laboratory to estimate the incidence of unhatched (sterile) eggs. Data on wild fly abundance and the natural rate of egg hatch also were collected in a remote area that received no sterile males. Despite that sterile:wild male ratios were significantly lower in the treated plot than in the control plot, the incidence of sterile eggs was significantly higher in the treated plot than in the control plot. Correspondingly, significantly higher values of Fried’s competitiveness index (C) were found, on average, for treated than control sterile males. This study is the first to identify an association between the GRO “status” of sterile males and the incidence of egg sterility in the field and suggests that prerelease, GRO exposure may represent a simple and inexpensive means to increase the effectiveness of Mediterranean fruit fly SIT programs.

Sterile insect technique and Mediterranean fruit fly (Diptera: Tephritidae): assessing the utility of aromatherapy in a Hawaiian coffee field.

The sterile insect technique (SIT) is widely used in integrated programs against tephritid fruit fly pests, particularly the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Unfortunately, the mass-rearing procedures inherent to the SIT often lead to a reduction in the mating ability of the released males. One potential solution involves the prerelease exposure of males to particular attractants. In particular, exposure of male Mediterranean fruit flies to ginger, Zingiber officinale Roscoe, root oil (GRO) has been shown to increase mating success in laboratory and field cage trials. Here, we describe a field experiment that compares the level of egg sterility observed in two Hawaiian coffee, Coffea arabica L., plots, with GRO-exposed, sterile males released in one (treated) plot and nonexposed, sterile males released in the other (control) plot. Once per week in both plots over a 13-wk period, sterile males were released, trap captures were scored to estimate relative abundance of sterile and wild males, and coffee berries were collected and dissected in the laboratory to estimate the incidence of unhatched (sterile) eggs. Data on wild fly abundance and the natural rate of egg hatch also were collected in a remote area that received no sterile males. Despite that sterile:wild male ratios were significantly lower in the treated plot than in the control plot, the incidence of sterile eggs was significantly higher in the treated plot than in the control plot. Correspondingly, significantly higher values of Fried's competitiveness index (C) were found, on average, for treated than control sterile males. This study is the first to identify an association between the GRO "status" of sterile males and the incidence of egg sterility in the field and suggests that prerelease, GRO exposure may represent a simple and inexpensive means to increase the effectiveness of Mediterranean fruit fly SIT programs.

Aromatherapy on a large scale: exposing entire adult holding rooms to ginger root oil increases the mating competitiveness of sterile males of the Mediterranean fruit fly in field cage trials

AbstractThe sterile insect technique (SIT) is widely used in integrated programs against fruit fly pests, particularly the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Unfortunately, the mass‐rearing procedures inherent to the SIT often lead to a reduction in male mating competitiveness. One potential solution involves the pre‐release exposure of males to specific attractants. In particular, male exposure to ginger root oil [Zingiber officinale Roscoe (Zingiberaceae); hereafter GRO] has been shown to increase mating success dramatically in field cage trials. Initial studies exposed small groups of males (25 individuals), but more recent work has demonstrated that GRO exposure involving standard storage boxes (containing ≈ 36 000 males) also results in enhanced mating performance. The objective of the present study was to determine whether aromatization of entire trailers, holding ≈ 14 million sterile males from a genetic sexing [temperature sensitive lethal (tsl)] strain, increases male mating success. Independent of the total dose, spatial distribution, or type of dispenser used, sterile males exposed to GRO for a 24‐h period displayed greater mating success than non‐exposed males in mating cage trials (in which tsl males competed against males from a standard, bisexual strain for females from this same standard strain). Averaged over all experiments, tsl males exposed to GRO obtained 54% of all matings compared to 38% for non‐exposed tsl males, an increase of 42%. The implications of these findings for SIT programs against C. capitata are discussed.

MATING COMPETITIVENESS OF MASS-REARED MALES OF THE MEDITERRANEAN FRUIT FLY (DIPTERA: TEPHRITIDAE) FROM ECLOSION TOWERS

In Florida, an ongoing Preventative Release Program utilizes the sterile insect technique to prevent infestations of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann). Unlike other such programs, which use plastic, storage (PARC) boxes, the Florida operation holds pupae and newly emerged adults in eclosion towers prior to release. Although eclosion towers save space and labor, few data exist regarding the quality of sterile male medflies held in towers versus PARC boxes. Here, we present the results of field-cage trials comparing the mating success of sterile males held in towers versus PARC boxes. In addition, previous research has shown that exposing PARC box-held males to the aroma of ginger root oil (GRO) increases their mating competitiveness. Consequently, we assessed whether a similar increase was evident for tower-held males. Finally, we performed a mark-release-recapture study involving GRO-exposed and non-exposed males and estimated their relative survival and dispersal in the field using the trap catch data. Data from the mating trials showed that sterile males held in towers displayed approximately the same mating success as sterile males held in PARC boxes and that, among tower-held males, GRO significantly increased mating competitiveness relative to non-exposed males. In the trapping study, significantly more GRO-exposed males were captured than non-exposed males, and there was no apparent difference in the duration of the post-release interval over which GRO-exposed and non-exposed males were captured. These findings, along with earlier comparisons of adult weight, flight ability, and yield suggest no obvious differences in the efficacy of tower and PARC-box eclosion systems for medfly sterile release programs.

The sterile insect technique and the Mediterranean fruit fly: assessing the utility of aromatherapy in large field enclosures

AbstractThe sterile insect technique (SIT) is widely used in integrated programs against tephritid fruit flies, particularly the Mediterranean fruit fly, Ceratitis capitata Wiedemann (Diptera: Tephritidae). Unfortunately, the mass‐rearing procedures inherent to the SIT often lead to a reduction in the male mating competitiveness. One potential solution involves the prerelease exposure of males to particular attractants. In particular, male exposure to ginger root oil [Zingiber officinale Roscoe (Zingiberaceae); hereafter GRO], has been shown to increase mating success dramatically in field cage trials. To evaluate more rigorously the effectiveness of GRO exposure, we here describe two projects that compared levels of egg sterility or pupal yield, respectively, following the release of wild flies and either GRO‐exposed (treated) sterile males or GRO‐deprived (control) sterile males in large field enclosures. In both projects, sterile males from a genetic sexing strain were exposed as adults to GRO for 24 h while held in large storage boxes. In Hawaii, we dissected eggs from fruits to determine the percentage of egg hatch at four overflooding ratios, ranging from 5 : 1 to 60 : 1 (sterile : wild males), and found that, at all four ratios, the proportion of unhatched (sterile) eggs was significantly greater in enclosures containing GRO‐exposed males than control males. In Guatemala, we allowed larvae to develop in fruits and counted the number of pupae produced. At the only overflooding ratio tested (25 : 1), pupal yield was approximately 25% lower for enclosures containing GRO‐exposed males than control males, although this difference was not statistically significant. An explanation for the differing outcomes is proposed, and the implications of these findings for the SIT are discussed.

Aromatherapy in the Mediterranean fruit fly (Diptera: Tephritidae): sterile males exposed to ginger root oil in prerelease storage boxes display increased mating competitiveness in field-cage trials.

Previous research showed that exposure to ginger root, Zingiber officinale Roscoe, oil increased the mating success of mass-reared, sterile males of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). This work, however, involved the exposure of small groups of males (n = 25) in small containers (volume 400 ml). Several sterile male release programs use plastic adult rearing containers (so-called PARC boxes; hereafter termed storage boxes; 0.48 by 0.60 by 0.33 m) to hold mature pupae and newly emerged adults before release (approximately = 36,000 flies per box). The objective of the current study was to determine whether the application of ginger root oil to individual storage boxes increases the mating competitiveness of sterile C. capitata males. Irradiated pupae were placed in storage boxes 2 d before adult emergence, and in the initial experiment (adult exposure) ginger root oil was applied 5 d later (i.e., 3 d after peak adult emergence) for 24 h at doses of 0.0625, 0.25, 0.5, 1.0, and 2.0 ml. In a second experiment (pupal-adult exposure), ginger root oil was applied to storage boxes immediately after pupal placement and left for 6 d (i.e., 4 d after peak adult emergence) at doses of 0.25 and 1.0 ml. Using field cages, we conducted mating trials in which ginger root oil-exposed (treated) or nonexposed (control) sterile males competed against wild-like males for copulations with wild-like females. After adult exposure, treated males had significantly higher mating success than control males for all doses of ginger root oil, except 2.0 ml. After pupal-adult exposure, treated males had a significantly higher mating success than control males for the 1.0-ml but not the 0.25-ml dose of ginger root oil. The results suggest that ginger root oil can be used in conjunction with prerelease, storage boxes to increase the effectiveness of sterile insect release programs.

Aromatherapy in the Mediterranean Fruit Fly (Diptera: Tephritidae): Sterile Males Exposed to Ginger Root Oil in Prerelease Storage Boxes Display Increased Mating Competitiveness in Field-Cage Trials

Aromatherapy in the Mediterranean Fruit Fly (Diptera: Tephritidae): Sterile Males Exposed to Ginger Root Oil in Prerelease Storage Boxes Display Increased Mating Competitiveness in Field-Cage Trials

Effects of diet, ginger root oil, and elevation on the mating competitiveness of male Mediterranean fruit flies (Diptera: Tephritidae) from a mass-reared, genetic sexing strain in Guatemala.

The release of sterile males is a key component of an areawide program to eradicate the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), from Guatemala and southern Mexico. The objective of our study was to assess the effects of adult diet, exposure to ginger root oil (Zingiber officinale Roscoe), and elevation on the mating competitiveness of the sterile males used in an areawide program. Sterile males were maintained on a protein-sugar (protein-fed) or a sugar-only (protein-deprived) diet and were exposed (for 4 h 1 d before testing) or not exposed to ginger root oil. In field-cage trials conducted at a high (1,500 m) and low (700 m) site, we monitored the influence of these treatments on the mating success of sterile males in competition with wild males (reared exclusively on the protein-sugar diet and without ginger root oil exposure) for wild females. Elevation and ginger root oil exposure had significant effects, with sterile males having higher mating success at the low-elevation site and ginger root oil-exposed males having greater success than ginger root oil-deprived males at both sites. Diet did not have a significant overall effect, and its influence varied with elevation (dietary protein seemed to provide an advantage at the high-elevation site but not at the low-elevation site). Possible implications of these findings for eradication programs against the Mediterranean fruit fly are discussed.

Effects of Diet, Ginger Root Oil, and Elevation on the Mating Competitiveness of Male Mediterranean Fruit Flies (Diptera: Tephritidae) from a Mass-Reared, Genetic Sexing Strain in Guatemala

The release of sterile males is a key component of an areawide program to eradicate the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), from Guatemala and southern Mexico. The objective of our study was to assess the effects of adult diet, exposure to ginger root oil (Zingiber officinale Roscoe), and elevation on the mating competitiveness of the sterile males used in an areawide program. Sterile males were maintained on a protein-sugar (protein-fed) or a sugar-only (protein-deprived) diet and were exposed (for 4 h 1 d before testing) or not exposed to ginger root oil. In field-cage trials conducted at a high (1,500 m) and low (700 m) site, we monitored the influence of these treatments on the mating success of sterile males in competition with wild males (reared exclusively on the protein-sugar diet and without ginger root oil exposure) for wild females. Elevation and ginger root oil exposure had significant effects, with sterile males having higher mating success at the low-elevation site and ginger root oil-exposed males having greater success than ginger root oil-deprived males at both sites. Diet did not have a significant overall effect, and its influence varied with elevation (dietary protein seemed to provide an advantage at the high-elevation site but not at the low-elevation site). Possible implications of these findings for eradication programs against the Mediterranean fruit fly are discussed.