Male Annihilation Technique Research Articles

Electrophysiological Responses to Cuelure of Raspberry Ketone-Fed Queensland Fruit Flies.

The sterile insect technique (SIT) and male annihilation technique (MAT) are important tools for the control of Queensland fruit fly (Q-fly), Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), a major insect pest of horticultural crops in Australia. In MAT, mature Q-fly males are attracted to a toxic bait using Cuelure, a synthetic analog of raspberry ketone (RK). Substantial improvements in control could be achieved by simultaneous use of SIT and MAT, but this requires suppression of the Cuelure response in released sterile flies. Recent studies report that prerelease feeding with RK during the first 48 h after emergence can reduce the response of mature Q-fly males to Cuelure, but the mechanism underpinning this is unknown. Here, to test whether reduced sensory sensitivity to Cuelure is involved, we evaluated the effects of RK supplements, adult diet (yeast-supplemented diet throughout adult stage vs yeast-supplemented diet only for 48 h), and age on electroantennogram (EAG) and electropalpogram (EPG) responses of Q-flies to Cuelure stimuli. EAG responses did not vary with RK supplements, sex, or age of Q-flies fed yeast-supplemented diet throughout the adult stage, but the responses of Q-flies fed other diet regime decreased with age. EPG responses of both sexes of Q-flies were affected by RK supplements, age, and their interaction, but without patterns that might indicate reduced maxillary palp response of RK supplemented flies to Cuelure. Our findings do not support the hypothesis that reduced Cuelure response of male Q-flies fed RK supplements is explained by reduced electrophysiological response in antennae or maxillary palps.

Effectiveness of Selected Parapheromones for Mass Trapping of Mango Fruit Fly, Ceratitis cosyra Walker and Oriental Fruit Fly, Bactrocera dorsalis Hendel (Diptera: Tephritidae) on Mango

Mango (Mangifera indica L.) is an important fruit crop in Nigeria. It is a source of essential vitamins and is also cultivated for its nutritional, medicinal and industrial uses. Fruit flies infest various commercial fruit crops and cause economic damage. Mass trapping and male annihilation technique (MAT) has been the most useful and common means of controlling fruit flies with special focus on Bactrocera dorsalis Hendel (Diptera: Tephritidae) on mangoes. The study evaluated the effectiveness of four types of parapheromones namely, methyl eugenol (liquid and solid forms), cuelure, terpinyl acetate and trimedlure for mass trapping of fruit flies on Mango. Modified Lynfield traps containing the parapheromones were randomly set on the mango orchards in three replicates in Nigeria Horticultural Research Institute (NIHORT) orchard, Okigwe, Imo state, Southeast Nigeria. This study was conducted during the mango fruiting period of 2019 season, when the density of fruit flies peaked. Effect of parapheromones on mean number of damaged dropped fruits was also evaluated. The mean population of B. dorsalis and Ceratitis cosyra was significantly higher (P>0.05) in liquid methyl eugenol traps when compared to other parapheromones. Bactrocera dorsalis recorded more than 90% of the fruit flies that were trapped especially in the first 3 weeks of trapping. In orchard I, Liquid methyl eugenol significantly (P<0.05) trapped highest number of B. dorsalis (270.20) in week I and similar trends were observed in orchard II. There was steady decline in damaged dropped mango fruits as the study progressed (Fig. 1 and 2). Use of liquid methyl eugenol was most effective in trapping B. dorsalis and C. cosyra, and it can be incorporated in Integrated Pest Management (IPM) programmes for the control of fruit flies.

Evaluation of a Genetic Sexing Strain of the Oriental Fruit Fly as a Candidate for Simultaneous Application of Male Annihilation and Sterile Insect Techniques (Diptera: Tephritidae).

The oriental fruit fly, Bactrocera dorsalis (Hendel), is an important pest of fruits and vegetables, and many countries operate surveillance programs to detect infestations and, if needed, implement costly control efforts. The Male Annihilation Technique (MAT), which involves deployment of the male lure methyl eugenol (ME) to reduce or eliminate the male population, has been used as a stand-alone strategy or as a precursor to the Sterile Insect Technique (SIT), which involves the release of sterile males to generate sterile male by wild female crosses and the production of inviable progeny. Modeling suggests that simultaneous implementation of MAT and SIT, rather than sequential deployment, increases the probability of successful eradication. Previous research has shown that B. dorsalis males that have fed on ME show reduced tendency to re-visit ME sources. Also, males fed ME gain a mating advantage over nonfed males. The goal of the present study was to evaluate the suitability of a genetic sexing strain of B. dorsalis as a candidate for concurrent implementation of MAT and SIT. Evaluation focused on the timing of prerelease exposure to methyl eugenol to identify the male age at which feeding upon the lure both i) reduces postrelease attraction to ME-baited traps (thus allowing the operation of MAT) and ii) enhances postrelease mating competitiveness (thus increasing the effectiveness of SIT). Results indicate that prerelease ME feeding by 6-d-old males, with release the following day, would allow effective, concurrent implementation of MAT and SIT.

Assessment of Olfactory Responses of Bactrocera zonata, B. cucurbitae and B. Dorsalis (Diptera: Tephritidae) to different biolure baits and Combined Use of Male Annihilation Technique (MAT) and sterile insect technique (SIT) in IPM programme for Bactorecera Fruit Flies

Assessment of Olfactory Responses of Bactrocera zonata, B. cucurbitae and B. Dorsalis (Diptera: Tephritidae) to different biolure baits and Combined Use of Male Annihilation Technique (MAT) and sterile insect technique (SIT) in IPM programme for Bactorecera Fruit Flies

Improving Chemo Taxis Effects of Methyl Eugenol Bait against Two Fruit Fly Species in Jujube Orchards Located in Tandojam, Pakistan

This study was designed to use different food additives to improve the efficacy of the Male Annihilation Technique (MAT) against fruit flies. The experiment was carried out at the Jujube Section, Agriculture Research Institute, Tandojam, Pakistan, during the beginning of jujube season (January to April) 2017. Methyl eugenol was tested in the presence of different food essences i.e. lemon (T1), strawberry (T2), almond (T3) and orange (T4), whereas; methyl eugenol (T5) without any essence was used as control. The experiment was laid out in a randomized complete block design (RCBD) with four blocks. Two fruit fly species; Bacterocera zonata and B. dorsalis were identified from the captured individuals. Our data revealed that the mean number of B. zonata collected was 1914.88, while the mean number of B. dorsalis collected was 148.69. The most efficient trap was T1 (Methyl eugenol + lemon essence), whereas; the lowest number of captures was observed at control traps. Furthermore, the highest numbers of flies from both species were recorded during the month of April, while the lowest number of captures was observed in January. The highest number of B. zonata and B. dorsalis were 334.14±9.39 and 17.25±0.75, respectively. In terms of treatment, the highest number of B. dorsalis was recorded with the lemon flavor (46.68); whereas, the lowest was observed in the control (17.02). There was a positive association between temperature and wind velocity for both B. zonata and B. dorsalis, whereas there was negative association with humidity. On the basis of the above mentioned results it is concluded that different food essences can enhance the capability of methyl eugenol to attract the fruit flies.

A field test on the effectiveness of male annihilation technique against Bactrocera dorsalis (Diptera: Tephritidae) at varying application densities.

Male Annihilation Technique (MAT) is a key tool to suppress or eradicate pestiferous tephritid fruit flies for which there exist powerful male lures. In the case of Bactrocera dorsalis (Hendel), a highly invasive and destructive species, current implementations of MAT utilize a combination of the male attractant methyl eugenol (ME) and a toxicant such as spinosad (“SPLAT-MAT-ME”) applied at a high density with the goal of attracting and killing an extremely high proportion of males. We conducted direct comparisons of trap captures of marked B. dorsalis males released under three experimental SPLAT-MAT-ME site densities (110, 220, and 440 per km2) near Hilo, Hawaii using both fresh and aged traps to evaluate the effectiveness of varying densities and how weathering of the SPLAT-MAT-ME formulation influenced any density effects observed. Counterintuitively, we observed decreasing effectiveness (percent kill) with increasing application density. We also estimated slightly higher average kill for any given density for weathered grids compared with fresh. Spatial analysis of the recapture patterns of the first trap service per replicate x treatment reveals similar positional effects for all grid densities despite differences in overall percent kill. This study suggests that benefits for control and eradication programs would result from reducing the application density of MAT against B. dorsalis through reduced material use, labor costs, and higher effectiveness. Additional research in areas where MAT programs are currently undertaken would be helpful to corroborate this study’s findings.

Chemotaxis of fruit fly species against Methyl eugenol in the presence of different food flavours in a guava orchard

Abstract Male annihilation technique has been successfully used against fruit flies. Number of experiments has been performed to improve this technique for more effective results. Similarly, in this study, different food additives were used in methyl eugenol traps to improve the attraction of the lure. A Randomized Complete Block Design experiment was designed and conducted at guava orchard in Agriculture Research Institute Tando Jam during the 2017 season. In each treatment, two wicks were used simultaneously, whereby one wick of methyl eugenol (ME 4ml/wick) contained 85% methyl eugenol, 10% sugar and 5% insecticide and the other 4ml/wick contained different food essences. The treatment were; T1 (ME+ lemon essence), T2 (ME + Mango essence), T3 (ME + Vanilla), T4 (ME + Orange essences) and T5 was used as control with only ME solution. Each treatment had four replications. Two Tephritid species; Bactrocera zonata and B. dorsalis were captured. The maximum mean number of B. zonata recorded was for T1 (312.72±4.39), while the minimum number of flies was captured in T5 (225.39±4.47). The results revealed that, the highest mean numbers of B. zonata (238.81±11.39) was in April while the minimum population was obtained in January (3.23±0.41). High significant difference (p<0.001) was recorded between treatments. Maximum number of B. dorsalis was collected in T1 (30.98±1.94), whereas; minimum number of flies was captured in T4 (17.62±1.64) and it reached its highest number in April (15.1±0.10). Positive correlation was reported between all treatments and temperature while it was negative with relative humidity. Keywords: Bactrocera dorsalis; Bactrocera zonata; Food essences; Guava; MAT http://dx.doi.org/10.19045/bspab.2018.700204

Raspberry ketone-supplemented diet has no effect on fitness parameters or lure responsiveness in male melon flies, Zeugodacus cucurbitae (Diptera: Tephritidae)

Abstract The male annihilation technique (MAT) and sterile insect technique (SIT) are often used to control pestiferous tephritid fruit flies (Diptera: Tephritidae). MAT involves the deployment of traps containing a male attractant and insecticide with the goal of drastically reducing male abundance and ultimately eliminating the entire population. SIT, which involves the mass production, sterilization, and release of the target species, may also be implemented to achieve final extirpation. Generally, simultaneous implementation of MAT and SIT is counterproductive, because the presence of large numbers of male-specific traps in the environment (MAT) would greatly reduce the number of sterile males available for copulating with wild females (SIT). However, studies on the Queensland fruit fly, Bactrocera tryoni (Froggatt), indicate that concurrent use of MAT and SIT may be feasible. Sexually mature males of B. tryoni are attracted to the raspberry ketone and its synthetic analogue cue-lure. Males of B. tryoni fed raspberry-ketone-supplemented diet when newly emerged showed lower attraction to cue-lure baited traps than control males. In addition, newly emerged males provided this diet displayed accelerated sexual maturation, which would allow the early release of sterile males and reduce pre-release holding costs. Here, we examined whether the addition of raspberry ketone to the adult diet of male melon flies, Zeugodacus cucurbitae (Coquillett), produced effects similar to those observed for B. tryoni. Despite using similar methods, no significant effect of raspberry ketone-supplemented diet on time to sexual maturity, survival, mating competitiveness, or attraction to cue-lure baited traps in mass-reared Z. cucurbitae males.

Correction: Suppression of cuelure attraction in male Queensland fruit flies provided raspberry ketone supplements as immature adults.

[This corrects the article DOI: 10.1371/journal.pone.0184086.].

Efficiency of Wooden Blocks for Attracting Peach Fruit Fly Males in Relation with Weather Conditions Effect on Loss of Methyl Eugenol under Field Conditions

The peach fruit fly, Bactrocera zonata (Saunders) is one of the most harmful tephtitid flies that infesting many commercial fruits causing a significant economic damage. The current study aims to evaluate the performance of open air blocks, plastic traps and cylindrical net traps for attracting and killing B. zonata males. Also, the study extends to assess the loss rate of methyl eugenol and Sumithion mixture(MES) under different weather conditions. The study was carried out in orchards at Fayoum governorate under different weather conditions throughout 4 successive climatic seasons including autumn (2016), winter (2016/2017), spring (2017), and summer (2017). Throughout autumn season, the net traps were significantly the most attracting with mean of 70.69 flies/trap/day followed by open air blocks, and plastic traps with respective means of 43.49 and 36.18 flies/trap/week. While, during summer season, the fresh blocks captured significantly the highest numbers of males followed by weathered open air blocks, plastic traps and net traps with the respective means of 194.87, 59.90, 38.20 and 29.26 flies / trap /week . The blocks were impregnated with a mean quantity of 10.34 cm3/ block during successive seasons, the MES loss rate of open air blocks during summer season was the highest and fastest averaging 55.13,67.51 and 71.67 % of its initial impregnated quantities after 4, 8 and 12 weeks of exposure respectively. While, during winter season, the loss rate % was the lowest and slowest averaging 8.49, 15.22 and 22.42 % of its initial impregnated quantities after 4, 8 and 12 weeks of exposure, respectively. The blocks of plastic traps were the lowest for losing MES followed by that fixed internally in cylindrical net traps during successive climatic seasons. Temperature correlated significantly with the loss rate for all tested blocks and was the significant variable factor that affecting the linear regression during autumn, winter and spring seasons, while, R.H. % was effective during summer season. Results indicated that the open air blocks are still the best for B.zonata males attraction up to 4 weeks for male annihilation technique (MAT) applications, however, there is a necessity for saving an alternative dispenser has the ability to lose its content of MES in regular release.

Sexual maturation of male Bactrocera correcta (Diptera: Tephritidae) and age-related responses to β-caryophyllene and methyl eugenol

Sexual maturation of male Bactrocera correcta (Bezzi) and age-related responses to β-caryophyllene (CP) and methyl eugenol (ME) were examined to identify effective attractants for sexually immature males of the species. Sexual maturation rates (100 × number of cages containing males which attained sexual maturity/total number of cages at a given day) over different ages were 0.0%, 6.7%, and 100.0% for 5-, 6-, and 13-day-old, respectively, and at all the different ages, more males were captured with CP than with ME. The capture rate (the predicted probability by logistic regression) with CP was 29.7% (30.6%) for 5-day-old males, which were still sexually immature, and 52.7% (38.2%) for 6-day-old males, for which the earliest sexual maturation was observed. In contrast, no 5-day-old males responded to ME (the probability was 12.6%), and the capture rate (the probability) of 6-day-old males was merely 0.3% (14.5%), while the rate gradually increased later. The present study revealed that certain males of B. correcta responded to CP prior to sexual maturation but not to ME under the laboratory conditions. These results imply that CP could be an effective attractant used in male annihilation techniques for B. correcta and that ME may not be useful.

Semiochemical mediated enhancement of males to complement sterile insect technique in management of the tephritid pest Bactrocera tryoni (Froggatt)

Queensland fruit fly, Bactrocera tryoni (Froggatt), is the most significant pest of Australia’s $9 billion horticulture industry. The sterile insect technique (SIT) and cue-lure (a synthetic analogue of raspberry ketone (RK))-based male annihilation technique (MAT) are two of the most effective management tools against this pest. However, combining these two approaches is considered incompatible as MAT kills sterile and ‘wild’ males indiscriminately. In the present study we tested the effect of pre-release feeding of B. tryoni on RK on their post-release survival and response to MAT in field cages and in a commercial orchard. In both settings, survival was higher for RK supplemented adults compared to control (i.e. RK denied) adults. A lower number of RK supplemented sterile males were recaptured in MAT baited traps in both the field cages and orchard trials compared to RK denied sterile males. The advantage of this novel “male replacement” approach (relatively selective mortality of wild males at lure-baited traps while simultaneously releasing sterile males) is increasing the ratio of sterile to wild males in the field population, with potential for reducing the number of sterile males to be released.

Suppression of cuelure attraction in male Queensland fruit flies provided raspberry ketone supplements as immature adults.

Tephritid fruit flies are amongst the most damaging insect pests of horticulture globally. Some of the key fruit fly species are managed using the sterile insect technique (SIT), whereby millions of sterile males are released to suppress reproduction of pest populations. Male annihilation technique (MAT), whereby sex specific lures are used to attract and kill males, is often used to reduce wild male numbers before SIT programs commence, providing released sterile males an increased numerical advantage. Overall program efficacy might be improved if MAT could be deployed simultaneously with SIT, continuously depleting fertile males from pest populations and replacing them with sterile males. However, such ‘male replacement’ requires a means of suppressing attraction of released sterile males to lures used in MAT. Previous studies have found that exposure of some fruit flies to lure compounds as mature adults can suppress subsequent response to those lures, raising the possibility of pre-release treatments. However, this approach requires holding flies until after maturation for treatment and then release. The present study takes a novel approach of exposing immature adult male Queensland fruit flies (Bactrocera tryoni, or ‘Qfly’) to raspberry ketone (RK) mixed in food, forcing these flies to ingest RK at ages far younger than they would naturally. After feeding on RK-supplemented food for two days after emergence, male Qflies exhibited a reduction in attraction to cuelure traps that lasted more than 20 days. This approach to RK exposure is compatible with current practises, in which Qflies are released as immature adults, and also yields advantages of accelerated reproductive development and increased mating propensity at young ages.

Management and eradication options for Queensland fruit fly

AbstractSeveral tephritid fruit flies have explosive population growth and a wide host range, resulting in some of the largest impacts on horticultural crops, reducing marketable produce, and limiting market access. For these pests, early detection and eradication are routinely implemented in vulnerable areas. However, social and consumer concerns can limit the types of population management tools available for fruit fly incursion responses. Deterministic population models were used to compare eradication tools used at typical densities alone and in combination against the Queensland fruit fly (‘Qfly’), Bactrocera tryoni. The models suggested that tools that prevent egg laying are likely to be most effective at reducing populations. Tools that induced mortality once Qfly was sexually mature only slowed population growth, as successful mating still occurred. Release of sterile Qfly when using the sterile insect technique (SIT) interferes with the successful mating of wild flies, and of the tools investigated here, SIT caused the greatest reduction in the population at the prescribed release rate. Used in tandem with SIT, protein baits slightly improved the rate of population reduction, but the male annihilation technique (MAT) almost nullified control by SIT due to the mortality induced on sterile flies. The model suggested that the most rapid decrease in population size would be achieved by SIT plus protein baits. However, the model predicted both the SIT and protein baits when used alone would result in population reduction. The MAT can be used prior to SIT release to increase overflooding ratios.

Survivorship of male and female Bactrocera dorsalis in the field and the effect of male annihilation technique

AbstractMale annihilation technique (MAT) is a key component of management of the Oriental fruit fly, Bactrocera dorsalis Hendel (Diptera: Tephritidae), because of the ‘strong’ attraction of males to the lure methyl eugenol. The optimal application density for MAT has not been investigated for this economically important pest species. We tested the effect of two levels of MAT application density compared to a no‐MAT control on the daily survivorship of male and female B. dorsalis estimated by mark‐release‐recapture (MRR) using a 1‐km2 passive sampling network. Estimated daily survivorship from two separate MRR trials under control (no MAT) conditions was 0.751 for males and 0.948 for females. Male survivorship was similar under control (no MAT) and high application density (256 spots km−2; daily survivorship 0.704). However, estimated male survivorship was significantly lower under the low application density (100 spots km−2; daily survivorship 0.211). A similar pattern was observed in estimated female survivorship, with a significant reduction in survivorship under the low rate compared with control and high application density (low‐density estimated survivorship 0.652, high density 0.881). The results suggest that a lower application density may be more effective against B. dorsalis than the high application density. A lower application density for effective MAT would benefit growers and the public with respect to management of B. dorsalis through reduced labor and material costs, limiting potential environmental impacts, and increased logistical simplicity finding application sites in urban environments.

Raspberry Ketone Analogs: Vapour Pressure Measurements and Attractiveness to Queensland Fruit Fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae).

The Queensland fruit fly, Bactrocera tryoni (Froggatt) (Q-fly), is a major horticultural pest in Eastern Australia. Effective monitoring, male annihilation technique (MAT) and mass trapping (MT) are all important for control and require strong lures to attract flies to traps or toxicants. Lure strength is thought to be related in part to volatility, but little vapour pressure data are available for most Q-fly lures. Raspberry ketone (4-(4-hydroxyphenyl)-2-butanone) and analogs that had esters (acetyl, difluoroacetyl, trifluoroacetyl, formyl, propionyl) and ethers (methyl ether, trimethylsilyl ether) in replacement of the phenolic group, and in one case also had modification of the 2-butanone side chain, were measured for their vapour pressures by differential scanning calorimetry (DSC), and their attractiveness to Q-fly was assessed in small cage environmentally controlled laboratory bioassays. Maximum response of one category of compounds, containing both 2-butanone side chain and ester group was found to be higher than that of the other group of compounds, of which either of 2-butanone or ester functionality was modified. However, linear relationship between vapour pressure and maximum response was not significant. The results of this study indicate that, while volatility may be a factor in lure effectiveness, molecular structure is the dominating factor for the series of molecules investigated.

Specialized Pheromone and Lure Application Technology as an Alternative Male Annihilation Technique to Manage Bactrocera tryoni (Diptera: Tephritidae).

The results of this study suggest that a novel male annihilation technique (specialized pheromone and lure application technology [SPLAT] incorporating cue-lure [CL] plus spinosad) is as effective as industry standard male annihilation controls, and is worth exploring further to manage Bactrocera tryoni (Froggatt) populations. Three lures were evaluated in a contact and feeding bioassay and a cage attractancy trial: 1) SPLAT-CL + spinosad; 2) SPLAT-CL without spinosad; and 3) wick-CL + malathion. In a field attraction trial, lures (1) and (3) were evaluated with a third treatment, caneite blocks-CL + malathion. Lures were weathered for 0, 1, 2, 4, or 8 wk, with an additional weathering treatment of 12 wk included in the field trial. In the contact and feeding bioassay, lures with SPLAT-CL + spinosad were >97% effective at 48 h for up to 2 wk weathering; however, wicks-CL + malathion killed B. tryoni within 2 h of exposure under all weathering periods. In the cage attractancy trial, SPLAT-CL + spinosad was as effective as, or performed better than, wicks-CL + malathion under all weathering treatments. The field study trap catches were similar for SPLAT-CL + spinosad and blocks-CL + malathion, and both had higher trap catches than wicks-CL + malathion at all weathering periods, except week 12. Overall, SPLAT-CL + spinosad compared favorably with current standard techniques for male annihilation and warrants further research. SPLAT-CL + spinosad may be a reduced-risk alternative for wicks-CL + malathion or blocks-CL + malathion for B. tryoni and other CL-responding fruit flies, such as Bactrocera cucurbitae Coquillett, because it contains a reduced-risk insecticide that poses a lower risk to humans and the environment and does not require labor-intensive handling and placement.

Male Annihilation Technique Using Methyl Eugenol for Field Suppression ofBactrocera dorsalis(Hendel) (Diptera: Tephritidae) on Mango in Kenya

The Oriental fruit fly, Bactrocera dorsalis (Hendel), is one of the most devastating tephritid fruit flies of horticulture worldwide. Field trials were carried out for two seasons on mango (Mangifera indica L.) to evaluate the use of male annihilation technique (MAT) using methyl eugenol laced with deltamethrin instead of the commonly used malathion for the suppression of the pest on mango in coastal Kenya. Prior to application of the MAT, mean total numbers of B. dorsalis flies per trap per day (FTD) in pre-suppression monitoring data were comparable in orchards assigned to MAT treatment (FTD = 3.5) and those assigned to the control (FTD = 3.5) in season 1 and 12.4 and 10.5 FTD, respectively, in season 2. Following the application of MAT systems, total FTD were significantly lower in MAT-treated orchards (0.1 and 2.7 FTD, for seasons 1 and 2, respectively) compared to that in the control (18.6 and 21.5 FTD, for seasons 1 and 2, respectively) at 49 days after deployment of the control measures. This repre...

Hydrolysis of Queensland Fruit Fly, Bactrocera tryoni (Froggatt), Attractants: Kinetics and Implications for Biological Activity

Queensland fruit fly (Q-fly), Bactrocera tryoni (Froggatt), is a major insect pest of horticultural crops in Australia. Cuelure is the most commonly used attractant for monitoring as well as for management of Q-fly populations through the male annihilation technique and mass trapping. There has been some concern that cuelure is susceptible to hydrolysis, which would limit its usefulness under conditions of high humidity and give rise to inconsistent fly population monitoring. To give some insight into the hydrolysis of cuelure and two closely related compounds, melolure and a newly developed lure, 4-(4-(2,2,2-trifluoroacetoxy)phenyl)-2-butanone (RKTA), the kinetics of hydrolysis of these compounds were quantitatively investigated by gas chromatography–flame ionization detection. From the experimental data, we found the hydrolysis half-lives of cuelure, melolure, and RKTA, at a water concentration of 25 mol L–1, to be ~20 days, 22 h, and 1.2 min respectively. When extrapolated to a water concentration of 1.3 mmol L–1, corresponding to atmospheric conditions of 100 % relative humidity at 25°C, the half-lives are ~1660, ~51, and ~1.4 years respectively.

Impact assessment of Integrated Pest Management (IPM) strategy for suppression of mango-infesting fruit flies in Kenya

We utilized two waves of data collected from a sample of mango farmers in Meru County in Kenya to evaluate the impact of Integrated Pest Management (IPM) strategy for controlling fruit flies in mango-production. We specifically explored the effect of five IPM practices including parasitoids (p) and Metarhizium anisopliae-based biopesticides (biop), orchard sanitation (os), spot spray of food bait (fb) and male annihilation technique (mat) on three outcome indicators: farmer pesticide expenditure, farm-level mango fruit yield losses and profit. We fitted difference-in-difference and household fixed effects regression models that account for unobserved heterogeneity across households. Our estimates differentiated the impact of the different IPM components, in comparison to farmers' practices as a control group. The descriptive statistics of the study show that application of the IPM strategy resulted in a 48% average increase in mango net income compared to the previous season irrespective of the IPM combination component used. The extent of improvement in net income, however, varied across treatments; treatments posfb and posmatfb registering the greatest improvements whereas the pos treatment generated the smallest increase in net income. The study findings further show mango yield losses due to fruit fly infestation reduced by an average of 19% among the IPM users. We also found a reduction in expenditure on pesticides, albeit across all the households. Regression model estimates show that, except for IPM combinations posbiop and pos, farmers using the rest of the IPM practices recorded significantly higher incomes from mango compared to their counterparts in the control group. We also noted that although average expenditure on pesticides decreased across all mango farmer households, the reduction was comparable between the treated and control farmer households. Our findings however, show significant decreases in mango damage due to fruit fly infestations among all farmers using the different IPM treatments. Our study recommends combinations of affordable and easy to apply and maintain IPM strategies that could yield significant impact on mango fruit fly control.