Male Annihilation Technique Research Articles

Evaluating the Efficacy of the Male Annihilation Technique in Managing Oriental Fruit Fly (Diptera: Tephritidae) Populations through Microscopic Assessment of Female Spermathecae.

The male annihilation technique (MAT) plays a crucial role in the pest management program of the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae). However, a suitable method for real-time and accurate assessment of MAT's control efficiency has not been established. Laboratory investigations found that motile sperms can be observed clearly under the microscope when the spermathecae dissected from mated females were torn, and no sperms were found in the spermathecae of virgin females. Furthermore, it was confirmed that sperms can be preserved in the spermathecae for more than 50 days once females have mated. Laboratory results also indicated that proportion of mated females decreased from 100% to 2% when the sex ratio (♀:♂) was increased from 1:1 to 100:1. Further observation revealed that there were no significant differences in the superficial area of the ovary or spermatheca between mated females and virgin females. Field investigations revealed that the proportion of mated females (PMF) could reach 81.2% in abandoned mango orchards, whereas the PMF was less than 36.4% in mango orchards where MAT was applied. This indicates that the PMF of the field population can be determined by examining the presence of sperms in the spermathecae. Therefore, we suggest that this method can be used to monitor the control efficiency when MAT is used in the field.

Comparative Responses of Two Major Cucurbit Pests, Zeugodacus cucurbitae and Zeugodacus tau to Phenylbutanoid Male Lures.

Zeugodacus cucurbitae and Z. tau are two major fruit fly pests of cucurbitaceous plants in the tropical and subtropical regions. The former species has a broader host range and wider world distribution than the latter. With global climate change, Z. tau shows great potential for geographical expansion with several invasion records in recent years. Males of both species are attracted to cue lure (CL) (and raspberry ketone (RK), a deacetyl derivative of CL), a common male lure used in fruit fly population detection, monitoring and control programs. Males of both species are also known to respond to zingerone (ZN), which are produced by some rainforest orchids. Previous studies have shown that fruit fly-male lure interactions are unique to species and lure types, and significantly impact the success of a lure-based fruit fly control program. We seek to compare the attraction of Z. cucurbitae and Z. tau males to CL, RK and ZN via Probit behavioral assays. Our results showed that CL is more attractive to Z. cucurbitae and Z. tau males than RK, while ZN is a poor lure for both species. Attraction Z. tau to CL is slightly lower than Z. cucurbitae, but the former is at least 1.71 times less attractive to RK than the latter. Together with published information on species' sexual development, our current study indicates a lure-based control program via male annihilation technique for Z. tau will be more challenging than Z. cucurbitae and should incorporate other integrated pest management strategies for a desirable outcome.

Evaluation of methyl eugenol-supplemented diet as pre-release treatment for simultaneous application of male annihilation and sterile insect techniques against Bactrocera dorsalis

Evaluation of methyl eugenol-supplemented diet as pre-release treatment for simultaneous application of male annihilation and sterile insect techniques against Bactrocera dorsalis

Consumption of β-Caryophyllene Increases the Mating Success of Bactrocera zonata Males (Diptera: Tephritidae).

The peach fruit fly, Bactrocera zonata (Saunders) (Diptera: Tephritidae), is an economically important polyphagous quarantine pest of horticultural crops endemic to South and Southeast Asia. Methyl eugenol (ME), a naturally occurring phenylpropanoid, is a male attractant used to lure and (when mixed with an insecticide) annihilate the males from the wild population, a method of pest control termed the male annihilation technique (MAT). ME is reported to enhance the mating success of sterile males of Bactrocera spp., which is critical for enhancing the effectiveness of the sterile insect technique (SIT). The suppressed response of ME-treated males to ME-baited traps/devices allows the simultaneous application of the MAT and SIT, increasing the efficiency of area-wide integrated pest management (AW-IPM) programs. However, ME treatment in sterile males in SIT facilities is logistically difficult. β-caryophyllene (BCP) is a widely occurring, safer plant compound and is considered suitable for treating males in SIT facilities. Here, we demonstrate that BCP feeding enhanced B. zonata male mating success to the same extent as ME feeding. Feeding on BCP suppressed the male's subsequent attraction to ME-baited traps, but not to the same degree as feeding on ME. The results are discussed and BCP is suggested as an alternative to ME for the concurrent use of the MAT and SIT.

Less is more: Fewer attract-and-kill sites improve the male annihilation technique against Bactrocera dorsalis (Diptera: Tephritidae).

The Male Annihilation Technique (also termed the Male Attraction Technique; "MAT") is often used to eradicate pestiferous tephritid fruit flies, such as Bactrocera dorsalis (Hendel). MAT involves the application of male-specific attractants combined with an insecticide in spots or stations across an area to reduce the male population to such a low level that suppression or eradication is achieved. Currently, implementations of MAT in California and Florida targeting B. dorsalis utilize the male attractant methyl eugenol (ME) accompanied with a toxicant, such as spinosad, mixed into a waxy, inert emulsion STATIC ME (termed here "SPLAT-MAT-ME"). While highly effective against ME-responding species, such applications are expensive owing largely to the high cost of the carrier matrix and labor for application. Until recently the accepted protocol called for the application of approximately 230 SPLAT-MAT-ME spots per km2; however, findings from Hawaii suggest a lower density may be more effective. The present study adopted the methods of that earlier work and estimated kill rates of released B. dorsalis under varying spot densities in areas of California and Florida that have had recent incursions of this invasive species. Specifically, we directly compared trap captures of sterilized marked B. dorsalis males released in different plots under three experimental SPLAT-MAT-ME densities (50, 110, and 230 per km2) in Huntington Beach, CA; Anaheim, CA; and Sarasota-Bradenton, FL. The plots with a density of 110 sites per km2 had a significantly higher recapture proportion than plots with 50 or 230 sites per km2. This result suggests that large amounts of male attractant may reduce the ability of males to locate the source of the odor, thus lowering kill rates and the effectiveness of eradication efforts. Eradication programs would directly benefit from reduced costs and improved eradication effectiveness by reducing the application density of SPLAT-MAT-ME.

Methyl eugenol aromatherapy: a delivery system facilitating the simultaneous application of male annihilation and sterile insect technique against the peach fruit fly.

The peach fruit fly, Bactrocera zonata (Saunders) (Diptera: Tephritidae) is an economically important polyphagous, quarantine pest endemic to South and South-East Asia. The male annihilation technique (MAT) and the sterile insect technique (SIT) are environmentally benign techniques used to suppress fruit fly populations on an area-wide basis. The MAT and SIT are typically used sequentially to avoid killing released sterile males; however, MAT and SIT potentially could be used simultaneously and thereby increase the overall efficiency of control programmes. Mating competitiveness of sterile males against wild counterparts is critical for the success of the SIT. Feeding on a semiochemical, methyl eugenol (ME) has been reported to enhance the male mating performance of many Bactrocera spp., including B. zonata, but its use in SIT operational programmes is limited owing to the absence of a viable delivery system. In the present study, we demonstrated that ME aromatherapy, a practical method for large-scale delivery of ME olfactorily, enhances the mating success of treated B. zonata males. ME aromatherapy application to 5-day-old immature males for a duration of 5 h resulted in increased mating success of males tested when sexually mature, compared to untreated males. The ME-aromatized males also exhibited reduced attraction to ME-lure. A practical delivery system for applying ME by aromatherapy to mass-reared males was developed. ME-aromatherapy enhanced male mating success and suppressed their subsequent attraction to ME, thus enabling the application of MAT and SIT at the same time. © 2023 Society of Chemical Industry.

The economic performance of mango integrated pest management practices at different scales of production.

Integrated pest management (IPM) strategies are being promoted to suppress tephritid fruit fly infestation and reduce economic damage in mango production. However, research on their economic performance across different mango production scales (measured by the number of mango trees) is limited. This study estimated the economic benefits of IPM practices (parasitoids, orchard sanitation, food bait, biopesticides, male annihilation technique, and their combinations) in Kenya's small-, medium-, and large-scale mango production systems. We used the value-cost ratio (VCR) and net present value methods to estimate the heterogeneous economic performance of IPM practices using data from two unique farm surveys. On average, all IPM practices were profitable across various production scales. However, we found that these practices were more profitable for medium-scale farmers than for small- and large-scale farmers. The results show that farmers need a minimum of 9-17 trees, depending on the practice used, to break even and that there are little to no economic benefits to using IPM practices for farmers with more than 320 mango trees. The male annihilation technique was the most profitable practice, with a VCR of 36, and consequentially, the most adopted practice across all scales of production. Overall, we found significant heterogeneity in the profitability of IPM practices across different scales of production. The reason for the lack of profitability of IPM on large-scale farms remains unclear and warrants further investigation.

One size does not fit all: Heterogeneous economic impact of integrated pest management practices for mango fruit flies in Kenya—a machine learning approach

AbstractMost previous studies evaluating agricultural technology adoption focus on estimating homogeneous average treatment effects across technology adopters. Understanding the heterogeneous effects and drivers of impact heterogeneity should enable interventions to be better targeted to maximise benefits. We apply machine learning using data from a randomised controlled trial to estimate the heterogeneous treatment effect of fruit fly IPM practices (i.e., parasitoids, orchard sanitation, use of food bait, biopesticides, male annihilation technique, and their combinations) in Central Kenya. Results suggest significant heterogeneity in the effect of IPM practices conditioned on household characteristics. The most important covariates explaining differences in treatment effects are wealth, distance to the mango fruit market, age of the household head, labour and experience in mango farming. Results further indicate that those with fewer mango trees benefit more from most IPM practices. Additional analysis across other covariates shows mixed results but generally suggests significant differences between households benefiting the most and those benefiting the least from IPM practices.

Response of some mango-infesting fruit flies to aqueous solutions of the basil plant Ocimum tenuiflorum L

IntroductionHorticulture is an important sub-sector for many African countries. Tephritid fruit flies continue to cause serious direct and indirect damage to the sub-sector. The male annihilation technique (MAT) using methyl eugenol (ME) is among the most revered techniques in fruit fly management. However, ME-based lures are only available to some farmers in Africa. Several basils of the genus Ocimum produce ME.MethodsIn laboratory experiments, we used a dual choice olfactometer to assess the attraction of adult oriental fruit fly Bactrocera dorsalis to intact plants, 100 µL commercial methyl eugenol (ME) (positive control), 10 mg/mL of O. tenuiflorum aqueous extract (Otae), and a negative control (blank). Large arena experiments were conducted to compare the responses of four fruit fly species of economic importance in Africa to Otae-baited traps.ResultsIn dual choice olfactometer assay, more B. dorsalis males (78.6%) than females (23.8%) were attracted to Otae. Most B. dorsalis males were attracted to the positive control (90.5%) and 10 mg/mL Otae (88.5%) compared to the whole plant (84.0%). In large arena experiments, Otae attracted the most B. dorsalis males (47.7%), followed by Zeugodacus cucurbitae males (25.1%), while males of Ceratitis species were the least attracted. The analysis of headspace volatiles from aerial plants, Otae and essential oil using gas chromatography-mass spectrometry detected 97 compounds. The intact plant without flowers, intact plant with flowers, Otae, and the O. tenuiflorum essential oil contributed 76, 62, 33 and 28 compounds, respectively. ME comprised the top three most abundant compounds, especially in the essential oil.DiscussionOur study confirms the potential of O. tenuiflorum as a source of ME for tephritid fruit fly integrated management in Africa. Otae, a readily available alternative to commercial ME, can be used to develop fruit fly-baited traps, particularly for smallholder farmers.

Assessment of non-methyl eugenol-responding lines of Bactrocera dorsalis (Diptera: Tephritidae) males on lure response and mating.

Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is a major global pest of fruits. Currently, the sequential male annihilation technique, followed by the sterile insect technique has been used to significantly reduce the population of feral males in this species. However, issues with sterile males being killed by going to male annihilation traps have reduced the efficacy of this approach. The availability of males that are non-methyl eugenol-responding would minimize this issue and increase the efficacy of both approaches. For this, we recently established two separate lines of non-methyl eugenol-responding males. These lines were reared for 10 generations and in this paper, we report on the assessment of males from these lines in terms of methyl eugenol response and mating ability. We saw a gradual decrease in non-responders from ca. 35 to 10% after the 7th generation. Despite that, there were still significant differences until the 10th generation in numbers of non-responders over controls using laboratory strain males. We did not attain pure isolines of non-methyl eugenol-responding males, so we used non-responders from the 10th generation of those lines as sires to initiate two reduced-responder lines. Using these reduced responder flies, we found that there was no significant difference in mating competitiveness when compared with control males. Overall, we suggest that it may be possible to establish lines of low or reduced responder males to be used for sterile release programs, that could be applied until the 10th generation of rearing. Our information will contribute to the further development of an increasingly successful management technique incorporating the use of SIT alongside MAT to contain wild populations of B. dorsalis.

Predicting point-source invasion success in the Queensland fruit fly (Bactrocera tryoni): An individual-based modelling approach

Fruit flies are a major pest worldwide for fruit producing industries. Incursions into fly free areas usually occurs via infested fruit; however, little is reported about the size of a propagule to start a new establishment. Propagule pressure is an important predictor of the probability that an invasive species will establish a breeding population. Recently, individual-based model (IBM) became a valuable modelling tool for exploring invasive species. Here, we developed a spatially-explicit individual-based model (IBM) specifically parameterized for the Queensland fruit fly (Qfly) (Bactrocera tryoni Froggatt), a major horticultural pest species in Australia and a major quarantine concern worldwide. Usually, new establishments or incursions originate from the introduction of infested fruit and larvae must progress through several stages to become sexually mature adults. For a Qfly incursion to establish a breeding population, flies must avoid predators and survive long enough to become reproductively mature, find a mate, and find ripening fruit. Additionally, their offspring must survive and successfully reproduce. The IBM model simulated release of a fixed number of flies into a heterogeneous environment of varying suitability. We conducted simulations to delineate the contributions of demographic stochasticity and Allee effects (finding a mate in a spatial environment) on establishment probability. Our model delineated several key influential factors, especially tree density, extrinsic mortality and mating range. We performed sensitivity analyses to identity which biological and ecological mechanisms strongly affect establishment probability. Integrating the model's findings with information on transport of infested fruit helps explain why Qfly incursions are common, but yet most fail to establish. Our model predicted that circa 16 and 50 flies were required for a 50% and 99% chance of establishment respectively. Additionally, our model predicted the mating distance for Qfly was 16.1 m. The mean daily dispersal distance was 30 m. We discuss how this knowledge might be used to better manage Qfly by alterations in surveillance and male annihilation technique.

Analysis of components in male annihilation blocks used to manage Queensland fruit fly Bactrocera tryoni (Froggatt)

The male annihilation technique (MAT) is used throughout the world to assist in the management and eradication of fruit flies. In Australia, often MAT was deployed using particle board blocks (50 × 50 mm) and was used in southern New South Wales to manage Queensland fruit fly Bactrocera tryoni. We sampled 120 MAT blocks over two years which were newly manufactured, new and stored (for later use), exposed for a four or twelve months period and analysed them for the effects of environmental exposure on chemical contents and the weight of blocks. Chemicals present in the blocks were malathion (toxicant), cuelure (male lure) and raspberry ketone (male lure). Total weight of the blocks and the weight of the chemicals from the block's central core and edge components were recorded separately. We found that the storage of newly manufactured blocks did not prevent chemical degradation; cuelure and malathion contents were reduced by 25% and 16%, respectively, in a stored block when compared to a new block. Most changes in the chemical contents of the blocks occurred in the first four months of field deployment, with 56% and 35% reduction analysed in cuelure and malathion contents, respectively. Loss in chemical contents and weight of blocks continued with long-term exposure of blocks from four to twelve months. Edges were found to degrade more as compared to the central core of the used blocks. Managers need to be aware of chemical degradation patterns if particle board is to be used in future MAT programs.

Developing Lines of Queensland Fruit Flies with Different Levels of Response to a Kairomone Lure.

Simple SummaryQueensland fruit fly (Q-fly) is widely recognized as one of the world’s worst economic pests of fruit. In this project, a series of artificial selection experiments were conducted to develop lines of Q-fly with different levels of response to the male-specific lure Cue-lure® (CL) and to assess the heritability of this particular trait. Although lines of high and low responsive males to Cl were successfully developed through five cycles of artificial selection, the response to CL did not completely disappear. I have demonstrated that relaxing artificial selection results in the loss of 35–46% of the selection response after a further two generations.The Queensland fruit fly (Q-fly), Bactrocera tryoni (Froggatt) is a serious horticultural pest in Australia because it is highly invasive and destructive. Among all pest management practices, sterile insect techniques (SIT) and male annihilation techniques (MAT) are important control options for many tephritid fruit fly pests, including Q-fly. However, simultaneous applications of MAT and SIT require the wild males to be responsive to a lure while the released sterile males remain largely unresponsive. In this study, a series of artificial selection experiments was conducted to develop lines of Q-fly with different levels of response to the male-specific lure Cue-lure® (CL). After only five cycles of artificial selections, lines of high responsiveness (HR) and low responsiveness (LR) males diverging significantly in their response to the lure were developed. In the field cage experiment, the number of trapped males in fruit fly traps was significantly lower in the LR line than both the HR line and the control which supports the laboratory results. However, when artificial selection was stopped at F5 and retested after two generations, the number of unresponsive males dropped drastically compared to the rate of response of wild flies. Because the selection can be conducted only on males, it would be difficult to eliminate the dominant responsive alleles in the system without continuous selection.

Management of Fruit Flies in Guava Through Male Annihilation Technique

Study on the management of fruit flies through male annihilation was undertaken on guava in five farmers’ orchards. Three orchards were installed with methyl eugenol traps @ 10, 20 and 40 traps/ ha. One orchard with 25 methyl eugenol traps/ ha as per the recommended package of practices (POP) of TNAU and without any trap was used as control. Significantly maximum catch of 178.83 males/ trap/ fortnight was caught with 40 traps, followed by the one with TNAU POP traps (100.25/ trap/ fortnight). The least fruit damage was (6.14%) in orchard where 40 traps were placed. TNAU POP traps placed orchard revealed the least fruit damage (10.71%).

Mating Competitiveness of Bactrocera dorsalis (Diptera: Tephritidae) Males From a Genetic Sexing Strain: Effects of Overflooding Ratio and Released Females.

The oriental fruit fly, Bactrocera dorsalis (Hendel), is a global pest that infests a range of fruit and vegetables. Males are attracted to methyl eugenol, and control is often achieved by the Male Annihilation Technique, where methyl eugenol + insecticide dispensers are deployed to eliminate males, preclude matings, and reduce population growth. The Sterile Insect Technique (SIT) has also been used to control B. dorsalis. The SIT involves the release of mass-reared, sterilized males to achieve matings with wild females, who then produce inviable eggs. Two key elements of SIT include the overflooding ratio achieved (sterile: wild males) and the strain type utilized, namely bisexual or genetically sexed (allowing male-only releases). Here, we describe the effects of these two factors on the mating competitiveness of a males from a genetic sexing strain of B. dorsalis, termed DTWP. Mating success was scored for DTWP versus wild males in field cages at ratios of 1:2, 1:1, 2:1, and 10:1 both when DTWP females were or were not concurrently released with DTWP males. Close correspondence was found between observed numbers of matings of particular male-female combinations and expected numbers based on the numbers of flies released of each sex and each strain. As a result, the proportion of total matings achieved by the DTWP across the eight treatments showed a corresponding increase with overflooding ratio. At a given ratio, DTWP males had a higher relative mating success when DTWP females were absent rather than present, although the reason for this was unclear.

Eradication of sweetpotato weevil, Cylas formicarius, from Tsuken Island, Okinawa, Japan, under transient invasion of males

AbstractAn eradication project against the sweetpotato weevil, Cylas formicarius (Fabricius) (Coleoptera: Brentidae), one of the most important pests of sweet potato in the world, was initiated in Oct. 2007 on Tsuken Island, Okinawa Prefecture, Japan. The sterile insect technique (SIT) and male annihilation technique (MAT) were employed as the main control measures to suppress and ultimately eradicate wild populations by impeding normal mating. In addition, two monitoring methods (host plant survey and trap survey) were used to evaluate the progress of the control actions. However, several years after the start of the project, wild male weevils were regularly captured by male‐attractant traps in seasonal patterns, although infestation was scarcely detected by host plant surveys. Evidently, the males flew to Tsuken Island from uncontrolled areas that were farther away than the weevils were previously expected to travel. Although the transient invasion of only males did not cause new colonization, it created a challenge for the progress of the project and the confirmation of the eradication of the weevil on Tsuken Island. To solve this problem, suppressive control measures in the uncontrolled area (Okinawa Island) to reduce transient invaders were implemented. In addition, to assess if control actions needed after eradication, a system was introduced to detect recolonization of the weevil based on trap catches of transient invading males. After the successive collection of 142,257 m of stem of host plants and 158.45 kg of root tubers of sweet potato without infestation (from February 2019 to November 2020), the eradication of C. formicarius from Tsuken Island was ultimately confirmed in November 2020.

Monitoring and management of fruit fly population using the male annihilation technique with different types of cost-effective traps in guava orchards of Punjab, Pakistan

Bactrocera zonata (Saunders) and Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) are major pests of fruits especially guava, posing a trade barrier of Pakistani fruits in foreign markets. Mass trapping of this pest by suitable selection of traps is necessary for its management by the male annihilation technique (MAT). Experiments were conducted in three different guava-producing districts of Punjab, i.e., Faisalabad, Sargodha, and Toba Tek Singh. Three locations in each district were selected for the experiment, three acres each. Three types of traps were used: the round trap (RT), the jar trap (JT), and the pet bottle trap (PBT), with six traps per acre. Multiple linear regression equations and correlations were computed on the mean population data for all traps in each year. April, May, and June (standard weeks 13-23) were fruit fly peak activity periods in all districts. Temperature exerted a highly significant and positive impact on fruit fly populations. Humidity was not significant, but showed a positive relationship with per unit population fluctuation. Rainfall was also not significant, but showed a negative relationship with per unit population fluctuation. The maximum impact of temperature was 43.5 and 42.8% in Faisalabad, the maximum impact of relative humidity was 26.2 and 22.2% in Sargodha, Faisalabad, and the maximum impact of rainfall was 26.3 and 15.1% in Sargodha. The PBT trap had significant and positive correlations with per unit population fluctuation in all three districts during 2015 and 2016. Pet bottle traps gave the maximum adult catches at all districts with minimum cost 13.30 $/ha in a year, which is suitable for farmer’s community to be used in a prediction model.

Insight on Fruit Fly IPM Technology Uptake and Barriers to Scaling in Africa

Tephritid fruit flies are considered one of the world’s most notorious pests of horticultural crops, causing extensive direct and indirect damage. Over the past two decades, a comprehensive, integrated pest management (IPM) package for the management of a plethora of fruit fly pests, including Bactrocera dorsalis, B. latifrons, B. zonata, Ceratitis cosyra, C. rosa, C. fasciventris, C. quilici, C. capitata, Dacus spp. and Zeugodacus cucurbitae, has been developed, disseminated and promoted among horticultural growers in Africa. To estimate the numbers of beneficiaries reached by the fruit fly IPM technology and the barriers to technology uptake, we interviewed 290 experts in 30 African countries covering five regions of the continent, and the responses collected were represented as follows: Southern Africa (39.1%), Eastern Africa (31.6%), Western Africa (18.0%), Central Africa (9.0%) and Northern Africa (2.0%). Our results revealed that the use of fruit fly IPM technologies varied across the regions, with Eastern Africa and Western Africa the leading regions, with the highest IPM technology penetration. Field sanitation remains the most common practice for managing fruit flies, followed by protein bait spray, use of biopesticides, male annihilation technique and parasitoid releases. According to the survey, over 101 million people have benefited from the fruit fly IPM interventions in the countries surveyed representing only 19.1% of the estimated beneficiaries. The region that benefitted the most was Eastern Africa (50.2 million), followed by Central and Western Africa (11.7 to 17.7 million), and Southern and Northern Africa had the fewest beneficiaries (10.4 to 11.0 million). The limitations to the IPM technologies uptake varied among the regions, but the common ones include a lack of awareness of the IPM technologies, a lack of access to the IPM products, insufficient training, a low involvement of private sectors and a lack of policies for the regulation of IPM technologies. Although significant strides have been made in promoting the fruit fly IPM technologies over the past two decades, our study reveals that the demand surpasses the current supply. Our study recommends a comprehensive strategy for the dissemination and promotion of the technologies through a multi-institutional alliance that enhances public and private partnerships, digital platforms and youth engagement to consolidate previous gains at the regional and continental levels.

Raspberry ketone diet supplement reduces attraction of sterile male Queensland fruit fly to cuelure by altering expression of chemoreceptor genes

Sterile male Queensland fruit fly, Bactrocera tryoni (Froggatt), fed as immature adults on the plant compound raspberry ketone (RK), show a reduced attraction to cuelure, a synthetic analogue of RK used as an attractant in Male Annihilation Technique. We hypothesized the reduced attraction of RK-fed adult males to cuelure may be a consequence of altered expression of chemoreception genes. A Y-tube olfactometer assay with RK-fed and RK-unfed sterile B. tryoni males tested the subsequent behavioural response to cuelure. Behavioral assays confirmed a significant decrease in attraction of RK-fed sterile males to cuelure. RK-fed, non-responders (to cue-lure) and RK-unfed, responders (to cue-lure) males were sampled and gene expression compared by de novo RNA-seq analysis. A total of 269 genes in fly heads were differentially expressed between replicated groups of RK-fed, cuelure non-responders and RK-unfed, cuelure responders. Among them, 218 genes including 4 chemoreceptor genes were up regulated and 51 genes were down regulated in RK-fed, cuelure non-responders. De novo assembly generated many genes with unknown functions and no significant BLAST hits to homologues in other species. The enriched and suppressed genes reported here, shed light on the transcriptional changes that affect the dynamics of insect responses to chemical stimuli.

Effect of variable storage periods of male annihilation technique (MAT) lure on their attractancy to tephritids, fruit flies, Bactrocera spp. (tephritidae: Diptera)

The data on number of fruit flies trapped per week for a period of 7 weeks were taken at cucumber field var., Pusa Sanyog. It can be inferred from the data that irrespective of container, the mean number of trapped fruit flies was found to be significantly more in lure stored for 10 days (259.25 flies/trap/7 weeks) and was at par those stored for 15 days (184.75 flies/trap/7 weeks). Overall mean numbers of fruit flies trapped at other storage periods were found at par. The trap catch of males in parapheromone traps is affected by a large number of factors including the abiotic factors of the environment which indirectly alter the target insect i.e., fruit fly and behavior of the target pest. The maximum trap catch at 10 days storage period could be ascribed due to peak activity of the pest during this period. The critical examination of data indicated a consistent trapping between 127.5–142.5 flies/trap/7 weeks at 5, 20, 25 and 30 days storage period. Efficacy on different insecticide revealed that wooden pheromones lures containing spinosad as insecticide resulted in attracting maximum fruit fly population (88.65 flies/trap/weeks) followed by malathion (28.32 flies/trap/weeks) and Lambdacyhalothrin (8.67 flies/trap/weeks).