BiOTRAP Tech Info

Evaluating Biotraps and Lynfield traps for the surveillance of Queensland fruit fly Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) and other tephritids in southern Australia.

Dominiak, B.C.^1*Bain, C²., Sharma, N³. and Cooper, D⁴.

¹ NSW Department of Primary Industries, The Ian Armstrong Building, 105 Prince Street, Orange, New South Wales, 2800, Australia

² Bio-Trap Australia Pty Ltd, Roditis Drive, Ocean Grove, Victoria, 3226, Australia.

³NSW Department of Primary Industries, Orange Agricultural Institute, 1447 Forest Road, Orange, New South Wales, 2800, Australia.

⁴NSW Department of Primary Industries, 2198 Irrigation Way, Yanco New South Wales, 2703, Australia.

^* Corresponding author

Email: bernie.dominiak@dpi.nsw.gov.au

Abstract

Fruit fly surveillance remains essential for international and domestic trade. The dry cuelure baited Lynfield trap has been the standard since the early 1990s. Here, we tested the two versions of Biotraps against the Lynfield traps in the Riverina area of New South Wales. The Biotraps were found to be superior in trapping Island flies and female Queensland fruit flies. Also, Biotraps were assessed as at least equal to or superior to Lynfield traps for trapping male Queensland fruit flies.

Keywords:

monitoring, dry trap, market access

Introduction

Tephritids are a pest of fruit crops and an impediment to trade throughout the world (Vargas et al. 2015). Despite this threat, tephritids are well suited to eradication or management because tephritids are attracted to lures (Suckling et al., 2016). In Australia, Queensland fruit fly (Qfly), Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), is the main pest of most tree crops and some vegetables along the east coast (Dominiak & Mapson, 2017).

Lures are essential for surveillance. Additionally, trap architecture is important and continues to evolve. Victoria and New South Wales (NSW) in south-eastern Australia were on the southern edge of the range of Qfly for many years. However, global warming, trade in fruit and the proliferation of alternative hosts facilitated the southern expansion of Qfly (Dominiak & Mapson, 2017).

Cuelure is an attractive male lure of Qfly (Monro and Richardson 1969). Jackson traps (delta design) baited with cuelure using sticky mats were originally used in the late 1980s in NSW. Cowley et al (1990) demonstrated the Lynfield traps were superior to the Jackson traps and subsequently, Lynfield traps became the standard trap design in southern Australia (Dominiak et al 2003). However, cuelure-baited Lynfield traps only trapped male Qfly. The protein-baited McPhail traps attract both males and females but are only about one-seventh as effective as Lynfield traps (Dominiak and Nicol, 2010). Protein-based McPhail traps are not used in standard trapping arrays but were used more frequently in incursion surveillance (Dominiak et al 2003).

Qfly is present in Australia and in several Pacific islands (Vargas et al. 2015). The presence of Qfly in production areas means that fruit for domestic or international market access must be disinfested (Jessup et al 1998) and this treatment comes at a significant cost. Growers and fruit fly managers/regulators continue to seek to optimise Qfly surveillance. The dry cuelure-baited Lynfield traps (males) and wet protein-baited MacPhail traps (female) remain the standards for international trade. However, alternative traps continue to be developed but need to be equivalent to current international standards. These options provide growers with a choice in traps to suit individual farming enterprises. In an initial assessment in Victoria, Bain and Dominiak (2022) found that the BioTrap baited with a protein gel was a suitable alternative to the Lynfield Trap. Here, we conducted an extensive scale assessment to compare the performance of Biotraps (protein gel-baited) with the Lynfield traps (cuelure-baited) in southern NSW for trapping Qflies (male and female), Newman flies and Island flies.

Materials and Methods

The trial was conducted at 11 sites in the Riverina in the districts of Hanwood, Tharbogang, Somerton Park, Corbie Hill, Paynter’s Siding, Nericon, Darlington Point, and Leeton. The assessment was conducted between 30 September 2014 and 22 June 2016.

Lynfield traps (Figure 1a) are a 1 L cylindrical clear plastic container (120mm in depth and diameter), a lid, and a lure dispenser (Cowley et al., 1990; Dominiak and Nicol, 2010). In the trap’s body, there are four 25mm holes drilled at equally spaced locations into the sides to allow the lure vapour to exit the trap and for insects to enter. Four additional 2 mm holes were drilled into the bottom to prevent any water accumulation. Lynfield lure dispensers comprised of cotton wicks [four dental cotton rolls (each 10 mm x 40 mm long) held together by a wire clamp] suspended from the middle of the trap lid. The wick hung at about the same level as the ingress holes in the side wall of the trap. The cuelure treatment was a 5 ml solution containing eight parts cuelure (4-(p-acetoxyphenyl)-2-butanone) and one part maldison (1150 gL^-1 active ingredient). Wicks were changed every six months.

Biotraps were designed and manufactured by Biotrap Pty Ltd (Figure 1b). Both versions of the Biotrap consist of two individual plastic bodies, the top or lid and the base. The top/lid is produced from clear PVC with a rounded skirt allowing it to be pushed onto the base. This rounded skirt has additional internal protrusions to ensure a firm grip on the base. There is a small centrally positioned hole to allow the clip to be pushed through to enable the trap to be hung from a suitable tree branch or similar.

The base is made by injection moulding using PMS 803 yellow HIPS ( High Impact Poly Styrene ), which results in a structurally ridged body. The base has a lip to fit within the skirt of the top; there are five vertically inclined entry holes of 10 mm diameter, four around the circumference and one in the centre.  The four cardinal positioned holes within the trap end abruptly to reduce the potential for insect exiting and their entry is via a scalloped section which provides shading. The centre hole with the base is a cone type with an entry size of 25 mm, rising 50 mm within the base to end in a 10 mm hole. There is an internal ridge around the circumference of the base to accommodate a sticky panel 5 mm below the entry holes. The width of the trap is 150 mm, the base is 75 mm and the top/lid is 75 mm making for a compact design that allows for easy stacking. The base has a capacity for 250 mL of liquid.

The female-biased protein lure was demonstrated to primarily attract the female Qfly, although males were also attracted. The attractant is a gel produced from a stabilised protein concentrate, ammonium compounds and a thickening agent (Xanthan gum). The lure was changed every three months. The toxicant is DDVP carried on a cube and DDVP cubes were replaced every three months. Two Biotrap versions were tested; version 1 (see Figure 1) between 30 September 2014 to 28 April 2015 (7 months: time period A) and version 2 between 11 May 2015 to 22 June 2016 (13 months: time period B).

Traps were hung in adjacent trees and were about 10 m apart. Traps were inspected weekly in the summer cycle (September to May) and fortnightly in winter (June to August). Flies in traps were placed in individual containers and labelled with the trap number and dates and were sent to Orange Agricultural Institute at Orange for further analysis. Entomologists identified fly species and numbers and entered data on the state database “PestMon” (see Dominiak et al 2007 for details). Data was extracted for analysis after the trial was terminated.

All statistical analysis was carried out using R version 4.0.3 (R Core Team, 2013). We applied a linear regression model (Seal, 1967) to estimate if the number of catches of two trap types differs significantly in the two time periods.

Results

Based on Table 1, we found that Biotraps performed better than the Lynfield trap catches in both time periods A and B. Linear regression results in Table 2 demonstrated the number of flies trapped by Lynfield and Biotraps was significantly different in both time periods A and B (p-value < 2e-16; Table 2). Table 1 also records the number of Qfly male, Qfly female, Newman fly and Island fly trapped by Lynfield and Biotraps in time periods A and B. For the Qfly males, Qfly females and Island flies, we found that the number of flies trapped differed significantly for the two trap types in both time periods (Table 2).

However, the number of Newman flies (Dacus newmani (Perkins)) trapped exhibited no significant difference between the two trap types in both time periods A and B. Moreover, the overall number of trapped Newman flies remained low compared to other fly types. Also, the Lynfield traps did not capture any female Qfly during both periods (Table 1). For Island flies (Dirioxa pornia (Walker)), the number of flies trapped in Lynfield traps was lower than the number of flies trapped by Biotraps (Table 1). On further analysis, it was detected that most Island flies were trapped in the months of April and May (Table 3). October was the peak month for Newman fly trappings.

Bactrocera neohumeralis (Hardy) was not detected during our trial and this is consistent with the known range (Dominiak and Worsely 2016). Dacus newmani was trapped and is consistent with the known distribution (Dominiak 2019).

Discussion

Traditional tephritid surveillance relies on trapping males using a male attractant. Hence, Australian surveillance for Qfly has used Lynfield traps baited with cuelure. Here, we demonstrated that the Biotrap baited with a protein gel was able to trap more flies than the traditional Australian Lynfield trap for male Qfly. In addition, Biotraps have the  benefit of trapping female Qfly. Dominiak and Nicol (2010) reported that the male:female ratio was about 7:1 with the MacPhail male:female Qfly captures . We found that the ratios for the Biotrap version 1 and version 2 ratios were 11.5:1 and 2.5:1, respectively. So for Qfly surveillance, the protein gel baited Biotrap combines the utility of both the Lynfield and the MacPhail traps in one design. For orchardists, Biotraps will provide a better insight into the female Qfly, that are potentially egg-laying.

During both versions/time periods, we found that Biotraps had significantly better performance to the cuelure Lynfield trap for not only male Qfly but also for female Qflies. Therefore Biotraps are an effective alternative surveillance option for Qfly monitoring.

The cuelure-baited dry Lynfield traps have been a standard Australian trap since about 1993. However, new traps are emerging. Dominiak et al. (2019) demonstrated that cone traps were one alternative. Ladd traps have advantages in some circumstances (Schutze et al. 2016). Similarly, Bain and Dominiak (2022) demonstrated that Biotraps were equivalent to Lynfield traps in Victoria. Fay et al (2022) used Biotraps to monitor Zeugodacus cucumis (French) in northern NSW. Here we demonstrated that Biotraps were better to Lynfield traps in the Rivernia region for monitoring for male Qfly. The added benefit is that Biotraps capture female Qfly while Lynfield traps do not. This added benefit may better inform fruit fly management regarding female populations in their orchards and help them make a better choice of management techniques.

Additionally, we demonstrated that protein-baited Biotraps captured large numbers of D. pornia flies in both time periods. This observation was consistent with Dominiak and Nicol (2010). Cuelure-baited Lynfield traps captured low numbers of D. pornia and this is consistent with earlier reports (Dominiak et al 2003; Dominiak and Nicol 2010). Dirioxa pornia does not infest undamaged fruit (Morrow et al. 2015) and is not a problem in well-managed orchards.

Regarding D. newmanii, Gillespie (2003) claimed this species was likely to be single-brooded. Dominiak (2019) reported a population peak in September. We found the peak in October but this may be related to seasonal variations: D. newmani populations increase during drier periods (Dominiak 2019).

Acknowledgements

Regulatory staff who inspected and cleared the traps are thanked. Identification staff at Orange Agricultural Institute are acknowledged for identification and data entry roles.

References

Bain, C. and Dominiak, B. (2022). Evaluating a new trap design for the surveillance of Queensland fruit fly Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) in southern Australia. General and Applied Entomology 50: 21-24.

Cowley, J.M., Page, F.D., Nimmo, P.R. and Cowley, D.R. (1990). Comparison of the effectiveness of two traps for Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) and the implications for quarantine surveillance systems. Australian Journal of Entomology 29: 171-176.

Dominiak, B.C., Gilmour, A.R., Kerruish, B. and Whitehead, D. (2003). Detecting low populations of Queensland fruit fly Bactrocera tryoni (Froggatt) with McPhail and Lynfield traps. General and Applied Entomology 32: 49-53.

Dominiak, B.C. and Nicol, H.I. (2010). Field performance of Lynfield and McPhail traps for monitoring male and female sterile (Bactrocera tryoni Froggatt) and wild Dacus newmani (Perkins). Pest Management Science 66: 741-744.

Dominiak, B.C. and Worsley, P. (2016). Lesser Queensland fruit fly Bactrocera neohumeralis (Hardy) (Diptera: Tephritidae: Dacinae) not detected in inland New South Wales or south of Sydney. General and Applied Entomology 44: 9-15.

Dominiak, B.C. and Mapson, R. (2017). Revised distribution of Bactrocera tryoni in Eastern Australia and effect on possible incursions of Mediterranean fruit fly: Development of Australia’s Eastern Trading Block. Journal of Economic Entomology 110: 2459-2465.

Dominiak, B.C., Galvin, T., Deane, D. and Fanson, B. (2019). Evaluation of Probodelt cone traps for surveillance of Dacinae in New South Wales, Australia. Crop Protection 126: 104940.

Dominiak, B.C. (2019). Review of the biology and distribution of Newman fruit fly, Dacus newmani (Perkins) (Diptera: Tephritidae), a cryptic Dacinae species from the dry inland of Australia. General and Applied Entomology 47: 17-24.

Fay, H.A.C., DeFaveri, S.G. and Dominiak, B.C. (2022). A new southern detection of Zeugodacus cucumis (French 1907) in northern New South Wales. General and Applied Entomology 50: 31-37.

Gillespie, P. (2003). Observations on fruit flies (diptera: Tephritidae) in New south wales. General and applied Entomology 32: 41-47.

Jessup, A.J., Carswell, L.F. and Dalton, S.P. (1998). Disinfestation of fresh fruit from Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) with combination mild heat and modified atmosphere packaging. Australia Journal of Entomology 37: 186-188.

Monro, J. and Richardson, N.L. (1969). Traps, male lures, and a warning system for Queensland fruit fly, Dacus tryoni (Frogg.) (Diptera: Trypetidae). Australian Journal of Agricultural Research 20: 325-338.

Morrow, J.L., Frommer, M., Shearman, D.C.A. and Riegler, M. (2015). The micriobiome of field-caught and laboratory-adapted Australian tephritid fruit fly species with different host plant use and specialisation. Invertebrate Microbiology 70: 498-508.

R Core Team, 2013. R Language and Environment for Statistical Computing. R foundation for Statistical Computing, Vienna, Austria. http://www.R-project.org/.

Schutze, M.K., Cribb, B.W, Cunningham, J.P., Newman, J., Peek, T. and Clarke, A.R. (2016). ‘Ladd traps’ as a visual trap for male and female Queensland fruit fly, Bactrocera tryoni (Diptera: Tephritidae). Austral Entomology 55: 324-329.

Seal, H.L., 1967. The historical development of the Gauss linear model. Biometrika 54(1/2), 1–24, 10.1093/biomet/54.1-2.1.JSTOR 2333849.

Suckling, D.M., Kean, J.M., Stringer, L.D., Caceres-Barrios, C., Hendrichs, J., Reyes-Flores, J. and Dominiak, B.C. (2016). Eradication of Tephritid Fruit Fly Populations: Outcomes and prospects. Pest Management Science 72: 456-465.

Vargas, R.I., Pinero, J.D. and Leblanc, L. (2015). An overview of pest species of Bactrocera fruit flies (Diptera: Tephritidae) and the intergration of biopesticides with other biological approaches for their management with a focus on the Pacific region. Insects 6:297-318.

Table 1. Trap catches of tephritids during two time periods using Lynfield and Biotrap designs. 

Table 2. Linear model showing comparisons of the total number of flies, Qfly male, Qfly female, Newman fly and Island fly trapped by two trap types in time periods A and B. Statistical comparisons resulting in p-values <0.05 (not highlighted in grey) were considered as significantly different.

Table 3. Trap catches of Island fly and Newman fly for different months of the year.

Figure 1. Images of fruit fly traps. Top image is an Australian standard Lynfield trap and the lower images are Biotraps.

Biotrap V1

Biotrap V2