Oviposition responses of Q ueensland fruit fly ( B actrocera tryoni ) to mineral oil deposits on tomato fruit

• Published in: Entomologia experimentalis et applicata Vol. 165; no. 1; pp. 19 - 28
• Main Authors: Nguyen, V. L., Beattie, G. A. C., Meats, A. W., Holford, P., Spooner‐Hart, R. N.
• Format: Journal Article
• Language: English
• Published: 01.10.2017
• ISSN: 0013-8703; 1570-7458
• DOI: 10.1111/eea.12601

Abstract Behavioural responses of wild and laboratory‐culture females of Queensland fruit fly, B actrocera tryoni ( F roggatt) ( D iptera: T ephritidae), to mineral oil deposits on tomato fruit dipped in aqueous oil emulsions were assessed in a no‐choice test and three choice tests. The oils were two commercial products used to manage plant pests and diseases, Ampol D‐C‐Tron NR and SK EnSpray 99, one distillation fraction of the base oil of the former, and four distillation fractions of the base oil of the latter. The initial and final boiling points of the fractions were equivalent to those of n ‐alkanes with chain lengths of C20–22 (Ampol), and C21–C23, C22–23.5, C22–24, and C22–24.5 ( SK ). For both fly types in the no‐choice test, numbers of punctures and eggs per fruit declined strongly as concentrations of the n C20–22 Ampol fraction in emulsions rose from 0.25 to 2% (vol/vol). Fly type affected the extent of responses but there was no significant interaction for fly type*oil concentration. Responses of laboratory‐culture females in the choice tests also declined as concentrations of SK and the four fractions of its base oil in emulsions rose from 0 to 0.25%. The SK n C22–24 and n C22–24.5 fractions had least impact. Responses of laboratory‐culture flies to 0.5% emulsions of the n C20–22 Ampol fraction and the n C21–23 SK fraction in choice tests were not significantly different. Likewise, responses of laboratory‐culture flies to 0.5% emulsions of the two commercial products were not significantly different. Emulsifier type did not affect numbers of punctures or eggs per fruit in choice responses of laboratory‐culture flies to 0.5% emulsions of the Ampol n C20–22 fraction or 0.5% emulsions of the SK n C21–23 fraction. If the equivalence of no‐choice and choice responses in the laboratory were to hold in the field, then unsprayed ‘sacrificial’ plants would not be necessary and oil emulsions could be used as cover sprays.