The accuracy and bias of visual assessments of fruit infestation by fruit flies (Diptera: Tephritidae).
Stonehouse J., Mumford J., Ashraf Poswal, Riaz Mahmood, Makhdum A. H., Chaudhary Z. M., Baloch K. N., Ghulam Mustafa, McAllister M.
Author Affiliation: Department of Environmental Science and Technology, Faculty of Life Sciences, Imperial College London, London SW7 2BP, UK.
Crop Protection 23 : 293-296
Abstract : The attacks of fruit flies are conveniently assessed by visual inspection of fruit. This study assessed the accuracy of this in Pakistan by recording visual diagnoses of attack on individual fruit and waiting to see if these were confirmed by subsequent emergence of prepupal larvae. Diagnoses as unattacked were overwhelmingly confirmed; diagnoses as attacked, by oviposition punctures, were confirmed by larval emergence in 56% of cases in melons, 39% in guavas, 40% in jujubes and 27% in mangoes. The fact that diagnoses as unattacked were confirmed more often than as attacked suggests that the discrepancy may not be in misdiagnosis but in larval mortality, and that visually recorded scars which led to no larval emergence were indications of eggs or larvae dying before maturity: this possibility has little economic significance, however, as larval survival and emergence, not oviposition, are the cause of losses to the farmer.