The attacks of fruitflies 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.
Stonehouse, J.M.; Mumford, J.; Poswal, A.; Mahmood, R.; Hamid-Makhdum, A.; Mahmood-Chaudhary, Z.; Nawaz-Baloch, K.; Mustafa, G.; McAllister, M. The accuracy and bias of visual assessments of fruit infestation by fruit flies (Diptera: tephritidae). Crop Protection (2004) 23 (4) 293-296. [DOI: 10.1016/j.cropro.2003.08.014]