Effect of ants on Tephritid fly samples in methyl eugenol-baited traps
Date Issued
2016
Date
2016
Author(s)
Chuang, Po-Tsun
Abstract
Methyl eugenol trap is one of primary methods for controlling and monitoring several fruit fly species including oriental fruit flies (Bactrocera dorsalis), a pest that causes serve ecological loss to tropical fruit trees. To accurately reflect field density of B. dorsalis, numerous studies focused on the intrinsic factors such as attractiveness of methyl eugenol. Extrinsic factors that may influence accuracy of fly density monitoring, however, receive less attention. The present study is therefore to explore the long term effect of the presence of ants on the number of B. dorsalis in the methyl eugenol traps. Relevant issues regarding attractiveness of methyl eugenol to the ants and time point(s) when the ants initiate intensive foraging activities in the traps were also discussed. B. dorsalis killed by freezing (FZ), toxicant (naled) methyl eugenol (TME) and pure methyl eugenol (ME) were offered to the acrobat ants (Crematogaster rogenhoferi) under a non-choice test, and results showed that the ants fed on the three types of B. dorsali with slight preference on FZ over others. High number of dead ants were found in TME treated groups, suggesting that TME may impose negative effects on the ants after consumed. Under both lab and field conditions, the acrobat ant nests were connected to McPhail trap in which a cotton containing TME and freshly killed B. dorsalis were placed, and number of fruit flies remained and dead ants in trap were recorded on a daily basis for two weeks. Results indicated that number of fruit flies was nearly the same after 14 days in lab conditions (walk-in chamber), but not those in field conditions where ants did consume on certain proportions of the fruit flies. Along with the finding of the number of dead ants being constantly high in both conditions, the presence of the ants in the traps as well as time point of the ants initiating foraging activities seem not affected by the amount of TME. Field experiments were also conducted in Miaoli County and New Taipei City to compare the number of B. dorsalis between conventional and glue-coated (string) methyl eugenol traps. It was observed that the proportion of intact fruit flies in the conventional traps is significant lower than the glue-coated ones, and number of ants per trap is predominantly higher in the conventional traps than in the glue-coated traps. Most of ant species observed were Crematogaster, Tetramorium and Ochetellus spp. Such patterns suggest that reduction of number of fruit flies in conventional traps likely result from foraging ants, and glue-coated trap can effectively prevent ants from entering into traps.
Subjects
ants
density monitoring
glue-coated trap
methyl eugenol
oriental fruit fly
Type
thesis
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