## 3 Results  
The volatile blends emitted from cattle dung samples were captured by SPME, and they were analyzed by GC-MS (Table 1). Accordingly, \(p\)-cresol (63.17%) was the most abundant compound in the volatile blend from fresh cattle dung, followed in lower amounts by phenol (0.84%); indole (5.46%); terpen (9.73%), including \(\upalpha\)-pinene (1.05%), \(\upbeta\)-pinene (1.39%), limone (1.52%), and \(\upbeta\)-caryophyllene (2.60%); and other common volatile organic compounds (VOCs) from cattle manure such as long-chain branched alcohols (0.65%), saturated branched hydrocarbons (1.41%), saturated unbranched hydrocarbons (3.28%), and unsaturated hydrocarbons (2.52%). Similar profiles were observed for volatile blends from aged cattle dung, which are compiled in Table 1. \begin{table}
\begin{tabular}{c c c c c c} \hline \multirow{2}{*}{**RT**} & \multirow{2}{*}{**KI**} & \multirow{2}{*}{**Compound**} & \multicolumn{2}{c}{**Fresh Dung**} & **Aged Dung \({}^{*}\)** & \multirow{2}{*}{**Identification**} \\ \cline{5-6}  & & & **Abundance (\%)** & & & \\ \hline
11.9 & 932 & \(\upalpha\)-Pinene & 1.05 & 0.02–0.10 & RI, MS, Co-I \\ \hline
13.3 & 966 & \(\upbeta\)-Pinene & 1.39 & 0.27–0.32 & RI, MS, Co-I \\ \hline
14.5 & 1000 & Decane & 1.22 & 0.84–1.55 & RI, MS \\ \hline
15.3 & 1022 & Limonene & 1.52 & 0.11–0.16 & RI, MS, Co-I \\ \hline
16.5 & 1061 & Undecane & 2.06 & 0.05–0.24 & RI, MS \\ \hline
16.8 & 1071 & Phenol & 0.84 & 2.14–39.63 & RI, MS, Co-I \\ \hline
17.3 & 1086 & \(p\)-Cresol & 63.17 & 26.48–43.02 & RI, MS, Co-I \\ \hline
23.5 & 1295 & 1-Tridecene & 0.44 & 1.00–1.56 & RI, MS \\ \hline
25.1 & 1358 & Indole & 5.46 & 1.03–2.95 & RI, MS, Co-I \\ \hline
26.3 & 1399 & Isocaryophyllene & 2.35 & 1.37–2.16 & RI, MS \\ \hline \end{tabular}
\end{table} 
Table 1: Chemical composition of the volatile blend emitted from fresh and aged cattle dung. In the olfactory bioassays, volatiles from fresh dung significantly attracted (\(p\leq 0.05\)) mixed-sex horn flies randomly selected, compared with the blank in a \"Y\"-tube olfactometer, with 68.4% \(\pm\) 2.5% of attraction (Figure 1, Left). Contrary, volatiles from 3-, 5-, and 7-day-old dung did not cause a significant difference in the olfactory response of mixed-sex horn flies compared with their respective blanks, where 47.8% \(\pm\) 2.0%, 48.9% \(\pm\) 2.5%, and 46.1% \(\pm\) 5.0% of the flies chose the treatment, respectively. Consequently, these samples were unattractive to mixed-sex horn flies (Figure 1, Left). In a similar manner, volatiles from fresh dung significantly attracted (\(p\leq 0.05\)) males, with 71.1% \(\pm\) 3.3% of attraction (Figure 1, \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**RT**} & \multirow{2}{*}{**KI**} & \multirow{2}{*}{**Compound**} & **Fresh Dung** & **Aged Dung *** & \multirow{2}{*}{**Identification**} \\ \cline{3-3} \cline{5-5}  & & & **Abundance (\%)** & & \\ \hline
26.5 & 1411 & \(\beta\)-Caryophyllene & 2.60 & 1.66–3.24 & RI, MS, Co-I \\ \hline
27.7 & 1458 & 2,6,10-Trimethyltridecane & 0.81 & 0.49–0.91 & RI, MS \\ \hline
28.3 & 1480 & Guaia-6,9-diene & 0.82 & 0.37–0.46 & RI, MS \\ \hline
32.4 & 1660 & _cis_-9-Tetradecen-1-ol & 0.65 & 0.18–8.76 & RI, MS \\ \hline
35.2 & 1789 & 1-Heptadecene & 1.62 & 1.69–5.03 & RI, MS \\ \hline
35.7 & 1813 & 2,6,10,14-Tetramethylhexadecane & 0.60 & 0.36–0.73 & RI, MS \\
36.4 & 1848 & _trans_-Phyt-2-ene & 0.46 & 0.84–2.13 & RI, MS \\ \hline \hline \end{tabular}
\begin{tabular}{c c c c} \hline \hline \multicolumn{3}{c}{Unknown compounds} & 12.94 & 9.36–32.65 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._  
Figure 1: Olfactory responses of horn flies to volatiles from fresh and aged cattle dung. **Left**: Response of mixed-sex flies randomly selected; **Center**: response of female flies; and **Right**: response of male flies. Values are mean \(\pm\) SD. Asterisks on the points indicate significant differences between treatments and blanks based on the Tukey HSD test (\(p\leq 0.05\)); N = 6.