## 2 Materials and Methods
### Sample Distribution for Analysis  
The insects' masses ranged from 20 to 200 mg depending on the available sample. In all cases, the sample was evenly divided for both the QuECHERS and HEADSPACE-SPME analyses. HPLC-grade ethyl acetate and standard chlorpyrifos were purchased from MERCK; the QuECHERS kit was purchased from Agilent. Solid-phase microextraction (SPME): To extract volatile compounds from the insect (Table 1), every sample was weighed before the extraction method (direct SPME or micro-QuECHERS). The extraction of volatile compounds from the free space of the samples was performed using polydimethylsiloxane/carboxen/divinylbenzene (PDMS/CAR/DVB) at a temperature of 105 \({}^{\circ}\)C. The extraction time for the fiber was 40 min, based on reported work related to pesticide detection in larvae (1998). Micro-QuECHERS: A QuECHERS method was adapted (1998) at the microgram level. The protocol was as follows: The sample was dried at 50 \({}^{\circ}\)C for 12 h and subsequently homogenized using a mortar. The weighed content was deposited in an Eppendorf tube to which 1 mL of ethyl acetate was added and shaken for one minute. QuECHERS Final Polish EMR-Lipid(r) (25-250 mg) was introduced and stirred for 1 min. The tube was centrifuged at 12,000 rpm for 4 min at room temperature. Subsequently, 600 uL of the supernatant was extracted and transferred to a new Eppendorf tube containing anhydrous MgSO4: PSA (12-120 mg). The contents were agitated for 1 min and then centrifuged at 12,000 rpm for 4 min at room temperature. The resulting supernatant was filtered for a GC/MS/MS analysis. GC/MS/MS Chromatographic Conditions: Thermo TSQ DUO equipment (Thermo Fischer Scientific, Waltham, MA, USA) was used in Selective Reaction Monitoring (SRM) mode. Helium served as the mobile phase with a flow rate of 1 mL/min, and the injector temperature was maintained at 230 \({}^{\circ}\)C. The RTX5-ms column was utilized under the following conditions: an initial temperature of 60 \({}^{\circ}\)C for 2 min followed by a temperature increase to 180 \({}^{\circ}\)C at a rate of 20 \({}^{\circ}\)C/min which was held for 2 min, and a further temperature increase to 270 \({}^{\circ}\)C at a rate of 10 \({}^{\circ}\)C/min which was held for 2 min. The mass spectrometer system was operated in electron ionization (EI) mode at 70 eV. The ion source and transfer line temperatures were both 280 \({}^{\circ}\)C.  
For quantifying the pesticide chlorpyrifos, the SRM method was optimized using the \"AUTO-SRM\" function, allowing for the selection of appropriate energies for the fragmentation of \"parent\" ions and monitoring \"daughter\" ions. Specifically, the 169 \(m/z\) ion was used for qualification, while the 79 \(m/z\) ion was selected for quantification (Table 2). The qualitative/quantitative data were processed using Chromeleon software version 7.2.10. The QuEChERS extraction was standardized with the pesticide chlorpyrifos (1 ng/mg of insect) using the spiked method, achieving an average recovery of 95.5% in pesticide-free insects with an RSD of less than 2% (Table 3). The HEADSPACE-SPME extraction technique is based on the release of the pesticide from the surface of the insect rather than the entire insect as in a \"bulk\" method (such as QuEChERS). Therefore, it depends on the adsorption and desorption relationship of these compounds on the insect's surface. We propose using different masses of chlorpyrifos in the HEADSPACE-SPME vial and constructing a calibration curve that allows for a good correlation as the volatile pesticide will be analyzed under the same incubation conditions as the insects themselves. In the case of the micro-QuEChERS technique, the limit of detection (LOD) was 0.9 ng/g, and the limit of quantification (LOQ) was 2.3 ng/g, whereas for HEADSPACE-SPME, the LOD was 2.6 ng/g, and the LOQ was 12 ng/g. For statistical comparison between the two pesticide detection methods used in this research, a paired \(t\)-test was performed with a statistical significance level set at 99%.