In insects, selection of insecticide-insensitive acetylcholinesterase (AChE) is a very common resistance mechanism.
Given the large natural variation of insect pathogens, selection for particular traits is an approach that could yield benefits if it were clear what traits were required for a particular strategy.
Olfaction is essential to insect survival and reproduction, such as in location of food sources and mate selection.
Although user identification of individual insects is not feasible when tracking a large number of insects, manual selection is often necessary in behavioral assays where the focal insects need to be accurately identified and tracked for the data to make any sense.
In such insects, divergent selection between host plants might occur for cryptic colouration (camouflage to evade visual predation), physiology (to detoxify plant chemicals), or both of these niche dimensions.
In other insects, positive selection has been found in ant and termite defensins [ 60 62].
Previous studies in natural and experimental populations of D. stramonium in their native range have reported that foliar damage caused by herbivorous insects imposes selection on resistance and/or tolerance (Núñez-Farfán and Dirzo 1994; Shonle and Bergelson 2000; Valverde et al. 2001, 2003; Fornoni et al. 2004).
Moreover, with few other plant species interfering with insect host plant selection behaviors, monocultures can facilitate for insects finding their host plants and enhance their dispersal from plant to plant, which could reduce competition for resources [7].
Hence, it is conceivable that even though DSX belongs to a highly conserved transcription factor protein family, it could be involved in the adaptive process and respond to the key force in insect evolution, sexual selection, by changing those protein regions involved in the control of expression of genes affecting dimorphic phenotypic traits in the two sexes.
