However, Drosophila males with either gustatory (Poxn-pRes) (M3) or olfactory (Or83b2) deficits (M4) displayed the scanning behavior (data not shown), which suggests that volatile or contact pheromones are sufficient to drive this behavior in the dark.
To ensure the high relative humidity needed during spore germination, as well as to eliminate possible volatile signal contact between 'receiver' and 'donor' plants, all 'receiver' plants were covered with an air-tight plastic bag during pathogen inoculation, and all inoculated and control 'donor' plant was covered with an air-tight plastic bag after pathogen inoculation.
Deprived of visual cues, a male presumably becomes more reliant on volatile or contact pheromones [ 7].
In these more volatile situations, contacts are often harder to find, as the population is more mobile and could be hiding from militias ― making it harder for contact tracers to locate and contain the outbreak. .
Instead, females learn an attraction to individual-specific airborne urinary volatiles on contact with male urine [ 17].
We found no support for alternative hypotheses, as mechanical stimuli due to wing fanning or antennal contact, volatile or nonvolatile pheromones from the antennae, and volatile pheromones from the mouthparts.
This scanning behavior is triggered by the decamping female (M2) and driven by volatile (M3) and contact pheromones (M4).
In terrestrial animals, distance pheromones are usually air transmitted and, as such, are volatile compounds, while contact pheromones are coated on the body surface [8] requiring physical tactile interaction.
For root-knot nematodes, the observations that the rate of clump formation is positively correlated with nematode population density and is accelerated by placement of a coverslip on the gel surface are consistent with the hypotheses that reduced oxygen, increased concentration of a volatile pheromone or contact with a solid surface can initiate or stabilize the clumping [6].
Darcin itself may also have some influence on the pattern of airborne volatiles learned on contact: while contact with BALB/c male urine plus r-darcin resulted in strong attraction to volatiles from this same stimulus, it resulted in only weak attraction to airborne volatiles from BALB/c male urine without r-darcin [Figure 10C g,j)].
