Responses of cotton stainers (dysdercus fasciatus sign.) to relative humidity and temperature, and the location of their hygroreceptors
MADGE, DAVID S.
Cotton stainers (Dysdercus fasciatus Sign.) are hygrosensitive to both dry and moist air, but not to intermediate relative humidities. The hygroreceptors are located on the 4-segmented antennae. Bilateral amputation of the terminal antennal segment results in a dry reaction; bilateral amputation of the terminal and sub-terminal segments result in a moist reaction. The sensilla basiconica (“peg organs”) on the terminal segment are probably responsible for the moist reaction, and the sensilla trichodea (“sensory hairs”) on the two terminal segments are probably responsible for the normal dry reaction. Other sensory areas on the antennae are probably not hygrosensitive. In temperature gradients of 15° C to 38° C (mainly in moist air) cotton stainers first aggregate at the cold end, and then aggregate in two peaks, one at the cold end and another at 23° C--34° C. The thermoreceptors are not located on the antennae, but elsewhere on the body.Show more [+] Less [-]