ECOLOGICAL STUDY OF COFFEE STEM BORER <I>XYLOT RECHUS QUADRIPES </I>CHEVROLAT (COLEOPTERA: CERAMBYCIDAE) IN NORTHERN THAILAND II. MATING AND REPRODUCTION

Abstract

Mating behavior and reproductive rate of the coffee stem borer, Xylotrechus quadripes Chevrolet were studied in both laboratory and 8 x 16 x 3.5 meters field cage. In the period of 15 days of observation, the results revealed that the copulation normally occured during the daytime. Both male and female were supposed to have the equal chances to search for each other for copulation. The flying female may approach a resting male or the male was stimulated by alighting female on the coffee bush.

The fecundity rate and longevity of adult stem borer were enhanced by the higher humidity rate. The range of relative humidity recorded during June to October was quite high as 74.17-78.69%. The maximum number of eggs were obtained at the optimum temperatures of about 31.02-31.52 °C. The temperatures beyound the optimum point caused a remarkable decrease in number of egg deposit. Beside the environmental factors, the body size of insect was also found to correlate  with both fecundity and longevity of adult female. The fecundity increased as their body size increased and similarly the longevity of the bigger size adult was longer than the smaller one. Interestingly it was noted that the virgin female did not lay any eggs even mature eggs were full in its abdomen.