SEASONAL DYNAMICS OF EGG DIAPAUSE IN MAHANARVA SPECTABILIS (DISTANT, 1909) (HEMIPTERA: CERCOPIDAE) ON ELEPHANT GRASS

Abstract

ABSTRACT This work examines the occurrence, duration and viability of diapause eggs of Mahanarva spectabilis (Distant, 1909) at different periods of the year. Adult insects were gathered twice a month in a greenhouse from September 2005 to May 2006 as well as in the same period in 2006-2007. The spittlebugs collected were taken to the laboratory, sexed and kept in cages containing one elephant grass plant potted in a 500 mL plastic cup with the upper part wrapped in gauze to serve as a substrate for egg laying. Around one hundred eggs obtained on each sample date were kept in climate-controlled chambers. The duration and viability of the eggs were analyzed daily. The viability was greater than 50% and 72%, respectively, in the evaluations for September 2005 to May 2006 and the same period of 2006-2007. The average embryonic period from September 2005 the first half of March 2006 varied from 15.79 to 28.24 days, except in the first half of January. In the other samples it varied from 94.80 to 139.04 days, with these being considered diapause. In the second study period (2006-2007), an embryonic period under 27 days was registered from September to the first half of November 2006 and again in January and February 2007. In the other evaluations the insects remained in the egg phase from 55.30 to 196.42 days. The largest number of diapause eggs occurred in the autumn, with 100% and 90% for the first and second evaluation periods, respectively.