General biology and reproductive fitness of Tasmanian lacewing, Micromus tasmaniae Walker : a thesis presented in partial fulfllment of the requirements for the degree of Master of Science in Plant Protection at the Institute of Natural Resources, Massey University, Palmerston North, New Zealand
Tasmanian lacewing, Micromus tasmaniae Walker, is an important predator of
a number of economically important pests such as aphids. This study was conducted
to investigate some aspects of general biology and factors affecting the reproductive
fitness of this species Emergence of M. tasmaniae peaked 3 h before light off and
there was no significant difference in emergence patterns between males and females.
Males became sexually mature earlier than females. Mating success significantly
increased from the first to the eleventh hour after lights on. Predation, development
and oviposition of M. tasmaniae were affected when reared under different
photoperiods [i.e. 24:0, 16:8, 12:12, 0:24 h (light:dark)]. Results indicate that no
individuals entered diapause at either an immature or adult stage. M. tasmaniae larvae
could feed in both the photophase and scotophase and late instar larvae consumed
significantly more aphids than early instar larvae. M. tasmaniae reared at 16:8 h
developed faster and had lower mortality, heavier adult body weight and higher
reproductive output in terms of fecundity and fertility rate. Therefore, mass-rearing
programmes are recommended to be carried out at 16:8 h to obtain the higher quality
of individuals and faster increase of populations. The larger-the better theory predicts
that the reproductive fitness is positively linearly associated with body size or weight.
However, the body weight of female M. tasmaniae had no effect on the reproductive
fitness in terms of fecundity, fertility, fertility rate, oviposition period and longevity.
The male body weight may contribute to the population growth of M. tasmaniae as
the average females that mated with average or heavy males had significantly higher
fecundity, fertility and fertility rate and longer reproductive period. These results
suggest that development of any control method that should selectively mass-produce
heavy and average individuals in the laboratory would help increasing M. tasmaniae
quality and populations. M. tasmaniae is a polygamous species. Results indicate that
female remating either with the same or different males was crucial for maximizing
their reproductive success. Males could inseminate up to eight females and father
about one thousand offspring during their life span.