Biology of Blaptica dubia (Blattodea: Blaberidae)

Abstract

The Dubia Cockroach, Blaptica dubia Serville, has become a popular food choice among amphibian and reptile enthusiasts. However, there has been little scientific research conducted on this species. My research consists of three topics: instar determination, temperature-dependent development, and parental care. Instar determination is fundamental to both basic entomological research and its application. A new method using Gaussian mixture models to determine the number of instars in this species was developed. Application of the method is illustrated by analysis of data collected on B. dubia. The analysis indicates that there are seven instars in B. dubia and that the growth ratio follows the Brooks-Dyar rule. The growth ratio of pronotal length, pronotal width, and head width are 1.26, 1.24, and 1.19, respectively. Since B. dubia shares a similar growth pattern with other paurometabolous insects, this method may be applicable to other species as well. Temperature-dependent development of the nymphs of B. dubia was described using data collected from constant-temperature laboratory experiments. Simple linear regression was used for the data from each instar. Degree-days required to complete each instar were estimated as 457.5, 668, 1031 .1317, 1515, 2071 for instars 1-7, respectively. The results could be used to control the development rate and find the optimal rearing conditions for B. dubia. The social behavior of cockroaches is less studied compared to other insect groups. Most information about cockroaches is from brief notes made during field studies. For parental care, most of these studies have been focused on the family Cryptocercidae and no studies have been conducted on the parental care behavior of the Blaberidae. The objective of this study was to measure the possible effects of parental care on the offspring of B. dubia. In this experiment, no parental care effects were detected although parental care behavior was observed in B. dubia.