The JapanSocietyJapan Society ofMedicalof Medical Entomology and Zoology [Med. Entomol. Zooi,VoL49 No.1 p.27-32 1998] Effects of mating on oviposition, and possibility of parthenogenesis of three domestic cockroach species, the American cockroach, Pignblaneta amen'cana; the Smoky brown cockroach, Rerij)laneta fuliginosa; and the German cockroach, Blattella gz?rmanica Xingfu XIAN BSI institute of Biologtcal Science, Azusatva 2-1 7-Z llabashi-hu, Tokyo, 1 74-O051 lbPan (Received: 16 July 1997; Accepted: 11 October 1997) Key words: cockroach, adult lifespan,ovlposltlon,ootheca, parthenogenesis, sexual reproduction Abstract: Three dornestic cockroach species, the American cockroach, Reripla- neta americana; the Smoky brown cockroach, Ptiriplaneta ftttiginosa; and the German cockroach, Blattella gemaaniea were used in this experiment to determine the effect of mating on oviposition and possibility of parthenogenesis. In comparison with mated females, unmated females ofR americana and R fttligt'nosa had a longer adult lifespan, but produced obviously fewer oothecae, including many malformed oothecae. The malformed ootheca rate was higher than 60%. However, unmated females of B. germanica were similar to mated females in adult lifespan and the oviposition cycle, and all the oothecae produced by unmated females were normally formed. Partheno- genesis was found in R americana and Il fuligr'nosa. The hatchability of oothecae produced by unmated females, which the malformed oothecae were not counted, was 18.7% in R americana, and 16.7% in R jutigt'nosa. All the parthenogenetic progeny were females. Parthenogenesis was not found in B. gennanica, oothecae deposited by unmated females were desiccated and fell off before new oothecae were produced. tics have not been well investigated, espe- INTRoDUCTION cially on the aspect of reproduction. Reproduction is a vital factor in the biol- Cockroaches are common and persistent ogy of an insect species, and cockroaches pests in comrnercial, domestic and institu- Mustrate this principle perfectly. Cock- tional premises. They are known to carry roaches become troublesome pests to a variety of bacteria and other pathogenic human life because they have a strong organisms (Roth and Willis, 1957), and im- vitality and high reproductive ability to munological studies also suggests that expand their sphere of influence. Hence, they may give rise to serious allergic reac- the reproduction of cockroaches is a sub- tions, including asthma, in a substantial ject of more than acadernic interest. Par- proportion of the allergen-sensitive popu- thenogenesis, a special reproductive sys- lation (Berton and Brown, 1964, 1972; tem, is widely found in insects. Many Kawakami et al., 1982; Berns, 1987; Chap- insect species, such as aphids and weevils, man, 1993). Although R americana, R .fut- can make use of parthenogenesis to rapid- igz'nosa and B. germanica are arnong the ly increase their population when the en- pests in homes and stores in Japan, their vironment is advantageous to propagate. physiological and ecological characteris- Some parasitic bee and fiy species also use NII-Electronic Library Service The JapanSocietyJapan Society ofMedicalof Medical Entomology and Zoology 28 Med. EntornoL ZooL parthenogenesis to leave progeny in a males from the culture tanks. In the par- temporary absence of males to copulate thenogenesis group, unmated females for sexual reproduction. On the other were kept without males during the adult hand, the banded psocid, LiPoscelis bostrz'c- life time. hophilus B, has to use parthenogenesis to All insects were kept in an incubator leave progeny because all the insects are where the temperature was maintained at female. 30℃ and the humidity was uncontrolled However, parthenogenesis of cock- throughout the experiment. Food, water roaches has seldorn been mentioned. Blatt- and harbourage were supplied at all times. ella orientalis (Short and Edward, 1991), Newly-produced oothecae of R amen'cana 1948), and R were transferred from Rycnoscelussurinamensis (Matthey, .fuliginosa Smpelta smpellectitium (Roth and Willis, the culture cases into glass specimen 1954) and R americana (Griffiths and tubes and incubated at 300C. When Tauber, 1942) have reported on this sub- nymphs hatched from oothecae, they were tanks × ject. In Japan, there have been no data transferred to largerplastic {65 45 available regarding parthenogenesis of × 45cm) and maintained at 30℃ with cockroaches. food, water and harbourage until adult. The objectives of this experiment were Oothecae that did not hatch after a period to study the reproduction of three domes- of 6 weeks were retained for more 3 weeks tic cockroach species, R a2nericana, R fitl- before being discarded. All the nymphs igt'nosa and B. ge7?nanica, especially in ovi- hatched from the parthenogenesis group position and parthenogenesis. were cultured. In the sexual reproduction group, 121 and 118 nymphs ofR america- MATERiALs and METHoDs na and R fttliginosa were reared and the others were discarded. In B. germanica, they Specimens of R amen'cana, R .ft41igz'nosa when oothecae felloff from females, and B. germanica were used in the present were collected and searched for hatching. study. They had been hatched in the lab- All the hatched nymphs were discarded. oratory from eggs taken from stock cul- tures on a diet of rolled feed for mouse REsuLTs propagation (Oriental Yeast Industry Co.). Water was supplied at all times. In June, 1. Adult longevity and ovtposition of cocleroaches thefinalinstarfemale nymphs of the cock- .female roaches were selected from culture tanks In R americana, the lifespan of adult and removed to new culture tanks. When females which mated with males was ap- the females newly emerged to adult, they proximately 6 months (187± 14 days, were immediately removed to 15 × 12 × 1 1 range 145-227 days). Unmated females cm plastic culture cases, separated into a lived for 212 ± 19 days (range 169-274 sexual reproduction group and a parthe- days), which were longer than that of the nogenesis group. The adult females of R mated females (Table 1). Newly emerged americana and R fttliginosa were individu- females produced the first ootheca after an ally placed in culture cases. Each group emergence time of 10.2 ± O.8 days when consisted of 10 cases <10 females). Five mated and slightly later (12.4± 2.1 days) adult females of B. germanica were trans- when unmated. Mated females produced ferred together into one culture case, and an average of 34.1± 3.5 oothecae (range In each group consisted of 6 cases (30 fem- 22-43) per female during their life. cycle was ales}. In the sexual reproduction group, mated females,the oviposition females were kept with males from the approximately 4 days (4.2± O.7 days, time of emergence until death. When the range 3-6 days> in the first 2 months and 6 males died, they were replaced with other days (6.3± 1.3 days, range 4-10 days) in NII-Electronic Library Service The JapanSocietyJapan Society of Medical Entomology and Zoology VoL49 No,1 1998 29 Table 1.Adult longevity and oviposition of female cockroaches, Meanlifespan(days)Mean preovi- Mean no, No. ofmsects Species position period oothecae (days> per female MatedUnmated 1010 187 ± 14 10.2± O,8 34,1 ± R americana 3,5 212 ± 19 l2.4± 2,1 8.9± 4.2 MatedUnmated 1010 149 ± 12181 9.8± 1.1 24.5 ± 2.7 R ftttigr'nosa ± 17 14.1± 2.7 6.2± 3.1 MatedUnmated 3030 98 ± 7lel 7,1± 1,17.3 3.8± O,83.9 B germanica ± 7 ± 1.0 ± 1.1 Table 2,Viability of oothecae of cockroaches, No, of Malformed Hatch-ability(%}* Mean no. Total Hatched Species malformed ootheca of nymphs oothecae oothecae oothecae rate (%) per ootheca Mated 341 1257 3.564.0 314 ± R amen'cana 95,418,7 12.0 O.3 Unmated 89 6 1LO ± L8 245 338 1.261.3 230 95.016.7 11.8± O.2 R futigt'nosaMatedUnmated 62 4 10,O± 1.0 Mated ll4117 oo oo 114 100 **o B, gennanica Unmated o o *, The malformed oothecae were not counted in. **, Not counted, months, the later and their oviposition In R ftttigi'nosa, the lifespan of adult was stopped at the last 16± 4 days before females which mated with males was 149 they died. The oviposition cycle of un- ± 12 days (range 117-174 days), but un- mated females was an average of 8.9± 2.1 mated females lived longer (181± 17 days, days (range 5-15 days) in the first term range 131-236 days) than mated females. and 17.0± 5.2 days (range 6-30 days) in Mated fernales produced the first ootheca the last term, which were significantly 9.8± 1.1 clays after emergence. They pro- longer than that of mated females, an av- duced an average of 24.5± 2.7 oothecae erage of 8.9± 3.2 oothecae was produced <range 17-35) per female during their life per female. As compared with the mated time. On the other hand, unrnated females females, unmated females also were early produced the first ootheca 14.1± 2.7 days to stop oviposition, the lastootheca was after emergence, which was longer than produced at 25 ± 11 days before death. that of the mated females. Each unmated Two unmated females completely ceased female produced approximately 6 oothe- to produce ootheca after emergence time cae (6.2± 3.1, range 3-14}, which was only of 40-50 days. Many malformed oothecae 25% of that produced by mated females. which had no eggs in the ootheca case The unmated females alsa were early to were obtained from the parthenogenesis stop oviposition in comparison with the group, the rate of malformed oothecae was mated femaies. The rate of malformed about 64% (Table 2). But the oothecae oothecae without eggs was about 60% in produced by mated females were almost the parthenogenesis group, while it was normally formed, and the malformed oot- only 1.2% in the sexual reproduction hecae only 3.5%.