No abstract

Bait (50 mg AI kg−1) and spray (10 mg AI m−2) formulations of the novel insect growth regulator (IGR) lufenuron were tested against populations of the Oriental cockroach Blatta orientalis L. and the German cockroach Blattella germanica L. that had been established in simulated domestic environments. The treated populations of B. germanica declined rapidly three to four months after the start of bait or spray treatment, and were completely eradicated after 12 months. As well as disrupting the moulting process, lufenuron affected the reproduction of B. germanica by preventing the hatch of the oothecae. In B. germanica, it appeared probable that lufenuron was transferred from female cockroaches to the oothecae while they were being carried. By contrast with B. germanica, the treated populations of B. orientalis did not show any substantial decline compared with the control, even after 18 months' exposure to lufenuron bait or spray treatments. Moreover, neither moulting nor reproduction in the populations of B. orientalis appeared to be affected by either of the lufenuron treatments. Subsequently, laboratory investigations with surface deposits of either technical or formulated lufenuron, applied at dose rates up to 50 mg AI m−2, failed to demonstrate any significant effects on the development or reproduction of B. orientalis. Laboratory tests with first‐instar nymphs of both species revealed substantial differences in sensitivity to the moult‐disrupting effects of the compound. These differences extended to the adult insects, where reproduction was markedly affected in B. germanica, but apparently unaffected in B. orientalis. Thus, both bait and spray formulations of lufenuron have been shown to provide rapid and effective control of German cockroach populations in simulated domestic environments. However, the same treatments were much less effective against similar populations of the Oriental cockroach. These results are discussed in terms of the potential effectiveness of lufenuron as a cockroach control agent, and in relation to the substantial differences in susceptibility to the inhibitory effects of this compound on reproduction that were apparent between Blatta orientalis and Blattella germanica.

No abstract

At 27 degrees C and 45% r.h. in the laboratory, the oriental cockroach Blatta orientalis (L.) developed to adulthood in seven to nine instars for males (66% had eight instars) and eight to ten instars for females (67% had nine instars) in mixed groups, with up to twelve instars for isolated females. Nymphal development lasted 185 +/- 2 days for males, 216 +/- 4 days for females, with 89% survival to adulthood. Adult longevity was significantly more for males than females in mixed groups. Virgin females lived for 135 +/- 6 days compared with 87 +/- 9 days for females kept with males. After an initial maturation time of 12.2-13.5 +/- 0.4 days for mated and unmated females, oothecae were produced, on average, every 6-7 (range 2-29) days. Ootheca viability was 68% from females kept with males, 32% from females kept apart from males. Numbers of nymphs emerging were 14.1 +/- 0.26 after 45 days from mated female oothecae 8.2 +/- 0.3 after 49 days from unmated females. With sexual reproduction the sex ratio of progeny reaching adulthood was 1.1 males per female (n = 443), whereas unmated females produced only female progency, which is consistent with parthenogenetic reproduction. Drawings of the ventral aspect of the terminalia are given to show features useful for instar determination and for distinguishing between male and female nymphs and adults of B. orientalis.