No abstract

The effects of two insect growth regulators on the productivity of Rhyzopertha dominica, Sitophilus oryzae and S. granarius were studied by exposing insects to wheat treated with methoprene (isopropyl 11-methoxy-3,7,11-trimethyldodeca-2,4-dienoate) or hydroprene (ethyl 3,7,11-trimethyldodeca-2,4-dienoate) at concentrations of 1, 5, 10 and 20 ppm. Parental adult mortality was generally higher on wheat treated with methoprene than with hydroprene, and this effect was usually enhanced under unventilated conditions. The productivity of the three species was markedly reduced, in some instances suppressed, under unventilated conditions, whereas only R. dominica productivity was depressed under ventilated conditions. When progeny were produced, their productivity was, in general, lower than normal.

The distribution and biology of Tribolium castaneum Herbst on temperature gradients varying in steepness was studied. It was found that the distribution of adults, eggs and pupae differed markedly on a shallow (0.08° C per cm) and steep (0.23° C per cm) gradient. However, this was not the case for the egg to adult developmental period, survival and eclosion pattern of adults. Clearly, some difference between adult distributions, or egg distributions, in gradient environments does not necessarily result in a noteworthy difference in biology though this possibility is not precluded. RÉSUMÉ DISTRIBUTION ET BIOLOGIE DE TRIBOLIUM CASTANEUM (COLEOPTERA, TENEBRIONIDAE) DANS DES GRADIENTS DE TEMPÉRATURE DE PENTE VARIABLE On a étudié la distribution et la biologie de Tribolium castaneum dans des gradients de température de pente variable. Il a été trouvé que la distribution des adultes, des œufs et des nymphes varie de façon importante dans un gradient peu rapide (0,085° C/cm) et dans un gradient rapide (0.238° C/cm). Cependant ce ne fut pas le cas pour la période de développement depuis l'œuf jusqu'à l'adulte, la survie et le rythme d'éclosion des adultes. Evidemment, quelque différence dans les distributions des adultes, ou des œufs, dans des gradients de l'environnement, ne se traduit pas nécessairement par une différence remarquable dans la biologie bien que cette possibilité ne soit pas exclue.

The effects were studied of incorporating three synthetic insect juvenile hormones and five analogues in flour diets for T. castaneum. The synthetic hormones used were: methyl 10,ll-epoxy-7-ethyl-3,ll-dimethyltrideca- 2,6-dienoate (compounds I and II; these had the same structure but consisted of different isomer ratios), and methyl cis-l0,11-epoxy-3,7,11-trimethyltrideca-trans-2,trans-6-dienoate (III). The analogues used were: 6',7'-epoxy-3',7'-dimethyloct-trans-2'-enyl 3,4-methylenedioxyphenyl ether (IV); 3'-methyl-7'-ethylnona-2',6'-dienyl 3,4-methylenedioxyphenyl ether (V); ethyl 3,7,11-trimethyldodeca-2,4-dienoate (VI); isopropyl 11-methoxy-3,7,11-trimethyldodeca-2,4-dienoate (VII); 6',7'-epoxy-3',7'-dimethyloct-trans-2'-enyl 4-ethylphenyl ether (VIII). Compounds II-VII were incorporated in flour media at concentrations of 5 and 20 p.p.m. and I and VIII at 5 p.p.m. only. The number of eggs laid in various treated media did not differ significantly from that in the control. Egg to adult development was inhibited by VII and VIII at 5 p.p.m. and by II, IV and VI at 20 p.p.m. Development was completed in other treatments but with a high level of adult morphological deformity except with V and VI at 5 p.p.m. The compounds tended to increase the developmental period from egg to adult.