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Daily oxygen uptake rhythms in male boll weevils, Anthonomus grandis boheman (Coleoptera: Curculionidae) of the ebony strain fed cotton squares (buds)
Abstract
1.1. Oxygen uptake was measured 8 times a day in 2–20-day old male and female boll weevils of the ebony strain.2.2. The insects were held under a 16 hr photophase or under continuous light.3.3. Time-of-day for low points and peaks of O2 uptake were established.4.4. O2 uptake was depressed when the light regime was switched from 16:8 L-D to continuous light.5.5. Presumptive evidence was obtained for the existence of an internal daily rhythm.
We measured oxygen uptake in 3- to 13-day-old Heliothis virescens (tobacco budworm) larvae. The “test” group was infected with cytoplasmic polyhedrosis virus (CPV) while the “control” group was not. The healthy budworms had an average oxygen uptake of 7.64 μl of O2/mg body weight, while those infected with CPV had an average uptake of 47.11 μl of O2/mg body weight/hr. The weights of larvae from the two groups were likewise recorded. Budworms from the “control” group showed an average weight of 186.9 mg, while larvae infected with CPV had an average weight of 18.3 mg.
We have studied the effects of the Ca2+ ionophores A23187 and ionomycin on ion transport across amphibian skin and urinary bladder. Both A23187 and ionomycin stimulated transepithelial Na+ transport across the skin. Ionomycin also markedly increased the conductance of an amiloride-insensitive pathway. Both ionophores markedly stimulated the release of prostaglandin E2 (PGE2) into the solution bathing the serosal surface of the skin. Addition of indomethacin to the serosal bathing solution of the skin blocked both the stimulation of short-circuit current (Isc) and the release of prostaglandin caused by the ionophores. Acetylsalicylic acid also blocked the ionomycin-induced stimulation of Isc. These results suggest that the stimulation of Na+ transport caused by Ca2+ ionophores is mediated by the release of a product of the cyclooxygenase pathway, very likely PGE2. Ca2+ ionophores also stimulated the release of PGE2 in urinary bladders; however, they generally depressed Isc. Since the effect on Isc caused by the addition of exogenous PGE2 was different in urinary bladders than in skins, we suggest that at least part of the difference in the action of ionophores is due to the difference in the sensitivity of these epithelia to PGE2. Our results suggest that the heterogeneity of effects that Ca2+ ionophores cause in the physiological parameters of tight epithelia are not always the direct result of increased cytoplasmic Ca2+ but that they may be mediated by other tissue responses triggered by the addition of the ionophores.
ESEARCH on the biological control of in- sects has become a prime concern of many entomologists in recent years, especially since the successful use of the sterile male technique in the eradication of the screw-worm, Cochliomyia hominivorax (Coquerel), in the Southeastern United States. Many of the new techniques may be broadly defined as control by manipulation of genetic phenomena (sterility by the induction of dominant lethals, breeding of tolerant or resistant plants, sexual dimorphism in response to release of phero- mones, competition between species for space or food)8. A related area of entomological research that has become important is the use of marking techniques in the study of population dynamics and behavior. A recent article8 outlined several methods of insect marking and listed criteria for an ideal marking technique, but use of genetic markers was not considered. Only one of the S3 references cited in this article dealt with the use of mutant genes, and that was cited in connection with the statistical treatment of marked populations. Genetic markers are now available in many orders of insects 1612. Such markers could be of great assistance in ento- mological research. Once the utility of genetic markers is established, many more mutants could be isolated for such use in a short time. A search for suitable markers in the boll weevil has already produced two mutants2. The purpose of the present article is twofold: 1) to report a series of five color mutations in the boll weevil, Anthonomus yrandis Boheman, which have been isolated primarily for use in entomological research, and 2) a discussion of the criteria for an ideal marking technique for insects6 that could make use of genetic markers.
1.1. Oxygen uptake was measured in 1- to 15-day-old male and female boll weevils of the ebony strain that were fed cotton squares (buds).2.2. O2 uptake was found to range between 19.51 and 10.64 μl O2/mg wet wt/hr for males and between 17.6 and 11.1 μl O2/mg wet wt/hr for females.3.3. Peak O2 uptake for males was recorded when they were 5 and 11–12 days old.4.4. Peak O2 uptake for females was recorded when they were 6 and 12 days old.
By using new techniques and complete mechanization to mass produce eggs of the boll weevil, Anthonomus grandis Boheman, more than 1 million eggs per week were obtained at a cost of less than 10 cents per thousand. Of 9 diets tested, 2 containing soybean protein were most satisfactory. Diets, formulated into pellets that also served as oviposition sites, were placed in wire baskets raised 3/16 inch above a screen-bottomed rearing cage designed with solid top and sides so that all light came from below the cage.
1.Oxygen uptake was measured in laboratory diet-fed 1- to 15-day old male and female boll weevils of the ebony strain.2.O2 uptake was found to be between 27·24 to 6·45 μl O2/mg wet wt per hr for males and between 26·37 and 5·64 μl O2/mg wet wt per hr for females.3.Peak O2 uptake for males was recorded when they were 4 and 12 days old.4.Peak O2 uptake for females was recorded when they were 6, 10, and 14 days old.