J.
Med. Entomol. Vol. 15, nos. 5-6: 459-461
4 September
©
1978 by
1979
the Ilishop Museum
THIOUREA-INDUCED STERILITY IN CHRYSOMYA MEGACEPHALA (DIPTERA: CALLIPHORIDAE) BY PUPAL AND ADULT TREATMENTS By Vishwa Deepakl•2
I
Abstract: IIlf«aceplUlla
urea of varying concentrations intervals.
Sterility in insects is usually induced by irradiation or chemicals. Irradiation often causes injury to the midgut epithelium and results in high mortality. Moreover, its use requires trained pel-sonne! and fairly expensive equipment. Consequently, since most chemosterilants cause less somatic damage, are less expensive and can be used by personnel having only a basic background in entomology, this method where applicable is preferred. Piquett & Keller (1962) reported the prevention of oviposition of Musca domestica (L.) by dipping pupae in thiourea solution; Gouck (1964) sterilized insects of the same species by dipping pupae in 3 different chemosterilants, viz, apholate, tepa, and metepa. On the other hand, Mitlin & Baroody (1958), LaBrecque et al. (1960), Gouck & LaBrecque (1964) and LeBras (1973) sterilized Musca domestica by feeding thiourea to newly emerged individuals. While a number of studies have reported sterilization of different species of flies using different chemosterilants, no work has yet been done to determine the susceptibility of Chrysomya to chemosterilants. To investigate this problem, we selected Chrysomya megacePhala (Fabricius) for our experiments. Because we found that thiourea is very toxic to larvae of this species and in view of a similar report by Mohiuddin et al. (1970) for Musca domestica, we treated only pupae and newly emerged adults of Ch1)ls01nyamegacephala with thio-
Pupal diPs. Newly formed pupae (2-6 hold) were obtained from the culture of C. megacephala maintained in the laboratory at 25°-28°C and 8085% RH. Groups of 150 pupae were dipped in solutions of 1.0%, 1.5% and 2.0% thiourea in small glass vials, each group dipped for 15, 30, 60 and 120 min. The pupae were then removed and each group was kept in separate vials. A group of untreated pupae dipped in water only were used as controls. After 4 days the vials containing the pupae were placed in separate breeding cages containing bread soaked with milk and sugar solution. Newly emerged adults were sexed and transferred to the mating cages. The following 4 mating crosses were made: (1) males from untreated and females from treated pupae, (2) males from treated and females from untreated pupae, (3) males and females from treated pupae, and (4) males and females from untreated pupae. Each cross was replicated twice. The females were then allowed to oviposit on pieces of goat liver held in petl-i dishes. The eggs were counted and kept on moist filter paper in petri dishes. The larvae that hatched were counted to estimate the number of viable eggs; mortality at adult eclosion was also noted. Adult treatments. Freshly emerged flies from the culture were sexed. Groups of 100 flies were kept in different cages and exposed to a diet of bread soaked with milk containing thiourea at concentrations of 0.25%,0.37%, and 0.5% for 12,24 and 48 h. Thereafter they were maintained on untreated food only. A group of flies fed on untreated food throughout was used as a control. The 4 types of mating crosses were made as in the pupal dipping experiments. Egg viability was also determined in a similar manner. For both pupal and adult treatment experiments, the percentage of sterility was calculated according to Chamberlain's formula (1962).
'University of Gorakhpur, Gorakhpur, 273001, India. 2% Or K. B. Lal, Professor & Head, Department of Mathematics, Universily of Gorakhpur, Gorakhpur, 27300 I, India.
MATERIALS
for different
time
AND METHODS
Downloaded from http://jme.oxfordjournals.org/ by guest on June 9, 2016
Pupae and newly emerged individuals of Chrysomya were subjected to dipping and feeding treatments, respectively, with thiourea solutions of varying concentrations for different time intervals. Pupal dipping treatment in some cases pmduced a high percentage of stel'ility, but pupal mortality was very high. On the other hand, exposure of adults to a [I'eated diet for 48 h produced 100% sterility with practically no mortality. Males were more susceptible to sterilization than were females.
and H. S. Chaudhry
J.
450
TAIILE I. Percentage sterility and percentage eclosion in Cln)somya megacephala pupae dipped in thiourea solution at different concentrations and for different time periods.
IMMERSION (min)
EcLOSiaN (%)
1.0
15 30 50 120
1.5
CONC. (%)
2.0
TABLE 2. Percentage sterility and percentage mortality of Chrysomya megacephala adults fed with thiourea at differ'ent concentrations and time periods.
STERILITY (%) WHEN FOLLOWING SEX TREATED
'i
0
'i & 0
83 62 50 42
8.1 31.6 44.9 58.1
19.1 34.5 47.8 62.5
26.5 58.8 73.5 83.8
15 30 50 120
70 55 43 18
33.8 47.1 72.1
37.5 51.5 74.3
51.0 76.5 92.6
15 30 60
47 34 10
72.1 95.6
77.2 100.0
94.9 100.0
120
10
CONe. (%)
FEEDING MORPERIOD TALITY (h) (%)
STERILITY (%) WHEN FOLLOWING SEX TREATED
'i
0
'i & 0
0.25
12 24 48
0.0 0.0 0.0
2.9 8.1 48.5
8.1 45.6 50.3
4.4 50.7 72.8
0.37
12 24 48
0.0 0.0 0.0
2.9 33.8 100.0
4.4 54.4 100.0
8.1 62.5 100.0
0.5
12 24 48
0.0 0.0 15.0
1.5 44.1 100.0
4.4 63.2 100.0
0.0 72.1 100.0
Control
0.0
95
of eggs by untreated females mated with treated males was not affected. But when treated females RESULTS were mated with untreated males, in most cases The results of mating experiments of adults ob- the number of eggs laid was considerably reduced. tained from treated pupae are shown in TABLE 1. Males, in general, were more susceptible to sterilOf 27 mating tests, a high degree (over 90%) of ization with thiourea than females. sterility was observed only in those tests where both sexes were obtained from the pupae treated with DISCUSSION a 1.5% concentration of thiourea for 15 and 30 Bofkovec (1966) reported that thiourea sterilizes min. Similar results were also obtained when feonly females of some species. He also noted that males or males obtained from pupae treated with the sterilant produces unusually erratic results and 2.0% thiourea for 30 min were crossed with norattributed this partly to its high toxicity. LeBras mal males and normal females, respectively. (1973) reported that thiourea causes sterility in Control flies exhibited 95% eclosion. In the tl-eated pupae, where the sterility was over 90%, both males and females of Musca domestica, though the eclosion was below 50%. Where the eclosion females were more sensitive than males. In the obpercentage was fairly low, further mating studies servations made by us on treatment of Chrysomya megacephala with thiourea, it was found that males were not done due to lack of sufficient numbers of in general are more susceptible to sterilization with individuals. this chemical than females. The results obtained when thiourea was fed to freshly emerged flies are shown in TABLE2. CONCLUSIONS By exposing either one or both sexes to the diet containing 0.5% and 0.37% concentrations of thioThe pupal treatment of Chrysomya megacephala urea for 48 h, all mating crosses resulted in 100% with thiourea effectively causes sterilization but sterility. When only females were exposed to 0.5% produces a high concurrent mortality. The feeding thiourea, no eggs were laid and mortality was method, while achieving 100% sterility, causes about 16%. When offered the diet treated with practically no adult mortality. For this reason, 0.37% thiourea, 86 eggs were laid but all were in- adult feeding is the recommended method for viable, and no mortality was observed. Further, sterilizing C. megacephala. when flies were fed for 12 h only, irrespective of the concentration of thiourea used, hardly any steLITERATURE CITED rility was recorded. In control flies, the average Borkovec, A. B. 1966. p. 39. Insect chemosterilants. Adv. Pest number of eggs laid by a female was 158 per batch. Control Res. Vol. 7. John Wiley & Sons, New York. 143 p. In almost all treatments, both in pupal dipping Chamberlain, W. F. 1962. Chemical sterilization of the screwworm. J. Econ. En/ollloi. 55: 240-48. as well as in adult feeding experiments, production
Downloaded from http://jme.oxfordjournals.org/ by guest on June 9, 2016
Control
Vol. 15, nos. 5-6
Med. Entomol.
1979
Deepak & Chaudhry:
Thiourea-induced
Gouck, H. K. 1964. Chemosterilization of house flies by treatment in the pupal stage. J. Econ. En/ornot. 57: 239-41. Gouck, H. K. & G. C. LaBrecque. 1964. Chemicals affecting fertility in adult house flies. J. Econ. En/ornot. 57: 663-64. LaBrecque, G. C., P. H. Adcock & Carroll N. Smith. 1960. Tests with compounds affecting house fly metabolism. J. Econ. En/ornot. 53: 802-05. LeBras, S. 1973. Action d'un chimio-sterilisant, la thiouree, sur Musca dornes/ica adulte. En/ornot. Exp. Appt. 16: 9-19.
sterility in Chrysornya rnegacephata
461
Midin, N. & A. M. Baroody. 1958. The effect of some biologically active compounds on growth of house fly ovaries. J. Econ. En/ornot. 51: 384-85. Mohiuddin, S., S. A. Qureshi & M. W. Roomi. 1970. Effects of thiourea on the house fly, Musca dornes/ica (1.) (Dipt., Muscid.). Z. Angew. Entornot. 66: 435-39. Piquett, P. G. & J. C. Keller. 1962. A screening method for chemosterilants of the house fly. J. Econ. Entornot. 55: 261-62.
Downloaded from http://jme.oxfordjournals.org/ by guest on June 9, 2016
Med. Entomol. Vol. 15, nos. 5-6: 459-461
4 September
©
1978 by
1979
the Ilishop Museum
THIOUREA-INDUCED STERILITY IN CHRYSOMYA MEGACEPHALA (DIPTERA: CALLIPHORIDAE) BY PUPAL AND ADULT TREATMENTS By Vishwa Deepakl•2
I
Abstract: IIlf«aceplUlla
urea of varying concentrations intervals.
Sterility in insects is usually induced by irradiation or chemicals. Irradiation often causes injury to the midgut epithelium and results in high mortality. Moreover, its use requires trained pel-sonne! and fairly expensive equipment. Consequently, since most chemosterilants cause less somatic damage, are less expensive and can be used by personnel having only a basic background in entomology, this method where applicable is preferred. Piquett & Keller (1962) reported the prevention of oviposition of Musca domestica (L.) by dipping pupae in thiourea solution; Gouck (1964) sterilized insects of the same species by dipping pupae in 3 different chemosterilants, viz, apholate, tepa, and metepa. On the other hand, Mitlin & Baroody (1958), LaBrecque et al. (1960), Gouck & LaBrecque (1964) and LeBras (1973) sterilized Musca domestica by feeding thiourea to newly emerged individuals. While a number of studies have reported sterilization of different species of flies using different chemosterilants, no work has yet been done to determine the susceptibility of Chrysomya to chemosterilants. To investigate this problem, we selected Chrysomya megacePhala (Fabricius) for our experiments. Because we found that thiourea is very toxic to larvae of this species and in view of a similar report by Mohiuddin et al. (1970) for Musca domestica, we treated only pupae and newly emerged adults of Ch1)ls01nyamegacephala with thio-
Pupal diPs. Newly formed pupae (2-6 hold) were obtained from the culture of C. megacephala maintained in the laboratory at 25°-28°C and 8085% RH. Groups of 150 pupae were dipped in solutions of 1.0%, 1.5% and 2.0% thiourea in small glass vials, each group dipped for 15, 30, 60 and 120 min. The pupae were then removed and each group was kept in separate vials. A group of untreated pupae dipped in water only were used as controls. After 4 days the vials containing the pupae were placed in separate breeding cages containing bread soaked with milk and sugar solution. Newly emerged adults were sexed and transferred to the mating cages. The following 4 mating crosses were made: (1) males from untreated and females from treated pupae, (2) males from treated and females from untreated pupae, (3) males and females from treated pupae, and (4) males and females from untreated pupae. Each cross was replicated twice. The females were then allowed to oviposit on pieces of goat liver held in petl-i dishes. The eggs were counted and kept on moist filter paper in petri dishes. The larvae that hatched were counted to estimate the number of viable eggs; mortality at adult eclosion was also noted. Adult treatments. Freshly emerged flies from the culture were sexed. Groups of 100 flies were kept in different cages and exposed to a diet of bread soaked with milk containing thiourea at concentrations of 0.25%,0.37%, and 0.5% for 12,24 and 48 h. Thereafter they were maintained on untreated food only. A group of flies fed on untreated food throughout was used as a control. The 4 types of mating crosses were made as in the pupal dipping experiments. Egg viability was also determined in a similar manner. For both pupal and adult treatment experiments, the percentage of sterility was calculated according to Chamberlain's formula (1962).
'University of Gorakhpur, Gorakhpur, 273001, India. 2% Or K. B. Lal, Professor & Head, Department of Mathematics, Universily of Gorakhpur, Gorakhpur, 27300 I, India.
MATERIALS
for different
time
AND METHODS
Downloaded from http://jme.oxfordjournals.org/ by guest on June 9, 2016
Pupae and newly emerged individuals of Chrysomya were subjected to dipping and feeding treatments, respectively, with thiourea solutions of varying concentrations for different time intervals. Pupal dipping treatment in some cases pmduced a high percentage of stel'ility, but pupal mortality was very high. On the other hand, exposure of adults to a [I'eated diet for 48 h produced 100% sterility with practically no mortality. Males were more susceptible to sterilization than were females.
and H. S. Chaudhry
J.
450
TAIILE I. Percentage sterility and percentage eclosion in Cln)somya megacephala pupae dipped in thiourea solution at different concentrations and for different time periods.
IMMERSION (min)
EcLOSiaN (%)
1.0
15 30 50 120
1.5
CONC. (%)
2.0
TABLE 2. Percentage sterility and percentage mortality of Chrysomya megacephala adults fed with thiourea at differ'ent concentrations and time periods.
STERILITY (%) WHEN FOLLOWING SEX TREATED
'i
0
'i & 0
83 62 50 42
8.1 31.6 44.9 58.1
19.1 34.5 47.8 62.5
26.5 58.8 73.5 83.8
15 30 50 120
70 55 43 18
33.8 47.1 72.1
37.5 51.5 74.3
51.0 76.5 92.6
15 30 60
47 34 10
72.1 95.6
77.2 100.0
94.9 100.0
120
10
CONe. (%)
FEEDING MORPERIOD TALITY (h) (%)
STERILITY (%) WHEN FOLLOWING SEX TREATED
'i
0
'i & 0
0.25
12 24 48
0.0 0.0 0.0
2.9 8.1 48.5
8.1 45.6 50.3
4.4 50.7 72.8
0.37
12 24 48
0.0 0.0 0.0
2.9 33.8 100.0
4.4 54.4 100.0
8.1 62.5 100.0
0.5
12 24 48
0.0 0.0 15.0
1.5 44.1 100.0
4.4 63.2 100.0
0.0 72.1 100.0
Control
0.0
95
of eggs by untreated females mated with treated males was not affected. But when treated females RESULTS were mated with untreated males, in most cases The results of mating experiments of adults ob- the number of eggs laid was considerably reduced. tained from treated pupae are shown in TABLE 1. Males, in general, were more susceptible to sterilOf 27 mating tests, a high degree (over 90%) of ization with thiourea than females. sterility was observed only in those tests where both sexes were obtained from the pupae treated with DISCUSSION a 1.5% concentration of thiourea for 15 and 30 Bofkovec (1966) reported that thiourea sterilizes min. Similar results were also obtained when feonly females of some species. He also noted that males or males obtained from pupae treated with the sterilant produces unusually erratic results and 2.0% thiourea for 30 min were crossed with norattributed this partly to its high toxicity. LeBras mal males and normal females, respectively. (1973) reported that thiourea causes sterility in Control flies exhibited 95% eclosion. In the tl-eated pupae, where the sterility was over 90%, both males and females of Musca domestica, though the eclosion was below 50%. Where the eclosion females were more sensitive than males. In the obpercentage was fairly low, further mating studies servations made by us on treatment of Chrysomya megacephala with thiourea, it was found that males were not done due to lack of sufficient numbers of in general are more susceptible to sterilization with individuals. this chemical than females. The results obtained when thiourea was fed to freshly emerged flies are shown in TABLE2. CONCLUSIONS By exposing either one or both sexes to the diet containing 0.5% and 0.37% concentrations of thioThe pupal treatment of Chrysomya megacephala urea for 48 h, all mating crosses resulted in 100% with thiourea effectively causes sterilization but sterility. When only females were exposed to 0.5% produces a high concurrent mortality. The feeding thiourea, no eggs were laid and mortality was method, while achieving 100% sterility, causes about 16%. When offered the diet treated with practically no adult mortality. For this reason, 0.37% thiourea, 86 eggs were laid but all were in- adult feeding is the recommended method for viable, and no mortality was observed. Further, sterilizing C. megacephala. when flies were fed for 12 h only, irrespective of the concentration of thiourea used, hardly any steLITERATURE CITED rility was recorded. In control flies, the average Borkovec, A. B. 1966. p. 39. Insect chemosterilants. Adv. Pest number of eggs laid by a female was 158 per batch. Control Res. Vol. 7. John Wiley & Sons, New York. 143 p. In almost all treatments, both in pupal dipping Chamberlain, W. F. 1962. Chemical sterilization of the screwworm. J. Econ. En/ollloi. 55: 240-48. as well as in adult feeding experiments, production
Downloaded from http://jme.oxfordjournals.org/ by guest on June 9, 2016
Control
Vol. 15, nos. 5-6
Med. Entomol.
1979
Deepak & Chaudhry:
Thiourea-induced
Gouck, H. K. 1964. Chemosterilization of house flies by treatment in the pupal stage. J. Econ. En/ornot. 57: 239-41. Gouck, H. K. & G. C. LaBrecque. 1964. Chemicals affecting fertility in adult house flies. J. Econ. En/ornot. 57: 663-64. LaBrecque, G. C., P. H. Adcock & Carroll N. Smith. 1960. Tests with compounds affecting house fly metabolism. J. Econ. En/ornot. 53: 802-05. LeBras, S. 1973. Action d'un chimio-sterilisant, la thiouree, sur Musca dornes/ica adulte. En/ornot. Exp. Appt. 16: 9-19.
sterility in Chrysornya rnegacephata
461
Midin, N. & A. M. Baroody. 1958. The effect of some biologically active compounds on growth of house fly ovaries. J. Econ. En/ornot. 51: 384-85. Mohiuddin, S., S. A. Qureshi & M. W. Roomi. 1970. Effects of thiourea on the house fly, Musca dornes/ica (1.) (Dipt., Muscid.). Z. Angew. Entornot. 66: 435-39. Piquett, P. G. & J. C. Keller. 1962. A screening method for chemosterilants of the house fly. J. Econ. Entornot. 55: 261-62.
Downloaded from http://jme.oxfordjournals.org/ by guest on June 9, 2016
