Efficacy of organic and synthetic insecticides on the control of cotton pests: The bollworm complex, Helicoverpa armigera, Diparopsis castanea, Earias insulana (Noctuidae) and the leafhopper, Jacobiell
- Malinga, Lawrence Nkosikhona
- Authors: Malinga, Lawrence Nkosikhona
- Date: 2012
- Language: English
- Type: Thesis , Masters , MSc (Zoology)
- Identifier: vital:11791 , http://hdl.handle.net/10353/d1006798
- Description: A research was conducted on cotton to test different plant extracts with potential insecticidal properties against bollworms (Noctuidae) and leafhoppers (Cicadellidae) for the use by small-scale, cotton farmers. The study was carried out during the 2006/07 and 2007/08 seasons at ARC Institute for Industrial Crops, Rustenburg (25°39.0 S, 27°14.4 E) in the North West Province of South Africa. Four organic insecticides, tobacco (Nicotiana tabacium), khaki weed (Tagetes minuta), thorn apple (Datura stramonium) and garlic (Allium sativum) were compared with two chemical treatments, Mospilan® (acetamiprid) and Decis® (deltamethrin), and an untreated control. The cultivar, DeltaOPAL, was planted and the trial conducted using standard practices. Overall, Decis® and tobacco treatments exhibited significantly less bollworm larvae than the other treatments. Tobacco was the most promising biological pesticide against American bollworm (Helicoverpa armigera) and spiny bollworm (Earias insulana) larvae. All the treatments were significantly effective against the red bollworm (Diparopsis castanea) larvae, but Decis® and Mospilan® provided the best control. Although khaki weed, garlic and thorn apple were promising biological pesticides against the bollworm complex, tobacco was the most effective organic treatment. Mospilan® seemed to be more effective on the control of leafhoppers (Jacobiella fascialis), followed by Decis® and tobacco. Among the plant extracts, tobacco and garlic gave higher seed cotton yields compared to the khaki weed and thorn apple during both study seasons. In 2006/07, none of the treatments reached the corresponding economic threshold levels (ETLs). In contrast, in 2007/08, only rarely were the treatments (mostly Decis® and Mospilan®) below the corresponding ETLs. These differences were attributed to the higher rainfall recorded during the 2007/08 season, which reduced the effectiveness of the treatments by partly washing away the pesticidal applications. In addition, a high weed infestation also created competition for nutrients in the soil, thus resulting in lower (0.50-1.25 ton/ha in 2007/08 vs 2.50-5.00 ton/ha in 2006/07), but acceptable cotton seed yields. In conclusion, it is suggested that some plant extracts (particularly from tobacco and garlic) can be used as a cheaper and more environment-friendly alternative to chemical insecticides for the control of bollworms and leafhoppers, although it has been demonstrated that their efficacy do not reach the one of chemical treatments. Further research in the near future is recommended.
- Full Text:
- Authors: Malinga, Lawrence Nkosikhona
- Date: 2012
- Language: English
- Type: Thesis , Masters , MSc (Zoology)
- Identifier: vital:11791 , http://hdl.handle.net/10353/d1006798
- Description: A research was conducted on cotton to test different plant extracts with potential insecticidal properties against bollworms (Noctuidae) and leafhoppers (Cicadellidae) for the use by small-scale, cotton farmers. The study was carried out during the 2006/07 and 2007/08 seasons at ARC Institute for Industrial Crops, Rustenburg (25°39.0 S, 27°14.4 E) in the North West Province of South Africa. Four organic insecticides, tobacco (Nicotiana tabacium), khaki weed (Tagetes minuta), thorn apple (Datura stramonium) and garlic (Allium sativum) were compared with two chemical treatments, Mospilan® (acetamiprid) and Decis® (deltamethrin), and an untreated control. The cultivar, DeltaOPAL, was planted and the trial conducted using standard practices. Overall, Decis® and tobacco treatments exhibited significantly less bollworm larvae than the other treatments. Tobacco was the most promising biological pesticide against American bollworm (Helicoverpa armigera) and spiny bollworm (Earias insulana) larvae. All the treatments were significantly effective against the red bollworm (Diparopsis castanea) larvae, but Decis® and Mospilan® provided the best control. Although khaki weed, garlic and thorn apple were promising biological pesticides against the bollworm complex, tobacco was the most effective organic treatment. Mospilan® seemed to be more effective on the control of leafhoppers (Jacobiella fascialis), followed by Decis® and tobacco. Among the plant extracts, tobacco and garlic gave higher seed cotton yields compared to the khaki weed and thorn apple during both study seasons. In 2006/07, none of the treatments reached the corresponding economic threshold levels (ETLs). In contrast, in 2007/08, only rarely were the treatments (mostly Decis® and Mospilan®) below the corresponding ETLs. These differences were attributed to the higher rainfall recorded during the 2007/08 season, which reduced the effectiveness of the treatments by partly washing away the pesticidal applications. In addition, a high weed infestation also created competition for nutrients in the soil, thus resulting in lower (0.50-1.25 ton/ha in 2007/08 vs 2.50-5.00 ton/ha in 2006/07), but acceptable cotton seed yields. In conclusion, it is suggested that some plant extracts (particularly from tobacco and garlic) can be used as a cheaper and more environment-friendly alternative to chemical insecticides for the control of bollworms and leafhoppers, although it has been demonstrated that their efficacy do not reach the one of chemical treatments. Further research in the near future is recommended.
- Full Text:
Spatio-temporal ecology of the yellow mongoose Cynictis penicillata in the Great Fish River Reserve (Eastern Cape, South Africa)
- Authors: Mbatyoti, Owen A
- Date: 2012
- Subjects: Carnivorous animals -- South Africa -- Eastern Cape , Spatial behavior -- South Africa -- Eastern Cape , Great Fish River Reserve (South Africa) , Mongooses -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Zoology)
- Identifier: vital:11792 , http://hdl.handle.net/10353/d1006856 , Carnivorous animals -- South Africa -- Eastern Cape , Spatial behavior -- South Africa -- Eastern Cape , Great Fish River Reserve (South Africa) , Mongooses -- South Africa -- Eastern Cape
- Description: Very little is known about the spatio-temporal ecology of the yellow mongoose Cynictis penicillata, despite this small carnivore being widely distributed in the southern African subregion. Until the present study, activity patterns and daily movement distances had only been investigated over a single season, and information on home range sizes was only available from a few populations. Here, I aimed at determining the activity patterns and the space use of yellow mongooses over the different seasons of the year in the Great Fish River Reserve (Eastern Cape, South Africa). In addition, I tested some predictions related to environmental factors (variations in photoperiod, climatic conditions and food availability over the year), as well as life cycle (reproduction) and morphological and physiological characteristics (sexual dimorphism and thermoregulatory aspects associated to the possession of an elongated body). From September 2005 to August 2011, spatio-temporal data were collected through 102 continuous tracking sessions (84 during the day and 18 during the night) of 12 adult individuals (seven males and five females) fitted with motion-sensor radio-collars. Additional data were obtained through semi-continuous tracking sessions and random locations. Yellow mongooses were essentially diurnal and crepuscular. Activity levels averaged 57 percent during the day (n = 11,807 fixes) and only 11 percent at night (n = 3,623 fixes). Yellow mongooses emerged from their burrows on average (± SD) 85 ± 62 min after sunrise (range: –11 to +369 min) and returned 21 ± 84 min before sunset (range: –518 to +225 min). The duration of the daily activity period varied between 12 min and 15 h 36 min, with a mean of 9 h 28 min. Both sexes exhibited some overground activity after sunset, but this was most pronounced in males than in females. Nocturnal activity outside the activity period was generally restricted to short underground bouts of activity occurring at anytime of the night. Diurnal resting, with up to 11 bouts per activity period, occurred in 98.8 percent of activity periods. Overall, yellow mongooses were active during 68 ± 17 percent of the time spent outside the burrow. Photoperiod acted as a zeitgeber and activity was negatively affected by adverse climatic conditions (very hot or conversely low temperatures, rain, wet soil) and probably low terrestrial arthropod activity/availability. No intersexual difference in activity levels was found, although the higher body mass of males (on average 16 oercent) implies higher metabolic demands. The total home range size (MCP 100 percent ) averaged 0.55 ± 0.65 km2 (range: 0.10–2.36 km2) and the related total perimeter measured on average 2.80 ± 1.71 km (range: 1.17–7.36 km). Male home ranges were on average more than twice large than those of females, but this difference did not reach statistical significance. However, males had larger daily home ranges (0.13 ± 0.15 km2) than females (0.05 ± 0.05 km2). In addition, daily movement distances of males were longer (1.99 ± 1.07 km) than those of females (1.29 ± 0.66 km). Males also travelled at a faster speed (0.29 ± 0.13 km/h) than females (0.18 ± 0.07 km/h). Overall, sex clearly appeared to play a role in the spatial ecology of yellow mongooses, but the underlying explanation does not seem to be linked to sexual dimorphism (body mass) or reproductive activity. Whilst the role of food availability on the space use of yellow mongooses is unclear, it is likely that low temperatures negatively affect yellow mongoose movements, as they do for their activity levels.
- Full Text:
- Authors: Mbatyoti, Owen A
- Date: 2012
- Subjects: Carnivorous animals -- South Africa -- Eastern Cape , Spatial behavior -- South Africa -- Eastern Cape , Great Fish River Reserve (South Africa) , Mongooses -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Zoology)
- Identifier: vital:11792 , http://hdl.handle.net/10353/d1006856 , Carnivorous animals -- South Africa -- Eastern Cape , Spatial behavior -- South Africa -- Eastern Cape , Great Fish River Reserve (South Africa) , Mongooses -- South Africa -- Eastern Cape
- Description: Very little is known about the spatio-temporal ecology of the yellow mongoose Cynictis penicillata, despite this small carnivore being widely distributed in the southern African subregion. Until the present study, activity patterns and daily movement distances had only been investigated over a single season, and information on home range sizes was only available from a few populations. Here, I aimed at determining the activity patterns and the space use of yellow mongooses over the different seasons of the year in the Great Fish River Reserve (Eastern Cape, South Africa). In addition, I tested some predictions related to environmental factors (variations in photoperiod, climatic conditions and food availability over the year), as well as life cycle (reproduction) and morphological and physiological characteristics (sexual dimorphism and thermoregulatory aspects associated to the possession of an elongated body). From September 2005 to August 2011, spatio-temporal data were collected through 102 continuous tracking sessions (84 during the day and 18 during the night) of 12 adult individuals (seven males and five females) fitted with motion-sensor radio-collars. Additional data were obtained through semi-continuous tracking sessions and random locations. Yellow mongooses were essentially diurnal and crepuscular. Activity levels averaged 57 percent during the day (n = 11,807 fixes) and only 11 percent at night (n = 3,623 fixes). Yellow mongooses emerged from their burrows on average (± SD) 85 ± 62 min after sunrise (range: –11 to +369 min) and returned 21 ± 84 min before sunset (range: –518 to +225 min). The duration of the daily activity period varied between 12 min and 15 h 36 min, with a mean of 9 h 28 min. Both sexes exhibited some overground activity after sunset, but this was most pronounced in males than in females. Nocturnal activity outside the activity period was generally restricted to short underground bouts of activity occurring at anytime of the night. Diurnal resting, with up to 11 bouts per activity period, occurred in 98.8 percent of activity periods. Overall, yellow mongooses were active during 68 ± 17 percent of the time spent outside the burrow. Photoperiod acted as a zeitgeber and activity was negatively affected by adverse climatic conditions (very hot or conversely low temperatures, rain, wet soil) and probably low terrestrial arthropod activity/availability. No intersexual difference in activity levels was found, although the higher body mass of males (on average 16 oercent) implies higher metabolic demands. The total home range size (MCP 100 percent ) averaged 0.55 ± 0.65 km2 (range: 0.10–2.36 km2) and the related total perimeter measured on average 2.80 ± 1.71 km (range: 1.17–7.36 km). Male home ranges were on average more than twice large than those of females, but this difference did not reach statistical significance. However, males had larger daily home ranges (0.13 ± 0.15 km2) than females (0.05 ± 0.05 km2). In addition, daily movement distances of males were longer (1.99 ± 1.07 km) than those of females (1.29 ± 0.66 km). Males also travelled at a faster speed (0.29 ± 0.13 km/h) than females (0.18 ± 0.07 km/h). Overall, sex clearly appeared to play a role in the spatial ecology of yellow mongooses, but the underlying explanation does not seem to be linked to sexual dimorphism (body mass) or reproductive activity. Whilst the role of food availability on the space use of yellow mongooses is unclear, it is likely that low temperatures negatively affect yellow mongoose movements, as they do for their activity levels.
- Full Text:
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