| dc.creator |
Mkenda, Prisila Andrea |
|
| dc.date |
2020-09-22T07:27:46Z |
|
| dc.date |
2020-09-22T07:27:46Z |
|
| dc.date |
2020-04 |
|
| dc.date.accessioned |
2022-10-25T09:19:43Z |
|
| dc.date.available |
2022-10-25T09:19:43Z |
|
| dc.identifier |
https://dspace.nm-aist.ac.tz/handle/20.500.12479/929 |
|
| dc.identifier.uri |
http://hdl.handle.net/123456789/94879 |
|
| dc.description |
A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor
of Philosophy in Life Sciences of the Nelson Mandela African Institution of Science and
Technology |
|
| dc.description |
Conservation biological control (CBC) is an attempt to protect the already existing natural
enemies (predators, parasitoids or pathogens) of insect pests within the agricultural systems
by manipulating the environment and farming practices to provide the required resources for
their survival. This study assessed the major arthropod predators and parasitoids of common
bean (Phaseolus vulgaris) insect pests in smallholder bean farming tropical ecosystem and
their contribution in pest management, in three elevation zones during 2016 and 2017. The
farmers’ knowledge about natural enemies, insect pest and pesticide use was investigated
followed by field surveys and experiments to determine the contribution of major predators
and parasitoids to pest management in smallholder bean fields. The importance of field
margin vegetation to the population of predators and parasitoids was also examined. The
study identified a severe lack of knowledge about natural enemies among the smallholder
farmers. However, the field survey revealed the existence of a rich community of natural
enemies, where a total of 5003 natural enemies were identified out of 13 961 insects
collected. The natural enemy abundance differed along the elevation gradient where the high
zone was leading with 50.3%, while mid and low zones had 31.7% and 18% respectively.
Majority of the natural enemies were sampled along the margin vegetation compared with the
bean fields for low (61.1% in margin vs 38.9% in field) and mid (52.1% in margin vs 47.9%
in field) zones, but in the high zone they were more abundant within the bean fields (44.6%
in margin vs 55.4% field). A dye experiment to monitor their movement revealed high levels
of spatial flux (71%) between the two locations. Aphids (Aphis fabae) mortality rates
measured by predation and parasitism of sentinel aphids did not significantly differ between
the field edges and field centre in all the three elevation zones, indicating the centre of the
fields still receive comparable pest control service as the field edge. Parasitoid wasps were
the most abundant natural enemy while A. fabae were the most damaging insect pests in the
smallholder bean fields. Molecular identification of A. fabae parasitoids revealed 85%
primary parasitoids (Aphidius colemani) and two species of secondary parasitoids
(Pachyneuron sp., 7% and Charipinae sp., 1%) which may have significant effects in
biological pest control. The study revealed the potential predators and parasitoids important
for pest control within the smallholder bean fields which can be enhanced through CBC. |
|
| dc.format |
application/pdf |
|
| dc.language |
en |
|
| dc.rights |
Attribution-NonCommercial-ShareAlike 4.0 International |
|
| dc.rights |
http://creativecommons.org/licenses/by-nc-sa/4.0/ |
|
| dc.subject |
Research Subject Categories::SOCIAL SCIENCES |
|
| dc.title |
Potential predators and parasitoids for conservation biological control in smallholder bean farming tropical ecosystem |
|
| dc.type |
Thesis |
|