Neem (Azadirachta Indica A. Juss.) Seed Powder and Extracts For the Control of the Spotted Stem Borer,Chilo Partellus (Swinhoe), on Maize and its Potential in Pest Management
No Thumbnail Available
Date
1999-12
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
The efficacy of neem (A. indica A. Juss.) seed products for the control of the spotted
stem borer, Chilo partelilis (Swinhoe) on H51l, ICZ3, ACV3, and Katumani maize
cultivars was investigated in two geographical locations. Maize plants were either
artificially infested with blackhead stage egg batches of C. partel/lIs, .01' were initially
left unprotected for natnral infestation to take place before application of treatments.
Neem seed powder (NSP) (3 g/plant), neem seed powder-sawdust mixtnre (NSP*SD) (6
g/plant), or 10 % aqueous neem seed extract (NSE) (500l/ha) were applied at four
weeks after crop emergence (W AE) with untreated controls. Dipterex (D PTX) (l
g/plant), or Sevin (500l/ha) were also used for comparison. Maize plants treated with
neem seed products or chemical insecticides sustained much less borer holes, reduced
leaf damage and stem tunneling than those in the controls in all the test cultivars
(P < 0.001). NSP provided comparable and effective protection ill par with Dipterex or
Sevin. NSP*SD and 10% NSE also showed more or less similar and appreciable effects
in reducing leaf damage and stem tunneling by C. partelilis larvae. Foliar applications
of neem seed products and chemical insecticides effectively suppressed the densities of
C. partelills and subsequently improved the yield in all the test cultivars (P < 0.05).
Foliar applications of neem seed products level to chemical insecticides in markedly
reducing primary crop damages, in effectively suppressing the level of infestation by C.
partelllls, and in improving yield in all the test cultivars. The findings unequivocally
demonstrated that applications of neem seed products effectively control C. partelllls
and avert serious crop damages and yield loss in field sitnations.
In the laboratory, neonate C. panelills larvae were reared on artificial diet containing
minute quantities of NSP (25, 50 or 100 ppm), 10% NSE (25, 50, or 100 ppm), or
neem bitter concentrate (NBC) (5, 10, or 25 ppm). Artificial diet without neem seed
products served as controls. Larvae were introduced singly into the cultnre vials
containing 10 ml of artificial diet incorporating the treatment types and were either
maintained on the same diet or transferred to standard diet two weeks after inoculation.
Per cent larval survival, pupal weight, per cent pupation and emergence as an adult
were examined and recorded. The duration of the developmental stages and total
development periods were studied. Larval growth index (LGI) and Adult growth index
(AGI) values were also determined. NSP (100 ppm) significantly reduced survival of
larvae to the pupal stage and to adult emergence as compared to the other treatment
types (P<0.005). NSP (50 ppm) and NBC (5, 10, 25 ppm) appreciably reduced the
percentages of larvae that survived to pupation and adult emergence.
NSP (50 and 100 ppm) markedly extended the larval period of C. partelills as compared
to the other treatment types and the controls (P<O.OOl). Both NBC and 10% NSE
showed less appreciable effects on the duration of the larval period at the concentrations
tested in this study. The pupal weights of male C. partelllls were markedly affected in a
concentration dependent manner. Diet with neem seed products appeared to produce
male pupae with inferior pupal weights as compared to the controls (P<0.05). Diet
with NSP (50 and 100 ppm), 10% NSE (100 ppm), and NBC produced pupae with
reduced body weight in varying degrees. The total developmental periods in both male
and female C. partelills were significantly prolonged on artificial diet containing NSP at
25, 50 or 100 ppm as compared with the other treatment types and the controls
(P<O.OOI). Artificial diet with NSP showed markedly extended developmental periods
in female and male moths. Insects reared on diet withNSP (50 and 100 ppm) also had
much lower LGI and AGI values (P<0.05). Diet with NBC also produced insects with
appreciably reduced LGI values as compared to diet with 10 % NSE or the control.
Insects reared on diet with NSP and NBC had more or less comparable and markedly
reduced AGI values. Reduced LGI and lowered AGI values obtained indicated that the
survival and development of c. partel/lls was markedly affected by neem seed products.
The relatively prolonged development period and the very low percentages of insects
that developed to adults indicates that NSP (50 or 100 ppm) renders the diet most
unsuitable and was effective in reducing the survival, growth and development of C.
partelills. Consequently, insects reared on artificial diet incorporating NSP at these
concentrations had much lower LGI and AGI values which indicates the potential of
neem seed products to effectively curtail or impair growth and development. Low
survival rates and impeded growth and development were more pronounced with an
increase in the concentration of the treatment types.
This study confirmed the efficacy of neem seed products to control C. partelills on
maize and offers potential prospects for a biorational management of this pest to reduce
yield losses below economic injury levels. It is recommended that further research
geared towards the development of appropriate formulations, convenient methods of
application, evaluation of the bioactive components in the seeds and other parts of the
neem tree, selection of improved ecotypes need to be undertaken. The use of neem seed
products for pest control is compatible with traditional farming practices and can easily
be adopted by resource-poor farmers in Ethiopia. It requires inexpensive and simple
pest management techniques for practical use. The development of relatively simple
procedures for processing pest control materials from A. indica and other plant species,
at the household or rural community level, is crucial and of paramount importance.
Further studies on the utility of neem seed products for use in crop protection against
by insect pests. It is therefore recommended to undertake research to determine
appropriate and optimal formulations and develop more refined methods of application
that would promote easy adoption for use by resource-limited farmers in rural areas.
The behavioural, histopathological, and physiological effects of the blend of bioactive
compounds in neem seed products need also be studied in order to elucidate their
biological effects and modes of action.
Description
Keywords
Biology