Annona muricata
Soursop
Annona
reticulata
Custard apple
Annona squamosa
Sweetsop
Annonaceae
Insecticidal Plants
More than 90
species of small tree and shrubs are known in the Annonaceae family. They occur
mostly in Tropical america, but some are found also in Asia and Africa. Soursop
and custard apple are widely distributed in Central America and the Carribbean,
while the sweetsop is commenest in India and Southeast Asia. They do not
require special conditions of soil or water, but thrive best in places
where there is a clear division between the rainy and the dry season,
and generally prefer dry sites in which to grow.
The effective
ingredients are in the unripe fruit, and in the seeds , leaves and roots.(107)
The oil content of the seeds amounts
to 42-45 %.
Contact - and
stomach poison
Insecticidal , larvicidal , repellent ,
antifeedant. (52)
Aphids
- general (13)
Brown rice
plant hopper - Nilaparvata lugens (13)
Diamondback
Moth - Plutella xylostella (59)
Chrysanthemum
aphid - Macrosiphoniella sanborni (59)
Grasshopper
- general
Green
bugs
- general (13)
Green rice leaf
hopper
- nephotettix virescens (13)
Potato
aphid
- Macrosiphum euphorbiae (59)
Red pumpkin
beetle
- Aulacophora foveicollis (59)
Whitebacked
rice plante hopper - sogatella furcifera (13)
Annona has not
proved effective against the
Saw-toothed
grain beetle
Oryzaephilus surinamensis (147)
Trouver une photo de Sweetop (Annona squamosa)
The toxic
effect of Annona sets in slowly , 2-3 days should be allowed.
Laboratory
trials have shown that by extracting Annona seeds with ether or petroleum
ether, the toxicity can be increased 50-100 times. But since laboratory methods
are impractical in the field, other locally available and cheap solvents could
be tried, like petrol or kerosene.
When
pulverising the seeds of A. squamosa , care should be taken to ensure that the
powder does not come in contact with the eyes as this causes great pain. (80)
The custard
apple is the most effective of annonas against insects.
Trouver une photo de Soursop ( Annona muricata
)
Relatively
little information exists on the preparation and use of Annona. Wide-ranging
laboratory trials have demonstrated its highly effective insecticidal values. Experimentally-inclined
farmers could contribute much needed information about widely distributed
plant.
A 10 % concentration of seed oil produces a 90 % death rate of the bug Urentius
echinus within 72 hours. A 5-7 % concentration is still effective, but low
concentration of 1 - 3 % produce no results.
Pulverised seeds are used in China and
the Philippines against Lecanium in West Africa. (68) The writers gives no
details regarding quantities.
An extract of the leaves with ether
proves highly successful against the red pumpkin beetle (Aulacophora
foveicollis). A diluted solution achieves a 91 % rate. (27)
Capsicum
frutescens
CHILIPEPPERS
Solanaceae
Insecticidal Plants
Chillies are
widely distributed in the tropics and subtropics and originate in South America
where they were early cultivated. They were introduced to the rest of the world
by the Spaniards and the Portuguese. The ripe fruit has insecticidal properties
and the effective substances are highest in the skin and in the seeds (47).
Stomach poison
Insecticidal repellent , antifeedant ,
fumigant , viroid. (52, 130)
Trouver une photo du chili (Capsicum
frutescens)
Ants
- general (152)
Aphids
- general (152)
Caterpillars
-
general (161)
Colorado
beetle
- Leptinotarsa decemlineata
(71)
Imported
cabbage worm
- Pieris rapae (161)
Rice
Weevil
- Sitophilus oryzae (41)
Warehouse
pests
- general (52)
Cucumber mosaic
virus
(161)
Cucumber
ringspot virus
(161)
Tobacco
etch
(161)
Tobacco mosaic
virus
(161)
Tobacco mosaic
virus
(161)
From Kenya good
results are reported on the control of aphids in home vegetable gardens.
Hot chillippers
are finely ground, stirred in water and allowed to stand overnight. After
filtering through a cloth the solution is sprayed onto the plants , or if no
syringe is available sprinkled with a whisk of twigs or grass. (152)
A similar
method is reported from Papua New Guinea where chilipepper is used as repellent
Finally ground
chillies are covered with water and soap either as flakes or liquid. The
mixture is well stirred and sprayed over
affected plants
(88).
Chilli spray
preparation are also well known in the Philippines (130) :
100 g chillies,
water, soap solution :
The chillies
are finely pulverised in a mortar, vigorously shaken with 1 litre of water and
filtered through a cloth. One part of this concentrate is diluted with five
parts of soapy water before spraying. It is effective against aphids and many
other vegetable pests.
Too strong a
concentrate causes burning of the leaves, so the right strength should be found
by testing.
Care should be
taken because the solution irritates the skin (130).
MCKEEN reports
that the young leaves of cowpea were rubbed with virus-infected sap expressed
from chilli leaves the colour change was markedly reduced. Mostly there was
even none. (The change of colour is regarded as an indicator of a virus infection).
When the experiment was repeated with the sap from virus-infected tobacco
leaves the cowpea leaves underwent a strong colour change, but when the tobacco
sap was mixed with 5 % of chilli sap the number of leaves which changed colour
was reduces by 95 %.
The effectiveness
of the virus inhibition depends on the host plant. It is probable that members
of the same plant family do not work infallibly on one another virus
inhibitors. Further tests showed that the virus-inhibiting ingredients is
present in all parts of the chilli plant. However, extracts from the leaves and
flowers showed the highest concentration and the roots are lowest.
In practise, it
is important that chilli sap should be applied as a preventive measure before
the virus infection affects the plant. Once the virus has taken hold it cannot
be effectively controlled.
This is
information is all derived from scientific sources. The writer has no results
taken from practice in the field (96).
Effective sprays are often prepared from a
mixture of different insecticidal plants.
To control
aphids a strong mixture of chilipeppers, garlic and onions can be made. The
three ingredients are finely grated, stirred well with water and sieved. To
increase the adhesive properties of the solution liquid soap should be added
(161). The quantities used were not given by the contributor, so experiments
should be made with different concentrations on small trials plots .
The following
chillipepper/garlic mixture has a repellent effect on leaf-eating
pests :
A handful of
finely shredded chillis and garlic is well stirred in a litre of water,
filtered and used as a spray. When no spray is available the liquid can be
distributed by means of a bundle of grasses flicked over the plants. A spreader
can also be manufactured from a tin by perforating it at the base (146).
According to a
source in the Philippines a mixture of the plant sap of chillipeppers,
lemongrass and agdao leaves is very effective against insects. It is said that
even the 'worst pests' of rice can be controlled with this preparation.
Each 5-6
tablespoons of the juice mixture from the three plants shouuld be stirred with
4 litres of water and shaken lightly before use. It was stated that 87 % of
pests were killed with this preparation, but does not specify which (9).
Rice farmers is
Southeast-Asia use the following preparation against stem borers :
Tubli roots (Croton tiglium)
Dried tobacco leaves
Chillipepper
The tubli roots
(no quantities given) chopped small and pounded, are mixed with 8 litres of
water and the liquid reduced to half by boiling. 50 gm dried tobacco leaves are
also mixed with 8 litres of water and also reduced to half by boiling.
4 tablespoons
of grated chillipepper are stirred in 2 glasses of water and again reduced to
half by boiling.
Finally all
three liquids are strained and thoroughly stirred together. For the application
1 glass of this mixture is diluted with 15 litres of water (7).