**3.3 Pests assessment on turnips**

On the turnips we identified six (6) Orders making a total of 34 insect's families. They are: 7 families of Beetles, 9 families of Hymenopterans, 8 families of Dipterans, 4 families of Hemiptera, 4 families of Lepidoptera and 2 families of Orthoptera.

91 % of these families were present on the untreated plots whereas 62 % were on the treated plot (spray plot) with Deltamethrin (Tabl 6, 7, 8,).


( - ) = Absent (+) = Present P = Pest insects T = Non -Target Insects N = Neutrals

Table 6. Order and Insects families' identified on the turnips

Quality of Vegetables and Pests Control in African Urban Cities 27

**THE LEPIDOPTERA ORDER** 

**THE ORTHOPTERA ORDER** 

We observed 91% of pests in untreated plots against 62% on the plots treated with deltarmethrin, and the Hemiptera also set up the most important group of pests. The pests recolonisation was done 8 days after the first application of deltarmethrin (Graphic 3). The first application of agrochemicals makes it possible to reduce by 42% the losses of

Traps

+ - - -

Traps

+ -

( - ) = Absent (+) = Present P = Pest insects T = Non -Target Insects N = Neutrals

FAMILIES RELATION Areas

FAMILIES RELATION Areas

R R

Table 8. Order and Insects families' identified on the turnips

R R R R

Noctuidae Pieridae Lycaenidae Yponomeutidae

Acrididae Gryllotalpidae

turnip production.

Graphic 3. Pests Control on Turnips

Treated Plots Untreated Plots

Treated Plots Untreated Plots

Areas Traps

> + + + +

Areas Traps

> + -

Grounds Traps

> + - - -

Grounds Traps

> + +

Grounds Traps

> + - - -

Grounds Traps

> + -


( - ) = Absent (+) = Present P = Pest insects T = Non -Target Insects N = Neutrals

Table 7. Order and Insects families' identified on the turnips

**THE HYMENOPTERA ORDER** 

**THE DIPTERA ORDER** 

**THE HEMIPTERA ORDER** 

Traps

+ + - -

( - ) = Absent (+) = Present P = Pest insects T = Non -Target Insects N = Neutrals

Traps

+ + + + - - - -

Traps


FAMILIES RELATION Areas

FAMILIES RELATION Areas

FAMILIES RELATION Areas

P P P P

Table 7. Order and Insects families' identified on the turnips

N P&N P N N P P T

N T T T T T T P T

Pompilidae Ichneumonidae Sphecidae Crabronidae Vespidae Nyssonidae Bethylidae Cephidae Chalcididae

Sarcophagidae Muscidae Agromyzidae Drosophilidae Stratiomyidae Lonchaeidae Cecidomyiidae Mycetophilidae

> Cicadellidae Cicadidae Miridae Aphididae

Treated Plots Untreated Plots

Treated Plots Untreated Plots

Treated Plots Untreated Plots

Areas Traps

> + - + + - + + + +

Areas Traps

> + + + + + + - -

Areas Traps

> + + - +

Grounds Traps

> + - - - - + - - -

Grounds Traps

> + - + + - - + +

Grounds Traps

> + - + +

Grounds Traps

> + + - - - - - - -

Grounds Traps

> - - + - + - - -

Grounds Traps

> + - + -


( - ) = Absent (+) = Present P = Pest insects T = Non -Target Insects N = Neutrals

Table 8. Order and Insects families' identified on the turnips

We observed 91% of pests in untreated plots against 62% on the plots treated with deltarmethrin, and the Hemiptera also set up the most important group of pests. The pests recolonisation was done 8 days after the first application of deltarmethrin (Graphic 3). The first application of agrochemicals makes it possible to reduce by 42% the losses of turnip production.

Graphic 3. Pests Control on Turnips

Quality of Vegetables and Pests Control in African Urban Cities 29

We identified only one pathogenic fungus on the lettuce (9 % of production). It is Cladosporium *sp of The* Amastigomycota *Divion*; *Group of Deuteromycete;* Hyphomycetes' Class and *Gender of Cladosporium.* This fungus is the agent responsible of Cladosporium gray mold, but the preventive spraying of Maneb (photo 6) gives efficient protection on the

The irrigation water is characterized by the presence of micro-organisms such as Thermotolerant Coliform and the fecal Streptococci. Their numbers areas respectively one hundred fifty (150) times and one thousand (1000) times higher than the criteria for international standard allowed for irrigation water quality in agricultural fields (Table 9 and

**Thermotolerant Coliform/g** 3.105 2.103 Faecal Streptococci/g 106 103

The microbiological analysis of the irrigation water highlighted an overload of thermotolerant Coliforms and fecal Streptococci. These bacteria which are not normally pathogenic are usually used to indicate the possible presence of pathogenic microfauna organisms. Thus their very high number compared to the threshold recommended shows a

 The strong presence of these indicator bacteria suggests a probable presence in the irrigation water of very dangerous pathogenic parasites that could develop and cause very

The contaminated vegetables can cause a certain number of diseases. Particularly, the contaminated salads are sources of bacterial diseases such as the typhoid and paratyphoid

BACTERIA RESULTATS CRITERIA

**3.4 Plants phytopathology and water monitoring** 

Table 9. Microbiology Monitoring of Irrigated Water

Photo 7. Irrigated water quality is doubtful

important damages to the plants, farmers and the consumers.

low water quality (Photo 7).

lettuce.

Photo 7).

Overall the application of Agrochemicals significantly reduced the number and the species of pests on the treated plots. The Coleoptera and the Hymenoptera contain the main species of the predatory and natural enemies thus auxiliary (no target insect) of plants protection, having a significant impact on the dynamics of the populations of pests. The preservation of these different auxiliaries is necessary for a sustainable management of natural resources. Deltamethrin has a good level of selectivity with a superior advantage for the management of pests and the environment over the Acephate which, has a low selectivity but a wide range of effectiveness against insect pest and good residual activity. The preservation of the auxiliaries of culture in spite of the chemical treatment is essential considering the important role that they play in the maintenance of agro-ecological balances.

The Lepidoptera (larva), Orthoptera and Hemiptera represent the most important group of insect pests, which attack and cause the highest damage in vegetable gardening of lettuce, spinach and turnip. However, the considerable differences in number of captured insects and pests found between the treated and untreated field plots show that a targeted application of agrochemicals against these groups of pests is efficient.

The majority of the groups of pests which attach and cause important damage on turnip, spinach and lettuce can be controlled by the application of agrochemical products applying good agricultural practices (GAP) compatible with the protection of the environment and the preservation of non-target organisms.

Photo 6. Pesticides Plastic container on the plot (Maneb)

However, one of the biggest problems encountered by vegetable producers is their lack of sufficient knowledge about how to use safely the agrochemicals. Very large numbers of empty pesticide containers are left lying in the fields because of the lack of collection and disposal facilities and constitute acute potential hazards for the environment and the fauna due to the left-over of toxic pesticides in the containers (Photo6).

The producers are not sufficiently aware of the risks of pesticides accumulation in vegetables, and the possible health problems for consumers being exposed to these risks. They are also often confronted with the problems of accessibility to agricultural credits.
