**4. Discussion**

The palm represents the symbolism of life in the arid and semi-arid area and being one of the oldest domesticated trees with multifold social and economical status [41, 42]. The *P. dactylifera* is a former species, which constitutes the pivot of the oasis agriculture in the south of Morocco. Out of an overall area estimated at 84500 ha in 1948, the Moroccan palm groves in 1994 covered an area of 44,450 ha occupied by a total of 4.42 million palm trees [9]. This population is currently estimated at 5.12 million palms on an area of 48,000 ha. The importance of the palm by province showed that the provinces of Ouarzazate (1,873,000 palm trees), Errachidia (1,250,000), Tata (Bani) (800,000), Marrakesh (799,000), Tiznit (139,140), Guelmime (138,000) and Figuig (125,500) were the most important

**501**

*Use of Olive Mill Wastewaters as Bio-Insecticides for the Control of* Potosia Opaca *in Date Palm…*

and thus constitute the largest phoenicultural areas (quoted by Sedra (2003) and updated by Meddich [43]. Meddich and Boumezzough [12] note that the prospected and infected *P. canariensis* palms were cultivated and located in the North-East palm grove of Marrakesh. This will allow exchanges of attacks between the two palm species studied. For the oasis ecosystem, the problem will cause a lot of damage and a serious socio-economical problem. Moroccan palms suffer from invasions by larvae and adults of *Rhinoceros Borer*; this is the case in Tunisia, the Middle East and Iran [33]. In Morocco, no *R. Borer* larvae or adults were found; also, the colonization of the wounds by the saprophytic fungi can lead to the appearance of rot and the dieback of the weakened palm. According to INRA (Institut National de Recherche Agronomique) reports and their research axis developed on *P. opaca* in oases newly identified in Morocco by Meddich and Boumezzough [12]. Tauzin [40] indicated the presence of this species in Anti-Atlas (Ifni, Tiznit), middle and southern of Morocco. The presence of *P. opaca* in the crown of the *P. canariensis* and *P. dactylifera* palm which can be explained only by the fact that adults have found an ideal biotope for egg laying and larval development. Meddich and Boumezzough [12] showed that *P. opaca* occurred in decaying wood of and *P. dactylifera*, also, where they consumed the wood and promote more rapid decay and laid their eggs in the hollows of branches. The finding of Meddich and Boumezzough [12] was supported by Mico and Galante [36]. Besides, adults of the Cetoniidae fly above the vault of the trees (including the palm tree) and feed on nectar plants and fruit trees and probably the inflorescences of the palm trees. In this way, it can be assumed that this species has undergone mutations by changing biotope and passing from saprophagous larvae (dead organic matter, compost) to saproxylophagous larvae (dead woods, rachis and dead and / or alive palms of the *P. canariensis* and *P. dactylifera*). As finding by Meddich and Boumezzough [12], *P. opaca* larvae was found of all studied sites. The phytophagous species (Scarabaeidae) were active at night. In the broad sense, saproxylophages cause damage by attacking either roots or leaves. Larvae (white worms) were generally the most harmful to palms. However, Meddich and Boumezzough [12] conclude that the degradation of the Moroccan palm grove may be linked to the attack of *P. opaca* larvae. They observed that the frequency of palms prospected and infected with *P. opaca* remains higher in the Marrakesh palm grove than in the south of Morocco. Date palm grove of Marrakesh is more confronted with anthropogenic constraints such as urban extension and air pollution by dust exceeding the tolerance threshold [43, 44]. Suspended particle concentrations in certain areas of Marrakesh are slightly above the limit value for health protection in Morocco [44]. This may induce the creation of biotopes necessary for the develop-

Many researches carried out in other countries have highlighted the danger of the red palm weevil for both species *P. dactylifera* and *P. canariensis*. In the Arab countries, the efforts deployed to control *R. ferrugineus* were based mainly on modified cultural practices, the application of traditional insecticides and traps that uses pheromones to lure *R. ferrugineus* [38]. Moreover, the control of *P. opaca* insect pests involves spreading chemicals (in the form of toxic pellets) as uniformly as possible in areas where the larvae are causing damage. The elimination of diseased palms (attacked bylarvae) can

reduce the spread of the pest and consequently limit the damage.

• Spray acetamiprid 100 g/L at 2–3 times / year.

For preventive treatments of the aerial parts and the crown of the palm:

• Use Imidacloprid (200 g/L) by spraying at the crown (stipe, palm and heart) 2 to 3 times every 3 months. It is a systemic insecticide for the selective control of

*DOI: http://dx.doi.org/10.5772/intechopen.93537*

ment of *P. opaca* larvae in this city.

scarabaeidae beetles.

#### *Use of Olive Mill Wastewaters as Bio-Insecticides for the Control of* Potosia Opaca *in Date Palm… DOI: http://dx.doi.org/10.5772/intechopen.93537*

and thus constitute the largest phoenicultural areas (quoted by Sedra (2003) and updated by Meddich [43]. Meddich and Boumezzough [12] note that the prospected and infected *P. canariensis* palms were cultivated and located in the North-East palm grove of Marrakesh. This will allow exchanges of attacks between the two palm species studied. For the oasis ecosystem, the problem will cause a lot of damage and a serious socio-economical problem. Moroccan palms suffer from invasions by larvae and adults of *Rhinoceros Borer*; this is the case in Tunisia, the Middle East and Iran [33]. In Morocco, no *R. Borer* larvae or adults were found; also, the colonization of the wounds by the saprophytic fungi can lead to the appearance of rot and the dieback of the weakened palm. According to INRA (Institut National de Recherche Agronomique) reports and their research axis developed on *P. opaca* in oases newly identified in Morocco by Meddich and Boumezzough [12]. Tauzin [40] indicated the presence of this species in Anti-Atlas (Ifni, Tiznit), middle and southern of Morocco. The presence of *P. opaca* in the crown of the *P. canariensis* and *P. dactylifera* palm which can be explained only by the fact that adults have found an ideal biotope for egg laying and larval development. Meddich and Boumezzough [12] showed that *P. opaca* occurred in decaying wood of and *P. dactylifera*, also, where they consumed the wood and promote more rapid decay and laid their eggs in the hollows of branches. The finding of Meddich and Boumezzough [12] was supported by Mico and Galante [36]. Besides, adults of the Cetoniidae fly above the vault of the trees (including the palm tree) and feed on nectar plants and fruit trees and probably the inflorescences of the palm trees. In this way, it can be assumed that this species has undergone mutations by changing biotope and passing from saprophagous larvae (dead organic matter, compost) to saproxylophagous larvae (dead woods, rachis and dead and / or alive palms of the *P. canariensis* and *P. dactylifera*). As finding by Meddich and Boumezzough [12], *P. opaca* larvae was found of all studied sites. The phytophagous species (Scarabaeidae) were active at night. In the broad sense, saproxylophages cause damage by attacking either roots or leaves. Larvae (white worms) were generally the most harmful to palms. However, Meddich and Boumezzough [12] conclude that the degradation of the Moroccan palm grove may be linked to the attack of *P. opaca* larvae. They observed that the frequency of palms prospected and infected with *P. opaca* remains higher in the Marrakesh palm grove than in the south of Morocco. Date palm grove of Marrakesh is more confronted with anthropogenic constraints such as urban extension and air pollution by dust exceeding the tolerance threshold [43, 44]. Suspended particle concentrations in certain areas of Marrakesh are slightly above the limit value for health protection in Morocco [44]. This may induce the creation of biotopes necessary for the development of *P. opaca* larvae in this city.

Many researches carried out in other countries have highlighted the danger of the red palm weevil for both species *P. dactylifera* and *P. canariensis*. In the Arab countries, the efforts deployed to control *R. ferrugineus* were based mainly on modified cultural practices, the application of traditional insecticides and traps that uses pheromones to lure *R. ferrugineus* [38]. Moreover, the control of *P. opaca* insect pests involves spreading chemicals (in the form of toxic pellets) as uniformly as possible in areas where the larvae are causing damage. The elimination of diseased palms (attacked bylarvae) can reduce the spread of the pest and consequently limit the damage.

For preventive treatments of the aerial parts and the crown of the palm:


*Biotechnological Applications of Biomass*

**Treatments LT50(h)**

Crude OMW

Cordus

Kemaban

*SE, standard error.*

*Potosia opaca larvae.*

*Df, degree of freedom.*

*a*

*b*

*c*

**Table 5.**

**(95% CL)a**

*95% lower and upper confidence limits are shown in parenthesis.*

*3.5.3 Spray toxicity bioassay*

**4. Discussion**

rate was 100% when larvae were treated with Kemaban at 218 and 216 h for 0.5 and 1 μL/mL, respectively. Otherwise, mortality of larvae treated with Cordus was significantly higher compared to other treatments. After 144 and 146 h, the effect began with doses of 1 and 0.5 μL/mL, respectively. However, larvae treated with OMW, Kemaban and Cordus started to die for the first time from day 9, 8 and 6 respectively. In contrast, the two commercial insecticides caused 100% mortality within 8 (Cordus) and 9 (Kemaban) days for all doses tested, compared to OMW

*LT50 and LT90 values of OMW and two positive controls applied by using spray toxicity bioassay to control* 

**LT90 (h) (95% CL)a**

95 mg/mL 245.39 (224.25–326.42) 323.86 (281.69–568.58) 0.01 ± 0.01 2.17 4

0.5 μL/mL 172.85 (128.56–201.58) 211.00 (188.72–383.17) 0.02 ± 0.01 1.98 4 1 μL/mL 160.02 (66.13–184.92) 199.23 (177.22–430.20) 0.02 ± 0.01 1.30 4

0.5 μL/mL 208.01 (173.03–249.35) 233.91 (217.58–623.46) 0.04 ± 0.24 2.52 4 1 μL/mL 197.53 (164.23–237.69) 228.65 (209.02–507.80) 0.02 ± 0.02 2.07 4

**Slope ± SEb** χ**<sup>2</sup> Dfc**

Boutaj et al. [31] reported that OMW showed insecticidal activity to control *P. opaca* larvae with LT50 and LT90 values of 245 h and 324 h, respectively (**Table 5**). Furthermore, a positive correlation was found between treatments and the duration of exposure (Letal time to kill 50% and 90% of the population). The highest efficiency was recorded for Cordus insecticide with LT50 of 160 h and 173 h for 1 and 0.5 μL/mL doses, respectively and LT90 of 199 h and 211 h for 1 and 0.5 μL/mL doses, respectively. Median lethal times (LT50 and LT90) generally decrease when insecticide concentrations increase. The least effectiveness was observed in *P. opaca* larvae for crude OMW. However, the results were close to Kemaban at a dose of 0.5 μL/mL.

The palm represents the symbolism of life in the arid and semi-arid area and being one of the oldest domesticated trees with multifold social and economical status [41, 42]. The *P. dactylifera* is a former species, which constitutes the pivot of the oasis agriculture in the south of Morocco. Out of an overall area estimated at 84500 ha in 1948, the Moroccan palm groves in 1994 covered an area of 44,450 ha occupied by a total of 4.42 million palm trees [9]. This population is currently estimated at 5.12 million palms on an area of 48,000 ha. The importance of the palm by province showed that the provinces of Ouarzazate (1,873,000 palm trees), Errachidia (1,250,000), Tata (Bani) (800,000), Marrakesh (799,000), Tiznit (139,140), Guelmime (138,000) and Figuig (125,500) were the most important

which showed 33 and 100% mortality after 9 and 19 days, respectively.

**500**


Efforts now focus on the development of integrated pest management methods based on biological control and pheromone traps rather than on conventional insecticides [45]. Since it is an internal tissue borer, *R. ferrugineus* is difficult to control in the early stage of attack [38–46]. Initial efforts to control red palm weevil in the Kingdom of Saudi Arabia using chemical insecticides were failed [47]. An integrated pest management strategy, developed in India, has successfully suppressed the pest in the date plantations in the Kingdom of Saudi Arabia [38]. The strategy is modeled on the lines of tackling the pest on coconut. The pheromone traps has been used successfully to monitor and mass attract the pest, and it could be considered as the core of in any integrated pest management [48–50].

There is a great danger from chemicals such as insecticides and fungicides in human's food and animal use. Recognizing this real danger, farmers and consumers turned their efforts to environmental and eco-friendly practices by using as well as consuming biological and healthy products. The polyphenols are natural molecules present in OMW from the olive fruit which could be an alternative and an asset for pest control. However, the amount of OMW polyphenols may vary based on multitude factors, such as climatic conditions, olive variety and fruit ripening stage as well as the harvest period [51–53]. The OMW phenolic compounds content, can be considerably affected by the technological processes used for olive oil extraction [54]. In this context, the phenolic compounds content of OMW which, presented potential insecticidal activity has been assessed and investigated by Boutaj et al. [31] in view to develop new valorization strategies. Additionally, an application of a hydroxytyrosol-rich OMW extract by spraying it against olive psyllid (*Euphyllura olivine*), in a drip-irrigated olive orchard for evaluating the insecticidal activity of OMW, was carried out in 2008 and 2009 [29]. The extract from OMW had a strong insecticidal activity control this insect when the applied concentration was 2 g/L. In addition, the authors observed a significant biocide effect depending on OMW phenolic extracts concentration on *E. olivina* larvae as well as adults. Indeed, OMW showed similar toxicity to the Kemaban insecticide at 0.5 μL/mL dose. Nevertheless, it is clear that the obtained results were attributed to the chemical molecules that contain the two commercial insecticides. Cordus presents two active molecules namely chlorpyriphos ethyl and cypermethrin. As for Kemaban contains a single active molecule which, is chlorpyriphos ethyl. These molecules act on the spread of nerve impulses along the axon (cypermethrin action) and inhibit the acetylcholine esterase by blocking the transmission of the nerve flux (chlorpyriphos ethyl action) [55, 56]. The main mechanisms which explain the OMW's biocide effect on invasive species in general including insects are not clarified. It has been suggested that the transmission of the nerve flux may be blocked by the high phenolic compounds content in OMW [57, 58]. A significant inhibition of acetylcholine esterase activity in a marine mollusk (*Mytilusgallo provincialis*) has been reported by Danellakis et al. [57] after exposition to OMW. While, Campani et al. [58] reported that the inhibition of acetylcholine esterase may be attributed to the potential presence in OMW of organophosphates and carbamates, two pesticides which, are strong inhibitors of acetylcholine esterase activity and commonly used to treat the olive fruit fly (*Bactroceraoleae*). However, the authors did not dismiss the inhibition of acetylcholine esterase possible which, could be explained, by the phenolic

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*Use of Olive Mill Wastewaters as Bio-Insecticides for the Control of* Potosia Opaca *in Date Palm…*

In this chapter, we present a new eco-friendly approach to control the spreading of *P. opaca* which started in Morocco. Microbiological analysis show the presence of saprophytic fungi and genus *Fusarium* with a non-virulent strain. On the other hand, the two insecticides used separately and crude OMW are toxic on *P. opaca* var. Cardui Gyllenhal larvae. These results are promising and suggest the possibility of using OMW due to their high content of phenolic compounds as a means of biological control to overcome environmental problems caused by synthetic pesticides. The OMW and their phenolic extract compounds could be used in agricultural systems. Moreover, focused field researches (each plant-pathogen system) could be carried out to understand and evaluate the effects of OMW on specific *in situ* pest problems. Based on the main findings, it is clear that OMW may contribute to improve the date palm protection to control *P. opaca* and could be used as bioinsecticides. Nevertheless, OMW could be used safely as a challenge to control plant pest without affecting negatively the soil and plants. Besides, the use of OMW combined with other pest bio-control practical methods which could be a sustainable approach to minimize the potential risks. In this context and to understand the beneficial effects of OMW, more investigations could be required to assess the feasibility of OMW application in bio-controlled systems at large-scale, and determining the limitations and advantages on the long term. Further, research works are needed to test, besides crude OMW, pretreated OMW (ultra-filtered or heated) and

compounds as well as metals and ammonia contained in OMW. Thus, the used OMW crude showed a toxic effect on *P. opaca* larvae. Danellakis et al. [57] noted that the toxicity is provided by the phenolic compounds and trace metals contained in OMW. Furthermore, Barbera et al. [59] showed that during their growth cycle, no phytotoxic effects were observed when OMW were applied on crops. This is related to plant phenological stage, the application modalities and the applied doses. The absence of harmful residues is the main advantage of OMW application to control plant pests as well as pathogens. Therefore, we can assume that there will be no need

for a preharvest interval on crops, after the application of OMW.

*DOI: http://dx.doi.org/10.5772/intechopen.93537*

**5. Conclusions and future directives**

its phenolic extracts as biodegradable pesticides.

*Use of Olive Mill Wastewaters as Bio-Insecticides for the Control of* Potosia Opaca *in Date Palm… DOI: http://dx.doi.org/10.5772/intechopen.93537*

compounds as well as metals and ammonia contained in OMW. Thus, the used OMW crude showed a toxic effect on *P. opaca* larvae. Danellakis et al. [57] noted that the toxicity is provided by the phenolic compounds and trace metals contained in OMW. Furthermore, Barbera et al. [59] showed that during their growth cycle, no phytotoxic effects were observed when OMW were applied on crops. This is related to plant phenological stage, the application modalities and the applied doses. The absence of harmful residues is the main advantage of OMW application to control plant pests as well as pathogens. Therefore, we can assume that there will be no need for a preharvest interval on crops, after the application of OMW.
