**3. Results**

*Biotechnological Applications of Biomass*

**2.10. Statistical analysis**

the Newman and Keuls test at the 5% threshold.

**Parameters Mean ± SD** pH 4.70 ± 0.11 EC (mS/cm) 23.50 ± 0.50 TOC (g/L) 26.23 ± 1.40 DM (g/L) 94.86 ± 1.66 TSS (g/L) 21.79 ± 0.50 Ash (g/L) 11.35 ± 0.67 TPC (g GAE/L) 8.38 ± 0.14 Residual Oil (g/L) 2.20 ± 0.30

Potosia opaca *larvae isolated from* P. canariensis *and* P. dactylifera *palms.*

plastic boxes. Cordus and Kemaban are composed of 50 and 48% chlorpyrifos-ethyl, respectively. Chlorpyrifos is an insecticide, acaricide and organophosphate miticide used mainly against insect pests. Concentrations of 0.5 and 1 μL/mL of Cordus and Kemaban were dissolved in distilled water. Many preliminary tests have been performed to select the doses to be used for positive controls. For each solution and crude OMW, a volume of 5 mL was sprayed on the surface of the palm compost every 24 hours for 6 days. Based on dry matter, the dose of OMW was calculated to be 94.86 g/L (≈95 mg/mL) (**Table 2**). The cumulative dosage of OMW polyphenols applied over a six days treatment was calculated. For each treatment, six larvae were placed in each box using ten replicates. Weight loss and mortality of positive controls and OMW were recorded 8 hours per day every 2 hours. Negative control was treated with distilled water. The larva was considered dead, when no movement was recorded

when shaking. Observations were made on all treated larvae until their death.

All results were analyzed statistically with the CO-STAT software (Statistical Software, New Style Anova). The study includes an analysis of variance followed by

*EC, electrical conductivity; TOC, total organic carbon; DM, dry matter; TSS, total suspended solids; TPC, total* 

**494**

**Table 2.**

**Figure 3.**

*phenolic content.*

*Physicochemical characteristics of crude OMW.*

#### **3.1 Microbiological analysis of crown palm**

In laboratory, the microbiological analysis showed fungal formations (blackish, whitish and greenish spots) observed on the Petri dishes that contain the extracts [12]. After observation on microscope, it has been found as saprophytic fungi in particular the Dimaties, with blackish spots; those take advantage of the damage already noted and the genus *Fusarium* with a non-virulent strain developed in whitish and pinkish spots with some conidia. The genus *Trichoderma* wide spread, in greenish spots and is often a key fungus in symbiosis and in biological control.

#### **3.2 Sampling techniques and prospecting the crown of palm**

During the exploration of the palm crown (*P. canariensis and P. dactylifera*), a number of soft arched larvae (grubs) with strong mandibles were harvested at the base of the green spine and / or dead. The first diagnosis of these larvae showed that they have a powerful mandibles, form "melolonthoides," sub-cylindrical strongly arched, whitish, with head, stigma and brownish legs; the head was always perpendicular to the body axis, with blackish posterior end; related to the Scarabaeidae beetles larvae (3 pairs of legs, antennae with 3 segments). Maximum width of head capsule: 4.6–4.9 mm. These larvae were either rhizophagous (melolonthoids), saprophytophagous or saproxylophagous (Cetoniidae). Initial research has shown that in the forms of phytophagous and saproxylophagous larvae, egg-laying can include about 100 eggs placed directly in the soil or in the wood, sometimes with the aid of an auger [40]. According to field investigations, Meddich and Boumezzough [12] observed the theft of a number of scarabaeidae beetles from the Cetoniidae family, but linking the larvae harvested at the level of the palm crown and the adults captured on the flight seems to be an illusory thing especially since all the larvae of Coleoptera belonging to the family Scarabaeidae were similar and that the systematic identification at the generic and specific level requires a rearing of the larvae under appropriate conditions of temperature and humidity for obtaining the adult. The ultimate stage of development of this Scarabaeidae and whose characteristics were indispensable for the identification of specimens. The evolution of the larvae is carried out at the base of the palms and rachis weakened and attacked by saprophytic fungi, which can lead to the appearance of rot and the dieback of the weakened palm [12]. Their presence at the top of the palm can also be explained by the fact that this beetle found an ideal biotope for the proliferation of larvae. Probably the adult manages to lay his eggs at the base of the weakened rachis and continues its development process while damaging the foliar bases as well as the heart of the palm. The larvae of this insect developing in the crown of the stem can infect the whole leaf mass and cause the crown tilt, which can be fatal to the palm. It should be noted that important attacks are observed at the palms base, at the crown; Attacks marked by the formation of galleries with a rejection of sawdust and dejections of white grubs (**Figure 4**) [12].
