Description of the subject:

Current control methods against Locusta migratoria use liquid insecticides whose active ingredients belong to the family of organophosphorus pyrethroids and synthetic carbamates, but these preparations have been found to be very harmful to the environment.

Objective:

The objective of the present study is to determine effect of the aqueous extract of Cornulaca monacantha on fifth-instar larvae (L5) of the migratory locust Locusta migratoria.

The methods:

The parameter studied was the mortality rate. We used three doses: a high dose (D1), an average dose (D2) and a low dose (D3). They were administered with two methods: contact and ingestion.

Results:

According to the results, a maximum mortality rate of 100% was recorded from the first day with the high D1 dose (by contact mode). However, the high D1 dose (by ingestion) induced a mortality rate of 83.33% on the first day, with a maximum mortality rate of 100% reached on the 2nd day. On the other hand, we note that the mortality rate began at 30% with the D2 dose (by ingestion), evolved towards 86.66% mortality on the third day and reached a maximum rate of 100% around the fourth day. The aqueous extract of Cornulaca monacantha was toxic by ingestion, with a highly significant difference between controls and treated larvae for the three doses—D1 (p = 0.0001074 < 5%), D2 (p = 0.0001382 < 5%) and D3 (p=0.0001387).

Conclusion:

The aqueous extract of C. monacantha greatly reduced the L5 population of Locusta migratoria.

The toxicity of the biopreparation is induced by the secondary molecules present in the leaves of the plant, especially polyphenols.