Comparative Study on the Effect of Biofertilizers and Pesticides on Growth and Yield of Lettuce Crop and Associated Snails

Abstract

Field experiments were carried out during the two growing seasons of 2022/2023 and 2023/2024 at a private farm in Shiba, Zagazig District, Sharkia Governorate, Egypt. These experiments aimed to study the effect of GA₃, seaweed extract, biofertilizers and biopesticides comparing to pesticides on growth, chemical content and yield of lettuce plants and associated snails that overcome or decrease of them in lettuce plants.

The experiment included 7 treatments as follows:

Control (without any addition)

2- Gastrotox: (Pesticide) Chemical name: Metaldehyde 5%

3-Biocyina WP 2.5% (Biocide)

(Beauveria bassiana) Used with concentrations: 2.5, 5, 15 %

Biometa WP 2.5% (Biocide)

(Metarhizium anisopliae) Used with concentrations: 2.5, 5, 15 %

Protecto WP 9.4 % (Biofertilizer)

(Bacillus thuringiensis, subsp Kurstaki) Used with concentrations: 2, 4, 10 %

6-Gabbrellic Acid (GA3),Molecular Formula: C₁₉H₂₂O₆

Used with concentrations: 5, 10, 20 %

7- Seaweed extract. (Alge fertilizer Potassium Alginate 20% - marine Alge, Molecular Formula: (C₆H₇KO₆)n ,Used with concentrations: 5, 10, 20 %

A randomized complete Block design (RCBD) with three replicates was followed in this study, which involved the treatments above men tined.

All the treatments were applied as foliar spray.

This study included two parts the first part on was some growth characters, and yield of lettuce plants, while the second part was the ecological studies on certain land snails attacked different vegetable crops at Sharkia Governorate.

The results revealed that GA₃, being the most effective vegetative growth characters and yield  of lettuce plants, followed by the treatments of seaweed extract, biopesticides, biofertilizers and control pesticides, respectively.

As well as, three species of land snails belonging to three families of order Stylommatophora found on different crops. These species were M. cartusiana (Hygromiidae), E. vermiculata (Helicidae) and S. putris (Succineidae) .The identified species varied in their incidence and level of infestation according to locality and host type. It was obvious that M. cartusiana snail has the superior incidence comparing with the other species in all surveyed localities.

The effect of six chemical compounds: Gastrotox 5%, biocyna, biometa, protecto, Alge and GA3 were tested against M. cartusiana snails as poison baits under laboratory. where  all tested compounds failed to exhibit any molluscicidal activity one-day post treatment. Mortality percentages increased by   increasing concentration and exposure periods.

As time elapsed, mortality percentages were increasing where it reached (100, 36.7, 30, 26.7 and 16.6 %) of Gastrotox, Alge, biometa, biocyna, protecto and, after 28-day post treatment, respectively. As for GA3, did not gave any molluscicidal activity at concentration 10% throughout the experiment period.

Determination of LC₅₀ After 7 days of treatment for the tested biocide was the height one Biometa and the lower one GA3 compared with the LC₅₀ after 3 days of treatment for the tested molluscicide.

Conclusion: The results indicate that the tested compounds differed markedly in their molluscicidal efficiency, with Gastrotox showing rapid, concentration- and time-dependent mortality that reached 100% within 14 days, reflecting strong acute and cumulative toxicity,