Investigation of biodegradable insecticide properties of different plant lectin proteins on tropinota (epicometis) hirta (poda,1761) (coleoptera: Cetoniidae)

Tropinota (Epicometis) hirta (Poda, 1761) (Coleoptera:Cetoniidae) is a polyphagous agricultural pest that causes significant economic damage to fruits, vegetables and cereals. Chemical control methods are not recommended because they are found in the same season as bees. This study aims to evaluate the effectiveness of plant lectins as bioinsecticides compared to synthetic insecticides. Adult insects were collected manually from wild mustard plants from various locations in İvrindi (Balıkesir) district of Turkey between 25 April and 12 July 2023 and 26 March and 06 June 2024. Insects were fed in vivo with different doses (50-300 mg/g) of Wisteria floribunda(WF), Phaseolus vulgaris(PV), Triticum vulgaris(TV) and Phytolacca americana(PA) lectins for 7 days. Mortality in insects increased proportionally with increasing lectin dose. According to the results, PA300 dose was determined as the most lethal dose. LD50 values were determined according to probit analysis. These values were calculated as PA:217.27 mg/g, PV:253.01 mg/g, TV:211.85 mg/g and WF:188.09 mg/g. According to daily mortality results, the PV300 dose was the lectin dose that showed early diffusion in the digestive system, killing % 5.6 of the insects on day 2. Total oxidant level (TOS) analysis was performed in the intestinal tissues of insects. According to the findings, TOS levels were significantly higher in the groups where PA100, TV150 and TV300 doses were applied compared to the negative control group. These results reveal that the applied lectins create oxidative stress in this insect species. Additionally, enzyme activities such as protease, trypsin-like, acid and alkaline phosphatase, exoglucanase, endoglucanase, β-glucosidase and α-amylase were examined in the intestinal tissues of insects. Most doses of lectins administered inhibited digestive enzyme activities. Among the applied lectins, especially TV and PA lectins caused devastating effects on TOS and digestive enzymes. Our findings suggest that lectins can be used as biodegradable insecticides as an alternative to chemical pesticides on T. hirta.