Lethal and sub-lethal effects of bio-and chemical insecticides on the tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

Abstract

The tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a destructive pest affecting the tomato crop causing a loss of 60-100% of the tomato crop production. In the present study, the lethal and sub-lethal effects of Bacillus thuringiensis (Bt), spinosad, and emamectin benzoate as bio-insecticides comparing with 2 synthetic insecticides: chlorpyrifos and indoxacarb against T. absoluta under laboratory conditions were evaluated. Take in consideration, life tables and reproductive parameters of treated larvae with LC 30 for each pesticide (bioand chemical insecticides) by using leaf dipping technique were calculated. The results showed that Lepinox formulation of Bt was the most effective one against the early 2nd instar larvae with 0.01 × 10 −2 mg/l (ppm), followed by spinosad with 0.07 × 10 −2 ppm comparing to indoxacarb and chlorpyrifos (0.01 and 11.44 μg/ml, respectively). Sub-lethal effect of the Bt formulations significantly increased pupal mortality by 29.77, 33.30, and 26.94% for Lepinox, Dipel 2×, and Protecto, respectively. In addition to their efficiency, Bt formulations and emamectin benzoate increased larval developmental period and reduced adult emergency percentage to 70.28, 66.70, 73.06, and 75.55% for Lepinox, Dipel 2×, Protecto, and emamectin benzoate, respectively. All bio-insecticides including Bt, spinosad, and emamectin benzoate caused abnormalities in different life stages. The results suggest these bio-insecticides are promising alternatives to synthetic insecticides for T. absoluta management.

Insecticidal Activity of Lemongrass Essential Oil as an Eco-Friendly Agent against the Black Cutworm Agrotis ipsilon (Lepidoptera: Noctuidae)

“…The newly emerged moths (males and females in ratio 7:5) were transferred to a bigger jar which was supplied with a hanged piece of cotton wool soaked in 10% sugar solution as a dietary supplement [26]. Strips of dark net were used as hanging sites for egg deposition by the mated female moths.…”

“…Therefore, to control its populations, an integrated pest management plan is required for efficient and cost-effective management of A. ipsilon. Most of the bio or chemical insecticides' toxicities were evaluated on the development and physiological response in insect pests [26].…”

Toxicity and Sublethal Effect of Farnesyl Acetate on Diamondback Moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae)

“…Larvae were reared on mustard plant, Brassica rapa , as food in a screen cage (35 cm × 35 cm × 47 cm) at 25 ± 1 °C with a photoperiod of 12 h/12 h (light (L)/darkness (D)). The newly emerged adults were transferred to new mustard plants for oviposition, and cotton wool soaked in 10% honey water placed inside the cage was added as a dietary supplement [ 36 ]. The experiments were started after the third generations of the moth.…”

Nano-Insecticides Against the Black Cutworm Agrotis ipsilon (Lepidoptera: Noctuidae): Toxicity, Development, Enzyme activity, and DNA Mutagenicity

“…The bottom of each jar was covered with a thick layer of fine sawdust and the usual rearing techniques were performed along with the developing instars larvae till pupation occurred. The emerged moths were supplied with a 10% sugar solution as supplement dietary [11].…”

“…The introduction of nanoinsecticides into the environment necessitates the careful identification of their potential. Generally, insecticide studies focus on evaluating the lethal and sublethal toxicity of insecticides on insect development and enzyme activities [11].…”