Influence of Non-lethal Doses of Natural Insecticides Spinetoram and Azadirachtin on Helicoverpa punctigera (Native Budworm, Lepidoptera: Noctuidae) Under Laboratory Conditions

Abstract

Helicoverpa punctigera (native budworm) is an important pest species in crops across Australia. From the third instar onward, this species causes severe damage to crop plants: therefore, caterpillars need to be managed at an early stage of their development. In our experiment, we raised H. punctigera on an artificial diet, which included different concentrations of the natural insecticides Spinetoram and Azadirachtin. The survival of the larvae, growth and body mass gain was recorded over 17 days. Only caterpillars raised on lowest toxin concentrations survived and molted successfully to the fifth instar, but had slower growth and body mass gain compared to the insecticide-free control group. Caterpillars fed on higher toxin concentrations never molted to the next instar or died in the first few days. To test how the toxins influence physiological conditions including metabolic rate and water loss, surviving fifth instar larvae were exposed to thermolimit respirometry: starting at 25°C following a constant increasing temperature ramping rate of 0.25°C –1 , until reaching the critical thermal maxima (CT max ). Caterpillars raised on a non-lethal dose of insecticides had higher metabolic rates and lost more water compared to the control group. Insects that have seem to consume more energy per mg tissue and have a higher water loss at high temperatures. Non-lethal concentrations of insecticides on pest insects physiology may reduce their impact on crops and may enable more targetted insecticide application.

Effects of spinetoram and glyphosate on physiological biomarkers and gut microbes in Bombus terrestris

“…Spinetoram is a semisynthetic insecticide obtained by synthetic modification of spinosyn biological insecticides ( Betz and Andrew, 2020 ). It acts on synaptic transmission ( Piovesan et al, 2020 ), and studies have shown that exposure to high levels of spinetoram threatens the survival of bumblebees ( Besard et al, 2011 ).…”

AMMI Analysis of the Effects of Different Insecticidal Treatments against Agrotis spp. on the Technological Yield from Sugar Beet

“…AMMI stability values (ASVs) differed in terms of stability of root weight between three treatments (variant based on the sums of effective temperatures (F1); the heat sums (F2); pest alerts (S)) (Table 2). Following the work of Purchase et al [17], a stable protective treatment is characterized by an ASV close to zero. According to this definition, it was demonstrated that treatments S (ASV 2.291) and F1 (ASV 2.800) were most stable, and the K2 variant (15.618) was least stable (Table 2).…”

“…Similarly, cutworms, or surface caterpillars, damage sugar beet plants and have negative impacts on obtained crop yields. Several species are known to damage sugar beet, including Agrotis spp., Euxoa spp., and Xestia c-nigrum (L.) Central and Northern Europe and the USA), Peridroma saucia (Hübner), Crymodes devastator (Brace), and Feltia ducens (Walker) (in the USA); in addition to those also mentioned the larvae of many other moths such as Hydraecia micacea, Loxostege sticticalis (L.), Scrobipalpa ocellatella Boyd, Spodoptera spp., and Pseudaletia unipunctata (Haworth) can also damage the foliage of beet plants [12][13][14][15][16][17][18].…”

Journal of Plant Protection Research

“…In recent years, several studies have demonstrated the suppressive effects of AZN on 250 species of insect pests, especially Lepidoptera (Martinez and Emden 2001;Liang et al 2003;Seljasen and Meadow 2006;Pineda et al 2009;Ünsal and Güner 2016;Boadu et al 2011;Darabian and Yarahmadi 2017;Zhong et al 2017;Heibatian et al 2018;Qin et al 2019;Betz and Andrew 2020). The objectives of the present study were to i) determine an efficient AZN concentration for pest management by dose dependent AZN toxicity and ii) assess the life cycle of S. ocellatella on sugar beet plants exposed to sublethal concentrations of AZN.…”