Toxicity and Bio-Efficacy of Indole-3-Acetic Acid, A Plant Growth Regulator, Against the Greater Wax Moth, Galleria mellonella Linnaeus (Lepidoptera: Pyralidae)

Abo Elsoud, A,El-Hela, A,Karem Ghoneim,Hamadah, Kh

doi:10.21608/eajbsa.2021.185451

Abstract

The greater wax moth Galleria mellonella L. is a dangerous pest for the apiculture industry in the world. The objective of the present study was to evaluate the insecticidal activity of the auxin plant growth regulator, Indole-3-acetic acid (IAA), against G. mellonella and its effect on the growth, development, metamorphosis and morphogenesis of this insect pest. The 3rd instar larvae were force-fed on an artificial diet supplemented with six concentrations, viz., 100, 10.0, 1.0, 0.1, 0.01 & 0.001ppm of IAA. The most important results could be summarized as follows. IAA exhibited the strongest acute toxicity on larvae at the higher two concentrations. At other concentrations, various degrees of toxicity on larvae were found in a dose-dependent course. No pupae or adults were produced at the higher two concentrations. IAA failed to display chronic toxicity on the developed pupae. All emerged adults died at 1.00ppm of IAA but no adult mortality was observed at the three lower concentrations. LC50 value was calculated in 0.24 ppm. IAA enhanced the treated larvae to grow with increasing weight gain. Also, it promoted the treated larvae, since the growth rate increased with the increasing concentration. IAA exhibited a retarding effect on the pupation, only at the higher two concentrations. The larval and pupal durations were significantly prolonged, in a dose-dependent manner. On the other hand, IAA failed to disturb the hormonal regulation of the development program, since no intermediate creatures were produced. Also, it failed to disrupt the pupal morphogenesis, since no pupal deformities had been observed.

Highlights

The greater wax moth Galleria mellonella Linnaeus (Pyralidae: Lepidoptera) is a cosmopolitan serious insect for the apiculture industry (Kwadhaet al., 2017)
Toxic Effect of Indole-3-acetic acid (IAA) on Different Developmental Stages of G. mellonella: After force-feeding of 3rd instar larvae of G. mellonella on diet mixed with six concentrations of IAA (100, 10.0, 1.0, 0.1, 0.01 and 0.001 ppm), data of its insecticidal activity were assorted in Table (1)
Depending on data of the same table, force-feeding of larvae on 1.00ppm IAA-treated diet resulted in complete mortality of the successfully emerged adults (100% adult mortality, at 1.0 ppm, vs. 0% mortality of control congeners) while no adult mortality had been recorded at the three lower concentrations

Summary

Introduction

The greater wax moth Galleria mellonella Linnaeus (Pyralidae: Lepidoptera) is a cosmopolitan serious insect for the apiculture industry (Kwadhaet al., 2017) It can be found in beehives or stored waxes because its larvae feed on the honeycomb, honey and wax (Büyükgüzel and Kalender, 2009; Roh et al, 2020). The adults of G. mellonella do not feed, because they have atrophied or ill-developed mouth parts, the voracious feeding nature of its larvae leads to the destruction of the honeycomb, and subsequent to the death of weak colonies (Ellis et al, 2013; Elbehery et al, 2016) It can destroy wax combs either inside or outside the hives (Awasthi and Sharma, 2013; Kwadha et al, 2017). Besides damaging wax combs and destroying frames and wooden parts in the hive, adults and larvae of G. mellonella can transfer pathogens of serious bee diseases, e.g. the bacterial disease foulbrood (Charrière and Imdorf, 1997; Owayss and Abd-Elgayed, 2007)

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