Silk recycling in larvae of the wax moth, Galleria mellonella (Lepidoptera: Pyralidae)

Abstract

Abstract. Galleria mellonella larvae spin protective tubes, which they use until they fi nish feeding, when they spin cocoons. A feeding choice experiment showed that some of the silk produced by feeding larvae was consumed in addition to the standard diet (STD). To determine the effect of feeding on silk, last instar larvae were fed for 24 h on foods based on STD but modifi ed by replacing the dry milk component (10% of the diet) with equal amounts of different kinds of silk. While each control larva consumed 21 ± 0.5 mg of the STD and produced 4.5 ± 0.1 mg of silk, larvae that ate the food that contained larval silk consumed 10 ± 0.4 mg of food and produced 6.1 ± 0.1 mg silk; the percentage ratio of silk produced to diet consumed was 21% and 61%, respectively. A more pronounced reduction in food consumption occurred when larvae were supplied with Galleria "cocoon" silk or the sericin fraction of such silk, and only 3.8 mg/larva was ingested of the diet containing Bombyx mori cocoon silk or its sericin fraction. Silk production expressed in terms of percentage of diet consumed was always higher than that recorded for larvae fed STD. We conclude that G. mellonella larvae recycle part of the silk that they produce during feeding. Presence of silk in the diet reduces food intake but increases the ratio of silk production to diet consumption. Sericin fraction of the cocoon silk seems to deter feeding.Abbrevations. BCF -Bombyx cocoon fi broin, BCS -Bombyx cocoon silk, BPS -Bombyx pad silk, BS -Bombyx sericin, CBS -Commercial Bombyx sericin, GCF -Galleria cocoon fi broin, GCS -Galleria cocoon silk, GLS -Galleria larval silk, GSGalleria sericin, STD -Standard diet.

The greater wax mothGalleria mellonella: biology and use in immune studies

“… 2017 ). If the amount of dietary protein falls below a certain level, the larvae cease spinning silk (Jindra and Sehnal 1989 ), probably due to the lack of essential amino acids for silk protein synthesis (Shaik, Mishra and Sehnal 2017 ). The protein content also affects the rate of larval development.…”

“…Feeding greater wax moth larvae spin protective silken tubes, within which they are not detected by bees (Shaik, Mishra and Sehnal 2017 ). However, host workers have been repeatedly observed removing dead larvae (presumably killed) of this pest (G. K. Wagner, oral information).…”

“…The composition of the silk from which the protective tubes are spun is similar to that in pupal cocoons. The core of the silk filament consists of heavy and light chain fibroins and the P25 chaperonin, whereas the filament coating is composed of sericins (Fedič, Žurovec and Sehnal 2002 ; Shaik, Mishra and Sehnal 2017 ). A feeding pause has been observed before each larval moult.…”

“…Cocoon construction takes on average 2.25 days, although this depends on the abiotic conditions of the environment (Paddock 1918 ). The cocoon protects first the larva and then the pupa against worker bees and possible parasites and probably also stabilises the abiotic conditions during pupal development (Jindra and Sehnal 1989 ; Shaik, Mishra and Sehnal 2017 ). The outer layer of the cocoon soon becomes hard while the interior remains soft (Ellis, Graham and Mortensen 2013 ).…”

Toxicological, histological and biochemical effects of Lepidium sativum seeds extract on Galleria mellonella L. (Lepidoptera: Pyralidae) larvae

“…Data revealed the amount of total soluble protein content is (32.08 mg/g) in treated larvae while reached to 80.5 mg/g in untreated ones. The reduction of protein level may affect protein synthesis responsible for spinning silk which is protective tubes, used in larval feeding at the cocoon stage as a result of the deficiency of essential amino acids needed (Shaik et al, 2017). Moreover, the explanation of protein deficiency perhaps might be attributed to 1) the utilization of protein in detoxification enzyme activity to eliminate the insecticidal action of L. sativum seed methanolic extract and 2) suppression of the synthesis of DNA and RNA (El-barky et al, 2008).…”