Effect of Gamma Irradiation and/or Entomopathogenic Fungi on Some Biological Aspects of Galleria mellonella L. (Lepidoptera: Pyralidae)

Abstract

Studying the impact of gamma radiation in conjunction with the LC₅₀ of the entomopathogenic fungi on a few biological characteristics of Galleria mellonella (L.) larvae was the goal of the current work. The effects of single doses of gamma radiation (70, 100, 125, and 150 Gy) given sequentially or combined with the LC50 of specific entomopathogenic fungi (Beauveria bassiana, Paecilomyces lilacinus) against the Greater wax moth. The first generation (F₁) of G. mellonella was examined for its larval pupal period, pupation percent, sex ratio, and adult survival percent. Gamma irradiation and LC₅₀ of combined treatments of Beauveria bassiana and Paecilomyces lilacinus prolonged the larval-pupal period, while pupation, adult emergence, survival and sex ratio were lower in the combined treatment than in either treatment alone get more. The combined treatment was greater than either, in the case of fungal or irradiation treatment alone.

1. Introduction

One of the most obnoxious and significant wax pests in the world is the greater wax moth (GWM), Galleria mellonella L. (Lepidoptera: Pyralidae) [1, 2, 3, 4]. In its larval stage, this larva badly harms comb wax by feeding on it. When bees neglect to tend to combs, the wax moth larvae severely damage them. Attacks are possible on combs in weak or dead colonies and storage spaces [5, 6]. The generations of virulent strains for target pests and their usage as biological control agents have attracted a lot of research attention [7, 3].

Scientists have given entomopathogenic fungi, which infect insects, a lot of thought because of their potential for biological pest control. While certain insect pathogenic fungus has narrow host ranges, others, including Beauveria bassiana and Paecilomyces lilacinus, have broad host ranges [8].

Entomopathogenic fungi (EPFs) are one of highly specialized microorganisms that could infect and grow on arthropods [9]. EPFs such as Beauveria bassiana and Metarhizium anisopliae are widely used in the control of several insects [10]. Beauveria bassiana (Balsamo) (Ascomycota: Hypocreales: Clavicipitaceae) is a common fungus with effects on a wide variety of insect species and is used as a biological pesticide [11]. Several studies have been published on the efficacy of EPF against G. mellonella [12].

The pathogenicity of the fungi against the tested larvae was increased by gamma irradiation. The two control methods may be combined to effectively eliminate the insect pest, especially in storage [1, 13].

The aim of the current work, study the effect of gamma irradiation in combination with LC₅₀ of entomopathogenic fungi on some biological aspects of the 2nd instar larvae of Galleria mellonella (L.)

2. Materials and methods

2.1 Insect rearing and irradiation process

The greater wax moth, G. mellonella larvae were obtained from infested hives and reared in the Nuclear Research Center (NRC), Egyptian Atomic Energy Authority (EAEA), Egypt, Anshas area, the bio-insecticide Production Unit, Plant Protection Research Institute, Agricultural Research Center, Giza, Egypt. G. mellonella larvae reared on the artificial diet at a constant temperature of 30°C and 65 ± 5% relative humidity (R.H) according to ref. [14]. The irradiation process was performed using cobalt-60 gamma cell 220 located at Cyclotron project, Nuclear Research Centre, Atomic Energy Authority (Anshas). The dose rate was 0.926 kGy/hour during the experiment. Full-grown pupae of G. mellonella were exposed to four doses 70, 100, 125, and 150 Gy to study the effect of irradiation on some biological aspects of F₁ progeny descendant of irradiated parental male and female pupae.

Ten larvae resulting from irradiated parental males and females and transferred to clean small plastic containers and allowed to feed on an artificial diet, each treatment was replicated five times. Dead larvae were counted. The larval and pupal period, pupation, adult emergence, sex ratio, Adult survival percentage, and the resulting progeny (F₁) were determined as well.

2.2 The experimental media

Culture media were adjusted by the addition of: −10 μg/ml Dodine, 100 μg/ml Chloramphenicol, 50 μg/ml Streptomycin and 32.5 g SDA (sabouraud dextrose agar) in 500 ml distilled water “Dodine media” [15].

Chloramphenicol, thiabendazole and cycloheximide (CTC) medium consisting of CDA supplemented with 0.5 g/l chloramphenicol and 0.25 g/l cycloheximide) and 0.002 g/l thiabendazole [16].

2.3 Isolation of the entomopathogenic fungi

The entomopathogenic fungal, Paecilomyces lilacinus isolates from soils and the entomopathogenic fungal, Beauveria bassiana isolates from dead insects [17].

2.3.1 Identification of the fungal isolates

The fungal colonies arising on the plates were purified. The purified cultures grown on CDA and SDA (sabouraud dextrose agar) media were identified at Mycological Center (AUMC), Assiut University, Egypt.

The strain numbers for the B. bassiana was (AUMC 9894) and strain numbers for the Paecilomyces lilacinus was (AUMC 9884).

2.4 Bio efficacy of Entomopathogenic fungi against G. mellonella 2nd instar larvae

To ascertain whether the most virulent isolate of fungi is pathogenic to G. mellonella larvae, According to ref. [1], the second instar larvae were each submerged for 30 seconds in nine ml of various spore concentrations from the fungal isolates. Larvae were dipped into a 0.02% Triton X-100 solution as the control treatment [18]. After that, the treated larvae were put one by one in little plastic containers and given an artificial food to consume. All treated larvae were incubated for 12 hours during the photo phase at 30°C, 65 ± 5% relative humidity. Five times each of each treatment’s batches of 10 larvae were reproduced. Daily counts of dead larvae were made. According to Finney’s approach, the median fatal concentration and time were determined [19].

2.4.1 The investigated entomopathogenic fungi’s latent effect on a few biological features of G. mellonella

Beauveria bassiana and Paecilomyces lilacinus were utilized to estimate biological activity in light of the high mortality rate. To investigate how Entomopathogenic fungi affect several biological characteristics, the concentrations necessary to kill 50% of larvae during the observation time (LC₅₀) were selected (Table 1).

Fungal isolates	Lc50 conidia/ml	Lc95 conidia/ml	slope	X^2	P value
Beauveria bassiana	1.2 × 10^5	1.9 × 10^8	0.2620 ± 0.0305	13.15	0.001
Paecilomyces lilacinus	2.3 × 10^5	4.3 × 10^11	0.2064 ± 0.0299	04.30	0.120

Table 1.

Virulence of fungal isolates against 2nd instar larvae of G. mellonella*.

^*

Expressed as the LC_50, LC_95, and slope of toxicity regression lines after 10 days of dipping in different concentration.

To evaluate the biological activity of G. mellonella under laboratory conditions, four replicates of the 2nd instar larvae (20 larvae for each) were dipped into 9 ml of LC₅₀ of the tested entomopathogenic fungi (B. bassiana and P. lilacinus) for 30 seconds. Then treated larvae were placed individually in small plastic containers and allowed to feed on the semi-synthetic diet. For the control treatment, larvae were dipped into 0.02% Triton X-100 solution Dead larvae were counted daily. Growth parameters, namely larval – pupal period, pupation, adult emergence, sex ratio and survival (%) were recorded.

2.4.2 Effect of entomopathogenic fungi and gamma irradiation on some biological aspects of G. mellonella

To investigate the combined affects of gamma irradiation with the (LC₅₀) of various Entomopathogenic fungi (B. bassiana and P. lilacinus), three dose levels of gamma irradiation (70, 100, 125) were used. Three experimental groups were set up to explore the influence on some biological characteristics of G. mellonella. The first group was made up of the 70, 100, and 125Gy-irradiated F₁ larvae offspring of the irradiated Parental females as fully formed pupae. The second group was made up of the 70, 100, and 125Gy-irradiated full-grown pupae of F₁ larvae descended from irradiated parental males. Insect males and females were utilized as a control in the third group, which served as a parallel group of unirradiated insects.

The progeny of F₁ larvae of each group were fed on an artificial diet till the 2nd instar larvae, five replicates from the 2nd instar larvae (10 larvae each) were dipped into 9 ml of LC₅₀ of the tested entomopathogenic fungi (B. bassiana and P. lilacinus) for 30 seconds in clean small plastic containers fitted with moist filter paper and allowed to feed on an artificial diet under laboratory condition (28 ± 2°C and 65 ± 5% relative humidity). Larval and pupal period, the percentage pupation, the percentage of adult emergence, sex ratio and the percentage of adult survival were determined.

2.5 Statistical analysis

The lethal concentration 50 was determined for established regression lines. All data obtained were analyzed using the Analysis of Variance (ANOVA) technique and the means were separated using Duncan’s multiple range test (P > 0.05) [20].

3. Results

The latent effect of gamma irradiation on the larval and pupal periods of F₁ progeny descendant of irradiated parental males and females as full-grown pupae.

Figure 1 demonstrates how gamma radiation affected the larval and pupal periods of the greater wax moth, Galleria mellonella, in F₁ male offspring of the irradiated paternal males and females as full-grown pupae with four doses of 70, 100, 125, and 150 gray with an increase in dose, the average larval and pupal period lengthens noticeably.

Figure 1.

The effect of gamma irradiation on the larval and pupal periods of the greater wax moth, Galleria mellonella, in the F₁ male progeny of the irradiated parental males and females as full-grown pupae. ^*Means followed by the same letter in each curve (small letters) represent that are not significantly different at (p < 0.05).

The larval and pupal periods of the greater wax moth, Galleria mellonella, in F₁ male offspring of the irradiated paternal males rises to 41.73, 44.72, 45.80, and 47 days for the four doses, respectively with an increase in dose in comparison to 35.25 days for the control treatment. Also, the larval and pupal periods of the greater wax moth, Galleria mellonella, in F₁ male offspring of the irradiated paternal females dramatically lengthens with an increase in dose, as seen in Figure 1. Compared to 35.25 days for the control treatment, it rises to 42.27, 44.41, and 46.26 days for the three doses, respectively.

The combined impact of Entomopathogenic fungi and gamma irradiation on the larval and pupal periods of F₁ progeny descendant of irradiated parental males and females as full-grown pupae.

Figure 2 shows the impact of gamma irradiation in conjunction with the LC₅₀ of the entomopathogenic fungi, B. bassiana and P. lilacinus, on the average larval and pupal period per day of G. mellonella descending of the irradiated parental males and females. As the irradiation dose was increased, there was a significant increase in the mean larval and pupal durations (Figure 2). The average larval and pupal period among F₁descendant of the irradiated parental males (Figure 2, Hist. 1) significantly increased from 36.22 days in the control treatment to 43.55, 46.33, and 48.10 days for B. bassiana combined with the doses of 70, 100, and 125 Gy, respectively. Additionally, for P. lilacinus paired with the identical prior irradiation dosages, it dramatically rose to 42.14, 45.21, and 46.63 days, respectively.

Figure 2.

The effect of gamma irradiation combined with the LC₅₀ of the entomopathogenic fungi on the average larval and pupal period per day of G. mellonella F₁ males. Hist. 1: F₁ male’s descendants of irradiated parental males at three different doses: 70, 100, and 125 gray. Hist. 2: F₁ male’s descendants of irradiated parental females at three different doses: 70, 100, and 125 gray. ^*Means followed by the same letter in each curve (small letters) represent that are not significantly different at (p < 0.05).

The effect of gamma irradiation in combination with the (LC₅₀) of the entomopathogenic fungi, B. bassiana and P. lilacinus, is shown in Figure 2, Hist. 2 with respect to the mean larval and pupal period of G. mellonella descending from the irradiated parental females. With increasing irradiation dose, the mean larval and pupal period increased considerably. It significantly increased from 36.22 days in the control treatment to 44.73, 47.56, and 48.70 days at 70, 100, and 125 Gy dosages combined with B. bassiana. Additionally, it significantly increased from 36.22 days in the control treatment to 43.27, 45.16, and 47.40 days at 70, 100, and 125 Gy, respectively, when coupled with P. lilacinus.

The impact of gamma radiation on the sex ratio of F₁ male’s descendant of the irradiated parental males and females as full-grown pupae of the Greater wax moth, Galleria mellonella.

Table 2 shows the impact of gamma irradiation on the sex ratio of F₁ male’s descendant of the irradiated parental males and females as fully grown pupae of the greater wax moth, Galleria mellonella. The average sex ratio through the irradiated parental males as full-grown pupae rose. At the four doses of 70, 100, 125, and 150 Gy, it rises to 1.20, 1.33, 1.40, and 1.60, respectively, as opposed to 1.18 for the untreated control treatment) however, this increase was not significant). As well as the sex ratio through the irradiated parental males as full-grown pupae, with the dose increase, the average sex ratio went up. At the three doses of 70, 100, and 125 Gy, it rose from 1.18 for the control treatment to 1.40, 1.60, and 1.80, respectively) also, this increase was not significant).

Doses (Gy)	Sex ratio ± SE
	irradiated parental males as full-grown pupae		irradiated parental females as full-grown pupae
	male	female	male	female
Control (0)	1.18 ± 0.13 a*	1	1.18 ± 0.13 a*	1
70	1.20 ± 0.08 a	1	1.40 ± 0.08 a	1
100	1.33 ± 0.09 a	1	1.60 ± 0.09 a	1
125	1.40 ± 0.18 a	1	1.80 ± 0.18 a	1
150	1.60 ± 0.24 a	1	1.18 ± 0.13 a	1
LSD 0.05	0.47		0.47

Table 2.

Effect of gamma irradiation on the sex ratio, of the greater wax moth, galleria mellonella, among F₁ male’s progeny of the irradiated parental males and females as full-grown pupae.

^*

Means followed by the same letter in each column (small letters) represent that are not significantly different at (p < 0.05).

The combined impact of Entomopathogenic fungi and gamma irradiation on the sex ratio of F₁ male’s descendant of the irradiated parental males and females as full-grown pupae of the Greater wax moth, Galleria mellonella.

Table 3 Demonstrated the relationship between the entomopathogenic fungi’s (LC₅₀) impact and gamma irradiation on the sex ratio of G. mellonella descending from irradiated parental males and females. The sex ratio of G. mellonella descending of the irradiated parental males reveals that it was 1.4 and 1.6 in favor of males for B. bassiana paired with doses of 70 and 100 Gy, respectively, but was 1:1 at the dosage rate of 125 Gy as opposed to 1.13:1.0 at the control treatment. Additionally, it rose to 1.33, 1.30, and 1.20 following P. lilacinus treatment in conjunction with the identical dosages of prior irradiation, respectively.

Radiation Doses (Gy)	Fungi	Sex ratio ± SE
		irradiated parental males as full-grown pupae		irradiated parental females as full-grown pupae
		Male ± SE	Female	Male ± SE	Female
Control	—	1.13 ± 0.11 a*	1	1.1 ± 0.11 a	1
70 Gy	B. bassiana	1.40 ± 0.48 a	1	1.5 ± 0.44 a	1
	P. lilacinus	1.33 ± 0.27 a	1	1.7 ± 0.43 a	1
100 Gy	B. bassiana	1.60 ± 0.24 a	1	1.0 ± 0.31 a	1
	P. lilacinus	1.30 ± 0.30 a	1	1.2 ± 0.37 a	1
125 Gy	B. bassiana	1.00 ± 0.31 a	1	0.6 ± 0.40 a	1
	P. lilacinus	1.20 ± 0.20 a	1	0.8 ± 0.37 a	1
LSD		0.904		1.06

Table 3.

The effect of gamma irradiation and the entomopathogenic fungi’s (LC₅₀) on the sex ratio of G. mellonella descending of the irradiated parental males and females.

^*

Means followed by the same letter in each column represent that are not significantly different at (p < 0.05).

The sex ratio of G. mellonella descending of the irradiated parental females also (Table 3) reveals that at the two doses of 70 Gy and 100 Gy mixed with B. bassiana, was in favor of males (1.5 and 1.0, respectively). However, it was decreased from 1.1 in the control treatment to 0.6 with a dose of 125 Gy. At the two doses of 70 Gy and 100 Gy mixed with P. lilaceous, it also climbed to 1.7 and 1.2, respectively. At 125 Gy, however, it decreased to 0.8. (All data in Table 3 was not significant).

The impact of gamma radiation on the percentages of pupation, emergence, and survival of F₁ male’s descendant of the irradiated parental males and females as full-grown pupae of the Greater wax moth, Galleria mellonella.

Figure 3 shows the percentages of pupation, emergence, and survival of G. mellonella in F₁ male descendants of irradiated parental males at four different doses: 70, 100, 125, and 150 gray (Figure 3, Hist. 1). The percentage of pupation and the rise in dosages were negatively correlated. When compared to 92% for the control treatment, the percentage of pupation significantly drops to 78, 74, 68, and 60% at the four doses of 70, 100, 125, and 150Gy, respectively. Meanwhile, the percentage of the F₁ generation’s adult emergence greatly drops for all treatments. It drops from 93.55% for the control treatment to 82.69, 80.71, 70.23, and 56.76% at the four doses of 70, 100, 125, and 150Gy, respectively (Figure 3, Hist. 1). Additionally, Figure 3, Hist. 1 shows that as the dose was increased, the proportion of larvae that reached the adult stage considerably dropped (% Survival). At the four doses of 70, 100, 125, and 150Gy, the survival percentage fell to 66, 60, 48, and 34, respectively, from 86% for the control treatment.

Figure 3.

A negative association between the increase in dosages and the percentage of pupation, emergence, and survival of G. mellonella. Hist. 1: F₁ males of G. mellonella descendants of irradiated parental males at four different doses: 70, 100, 125, and 150 gray. Hist. 2: F₁ males of G. mellonella descendants of irradiated parental females at three different doses: 70, 100, and 125 gray. ^*Means followed by the same letter in each curve (small letters) represent that are not significantly different at (p < 0.05).

The percentages of pupation, emergence, and survival of G. mellonella in F₁ male descendants of irradiated parental females at four different doses: 70, 100, 125, and 150 gray, It has been stated in the Figure 3, Hist. 2. At the four dosages of 70, 100, and 125 Gy, respectively, the percentage of pupation significantly decreased to 62, 54, and 38% compared to 92% for the control treatment, while, the parental females that received the dose of 150 Gy did not produce any offspring.

At all treatments, there was a considerable reduction in the F₁ generation’s (F₁ females’) adult emergence percentage. It drops from 93.55% for the control treatment to 67.23, 62.00, and 58.66% for the three dosages of 70, 100, and 125 Gy, respectively (Figure 3, Hist. 2) while, the parental females that received the dose of 150 Gy did not produce any offspring as mentioned previously.

Additionally, a significant decrease in the percentage of larvae that reached the adult stage (Figure 3, Hist. 2) was seen as the dose was increased. In comparison to the control treatment, the percentage of survivorship reduced to 42, 34, and 22% at the three doses of 70, 100, and 125 Gy, respectively.

The combined impact of Entomopathogenic fungi and gamma radiation on the percentages of pupation, emergence, and survival of the F₁ males of the Greater wax moth, Galleria mellonella descendant of irradiated parental males and females.

Figure 4 illustrates how gamma radiation and the entomopathogenic fungi’s LC₅₀ affect the proportion of pupation, emergence, and survival of the F₁ males of the Greater wax moth, Galleria mellonella descendant of irradiated parental males and females.

Figure 4.

The effected of gamma irradiation and the entomopathogenic fungi’s (LC₅₀) on the percentage of pupation, emergence, and the adult survival of G. mellonella. Hist. 1: F₁ males of G. mellonella descendants of irradiated parental males. Hist. 2: F₁ males of G. mellonella descendants of irradiated parental females. ^*Means followed by the same letter in each curve (small letters) represent that are not significantly different at (p < 0.05).

The effects of Entomopathogenic fungus and gamma radiation on F₁ males of G. mellonella descendants of the irradiated parental males with doses of 70, 100, and 125 Gy are explained in Figure 4, Hist. 1. With increasing irradiation dose, the percentage of pupation was dramatically reduced, and treatments on B. bassiana showed greater declines than those on P. lilacinus. When combined with doses of 70, 100, and 125 Gy, respectively, it significantly decreased for B. bassiana to 42, 30, and 22%, respectively, compared to 80% in the control treatment, while it significantly decreased for P. lilacinus to 50, 38, and 28%, respectively, when combined with the same previous irradiation doses.

Also, with increasing irradiation dose, the percentage of pupation among F₁ males of G. mellonella descendants of irradiated parental males (Figure 4, Hist. 1) was significantly reduced, and treatments on B. bassiana showed greater declines than those on P. lilacinus when combined with doses of 70, 100, and 125 Gy, respectively, it significantly decreased for B. bassiana to 42, 30, and 22%, respectively, compared to 80% in the control treatment, while it significantly decreased for P. lilacinus to 50, 38, and 28%, respectively, when combined with the same previous irradiation doses. In comparison to the control treatment, the percentage of adult emergence for B. bassiana combined with doses of 70, 100, and 125 Gy was considerably reduced to 71, 63.33, and 70%, respectively. Additionally, for P. lilacinus paired with the identical prior irradiation dosages, it significantly decreased to 75, 70, and 63.33%, respectively (Figure 4, Hist. 1).

Figure 4, Hist. 1 also shows that as the irradiation dose was increased, the proportion of survival fell. In comparison to the control treatment, it was significantly reduced, dropping to 30, 20, and 16% for B. bassiana paired with dosages of 70, 100, and 125 Gy, respectively. Additionally, for P. lilacinus treatment paired with the same prior irradiation dosages, it significantly decreased to 38, 26 and 18%, respectively.

The percentage of pupation, emergence, and adult survival of G. mellonella descended from irradiated parental females is shown in Figure 4, Hist. 2 to be affected by gamma irradiation and the entomopathogenic fungi’s (LC₅₀). The percentage of pupation was significantly decreased with the increasing irradiation dose. It significantly decreases to 36, 22 and 16% with the three doses 70, 100 and 125 Gy combined with B. bassiana respectively, compared to 80% in the control treatment. Also, it significantly decreased to 46, 26 and 20% with the three doses 70, 100 and 125 Gy combined with P. lilacinus respectively.

Additionally, Figure 4, Hist. 2 shows that for all treatments in B. bassiana and P. lilacinus, the percentage of emergence decreases when the irradiation dose is increased. In comparison to the control treatment, it considerably dropped from 95% to 64.33, 73.33, and 60.00% at the three doses of 70, 100, and 125 Gy coupled with B. bassiana, respectively. While it significantly decreases from 95% in the control treatment to 74.00, 65.00, and 53.000% at the three dosages of 70, 100, and 125 Gy coupled with P. lilacinus, respectively.

Also, Figure 4, Hist. 2 shows that as the irradiation dose are increased, the percentage of adult survival decreases and it decrease more in B. bassiana than in P. lilacinus. When joined with B. bassiana at the three doses of 70, 100, and 125 Gy, it was significantly reduced from 76% in the control treatment to 24, 16, and 10%, respectively. While at the three doses of 70, 100, and 125 Gy joined with P. lilacinus, it significantly decreases to 34, 18 and 14%, respectively.

4. Discussions

Studies have been done on the biological activity (larval and pupal period, pupation, adult emergence, sex ratio, and survival) of G. mellonella second instar larvae fed with LC₅₀ amounts of B. bassiana and P. lilacinus. According to the data, the entomopathogenic fungi’s LC₅₀ significantly lengthened the larval and pupal stages compared to the control. These findings support those of ref. [21]. The screening of isolated fungi’s crude extracts for G. mellonella was acknowledged in 2012. Different fungal crude extracts of isolates were used, with varying effects on the percentages of larval and adult mortality. The Siwa and El-Farafra isolates of Beauveria bassiana had an impact on G. mellonella larvae, causing total mortality percentages of 82.48 and 74.22%, respectively, in comparison to the control treatment of 0%. The results showed that B. bassiana (El-Farafra and Siwa Oasis isolates) had a substantial impact on G. mellonella (larval and pupal weights). With increasing B. bassiana crude extract content, the percentage of larval mortality rose (El-Farafra and Siwa isolates). Similarly, ref. [22] discovered that B. bassiana dramatically shortened the S. litura larval period, and that this shortened period was observed in treated larvae of the second and fourth instars. Additionally, the LC₅₀ of B. bassiana and P. lilacinus decreased G. mellonella pupation, adult emergence, and the percent survival. Similar to that, the current experiment supports [23] findings that B. bassiana at 10⁸ conidia /ml reduces G. mellonella pupation and adult emergence to 20 and 13.33%, respectively. Additionally, ref. [24] discovered that B. bassiana caused the least amount of pupation and adult emergence of S. litura at spore concentrations of 2.4 × 10⁷ and 2.4 × 10⁴ conidia/ml, respectively. In contrast, ref. [23], who noted that when G. mellonella larvae in their fourth instar were treated with B. bassiana, the male to female ratio was higher. The sex ratio of the F₁ progeny was also biased in favor of the males. In their studies on Spodoptera litura in 2002, ref. [25] found that the sex ratio was biased in favor of males. Our findings demonstrated that the combined effect decreased the percentage of pupation, adult emergence, and survival; it also lengthened the larval and pupal duration. The F₁ generation’s gender ratio likewise shifted more in favor of males. The results of the current investigation showed that gamma irradiation and entomopathogenic fungi worked together to produce effects that were more notable than any of them working alone. The effectiveness of B. bassiana increased, especially when the gamma irradiation dose was increased, where no adults were produced with both the fungal concentrations and 150 Gy gamma irradiation dose, according to ref. [23] study using B. bassiana at 10⁴ and 10⁸ spores per milliliter combined with different doses of gamma irradiation (50, 100, and 150). According to ref. [1] gamma irradiation increased the fungi’s pathogenicity toward the studied larvae. The two pest-control instruments working together could effectively eliminate insects, especially in storage. Ref. [3] Investigated the effectiveness of Beauveria bassiana (Biovar), Trichoderma album (Biozed), and Metarhizium anisopliae (Bioranza) on Galleria mellonella (L.) greater wax moth larvae (Lepidoptera: galleriidae). They stated that some biological characteristics of Galleria mellonella larvae are significantly impacted by the three tested biocides.

5. Conclusions

In general, the results indicated that females were more radiosensitive to gamma irradiation than males. The F₁ progeny resulting from the irradiated full-grown male pupae was more sterile than the irradiated P₁ males and the F₁ males were usually more sterile than the F₁ females. The entomopathogenic fungi, B. bassiana and P. lilacinus were the most virulent isolates causing the highest adult longevity against 2nd instar larvae of Galleria mellonella and had the lowest LC₅₀ values. Full-grown male and female pupae irradiated with different doses of gamma irradiation (70, 100, 125 and 150 Gy) showed delayed effects on the different biological aspects of G. mellonella females were more radiosensitive than males. The sterilizing dose for males was above 150 Gy, while the sterilizing dose for females was 150 Gy.

The second instar larvae of Galleria mellonella descending of the irradiated parental male or female pupae with 70, 100 and 125 Gy then treated with the LC₅₀ of B. bassiana and P. lilacinus adversely affected on the different biological aspects. The combined treatment was greater than either, in the case of fungal or irradiation treatment alone.

Conflict of interest

The authors declare no conflict of interest.

Authors’ contributions

The Manuscript writing was done by all authors. Tables and reference settings were done by all authors. Then, final manuscript was read and approved by all authors. All authors read and approved the final manuscript.

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