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Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes

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A special issue of Insects (ISSN 2075-4450). This special issue belongs to the section "Insect Physiology, Reproduction and Development".

Deadline for manuscript submissions: closed (30 June 2023) | Viewed by 27585

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Special Issue Editors

Dr. Marc Vreysen

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Guest Editor

Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Department of Nuclear Applications, International Atomic Energy Agency, 2444 Seibersdorf, Austria
Interests: sterile insect technique; area-wide integrated pest management; food security and food safety
Special Issues, Collections and Topics in MDPI journals

Dr. Des Conlong

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Guest Editor

South African Sugarcane Research Institute, Mount Edgecombe 4302, South Africa
Interests: sterile insect technique; area-wide integrated pest management; food security and food safety
Special Issues, Collections and Topics in MDPI journals

Dr. Rachael M. Horner

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Guest Editor

New Zealand Institute for Plant and Food Research, Lincoln 7608, New Zealand
Interests: sterile insect technique; area-wide integrated pest management; food security and food safety

Special Issue Information

Dear Colleagues,

Lepidoptera are key pests that require control to avoid significant losses in many cropping systems worldwide. Many major lepidopteran pests are currently undergoing geographical range expansion. Control options exist for moth pests, but most have issues of cost, efficacy or non-target impacts. The sterile insect technique (SIT), which involves the mass-rearing and release of sterile insects to overflood the wild population of the pest, has been used successfully against a number of moth species. However, despite successes, the wider development and deployment of SIT has important issues that need further investigation. A coordinated research project was implemented from 2016 to 2021, and research was conducted on the following tied to the field performance of the sterile insects: (1) improved rearing and maintenance of colonies based on selection for favourable behaviours, (2) better collection and irradiation methods to enhance results, (3) the application of two-sex or male-only release strategies, (4) improved handling, transport and release methods, (5) practical and effective methods for quality assessment, and (6) better deployment strategies to improve cost-effectiveness and outcomes.

The Special Issue aims to provide a summary of the research conducted during the period 2016–2021 on the following topics: 1. determining the effect of different rearing parameters and behavioural traits that have an impact on the competitiveness of sterile moths, by the correlation of laboratory, semi-field, and open-field performance, 2. determining the impact of adult and pupal collection and irradiation methods on field competitiveness, 3. determining the effect of sterile females on population suppression, 4. determining best practice methods for handling, transporting and releasing sterile moths to maintain field competitiveness, 5. determining the relative effectiveness of different methods for quality assessment of sterile and wild moths, and 6. developing the best practice deployment of sterile insects in relation to hotspots, taking into account moth competitiveness and field performance.

Dr. Marc Vreysen
Dr. Des Conlong
Dr. Rachael M. Horner
Guest Editors

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Keywords

sterile insect technique
area-wide integrated pest management
lepidopteran pests
field competitiveness
handling and behavioral traits

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Published Papers (13 papers)

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Research

17 pages, 1427 KiB

Open AccessArticle

Development of a Diet Production System for Conopomorpha cramerella (Lepidoptera: Gracillariidae), a Major Cocoa Production Pest in Southeast Asia and the Pacific Islands

by Jerome Niogret, Anisah Binti Savantil, Arni Ekayanti, Mavis Peter Jaus, Wulan Wulan, Elviah Mitzo, Jean-Philippe Marelli and Desmond Conlong

Insects 2023, 14(8), 708; https://doi.org/10.3390/insects14080708 - 14 Aug 2023

Viewed by 1511

Abstract

The development of artificial diets for the cocoa pod borer Conopomorpha cramerella, a major pest of cocoa plants, has undergone significant advancements. In this study, we present the success rates of two diet formulations, MM1 and MM4, which have been progressively improved. Nutritional composition analysis revealed that the MM1 diet differed from the natural host, cocoa pods, in several aspects, including protein, carbohydrate, and vitamin C content. To address these differences, modifications were made to the diet compositions, leading to the MM4 diet version. These modifications resulted in improved diet quality and reduced contamination, leading to enhanced success rates in all stages of C. cramerella development. Larval development, pupation success rates, and adult emergence rates were significantly higher in the MM4 diet compared with the MM1 diet. Moreover, the duration of larval development and pupal stage decreased, while adult longevity increased with the MM4 diet. The overall development success of diet-reared insects from egg to adult was comparable with that of insects reared on cocoa pods. However, the cocoon formation, body length and fresh weight of the adults reared on the artificial diets were lower than those reared on cocoa pods. This diet formulation provides a promising approach for laboratory rearing of C. cramerella and opens avenues for further research and mass-rearing initiatives to mitigate the impact of this pest on cocoa production. Full article

(This article belongs to the Special Issue Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes)

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19 pages, 1688 KiB

Open AccessArticle

Receptivity and Remating Propensity in Female Spodoptera litura (Fabricius) after Mating with an Irradiated Male or Its F₁ Male Progeny

by Nilza Angmo, Madhumita Sengupta, Neha Vimal and Rakesh Kumar Seth

Insects 2023, 14(7), 651; https://doi.org/10.3390/insects14070651 - 20 Jul 2023

Viewed by 1080

Abstract

The ‘Inherited or F₁ sterility technique’ (IS), using sub-sterilized male moths, is a widely proposed pest management tool for Lepidoptera pests in general, and the tobacco cutworm Spodoptera litura (Fabr.) in particular. However, the multiple mating tendency of female moths and the ejaculate quality of male moths might influence the efficiency of this technique. Reduced ejaculate quality was observed in irradiated males, as evidenced by radiation’s impact on certain bio-parameters, such as the weight of the spermatophores and their protein content, sperm count, the molecular expression of the sex peptide receptor (SPR) and egg fertility, with a greater impact in F₁ male progeny. During the remating of females with untreated males, irrespective of the irradiation status of the first male, there was an increase in calling behavior, remating propensity and fertility in females, with a larger time gap between consecutive matings. The ability of F₁ male progeny to check remating propensity in females 24 h after the initial mating was lower than that of unirradiated males. Partially sterile (130 Gy) males were as successful as unirradiated males in inducing the level of mating refractoriness in females. Decreased ejaculate quality in F₁ male progeny could be associated with increased female receptivity during remating. Understanding the influence of male moth irradiation, insemination quality and post (initial)-mating intervals on the remating behavior of normal female moths and induced sterility might help in simulation modeling and optimizing IS insect programs. Full article

(This article belongs to the Special Issue Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes)

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18 pages, 3511 KiB

Open AccessArticle

Improved Quality Management of the Indian Meal Moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) for Enhanced Efficacy of the Sterile Insect Technique

by Md. Mahbub Hasan, Md. Akhtar Hossain and Christos G. Athanassiou

Insects 2023, 14(4), 344; https://doi.org/10.3390/insects14040344 - 31 Mar 2023

Viewed by 1792

Abstract

The sterile insect technique (SIT) is considered an environmentally friendly, autocidal control tactic to manage insect pests. This work dealt with the improvement of quality management of the Indian meal moth Plodia interpunctella (Hübner) for enhanced efficacy of the SIT. The results indicated that egg hatching of irradiated mature eggs of P. interpunctella was higher than that of younger eggs, indicating that mature eggs were significantly more tolerant than younger eggs. Moreover, our data revealed that a dose of 500 Gy completely prevented pupal formation in irradiated young and mature larvae. Crosses between irradiated and non-irradiated adults resulted in considerable variations in fecundity. The mating competitiveness index (CI) value was higher for a ratio of 5:1:1 (sterile male, fertile male, and fertile female, respectively) as compared with the ratio 1:1:1 for the irradiated individuals of all life stages. Low temperature (5 °C) maintenance of irradiated pupae significantly affected adult emergence. Using cylinders to assess flight ability, we found that the flight performance of adults that were developed from cold treated irradiated pupae was influenced by cylinder diameter, cylinder height and the number of hours the insects were in the cylinders. The percentage of DNA damage of the reproductive organs of adults developed from cold treated pupae that were irradiated with 100 and 150 Gy varied significantly. The results of this study should be used to implement pilot-scale field tests aiming at a sterile- to-fertile male ratio of 5 to 1. Full article

(This article belongs to the Special Issue Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes)

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14 pages, 1840 KiB

Open AccessArticle

Mating Competitiveness of Male Spodoptera frugiperda (Smith) Irradiated by X-rays

by Shan Jiang, Xiao-Ting Sun, Shi-Shuai Ge, Xian-Ming Yang and Kong-Ming Wu

Insects 2023, 14(2), 137; https://doi.org/10.3390/insects14020137 - 29 Jan 2023

Cited by 3 | Viewed by 2110

Abstract

Spodoptera frugiperda, an invasive pest, has a huge impact on food production in Asia and Africa. The potential and advantages of sterile insect techniques for the permanent control of S. frugiperda have been demonstrated, but the methods for their field application are still unavailable. For the purposes of this study, male pupae of S. frugiperda were irradiated with an X-ray dose of 250 Gy to examine the effects of both the release ratio and the age of the irradiated males on the sterility of their offspring. The control effect of the irradiated male release ratio on S. frugiperda was evaluated using field-cage experiments in a cornfield. The results showed that when the ratio of irradiated males to non-irradiated males reached 12:1, the egg-hatching rate of the offspring of S. frugiperda decreased to less than 26%, and there was also no significant difference in mating competitiveness among the different ages. Field-cage testing showed that when irradiated males were released at ratios of 12:1–20:1 to normal males, the leaf protection effect for the corn reached 48–69% and the reduction in the insect population reached 58–83%. In this study, an appropriate release ratio is suggested, and the mating competitiveness of irradiated and non-irradiated males of S. frugiperda is investigated, thus providing a theoretical basis for the use of sterile insect techniques to control S. frugiperda. Full article

(This article belongs to the Special Issue Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes)

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10 pages, 271 KiB

Open AccessArticle

Mating Competitiveness of Irradiated Lobesia botrana (Lepidoptera: Tortricidae) in Male-Only and Both Sex Release Strategies under Laboratory Cage Conditions

by George Saour, Ali Hashem and Iyad Jassem

Insects 2023, 14(1), 18; https://doi.org/10.3390/insects14010018 - 23 Dec 2022

Cited by 2 | Viewed by 1801

Abstract

This laboratory study explored the concept of whether irradiated male-only releases are more or equally efficient as releases of both irradiated males and females in the context of using the sterile insect technique/inherited sterility (SIT/IS) for the management of the European grapevine moth Lobesia botrana. The current study examined the mating competitiveness of 150-Gy-treated L. botrana male and female moths or 150-Gy-treated male moths only, with untreated moths in laboratory cages. Our results showed that the release of both sexes significantly increased the competitiveness value (C) and the biological efficiency index (BE) as compared with male-only release, and this was independent of the male to untreated male ratio. Moreover, a single release of 150-Gy-treated and untreated males and females at a 1:1:10:10 ratio (untreated male:untreated female: treated male:treated female) significantly reduced egg hatch, and the number of first-generation offspring (F₁) was small. The emergence of F₂-moths per untreated F₁ male and female moth was low, but these undesired fertile moths should be eliminated in order to achieve effective control. The results presented herein provide useful information on the impact of 150-Gy-treated male-only, versus releases of both treated males and females on untreated moths, which is essential to managing L. botrana populations with SIT/IS. Full article

(This article belongs to the Special Issue Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes)

16 pages, 2965 KiB

Open AccessArticle

Radiation Hormesis to Improve the Quality of Adult Spodoptera litura (Fabr.)

by Neha Vimal, Nilza Angmo, Madhumita Sengupta and Rakesh Kumar Seth

Insects 2022, 13(10), 933; https://doi.org/10.3390/insects13100933 - 15 Oct 2022

Cited by 8 | Viewed by 1855

Abstract

Mass rearing of insects of high biological quality is a crucial attribute for the successful implementation of sterile insect release programs. Various ontogenetic stages of Spodoptera litura (Fabr.) were treated with a range of low doses of ionizing radiation (0.25–1.25 Gy) to assess whether these gamma doses could elicit a stimulating effect on the growth and viability of developing moths. Doses in the range of 0.75 Gy to 1.0 Gy administered to eggs positively influenced pupal weight, adult emergence, and growth index, with a faster developmental period. The enhanced longevity of adults derived from eggs treated with 0.75 Gy and 1.0 Gy, and for larvae and pupae treated with 1.0 Gy, indicated a hormetic effect on these life stages. Furthermore, the use of these hormetic doses upregulated the relative mRNA expression of genes associated with longevity (foxo, sirtuin 2 like/sirt1, atg8) and viability/antioxidative function (cat and sod), suggesting a positive hormetic effect at the transcriptional level. These results indicated the potential use of low dose irradiation (0.75–1 Gy) on preimaginal stages as hormetic doses to improve the quality of the reared moths. This might increase the efficiency of the inherited sterility technique for the management of these lepidopteran pests. Full article

(This article belongs to the Special Issue Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes)

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14 pages, 802 KiB

Open AccessArticle

Effect of Irradiation on Reproduction of Female Spodoptera litura (Fabr.) (Lepidoptera: Noctuidae) in Relation to the Inherited Sterility Technique

by Madhumita Sengupta, Neha Vimal, Nilza Angmo and Rakesh Kumar Seth

Insects 2022, 13(10), 898; https://doi.org/10.3390/insects13100898 - 2 Oct 2022

Cited by 4 | Viewed by 1915

Abstract

Radiobiological investigations on the reproductive behavior of female Spodoptera litura (Fabr.) were conducted with the aim of determining the suitable radio-sterilizing dose for females in order to release them along with sub-sterile males for effective implementation of the Inherited Sterility technique against this pest. Calling and copulation duration significantly increased, while mating success, oviposition, fertility and longevity significantly decreased with increasing radiation dose (100–200 Gy) compared to control. In view of the effect of irradiation on mating behavior and reproductive viability of female S. litura, 130 Gy was identified as a suitable radio-sterilization dose. Further molecular studies were conducted to corroborate this dose for female sterilization, along with a higher dose of 200 Gy in order to validate the gradational response of ionizing radiation. GC-MS analysis indicated decreased sex pheromone titer at 130 Gy, which was more pronounced at 200 Gy. Pheromone-associated genes, PBAN and PBAN-R showed decreased expression at 130 Gy, and were drastically reduced at 200 Gy. The fertility-related Vg gene also showed a negative correlation with radiation exposure. Based on these radiation responses of female S. litura, 130 Gy might be considered a suitable dose for complete female sterility and its inclusion in sterile insect programs against S. litura. Full article

(This article belongs to the Special Issue Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes)

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12 pages, 1421 KiB

Open AccessArticle

Flight Performance, Fecundity, and Ovary Development of Grapholita molesta (Lepidoptera: Torticidae) at Different Ages

by Sha Su, Xiaohe Zhang, Jilong Zhang, Baojian Huang, Chengzhi Jian, Xiong Peng, Marc J. B. Vreysen and Maohua Chen

Insects 2022, 13(9), 837; https://doi.org/10.3390/insects13090837 - 14 Sep 2022

Cited by 5 | Viewed by 2329

Abstract

Grapholita molesta is one of the most serious pests in fruits orchards. Flight performance of male insects and fecundity of female insects are important quality control parameters when moths are mass-reared for use in environment-friendly control strategies such as the sterile insect technique (SIT). However, information about flight performance, fecundity, and ovary development of G. molesta at different ages is scarce. In this study, we used a flight mill information system to measure the flight ability of female and male adults of G. molesta at different ages, and evaluated fecundity and ovarian development of female adults at different ages. The results demonstrated that the flight parameters (cumulative flight distance, cumulative flight time, maximum flight distance and maximum flight duration) of female and male G. molesta varied with age. Six-day-old female moths and three-day-old male moths were the strongest fliers, whereas the fecundity of one-day and two-day-old female moths was significantly lower than that of three to seven-day-old females. Five-day-old females had the highest fecundity. Their ovaries demonstrated mature eggs in the lateral and middle oviducts as of the third day post-emergence. It is suggested that the optimal age for moths to be released in SIT programs is three days, and moths older three days can be used for mass-rearing in a factory. Full article

(This article belongs to the Special Issue Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes)

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12 pages, 2071 KiB

Open AccessArticle

Effects of Adult Feeding Treatments on Longevity, Fecundity, Flight Ability, and Energy Metabolism Enzymes of Grapholita molesta Moths

by Sha Su, Xiaohe Zhang, Chengzhi Jian, Baojian Huang, Xiong Peng, Marc J. B. Vreysen and Maohua Chen

Insects 2022, 13(8), 725; https://doi.org/10.3390/insects13080725 - 13 Aug 2022

Cited by 4 | Viewed by 1996

Abstract

The oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae) is one of the most severe fruit tree pests in China, causing huge economic losses to fruit production. So far, there are few detailed reports on the rearing protocols of G. molesta. In this study, we compared the longevity, 10-d fecundity, flight ability, and the activity of major energy metabolism enzymes in the flight muscles of G. molesta under three feeding regimes (supplement with sterile water, supplement with 10% honey solution and starvation) of the adult moths. The results showed that the longevity, 10-d fecundity, and flight parameters (cumulative flight distance and time, maximum flight distance and duration, and the average flight speed) of adult moths when supplemented with sterile water or honey solution were significantly higher than those of moths that were starved. There were no significant differences in the 10-d fecundity, flight parameters, and the activity of major energy metabolism enzymes of flight muscles between moths that were supplemented with sterile water or 10% honey solution. The flight muscles of G. molesta mainly used carbohydrates as an energy source when sterile water and honey solution were supplemented, and the moth mainly used lipids as an energy source under starvation. Considering the cost and potential for diet contamination during mass-rearing, supplying sterile water is considered a cost effective option for food substitution of adult G. molesta. Full article

(This article belongs to the Special Issue Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes)

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11 pages, 531 KiB

Open AccessArticle

Reproductive Behaviour of 150-Gy-Treated Female Lobesia botrana (Lepidoptera: Tortricidae)

by George Saour, Ali Hashem and Iyad Jassem

Insects 2022, 13(7), 600; https://doi.org/10.3390/insects13070600 - 30 Jun 2022

Viewed by 2256

Abstract

The sterile insect technique/inherited sterility (SIT/IS) has been suggested as an eco-friendly control tactic for area-wide integrated pest management approaches in order to control the European grapevine moth, Lobesia botrana. This study assessed the effects of an irradiation dose of 150 Gy administered to newly emerged female moths on their egg laying behaviour and mating ability at different ages at mating. Moreover, the effects of multiple mating on the mating ability of treated females, pattern of sperm precedence in twice-mated females and the flight response of treated and untreated males to treated and untreated calling females were also investigated. Females treated with 150 Gy initiated calling in a way similar to untreated females. When treated females were paired with untreated males, the mean number of eggs oviposited per female during 6 days was reduced (59.6 and 82.8 eggs/female, respectively), as was their mating ability and multiple mating compared with untreated females. The proportion of offspring fertilized by the second of the two males to mate with the female or last-male sperm precedence (P2 value) constituted 97% of the eggs, suggesting that the second male mate fathered the most offspring. The outcome of this work could be viewed as an integrated approach for improving effectiveness and enabling successful implementation of a SIT/IS program against L. botrana. Full article

(This article belongs to the Special Issue Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes)

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19 pages, 1477 KiB

Open AccessArticle

Formulation of Artificial Diets for Mass-Rearing Eldana saccharina Walker (Lepidoptera: Pyralidae) Using the Carcass Milling Technique

by Nomalizo C. Ngomane, Elsje Pieterse, Michael J. Woods and Des E. Conlong

Insects 2022, 13(4), 316; https://doi.org/10.3390/insects13040316 - 23 Mar 2022

Cited by 7 | Viewed by 3059

Abstract

The carcass milling technique (CMT) formulates specific diets from nutrient analyses of species to be reared and their natural host plants. The first of four diets developed used the minimum ingredient specifications (MS) of published diets for Eldana saccharina. The remaining were based on the ideal amino acid composition and profile (IAAP) of its second (IAAP2), third/fourth (IAAP3/4) and fifth/sixth (IAAP5/6) instar larvae. The control was a modified Ostrinia nubilalis diet. Survival to pupae of inoculated E saccharina neonates was high on all CMT formulations (>92% at day 20 and >97% at day 27). Larvae developed fastest on the IAAP3/4 and MS diets (25% and 17% prepupae and pupae on day 20, respectively). Pupal weights were not significantly influenced by CMT diets (0.1121 g male; 0.1864 g female). The control group produced heavier male and female pupae (0.1204 g; 0.2085 g, respectively). Adult emergence was highest from the MS (98%), then the IAAP3/4 (97%) and control (96%) diets. Sex ratio of adults from all diets was close to one. Males from the IAAP5/6 diet mated with significantly more females (six), and females from the MS diet mated with more males (three) than those from remaining formulations. All females produced in excess of 870 eggs, more than 90% were fertile after mating. The pH (4.79); moisture content (81.43%) and water activity (0.92 a_w) of the diets were not significantly different, maintaining quality and stability throughout the larval period, ensuring optimal growth and development. The MS diet formulation was the preferred choice to replace the current E. saccharina diet. Full article

(This article belongs to the Special Issue Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes)

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19 pages, 1563 KiB

Open AccessArticle

Consequences of Thermal Variation during Development and Transport on Flight and Low-Temperature Performance in False Codling Moth (Thaumatotibia leucotreta): Fine-Tuning Protocols for Improved Field Performance in a Sterile Insect Programme

by Elizabeth J. Huisamen, Minette Karsten and John S. Terblanche

Insects 2022, 13(4), 315; https://doi.org/10.3390/insects13040315 - 23 Mar 2022

Cited by 2 | Viewed by 2486

Abstract

Here we aimed to assess whether variation in (1) developmental temperature and (2) transport conditions influenced the low-temperature performance and flight ability of false codling moth (FCM) adults in an SIT programme. To achieve the first aim, larvae were exposed to either a (control) (constant 25 °C), a cold treatment (constant 15 °C) or a fluctuating thermal regime (FTR) (25 °C for 12 h to 15 °C for 12 h) for 5 days, whereafter larvae were returned to 25 °C to pupate and emerge. After adult emergence, critical thermal minimum, chill coma recovery time, life history traits and laboratory flight ability were scored. For the second aim, adult FCM were exposed to 4 or 25 °C with or without vibrations to simulate road transportation. After the pre-treatments, flight ability, spontaneous behaviour (i.e., muscle coordination by monitoring whether the moth moved out of a defined circle or not) and chill coma recovery time were determined. The first experiment showed that FTR led to enhanced cold tolerance, increased flight performance and high egg-laying capacity with minimal costs. The second experiment showed that transport conditions currently in use did not appear to adversely affect flight and low-temperature performance of FCM. These results are important for refining conditions prior to and during release for maximum field efficacy in an SIT programme for FCM. Full article

(This article belongs to the Special Issue Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes)

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21 pages, 1585 KiB

Open AccessArticle

The Addition of Sterols and Cryoprotectants to Optimize a Diet Developed for Eldana saccharina Walker (Lepidoptera: Pyralidae) Using the Carcass Milling Technique

by Nomalizo C. Ngomane, John S. Terblanche and Des E. Conlong

Insects 2022, 13(4), 314; https://doi.org/10.3390/insects13040314 - 23 Mar 2022

Cited by 4 | Viewed by 2128

Abstract

Various combinations and concentrations of cholesterol (C) and stigmasterol (S) were added into a base diet developed for Eldana saccharina. Survival of inoculated neonate was high on all diets (>92% at day 20 and >95% at day 27). Fastest larval development occurred on the minimum specification (MS) (+1.0 gS) and MS (+0.2 gC: 0.2 gS) diets (72 and 70% pupation respectively at day 20). Significantly slower development (15% pupation) occurred on the control diet at day 20. Female pupal weight increased when larvae fed on the MS (+0.1 gC), (+0.1 gS) and (+0.2 gC:0.2 gS) diets (0.2143 ± 0.00 g, 0.2271 ± 0.01 g and 0.2252 ± 0.01 g, respectively) as compared with the control diet (0.1886 ± 0.00 g). Adult emergence was significantly higher (100%) from the MS (+0.1 gS) and MS (+0.2 gC:0.2 gS) diets, as compared with the remaining sterol (95%) and control diets (97%). To potentially increase E. saccharina’s cold tolerance, inclusion of cryoprotectants L-proline (P) and trehalose (T) into the MS diet was investigated. Males from the MS (0.2 gP:0.2 gT), MS (0.5 gP:0.5 gT) and MS (1.0 gT) diets recovered fastest from chill coma treatment (204 ± 44 s, 215 ± 7 s and 215 ± 9 s, respectively) than those from the remaining cryoprotectant diets (305 ± 22 s). The addition of cryoprotectants severely reduced female fertility (<44%) when mated with non-chill coma exposed males. In contrast, eggs from females not exposed to chilling treatment were 84% fertile when mated with males from the same source. The MS (0.2 gC:0.2 gS) diet is the preferred choice to replace the currently used diet, reducing the larval growth period by 60% without negative effects on key life cycle parameters of E. saccharina. Full article

(This article belongs to the Special Issue Improved Field Performance of Sterile Male Lepidoptera to Ensure Success in SIT Programmes)

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