General biology ofEldana saccharina(Lepidoptera: Pyralidae): A Target for the Sterile Insect Technique

Abstract

Eldana saccharina Walker (Lepidoptera: Pyralidae: Gallerinae) occurs on many graminaceous crops and several wild grasses and sedges throughout Africa. It has been reared at the South African Sugarcane Research Institute (SASRI) since the 1970s to study its biology and behavior, as a host for natural enemies and to provide insect material for the plant breeding program. Studies were completed on laboratory-reared E. saccharina of South African origin to assess fecundity, fertility and male and female mating frequencies. Mean fecundity of E. saccharina was 518 ± 27.5 (mean ± SE) eggs per female, up to a maximum of 798 eggs. Mean egg hatch (fertility) of E. saccharina was 63.2 ± 4.2%. In the laboratory, 56.7% of E. saccharina females mated only once but on average females mated 1.5 ± 0.1 times (maximum of 3). Males mated with a maximum of 6 females per male but on average males mated 3.3 ± 0.7 females. Most matings (93%) occurred on the first and second nights after male emergence, and the females oviposited most of their eggs (49.9 ± 3.9%) on the second night after emergence. Eldana saccharina's high fecundity confirmed its potential as a crop pest. This study has, for the first time, confirmed that male and female E. saccharina were able to mate more than once under controlled laboratory conditions. This has important implications for calculating required release rates of sterilized males to obtain adequate sterile to wild male over-flooding ratios in area-wide integrated pest management programs that have a SIT component.

Radiation Biology ofEldana saccharina(Lepidoptera: Pyralidae)

“…Eldana saccharina was routinely reared at the South African Sugar Cane Research Institute (SASRI) using the methods described by Graham & Conlong (1988). The modified Sesamia calamistis Hampson (Lepidoptera: Noctuidae) diet described by Graham & Conlong (1988) was further modified by Gillespie (1993), and ferric citrate and formaldehyde were removed (Walton & Conlong 2016). Plastic multicell trays (32 cavities) containing 8 mL of artificial diet in each cell and developing E. saccharina larvae were routinely maintained in rearing rooms held at 28 ± 2 °C, 75 ± 5% RH and 0:24 h L:D photoperiod for approximately 619 degree days (DD), which is the time for peak pupal production (Way 1995).…”

“…Moths were held at the DFPT laboratories (26 ± 2 °C; 65 ± 5% RH; 16:8 h L:D photoperiod) for mating and oviposition. Oviposition substrates were changed daily until the female died or until the pair was 5 days old (as by then the majority of eggs had been oviposited) (Dick 1945;Betbeder-Matibet 1981;Sampson & Kumar 1985;Walton & Conlong 2016). The removed oviposition substrates were placed into re-sealable transparent plastic bags and labelled with the date, sex irradiated (either male or female) and radiation dose received.…”

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

“…Artificial diets for mass-rearing E. saccharina have been developed [17][18][19][20][21][22][23][24] and these diets effectively supported optimum survival and development of E. saccharina for the purposes for which they were developed. Growth parameters and biological quality traits of the pest have also been investigated by the authors on their developed diets.…”

The development of an improved artificial diet for the mass rearing of Eldana saccharina Walker (Lepidoptera: Pyralidae)

“…Diet development is a continuous process, as demonstrated in the E. saccharina IPM program. Atkinson, 22 Graham and Conlong, 23 Graham, 24 Gillespie 25 and Walton and Conlong 26 developed diets that continuously improved the quality and production of the insects needed for the various IPM programs. A new and improved artificial diet based on one developed for Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), 27 with lucerne meal supplied in rabbit pellets as the main ingredient, recently replaced the previous conventional sugarcane-based diet used to routinely rear E. saccharina, as insects were produced faster, were of higher quality, and were less expensive than those reared on the previously used diets.…”

“…The diet currently in use to mass-rear E. saccharina at SASRI 28 was recalculated to nutrient composition using Winfeed (EFG Software, 2017) and the calculated nutrient composition used as the control nutrient specification (CON). Ingredient compositions of three diets 25,26,28 which yielded satisfactory results for the rearing of E. saccharina were recalculated to nutrient composition (16 nutrients) using Winfeed 31 (Table 2). No energy value could be found for insects and in order to maintain a standard and comparable method, the digestible energy value of the raw materials for pigs were used (DE(pig)).…”