Enhancement of the sterile male performance in Bactrocera philippinensis through access to protein (yeast hydrolysate) and/or exposure to methyl eugenol (ME) was investigated in this study. The temporal occurrence of sexual maturity of B. philippinensis was determined for both laboratory sterile and wild flies. Laboratory tests were also conducted to determine the peak age of ME feeding in relation to male fly age and sexual maturity and effect of protein on the longevity of sterile males. Field cage mating tests were performed to examine the effect of adult diet (P+ vs. P−) and ME exposure (ME+ vs. ME−) on the mating competitiveness of the sterile male B. philippinensis. P+ME+ sterile male flies achieved significantly more matings with wild females than P+ME− or PE−ME− sterile males. Based on the relative sterile index, P+ sterile male flies were significantly more sexually competitive when competing for wild females than P− flies. The results confirm that the pre‐release diet can be significantly improved to increase the effectiveness of the application of the sterile technique against B. philippinensis.
The mango pulp weevil, Sternochetus frigidus (F.), is an important quarantine pest preventing the export of mangoes from the Philippines to the United States and other countries. Previously, a radiation dose of 100 Gy was proposed for phytosanitary treatment of S. frigidus based on dose-response studies with larvae, pupae, and adult weevils. To validate an irradiation treatment, large-scale confirmatory tests were conducted with adults (the most radiation-tolerant stage) in mangoes at 100 and 150 Gy. After treatment, adults were removed from fruit, sexed, and mated in pairs to observe any reproduction. At 100 Gy, adults laid a small number of eggs but none of the eggs hatched. At 150 Gy (measured doses 96.7-164.1 Gy),4,559 treated weevils laid no eggs, indicating that this dose caused complete sterility. Irradiation treatment with a minimum absorbed dose of 165 Gy will therefore provide quarantine security for S. frigidus in exported Philippine mangoes.
The effect of irradiation on the fecundity, egg hatchability, and longevity of the coconut leaf beetle (CLB) – Brontispa longissima (Gestro) – was studied using different doses of gamma radiation ranging from 20–50 Gy for pupa and adult males, and 20–40 Gy for adult females. The fecundity and fertility of adults decreased with irradiation dose. The pupae were more sensitive to irradiation than the adults based on LD50 values after 14 d. Adult females were more sensitive to irradiation than males based on fecundity and egg hatchability. No eggs were hatched at 40 Gy in irradiated females (IF) mated with unirradiated males (UM) and at 50 Gy in unirradiated females (UF) mated with irradiated males (IM), albeit with a significant effect on longevity at this dose. Using 45 Gy for mating competitiveness studies at a ratio of 1:15:1 (UF: IM: UM), wild females’ acceptance of IM was high based on the relative sterility index (RSI) value of 0.66.
Aedes aegypti strain obtained from field collections in Old Balara, Quezon City, Philippines was colonized at the Department of Science and Technology–Philippine Nuclear Research Institute (DOST-PNRI) laboratory. The number of eggs and their weight followed a significant linear relationship for the Ae. aegypti colony. Storing the hatching solution composed of nutrient broth (NB) and brewer’s yeast (BY) longer for at least 16 h hatched the mosquito fastest within 4h. Among the different ages tested, 2-wk-old eggs had the highest hatch rate. After collecting eggs from rearing cages, eggs for 6 wk still produced a high hatch rate and pupal recovery. Mosquito eggs can be effectively stored in cup and ziplock with a hatch rate of at least 77% on the third week, and at least 71% on the fourth week. Eggs stored in plastic cups can be best stored at 17–20 °C in the incubator 4 wk without a decrease in hatch rate. Eggs at these temperatures still produced about 50% egg hatch even until 3 mo.
The pupal eye color of Peach fruit fly Bactrocra zonata (Saunders) was documented at different holding temperatures. When holding mature pupae samples at 19, 25 (standard holding temperature), 28, and 22–34 ºC (natural environment), the development of pupae were 18–19, 9, 7, and 8 d, respectively. Holding pupae at lower temperature delays pupal development and slows down the progression of eye color changes. This is very important in manipulating pupal development, especially when problems occur during sterile insect technique (SIT) operations. The recommended timing of pupal irradiation for B. zonata at 25 ºC is at 2 d before adult emergence, where the pupae are 9 d old and the eye color is dark reddish-brown. Using eye color as a reference guide for irradiation of pupae, the optimum age when held at 19, 28, and 22–34 ºC (natural environment) was 18–19, 7, and 8 d old, respectively. Documented and a close-up photograph of pupal eye color was used as a reference guide to determine the best time for the irradiation of pupae in an SIT program for B. zonata.
In this study, new methods to improve the mass production of the Philippines fruit fly Bactrocera philippinensis Drew & Hancock were assessed. A new adult screen cage equipped with perforated egging tubes was designed. The replacement of sweet potato with sugarcane bagasse, rice straw or powdered corn as an alternative bulking agent in the standard artificial larval diet was found to lead to positive results in large-scale rearing. Rearing protocols and product quality control procedures for egg incubation, sieving of pupae and pupal holding were examined. The adoption of these new rearing procedures at low cost was found to increase the production of the Philippines fruit fly in a massrearing facility without reducing the fitness of the insect.
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