Effects of protein levels on production performance, nutritional values, and phase feeding of two-spotted cricket.

Two experiments were conducted to determine the effects of different protein levels on the growth performance, feed efficiency and nutritional values, and phase feeding of the 2-spotted cricket (Gryllus bimaculatus de Geer). In experiment 1, 4 crude protein (CP) diets were formulated to contain 18%, 20%, 22%, or 24% CP, respectively. A sample of 7-day-old 3,600 crickets was equally divided into 24 plastic boxes (150 crickets each) in a completely randomized design with 4 diets and 6 replications. In experiment 2, 2-phase feedings were used. For starting period (days 7-18), crickets in all treatments were fed a diet containing 22% CP. During the growing period (days 19-35), 3 groups of crickets were fed diets containing 18%, 20%, and 22% CP. In the overall period of experiment 1, the crickets fed with 22% CP diet had greater body weight compared to those fed with 18% CP diet. In addition, the crickets fed with 22% CP diet had the lowest feed conversion ratio (FCR). The broken-line model indicated the growth pattern changed on day 18. In experiment 2, the crickets fed with 20% CP diet from days 19 to 35 had greater growth performance and lower FCR than those fed with 18% CP, but not different from those fed with 22% CP. In conclusion, 22% CP can increase growth performance by improving the feed efficiency of crickets. The implementation of 2-phase feedings using 20% CP, during the growing period, could be considered as a cost-effective strategy for sustainable cricket production.

Insecticidal Activity of Plectranthus amboinicus Essential Oil against the Stable Fly Stomoxys calcitrans (Diptera: Muscidae) and the Horse Fly Tabanus megalops (Diptera: Tabanidae).

The stable fly, Stomoxys calcitrans (Diptera: Muscidae), and the horse fly, Tabanus megalops (Diptera: Tabanidae), are important ectoparasites of livestock in Thailand. These species affect animal health and cause economic losses. This study investigated the insecticidal activity of Plectranthus amboinicus essential oil against S. calcitrans and T. megalops through contact and fumigant toxicity tests and evaluated the effects of the essential oil on these flies through histopathological and scanning electron microscopic (SEM) studies. The results of the contact toxicity test indicated that the median lethal dose against S. calcitrans and T. megalops was 12.05 and 131.41 µg/fly, and the 90% lethal dose was 45.53 and 200.62 µg/fly, respectively. The results of the fumigant toxicity test showed that the median lethal concentration against S. calcitrans and T. megalops was 1.34 and 7.12 mg/L air, and the 90% lethal concentration was 4.39 and 30.37 mg/L air, respectively. Histopathology revealed neuronal degeneration in the brain of S. calcitrans and interstitial neuronal edema of the brain and ovarian necrosis in T. megalops. No external morphological changes were observed via SEM. Given its insecticidal properties against S. calcitrans and T. megalops, P. amboinicus essential oil could be developed into a natural insecticide to control these fly species.

Comparison of blue cotton and blue polyester fabrics to attract hematophagous flies in cattle farms in Thailand.

Tabanids and stable flies are important nuisances to livestock and sometimes humans. Nzi, Vavoua, and Biconical traps or insecticide-impregnated blue screens are commonly used to attract and catch these flies. Such devices are made of a specific cotton or cotton-polyester phthalogen blue fabric acting as a visual attractant. However, the cost of cotton fabrics is high, and they are no longer available due to toxic dyes. The present study compared four blue polyester fabrics produced in Thailand with a reference blue cotton-polyester fabric made in France by TDV® to attract hematophagous flies. Vavoua traps and blue screens covered with a sticky film made with the five different blue fabrics were compared. The TDV® had the highest trapping scores; however, there was no significant difference between TDV® and some polyester fabrics. Among the tested polyester fabrics, CR Solon No.41 was nearly as effective as the TDV® in attracting biting flies. The mean attractivity indices of CR Solon No.41, NS No.1469, Globe 2000 No.21, Globe 2000 No.34 were 0.86, 0.79, 0.69, and 0.39, respectively. Thus, we recommend that CR Solon No.41 would be the appropriate fabric for the further development of low-cost and optimized screens and traps in Thailand and other countries.

Contrasting evolutionary patterns between two haplogroups of Haematobia exigua (Diptera: Muscidae) from the mainland and islands of Southeast Asia.

Uncovering the hidden diversity and evolutionary history of arthropods of medico-veterinary importance could have significant implications for vector-borne disease control and epidemiological intervention. The buffalo fly Haematobia exigua is an obligate bloodsucking ectoparasite of livestock. As an initial step towards understanding its population structures and biogeographic patterns, we characterized partial cytochrome c oxidase subunit I (COI) and cytochrome b (Cytb) sequences of H. exigua from three distinct geographic regions in Southeast Asia. We detected two distinct mitochondrial haplogroups of H. exigua in our surveyed geographic regions. Haplogroup I is widespread in the Southeast Asian mainland whereas haplogroup II is generally restricted to the type population Java Island. Both haplogroups were detected co-occurring on Borneo Island. Additionally, both haplogroups have undergone contrasting evolutionary histories, with haplogroup I exhibited a high level of mitochondrial diversity indicating a population expansion during the Pleistocene era dating back to 98,000 years ago. However, haplogroup II presented a low level of mitochondrial diversity which argues against the hypothesis of recent demographic expansion.