Effect of Bio-Chemical Properties of Various Grains on the Quality Rearing of Factious Host, Sitotroga cerealella (Olivier) and its Subsequent Effect on Trichogramma chilonis in Vitro

Abstract

A ngoumois grain moth, Sitotroga cerealella (Lepidoptera: Gelechiidae), which is an important stored grains pest, is a common host for rearing Trichogramma chilonis. Development of S. cerealella takes place inside the grains, which are directly damaged (Weston and Rattlingourd, 2000). Cereals, like rice, wheat and corn are suitable for S. cerealella; however, their chemical and physical nature, carbohydrate, fat, and protein content is responsible Abstract | This study investigated the host preference and development of Sitotroga cerealella as well as its effect on the quality of Trichogramma chilonis under laboratory conditions at Agriculture Research Institute (ARI), Tarnab, Peshawar-Pakistan during, 2017-2018. The cereals (maize, oat, wheat and barley) were evaluated on the basis of total adult emergence, egg laying ability, developmental time of S. cerealella and enhancing parasitism along with sex ratio of T. chilonis raised on eggs from moths reared on cereals. The response of cereals to S. cerealella in no choice test revealed significantly greater adult emergence (18.9±12.6) and egg laying efficiency (82.2±6.8 eggs/female) with shortest developmental time (27.6±0.6 days) in wheat, while adult emergence (9.62±6.1) was less in maize grains. In choice test, significant effect of developmental time of S. cerealella was observed with wheat (27.4±0.2 days) and barley (27.2±0.2 days) allowing short duration. Similarly, T. chilonis preference to eggs of S. cerealella adults reared on different cereals showed that percent egg parasitism (89.6±1.7, 85.2±2.1), percent adult emergence (95.6 ±1.3, 92.1±1.4) and female sex ratio (73.1±0.7, 69.6±1.2) of T. chilonis was significantly high in moth eggs reared on maize and wheat in no choice conditions respectively. In choice test, sex ratio was significant and maximum females (70.4±0.5, 77.4±0.6) were observed in eggs from moth reared on wheat and maize. A positive strong correlation of percent adult moth emergence with protein and strong negative between development time and moisture content and carbohydrate was observed. Wheat proved to be suitable as host with high bio-chemical contents for mass rearing of S. cerealella that provide maximum moths in short duration and their eggs yield more of T. chilonis, thus recommended for production system of T. chilonis.

Toxicity of Selective Insecticides against <i>Trichogramma chilonis</i>

“…To investigate the cytotoxicity of insecticides against T. chilonis, an egg card bioassay was conducted to check the effect of parasitism. The quantification of the impact of insecticides on Sitotroga cerealella parasitized eggs was assessed throughout the developmental stages of T. chilonis, as T. chilonis parasitizes the eggs of Sitotroga cerealella (Ahmad et al, 2021). Five randomly selected egg cards, each having 40 parasitized eggs, were dipped in each for ten sec on the 1 st , 2 nd , 3 rd , 4 th , 5 th , 6 th , and 7 th life stages of parasitized eggs.…”