Maize stem borer, Chilo partellus, is a serious pest of maize in India. Insecticides are not the right choice as larvae feed internally. Moreover, the indiscriminate use of pesticides increases the cost and accounts for health and environmental hazards. Adopting non-chemical methods such as biological control is an important strategy for effective suppression of the pest population. Biological control agents such as egg parasitoids, Trichogramma spp. (Hymenoptera: Trichogrammatidae) substantially reduce the pest population and are widely used against lepidopteran insect-pests. We studied the efficacy of egg parasitoid, T. chilonis against C. partellus in Kharif maize and recorded maximum egg parasitism by T. chilonis when released twice at higher rates (i.e. 1,25,000 and 1,00,000 parasitized eggs ha^-1). However, treatments with low release rates (one and two releases @ 75,000 parasitized eggs ha^-1, one release @ 1,00,000 parasitized eggs ha^-1) experienced significantly high plant damage and did not provide satisfactory monetary returns. In contrast, treatments with higher release rates (i.e. T. chilonis @ 1,25,000 parasitized eggs ha^-1 at 7 and 14 DAG; T. chilonis @ 1,00,000 parasitized eggs ha^-1 at 7 and 14 DAG) effectively suppressed plant infestation, dead heart formation and leaf injury by C. partellus. These treatments were statistically comparable with chemical control (dimethoate @ 660ml ha^-1 at 7 DAG). It can be concluded that one release of T. chilonis is insufficient, and two releases are required for effective management of C. partellus. T. chilonis provides the best result when released twice @ 1,25,000 parasitized eggs ha^-1 at 7 and 14 DAG (B:C ratio=1.42) which is at par with two releases @ 1,00,000 parasitized eggs ha^-1 (B:C ratio=1.41). Although pesticide-treated plots (Dimethoate 30 EC @ 660 ml/ha at 7 DAG) provide a satisfactory monetary return, they are not environmentally compatible and ecologically viable for the long run.

中文翻译：

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卵寄生性拟南芥（Trichogramma chilonis（Ishii））对斑节菜bore，Chilo partellus（Swinhoe）在哈里夫玉米中的生物功效

玉米stem虫，Chilo partellus，是印度的一种严重的玉米害虫。杀虫剂不是合适的选择，因为幼虫内部喂食。此外，不加选择地使用杀虫剂会增加成本，并造成健康和环境危害。采用非化学方法如生物防治是有效抑制有害生物种群的重要策略。生物防治剂，如卵类寄生虫，赤眼蜂。（膜翅目：Trichogrammatidae）大大减少了害虫的数量，并广泛用于鳞翅目昆虫的害虫。我们研究了卵寄生的功效，T. chilonis对C. partellus在秋收玉米和记录最大鸡蛋由寄生T. chilonis以较高的速率释放两次（即1,25,000和1,00,000寄生虫卵ha ^-1）。但是，低释放率的处理（在75,000个寄生虫卵ha ^-1下释放一个和两个，在1,000,000个寄生虫卵ha ^-1下释放一个）对植物的伤害很高，并且不能提供令人满意的金钱回报。与此相反，具有较高的释放速率的处理（即 T. chilonis @ 1,25,000寄生鸡蛋公顷^-1在第7和14 DAG; T. chilonis @ 1,00,000寄生鸡蛋公顷^-1在第7和14 DAG）有效地抑制植物侵染，死心形成和叶片损伤C.partellus。这些处理在统计学上可与化学对照相比（在7 DAG时，乐果@ 660ml ha ^-1）。可以得出结论，Chilonis的一个释放是不充分的，要有效地处理Part。C. partellus需要两个释放。T. chilonis在7和14 DAG分别以1,25,000个寄生虫卵ha ^-1释放两次时（B：C比率= 1.42）提供了最佳结果，与两次释放@ 1,00,000寄生虫卵ha ^-1（B ：C比= 1.41）。尽管经过农药处理的地块（Dimethoate 30 EC @ 660 ml / ha，在7 DAG处）可提供令人满意的收益，但从长远来看，它们在环境上不兼容且在生态上不可行。