ABSTRACT
Selecting the candidate agents or species is a fundamental step in developing effective biological control programs. However, no attempts have been made to evaluate the efficacy of Trichogramma Westwood (Hymenoptera: Trichogrammatidae) strains against the Asian corn borer, Ostrinia furnacalis Guenée (Lepidoptera: Crambidae) in Myanmar. In this study, Trichogramma strains were investigated through a series of glass tube bioassays and under a semifield condition. Ostrinia furnacalis or Corcyra cephalonica egg preferences were compared among six strains of Trichogramma ostriniae, three of Trichogramma chilonis, and four of Trichogramma dendrolimi using a choice-test assay design. Significant differences were observed at the inter- and intraspecific levels. Four strains of T. ostriniae and two of T. dendrolimi showed a strong preference for O. furnacalis eggs, while two strains of T. chilonis and one T. dendrolimi strain preferred Corcyra cephalonica Stainton (Lepidoptera: Pyralidae) eggs. The remaining strains showed no preference. Eleven strains were examined on O. furnacalis eggs only, wherein parasitism, sex ratio, and total progeny per female were highest for two strains of T. ostriniae (respectively: 67.6 ± 3.0%, 82.7 ± 2.3%, 49.6 ± 2.8, and 67.6 ± 3.6%, 90.0 ± 2.4%, 42.7 ± 2.6), and one strain of T. dendrolimi (65.2 ± 3.2%, 84.7 ± 2.6%, 46.3 ± 2.8). Parasitism and searching capacity were evaluated for the three, best performing strains in cages containing maize plants. One T. ostriniae from Southern Shan State, Myanmar parasitized ~81% of egg masses, and should be considered a candidate biological control agent against O. furnacalis in Myanmar.
Subject(s)
Hymenoptera , Lepidoptera , Moths , Wasps , Animals , Biological Control Agents , Female , Myanmar , Zea maysABSTRACT
The Asian corn borer, Ostrinia furnacalis (Guenée), is the most devastating maize pest in Myanmar. The damage caused by this pest has become a significant obstacle to farmers' income and the national economy. Control of O. furnacalis is challenging due to its protected feeding sites and the crop's height during later phases of the pest's attack. Trichogramma (Hymenoptera: Trichogrammatidae) parasitoids have been used successfully against corn borers in other countries, but knowledge on the species composition in Myanmar is limited. As a first step for potential biological control of Asian corn borer in Myanmar, Trichogramma were collected from major maize growing regions. Identification was performed based on both morphological and molecular techniques. The majority of collected specimens were identified as Trichogramma ostriniae Pang and Chen, T. chilonis Ishii, and T. dendrolimi Matsumura. This is the first report on the composition of Trichogramma species, and an important step towards the establishment of biological control against O. furnacalis in Myanmar.