Abstract
Genus Trichogramma Westwood is being utilized in various biological control programme worldwide. Trichogramma spp. are egg parasitoids which lay their eggs inside the host eggs. More than 240 species are known, of which, 45 species are recorded from India. It is quite difficult to identify and differentiate among the species of Trichogramma due to smaller size. In present study, we hypothesized a methodology to identify the Trichogramma species based on potential morphometric characteristics. The males and females of five different species of Trichogramma namely, T. brassicae, T. chilotraeae, T. danaidiphaga, T. danausicida and T. dendrolimi were morphometrically analysed. A total of 33 characters in males and 27 in females were taken into consideration for morphometric identification and analysis using principal component method. It was observed that few characters of male like body length, length of flagellar hair, maximum marginal hair length of fore wing, genitalia characters including aedeagus length, distance between chelate structure and gonoforceps, and others were identified as important morphometric characters. Similarly, in females, ovipositor length, body and head length, eye width, antennal club width and number of setae in forewings were found important for taxonomic identification. Male and female of each species are clearly identified from high definition microscopic images.
Highlights
Insects play an important role in the biological system including pollination, regulation of population density of pests and many others [1] but at the same time, some insects have negative impact on plants and food chains
In males of Trichogramma, the identification is mostly based on genitalia characteristics, antennae and forewings [19, 20, 21] whereas, in females, ovipositor and hind tibia length are considered for identifying different species
Five Trichogramma spp. namely, T. brassicae Bezdenko, T. chilotraeae Nagaraja and Nagarkatti, T. danaidiphaga Nagaraja and Prashanth, T. danausicida Nagaraja and T. dendrolimi Matsumura were studied for morphometric analysis due to the following reasons: 1) large host range for T. brassicae and T. dendrolimi, 2) availability of T. chilotraeae, T. danaidiphaga and T. danausicida from India, and 3) cultures availability of both sexes of these species from India for rearing and morphometric analysis
Summary
Insects play an important role in the biological system including pollination, regulation of population density of pests and many others [1] but at the same time, some insects have negative impact on plants and food chains. In males of Trichogramma, the identification is mostly based on genitalia characteristics, antennae and forewings [19, 20, 21] whereas, in females, ovipositor and hind tibia length are considered for identifying different species Various researchers such as Pinto and Oatman [22], Nagaraja [23], Nagaraja and Gupta [24], Burks and Heraty [25], Yousuf et al [26], Nagaraja and Mohanraj [27, 28] & Fursov and Kodan [29] have provided taxonomic approaches for identification of Trichogramma spp. We studied the male and female of five different Trichogramma species It is to propose the morphometric and traditional basis for identification and differentiation among Trichogramma spp. which are very important in forest tree species
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