Incidence of Groundnut Leafminer (GLM), Aproaerema modicella (Deventer) (Lepidoptera: Gelechiidae) and its Parasitic Fauna on Alternate Leguminous Hosts in Tamil Nadu, India

Background: The groundnut leafminer (GLM), Aproaerema modicella is an important pest of several legume crops which causes 50 to 100 per cent yield loss in India. The exploration of indigenous natural enemies is crucial to the success of every biological control strategy. Besides, alternative host plants act as a source of both herbivorous pests and their natural enemies. In this view, occurrence of GLM and their parasitic fauna on groundnut, alternate leguminous hosts viz., redgram and babchi were recorded. Methods: Survey on damage potential of GLM and their parasitic fauna were recorded on groundnut at Sivagangai and Coimbatore districts of Tamil Nadu, India during 2016 to 2018. Survey was also conducted to find the damage potential of A. modicella on alternate leguminous hosts viz., redgram, babchi and their parasitic fauna at Coimbatore district. The damage potential of A. modicella, per cent parasitization and parasitoid emergence were assessed from A. modicella infested groundnut, redgram and babchi leaves. Result: Severe incidence of A. modicella was recorded as 98.10% (2016 to 2017) and 98.45% (2017 to 2018) at Sivagangai district. The parasitization of GLM was also found higher at Sivagangai recording 46.67% in both the years which was positively related with the pest population. 13 hymenopteran parasitoids belonging to eight families were recorded. Among them, Avga choaspes Nixon recorded high per cent parasitoid emergence (20.00%). Furthermore, GLM incidence on redgram and babchi indicated the highest damage potential of 38.20 and 34.50 per cent and parasitization of 33.33 and 20.00 per cent, respectively during 2017 to 2018.

Assessment of Diversity Indices and DNA Barcoding of Parasitic Fauna Associated with Groundnut Leafminer (GLM), Aproaerema modicella Deventer (Lepidoptera: Gelechiidae)

Background: Parasitoid wasps have received a great share of heed in the biological control of pests. However, they are often difficult to identify because of their small body size and profound diversity. In this view, biodiversity indices of parasitic fauna was reckoned and proper identification of those biocontrol agents were done through morphological and molecular technique such as DNA barcoding.Methods: Biodiversity indices of parasitoid of Groundnut Leafminer (GLM), Aproaerema modicella Deventer were reckoned for three agroclimatic zones viz., Irrigated Eastern zone (IE), Rainfed zone (R) and Irrigated Western zone (IW) of Tamil Nadu. Biodiversity indices viz., Relative density, Simpson’s Index, Shannon-Wiener Index, Pielou’s Evenness Index, Margalef Index and Beta diversity were assessed for the parasitic fauna associated with GLM. Apart from this, morphological characterization of prominent parasitoids were done with the help of available literatures and taxonomic experts. The molecular characterization of parasitoids were done using mitochondrial Cytochrome Oxidase I (mtCOI).Result: The relative density of parasitoid families and species indicated the dominance of braconidae and Chelonus blackburni Cameron. Among the agroclimatic zones, rainfed zone had higher species diversity, richness and evenness. In addition, the morphological and molecular confirmation revealed that the parasitoids associated with A. modicella as Temelucha spp., Stenomesius japonicus, Bracon hebetor, Sympiesis dolichogaster, Chelonus blackburni and Avga choaspes. The amplified sequences were submitted to NCBI database and accession numbers were obtained.

Influence of calcium silicate application on the population of Aproaerema modicella Deventer (Lepidoptera: Gelechiidae) on groundnut

Field experiments with foliar application of calcium silicate @ 2.0, 3.5 and 5.0 per cent, soil drenching of calcium silicate @ 10.0, 15.0 and 20.0 per cent and combination of foliar and soil drenching (@ 2.0% + 20.0%, 3.5% + 15.0% and 5.0% + 10.0%) were evaluated on 20 days old groundnut plant and compared with an untreated check. Application of calcium silicate via foliage and soil simultaneously @ 5 and 10 per cent on 20 days after dibbling of groundnut was effective to reduce the population of leaf miner and their leaflet damage, recording mean population of 5.25 nos. of larvae/10 plants and 16.46 per cent leaflet damage, respectively, while it was 12.25 nos. of larvae/10 plants and 27.95 per cent leaflet damage in untreated control. Reduction in population of leaf miner in groundnut might be due to silica induced plant defensive enzymes, however, the moderate reduction in population of leaf miner pest in groundnut can be well explained due to the high accumulation of silica in groundnut plants.

Field evaluation of methoxyfenozide 24 SC against leaf miner, Aproaerema modicella (Deventer) and its effect on predatory coccinellids of groundnut

The experiment on efficacy of methoxyfenozide 24 SC on leaf miner, Aproaerema modicella and its effects on coccinellids was conducted during kharif 2012 and rabi 2013 on groundnut variety, VRI 1. Among different doses of methoxyfenozide 24 SC (180, 210 and 240 g a.i/ha), chlorpyriphos 20 EC@225 g a.i/ha, lamda cyhalothrin 5 EC@15 g a.i/ha and dichlorvos 76 SC@750 g a.i/ha, the significant least incidence of Aproaerema modicella was recorded in methoxyfenozide @240ga.i./ha(4.8%/plants) followed by methoxyfenozide@210 g a.i./ha (5.6%/plants) and methoxyfenozide@180 g a.i./ha (7.2%/ plants). Maximum population of coccinellids was recorded in the untreated check (3.4 nos./plant) followed by methoxyfenozide@180 g a.i./ha (2.9nos./plant),methoxyfenozide@210 g a.i./ha (2.8 nos./plant) and methoxyfenozide@240 g a.i./ha (2.7nos./plant).High pod yield was recorded in the plots treated with methoxyfenozide@240 g a.i./ha (3704.5 kg/ha) followed by methoxyfenozide@210 ga.i./ha (3559.5 kg/ha) and methoxyfenozide @180ga.i./ha (3441.5 kg/ha).