Mirid bug Nesidiocoris tenuis (Reuter), a potential challenge to bottle gourd Lagenaria siceraria (Molina) Standley production: a study from India

Mirid bug has become challenging pest infesting bottle gourd crop at Haryana state and Delhi NCR region in India. The feeding punctures caused on fruits due to bugs appears to be light reddish brown spots/blister, leading to blemished fruits which often fail to fetch a good market price. In the present study, we have endowed the species diagnosis (morphological and molecular), population dynamics, biology, fruit damage intensity and ecofriendly management of mirid bugs in bottle gourd crop. From the morphological studies it was found that, the mirid bug so investigated was found to be the zoophytophagous plant bug, Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae). In addition, the molecular analysis (DNA Barcoding) also confirmed the species identity with the DNA sequence generated (Accession No. OM117590) matching up to 99.86% with that of the available relative sequences with a total branch length of 0.10 base substitutions per site in the phylogenetic tree. Across the fields surveyed, it was found that on an average the maximum abundance of N. tenuis was noticed at tender tip of vines (7.0 bugs per tender tip of vine) followed by fruits (4.9 bugs per fruit) and leaves (4.1 bugs per leaf). There were two peak incidence of N. tenuis noticed during the study. First peak during 21st SMW (4th week of May) (8.7 bugs per leaf and 12.7 bugs per tender tip of vine) and second peak during 24th SMW (3nd week of June) (7.3 bugs per leaf, 10.5 bugs per tender tip of vine and 5.7 bugs per fruit). During the study, it was found that the maximum temperature, mean temperature and sunshine hours showed significant positive relationship with N. tenuis population on leaves (r = 0.800, 0.560 and 0.770, respectively), tender tip of vine (r = 0.880, 0.550 and 0.780, respectively) and fruits (r = 0.801, 0.553 and 0.549, respectively). In the present investigation it was found that N. tenuis successfully completed its life cycle on bottle gourd plants with total life cycle duration of ~ 34 days. The mean fecundity was observed to be 10.8 eggs. The age-stage specific survival rate (Sxj) and life expectancy (Exj) studies revealed that the survival rate and life expectancy of adult females was higher than that of adult males of N. tenuis. The % fruit damage due to N. tenuis ranged between 61.90 – 73.68% and damage intensity ranged from 20.4 to 27.4 numbers of damage punctures per 2 cm2 area of fruit rind. Due to bagging of fruits, there was 67.60% reduction in fruit damage and 96.05 – 98.61% increase in number of marketable fruits which clearly envisage the farmers to adopt bagging technique in bottle gourd against N. tenuis to obtain quality fruits with higher economic yield.