Abstract
Cashew (Anacardium occidentale Linn.) has become a very important tree crop in India. Several insect pests, however, have been recorded on cashew and prominent among which is the tea mosquito bug (TMB), Helopeltis spp. (Hemiptera: Miridae). Field survey from November 2009 to November 2011 suggests that Helopeltis antonii was dominant, which accounted for 82% of all Helopeltis spp. collected; whereas, Helopeltis bradyi and Helopeltis theivora accounted for 12 and 6%, respectively. No significant differences in egg hatchability percentage among the three species were observed. The study showed that there is significant variation in developmental rate of 2nd, 3rd and 4th instar nymphs of Helopeltis spp. The total developmental time for H. antonii, H. bradyi and H. theivora were 224.19, 211.38 and 214.59 hours, respectively. Survival rates of the nymphal instars of H. antonii were significantly high compared to H. bradyi and H. theivora. The sex ratio of H. antonii was highly female biased. The adults of H. bradyi and H.theivora survived longer and produced significantly higher number of eggs than H. antonii. The outcome of this study is very important in planning control as insect monitoring and biological studies are important components of Integrated Pest Management (IPM). Key words: Helopeltis antonii, Helopeltis bradyi, Helopeltis theivora, cashew, relative abundance, developmental rate, survival rate, sex ratio, longevity, fecundity.
Highlights
Cashew (Anacardium occidentale L.), a native of Brazil, was introduced in to the West Coast of India by the Portuguese during the sixteenth century (Devasahayam and Nair, 1986)
The Helopeltis species can be morphologically differentiated of H. antonii are reddish orange in colour (Figure 2); whereas, they are light brown in H. bradyi (Figure 4) and slight greenish in H. theivora (Figure 6)
Adults of Helopeltis spp. collected from the field were identified by using the keys (Stonedahl, 1991) as H. antonii (Figure 3), H. bradyi (Figure 5) and H. theivora (Figure 7)
Summary
Cashew (Anacardium occidentale L.), a native of Brazil, was introduced in to the West Coast of India by the Portuguese during the sixteenth century (Devasahayam and Nair, 1986). Several insect pests have been recorded on cashew in India (Sundararaju, 1993), prominent among which is the tea mosquito bug (TMB), Helopeltis spp. The adults and nymphs of TMB damage caused 30 to 50% yield loss (Abraham and Nair, 1981; Ambika and Abraham, 1984; Pillaiet et al, 1984). Three species of TMB, Helopeltis antonii Signoret, Helopeltis bradyi Waterhouse and Helopeltis theivora Waterhouse (Stonedahl, 1991 and Sundararaju, 1996) were recorded in India. H. antonii is the dominant species (Sundararaju and Bakthavatsalam, 1994). Despite their pest status, Helopeltis spp. attacking cashew has received relatively little research attention in India, and little is known of their species. Earlier H. bradyi was not known to occur in the Indian Region, except as established by De Silva (1957)
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