Life History, Aggregation and Dormancy of the Rubber Plantation Litter Beetle,Luprops tristis, from the Rubber Plantations of Moist South Western Ghats

Abstract

Life history, aggregation and dormancy of rubber plantation litter beetle Luprops tristis Fabricius, (Tenebrionidae: Coleoptera) is described from rubber plantation belts in the western slopes of Western Ghats from the south Indian state of Kerala. The life cycle lasted 12 months, including the 5 larval instars lasting 1 month, the 3 day pupal stage, and the adult stage that can last 11 months. The adult stage includes an inactive dormancy phase of 9 months in shelters and 1 month each of active pre-dormancy (feeding) and post-dormancy (feeding and reproduction) phases that occur in rubber plantation litter. Reproductive activities are confined to the post-dormancy phase. With the onset of summer rains, huge aggregations of adults invade residential buildings and enter into a state of dormancy for 9 months. Beetle aggregations were in the range of 0.5 million to 4.5 million individuals per residential building. Dormancy in L. tristis is best classified as oligopause, which is intermediate between quiescence and diapause. Adults and larvae feed preferentially on wilted rubber tree leaves. Age-specific variation in mortality during dormancy is distinct with higher survivability for adults that have a longer pre-dormancy period. Generations are non-overlapping.

Dormancy‐inducing factors of rubber litter beetle, Luprops tristis (Coleoptera: Tenebrionidae)

“…Subsequently, they congregate in dark, undisturbed areas such as attics and wall voids and remain dormant for 9 months during the wet monsoon period. They do not sting or bite, but when disturbed (such as picking them off the walls or when they are squashed or pressed against while sleeping), they release an irritating odoriferous phenolic secretion that burns the skin (Sabu et al, 2008;Sabu & Vinod, 2009a). Post-dormancy beetles return to the rubber plantation litter floor in time with the annual leaf shedding of rubber plants during the presummer period.…”

“…Teneral adults undergo intensive feeding till the onset of summer showers and annual migration to shelters. Although the life biology (Sabu et al, 2008), phenology (Sabu & Vinod, 2009a) and feeding preferences (Sabu & Vinod, 2009b) of L. tristis are well studied, nothing is known about the dormancy-inducing factors of L. tristis.…”

Host Plant and Leaf-Age Preference ofLuprops tristis(Coleoptera: Tenebrionidae: Lagriinae: Lupropini): A Home Invading Nuisance Pest in Rubber Plantation Belts

“…To ensure uniformity of age at the beginning of the experiment, teneral adults were collected based on their brownish white body color [1] from rubber plantation litter in the college hostel premises. Collected beetles were reared in clay vessels placed in an environmental chamber and fed with a mixture of diced tender and mature leaves of all eight leaf types for 10 days to reduce the possible effect of leaf quality variations on growth rate and feeding preference.…”

“…Seasonal mass invasion of a litter-dwelling detritivorous beetle, Luprops tristis (Fabricius, 1801) (Coleoptera: Tenebrionidae: Lagriinae: Lupropini), numbering 0.5-4 million per residential buildings prior to the onset of south west monsoon showers and subsequent aggregation in prolonged state of dormancy ( Figure 1) render them a very serious nuisance pest in rubber plantation tracts in the Western Ghats in southern India [1]. Litter stands of rubber tree [Hevea brasiliensis, (Willd.…”

“…Data generated is expected to contribute towards adoption of control strategies to prevent the possible spread of L. tristis to nonrubber plantation belts where plantations of potential host plants are prevalent. (Fabricius, 1801) is generally regarded as an inconspicuous litter-dwelling detritivore but for their exceptionally high abundance in the rubber plantation litter stands across the moist south Western Ghats [1]. They are regionally referred to as "Mupli vandu" in Central and South Kerala and "Ola prani," "Ola chathan," or "Otteruma" in North Kerala in South India.…”