Paulinia acuminata De Geer

Paulinia acuminate was found to be one of the promising natural enemies of Salvinia molesta (D.S. Mitchell) in South America. It was introduced in India for trials against Salvinia molesta.

The adult male and female mate within 24 hours after the final moulting. The pre-oviposition period lasts 4 to 7 days. During oviposition, the female inserts its abdomen between the leaves and deposits one or sometimes two oothecae per day. The shape and size of the oothecae vary depending on the number of eggs it contains, usually the number varies from 2 to 5.

The incubation period varies from 12 to 18 days. First instar larva is greenish in colour and moults into second instar in 7 to 13 (average 7.81) days. The second instar lasts for 4 to 7 days (average 6.3 days). The 3rd, 4th and 5th instar periods also last 4 to 7 days with an average of 5.81, 5.62 and 5.71 days respectively. After the fifth moult the males become adults whereas females become adults only after the 6th moult. The total larval period for the males and females last 32 and 37.5 days respectively. The adults live for 30-60 days.

Fresh and healthy plants are placed in 5 liters plastic basin with fresh water. Each such basin can accommodate about 100 plants. Thereafter 20 pairs of adults are released (after pre-oviposition period is over) for three days and basins are covered with ventilated lids. After exposure adults are collected back. Generally adults hide inside buds or in rhizomes. While collecting adults back, care should be taken that the plants are not damaged. Exposed plants can be transferred in 61 x 40 x 30 cm opaque plastic troughs filled with water or in plastic fishing pools or cemented tanks. Exposure with same set of adults can be repeated for 15 times. Each through which can accommodate about 400 plants can yield 100-150 adults

Alternatively, Salvinia are released at the rate of about 5 per square meter. Fresh adults can be collected for field releases after 45 days. Collections can be made by placing fresh Salvinia plants among the browning weed-mat, on which the insects congregate.