Six ecotypes of Trichogramma chilonis collected from Gudimangalam, Palladam, Udumalpet, Pongalur, Chingleput and Mettupalayam, were compared with the laboratory strain of the same species (Coimbatore). All the ecotypes were significantly superior to the laboratory strain in parasitizing the eggs of Corcyra cephalonica, Heliothis armigera and Spodoptera litura and showed a distinct preference for H. armigera eggs. The Palladam ecotype was able to withstand starvation to a maximum extent of 6.86 days.
The objective of this study is to elucidate the role of H 2 O 2 in wheat male sterility induced by SQ-1, a new kind of chemical hybridizing agent. We investigated the effects of SQ-1 ? DMTU and SQ-1 on the content of H 2 O 2 , the transcript levels and activities of SOD, POD, CAT, and APX, and the relative male sterility rate and seed setting rate, and starch-KI staining of pollen grain. The results showed that SQ-1 increased production of H 2 O 2 , the activity of APX and the transcript levels of POD and APX, and decreased the activities of SOD, POD, and CAT and the transcript levels of SOD and CAT, compared with control. SQ-1 ? DMTU could decrease the production of H 2 O 2 and the transcript levels of POD and APX and increase the activities of SOD, POD, and CAT, compared with SQ-1 alone. However, DMTU could only partly reversed the relative male sterility rate and seed setting rate induced by SQ-1. SQ-1 decreased the number of pollen grains dyed black, compared with control. Treatment with SQ-1 ? DMTU increased the number of pollen grains dyed black, compared with SQ-1 alone. Our results indicated that the overproduction of H 2 O 2 was one of reasons for the male sterility induced by SQ-1.
Comparative biology of Aproacrema modicella (Deventer) was studied on the two principal hosts viz., soybean and groundnut to select the better host for mass culturing of this insect under controlled conditions for laboratory studies. It was concluded that soybean is better suited for mass culturing and it is evidenced by the fact, that more number of eggs, high hatching per cent, shorter larval and pupal periods with low larval mortality. higher pupal weight and high per cent adult emergence with more of females were noticed when reared on soybean.
A laboratory experiment was conducted to study the effect of water extracts of neem seed and neem cake (Azadirachta indica A. Juss), pungam seed (Pongamia glabra Vent), pinnai seed (Calophyllum inophyllum Linn.) and illupai seed (Basia latifolia) Boxb. at 1 and 2 per cent concentrations on the feeding activity and mortality of grape flea beetle, Scelodonta strigicollis L. Two per cent neem seed extract was found to be the best in deterring the feeding activity which recorded the lowest area of feeding (16.7 mm²) followed by 2 per cent pungam seed extract (20.3 mm²). The highest mortality (67.2%) was recorded in pungam seed extract 2 per cent followed by neem seed extract 2 per cent (58.8%).
Chilli mite, Polyphagotarsonemus latus (Banks) causes severe damange to chilli crop at flowering and fruiting stages. Use of chemical insecticides induces resurgence of this mite in most cases, besides residue problems in green chillies. Atternps made to find out the natural enemies of this mite revealed the potential feeding nature of a predatory phytosciid mite, Amblyseius ovalis (Evans). The predatory potential of A.ovalis worked out in the laboratory indicated that the adult predators were the most efficient in devouring the chilli mite at an average of 5.76, 4.64, 3.20, 3.12 and 2.12 eggs. first instar, second instar nymphs, pupae and adults respectively. The efficiency was gradually reduced in deutonymph and protonymph of the predator and the larva was the least effective in predatory potential against chilli mite.
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