New threats of insect pests and disease in litchi (Litchi chinensis Sonn.) in India Vinod Kumar, Amrendra Kumar. Vishal Nath and Rajesh Kumar

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1 New threats of insect pests and disease in litchi (Litchi chinensis Sonn.) in India Vinod Kumar, Amrendra Kumar. Vishal Nath and Rajesh Kumar Rajesh Kumar National Research Centre for Litchi, Muzaffarpur, Bihar , INDIA rajeshkr_5@yahoo.com

2 Litchi (Litchi chinensis Sonn.) is one of the important evergreen subtropical fruit known for its fragrance, juicy and quality aril contributing significantly to the growers economy in Bihar, Uttarakhand and West Bengal province of India. Bihar produces 70% of total litchi production and occupies nearly 54% of the area under litchi plantation in the country. In this province litchi is mainly cultivated in almost throughout the region in concentrated and sporadic form.

3 MAJOR LITCHI GROWING AREAS IN BIHAR

4 Among many factors affecting production and productivity, insect pests and disease are one of the major constraint. Insect pests infesting litchi have been recorded as Leaf mite : (Acerya litchi Keifer), Leaf miner : (Conopomorpha cramerella), Fruit borers : (Conopomorpha cramerella, (Platypeplus aprobola Meyer) & (Dichocrosis sp.) Leaf webber/roller : (Platypepla aprobola Meyer), Litchi bug : (Tessarotoma javanica Thunb), Bark eating caterpillar : (Indarbela quadrinotata) & (I. tetraonis ) Shoot borer : (Chlumetia transversa) etc.

5 Borer complex of litchi are most important as they extensively damage the developing and matured fruits reducing the yields and marketability.

6 Fortunately, litchi plants as compared to many fruit bearing species are less affected by diseases in India. Among the diseases at pre-harvest, so far anthracnose (Colletotrichum gloeosprioides Penz.) was of economic importance, The post-harvest losses due to fruit rots caused by several pathogens : (Aspergillus, Cylindrocarpon, Botryodiplodia and Colletotrichum etc) was of concern.

7 In continuous monitoring of insect pests and diseases at NRCL, Muzaffarpur (Bihar) a few new threats of pests and diseases were observed. This paper reports such emerging threats in litchi growing areas necessitating continuous surveillance and attention of researchers

8 To assess the occurrence and extent of damage by new threats of insect-pests and diseases To study characteristics of insect-pest, and describe the symptoms of disease 8

9 Scouting and fixed plot surveys of litchi were conducted in litchi orchards Incidence of pests and diseases were recorded between July 2011 to June Ten trees in each block were randomly selected for sampling foliage damage by insect pests and foliar diseases. Infestation level of pests and severity of diseases were recorded based on the per cent leaf area (the length and diameter of the leaf) damaged during vegetative phase.

10 Insect morphology was studied with the help of a stereo binocular microscope. Standard field and laboratory techniques were used for etiological studies.

11 New threats of insect pests In Litchi 1. Red weevil (Apoderous blandus Faust.) 2. Semilooper (Achaea janata Linneaus) -? 3. Bagworm (Eumeta crameri Westwood) 11

12 1. RED WEEVIL (Apoderous blandus) 12

13 It was bright brownish red in colour, about 5-7 mm in length and having elongated snout. Red weevil causes severe leaf damage on young shoots. It was found feeding on young foliage. It was a solitary feeder but extensively damaged young foliage and shoots. The insect fed on leaves by pricking the surface of leaf. As a result of feeding, leaves dried up from the pricked parts giving blighted appearance to the twigs.

14 Young growing trees of less than five years age were devastated. Infestation of the weevil was observed throughout the year but was less during December and January due to extremely low temperature. Considering the extent of leaf damage it causes, it can be regarded as second only to fruit borer in economic importance.

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21 The head, prothorax and elytra are bright brownish red. The ventral side (abdomen) is pale brown, and parts of the mouth and claws are brownish red The head is elongated triangular, strongly constricted behind. In the sitting position, the neck and the front portion of the insect body remain elevated and facing upward. Eyes are rather wide, in dorsal view protruding from head contour. The antennae are distinctive, straight i.e. without a developed scape, and with a loose three segmented club, inserted in a prominent zone of the dorsal surface of rostrum

22 It has flat, almost parallel-sided elytra without any protuberances. Legs are long and femora are clavate. The forelegs emanating from prothorax are the largest in size. Based on the characteristics of the weevil it was identified as Apoderus blandus Faust. However, it differs from typical A. blandus in having brownish red colour of head, prothorax and antennae.

23 2. LITCHI SEMILOOPER Achaea janata L (?) 23

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30 The biology of semilooper was studied in laboratory by rearing them. There was lot of variation in the colour of larvae of different instar from black to dark brown with banded appearances. In the last instar the dimension of larvae was 2 mm wide and cm long. The size of the pupae was cm and the size of the adult was cm with wing fully spread.

31 It completes its life cycle in days out of which larval period is 10-12, pupal period is 2-3 days and adult 1-2 days. The adults however failed to mate and hence study of egg stage could not be done. The pest closely resembled to Achaea janata (castor semilooper). This seems to be a polyphagous pest which feeds on a variety of perennial plants. An effort for exact identification, however, was in progress.

32 Incidence and damage of semilooper in Bihar province of India

33 Observation on incidence and severity of the pest damage were taken in ten experimental blocks at NRCL Farm. Each block contained about 140 plants Plants having highly damaged canopies (>50% top foliage) varied from % while partially damaged (10-30% foliage) plants were %. The total incidence of semilooper in these blocks was 2.1 to 40.3%. Semilooper voraciously fed on young foliage and in a few days only bare rachis left on the top canopy

34 Percent incidence and severity of damage at NRCL Experimental Farm

35 3. Bagworm (Eumeta crameri) 35

36 Bagworm affected tree 36

37 Bagworm damage on litchi leaf 37

38 Field view of bagworms affected leaf 38

39 Bagworm when forcefully removed out of its case 39

40 New threat of disease LEAF AND TWIG BLIGHT (Colletotrichum gloeosporioides Penz.) (Gloeosporium sp.) 40

41 The symptoms appeared as death of leaves on new shoots and a foliar blight and tip dieback which was difficult to separate. The leaf blight appeared as tan spots on the leaves. The afflicted leaves look like they were scorched from the sun. The twig blight along with infestation of foliage feeding pest complex not only severely hampered the young plants growth but also reduced the potential fruit bearing flushes in grown-up orchards. The disease manifested itself from the beginning of August to the end of February.

42 Leaf and twig blight of litchi 42

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44 The incidence of the disease was 44.5% to 61.8% in August 2011 at NRCL farm, where as it was from 28.1% to 66.3% in farmers field in February 2012 The percent infected leaflets in a tree varied from 21.0 to 37.0 in two litchi blocks at NRCL farm, whereas it was 26.7 to 69.3 in farmers orchard The percent leaf area damaged i.e. PDI was in the range of 3.7 to 47.8

45 Incidence and severity of leaf and twig blight disease at NRCL research farm and farmers fields * Average of three replications

46 The result of the present study shows that red weevil, semilooper and bagworms are new threats. Besides, the twig blight is an emerging disease problem to litchi in Bihar province of India The occurrence of A. janata and E. crameri is being reported on litchi for the first time from India. The emerging insect pests and diseases may become a limiting factor to litchi cultivation and will have socioeconomic impact for litchi growing areas. 46

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