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POLLINATOR DIVERSITY AND ABUNDANCE IN CERTAIN OILSEED CROPS

KrishiKosh

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Title POLLINATOR DIVERSITY AND ABUNDANCE IN CERTAIN OILSEED CROPS
 
Creator NAVATHA, L
 
Contributor SREEDEVI, K
 
Subject biological phenomena, developmental stages, crops, niger, mustard, sowing, linseed, oilseeds, planting, honey
 
Description The present studies on “Pollinator diversity and abundance in certain oilseed crops” were carried out at S.V. Agricultural College, Tirupati during 2011 and 2012.
Pollinator diversity, species relative abundance, foraging activity, foraging behaviour and its correlation with floral morphometrics and weather parameters in niger, mustard, safflower and linseed were studied.
A total of 42 insect species viz., 14 hymenopterans, 12 lepidopterans, six coleopterans, five hemipterans, two dipterans and Dictyoptera, Orthoptera, and Odonata with one species each were observed to visit niger flowers. The relative abundance of Hymenoptera and Lepidoptera together constituted 94.72 per cent of the total insect visitor population. Among these insect visitors, A. florea, E. core, H. misippus, T. limniace and Halictus sp. were the most frequent visitors.
The pollinator diversity in mustard was moderate with 27 insect species from 15 families of six orders viz., nine hymenopterans, seven lepidopterans, five coleopterans, three hemipterans, two dipterans and one orthopteran. Among all insect visitors Hymenoptera order constituted major chunk of pollinators (88.55%). Among these insect visitors Trigona sp., Halictus sp., Ceratina sp. and Muscid fly were the most frequent visitors.
In safflower, 20 insect species from eleven families of six orders viz., 10 hymenopterans, six lepidopterans, and Diptera, Coleoptera, Odonata and Orthoptera included only one species of each were recorded. The floral visitors in Hymenoptera order were the dominant species which constituted
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95.08 per cent. Among all insect visitors Trigona sp., Camponotus compressus and Halictus sp. were the most frequent visitors on safflower heads.
A total of 18 insect visitors viz., nine lepidopterans, three hymenopterans, three hemipterans, and one species from Diptera, Coleoptera and Orthoptera were recorded in linseed. The relative abundance of Diptera alone constituted 32.00 per cent of the total population of the insect visitors followed by Hymenoptera (31.36 %), Lepidoptera (21.98%). Muscid fly and Halictus were the predominant species in linseed.
The mean foraging activity of major pollinators in niger was high during 11.00 h and 12.00 h. and it was highest for A. florea (6.08 bees/m2/5 minutes) followed by E. core ( 2.02 butterflies /m2/5 minutes), H. misippus (1.61 butterflies /m2/5 minutes). T. limniace (1.24 butterflies /m2/5 minutes) and Halictus sp. (1.22 bees/m2/5 minutes. In case of mustard the peak foraging activity was observed during 0.900 h and 10.00 h. and maximum foraging activity was recorded for Trigona (6.05 bees/ten racemes/5 minutes), followed by Halictus (1.89 bees/ ten racemes/5 minutes), Ceratina (1.23 bees/ ten racemes/5 minutes) and Muscid fly (0.43 flies / ten racemes/ 5 minutes). In safflower the peak foraging activity was recorded at 10.00 h and it was higher for Trigona (1.63 bees / m2 / 5 minutes), followed by C. compressus (1.33 ants/m2/ 5 minutes) and Halictus sp. (0.56 bees / m2 / 5 minutes). In linseed the peak foraging activity was observed at 08.00 h and 09.00 h and Muscid fly showed higher activity with 0.40 flies / m2 / 5 minutes followed by Halictus sp. with 0.31 bees /m2/5 minutes.
In niger, the higher foraging rate was exhibited by E. core followed by A. florea. The mean time spent on niger flower was least in case of A. florea. The foraging rate of Ceratina was higher followed by Trigona in mustard flowers and Trigona spent least time on mustard flower. In safflower the maximum number of heads were visited by Halictus sp., followed by Trigona sp. and Halictus sp. spent least time on safflower heads. The foraging rate of Halictus was higher in linseed and it spent less time on each flower of linseed.
The seed set was high in open pollination (71.77 % to 83.5 %) in all four oilseed crops and and there was less seed set in closed pollination where pollinators were excluded. The per cent increased seed set was more in niger ((61.7%) followed by mustard (34.5%), linseed (19.8%) and safflower (19.0%).
The activity of E. core showed significant positive association with length of corolla tube and negative association with plant height , whereas, Halictus sp. showed negative correlation with length of ovary in niger. The Trigona activity showed significant negative association with stigma length and plant height in mustard and safflower, respectively. Whereas, in linseed muscid fly showed significant negative association with length of anther. The foraging activity of A. florea, E. core and T. limniace showed significant positive association with maximum temperature and negative association with relative humidity and rainfall. Apis florea and Ceratina sp. showed significant negative association with minimum temperature. Trigona sp. and Halictus sp. showed significant negative association with relative humidity and rainfall. Muscid fly showed negative correlation with minimum temperature, relative humidity and rainfall.
It is concluded that hymenopterans were the dominant species among all the insect visitors in oilseed crops followed by lepidopterans. This study reveals that the insect pollinators play a major role in seed set and production of oilseeds. Hence, the conservation of the same is necessary in lines of biodiversity and sustainability.
 
Date 2016-06-16T15:31:26Z
2016-06-16T15:31:26Z
2012
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/67489
 
Language en
 
Relation D9348;
 
Format application/pdf
 
Publisher ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY