Iranian Journal of Plant Protection Science

Iranian Journal of Plant Protection Science

Interaction of pollinator fig wasp (Blastophaga psenes) and caprifig syconium nematode (Schistonchus caprifici) in caprifig genotypes of Fars province

Document Type : Research Paper

Authors
Hadi Karimipour Fard 1
Hamid Zare 2
Masoud Latifian 3
Nazanin Doryanizadeh 4
1 Plant Protection Research Department,, Kohgiluyeh and Boyer-Ahmad Agricultural and Natural Resources Research and Education Center, AREEO, Yasuj, Iran
2 Horticultural Science Research Institute,, AREEO, Karaj, Iran
3 Temperate Fruits Research Center, Horticultural Sciences Research Institute, AREEO, Karaj, Iran
4 Plant Protection Research Department, Kohgiluyeh and Boyer-Ahmad Agricultural and Natural Resources Research and Education Center, AREEO, Yasuj, Iran
10.22059/ijpps.2025.383001.1007068
Abstract
Populations of the caprifig syconium nematode (Schistonchus caprifici) invade the flowers of fig trees. Fig wasp Blastophaga psenes (L.) also plays a major role in the caprification of edible figs. To investigate the interaction between pollinator fig wasp and caprifig syconium nematode in caprifig genotypes of Fars province, a total of 175 profichi caprifig syconium samples (early, mid-early, and late-early fruits) of 43 genotypes of caprifig from Estahban, Ij, Khafr, Sarvestan, Kavar and Shiraz counties in Fars province were collected during the spring of 2022 to 2023. The samples were assessed based on regions and genotypes, separately. Disinfected profichi syconia surfaces were cut into pieces with a scalpel. Extraction, identification, and population density determination were done according to the routine procedure in nematology laboratories, and the population of nematodes in a certain volume of extracted suspension was further determined using a counting slide. The nematodes species, S. caprifici, was identified by its morphometric and morphological characteristics. The number of fig wasps in each syconium of the caprifig genotypes was also counted under a stereo microscope. Relation indices between the pollinator wasp and caprifig syconium nematode populations were calculated. Factor analysis was conducted based on the set of observable indices to identify unobservable combined factors affecting the correlation of these two species. Cluster analysis was employed to categorize the best genotypes based on the correlation between wasp and nematode populations. The genotypes Nok-Ghermezi, Haj Mohammad Ali, and Shah Anjiri Dane Sefid exhibited the lowest correlation rank between the wasp population and S. caprifici which indicates the least effect on the pollination efficiency of these three genotypes. The level of infestation index expected relative infestation, average population density, relative density, Okiai degree of overlap, and the Jaccard index of wasps and nematodes were 27, 50.17, 248.50, 18.17, 0.74, and 0.26, respectively. In any Fig genotype, where the overlap between the two species is higher, pollination efficiency decreases because the nematode uses the wasp as a phoretic and somewhat acts as a parasite on the pollinating wasp. Caprifig genotypes with a high number of B. psenes wasps and without or with a low population of S. caprifici can serve as a useful index for identifying fig genotypes with high potential for caprification. These genotypes could be considered in fig production or future breeding programs.
Keywords
Phoresy
Carrier
Population Changes
Fig Pollinator Wasp
Caprifig Nematode

Extended Abstract

Introduction

Populations of the caprifig syconium nematode (Schistonchus caprifici) invade the flowers of fig trees. Fig wasp Blastophaga psenes (L.) also plays a major role in the caprification of edible figs. Most fig trees (Ficus spp.) rely on an obligate mutualistic relationship with fig wasps (Hymenoptera: Agaonidae) for pollination and fruit production. The necessity of pollination varies according to the fig type. There are four fig types: caprifig, Smyrna, San Pedro, and Common fig. Smyrna-type figs develop only when fertile seeds are present. San Pedro-type first-crop figs develop without flower pollination, but the second-crop, which develops in the leaf axils, requires pollination. Common figs do not require pollination for either crop, and the seeds in the mature fruit are usually hollow. Various Blastophaga species of pollinator wasps play a crucial role in fig pollination. In addition to fig wasp pollinators, other organisms inhabit the fig’s inflorescences including several species of nematodes, such as caprifig syconium nematode (S. caprifici). In certain caprifig-growing areas of Fars province, some caprifig trees have encountered damage caused by S. caprifici which invades the flowers of fig trees, reducing the food quality and pollination efficiency. Considering the significant role of fig wasps in fig pollination and the damaging effects of fig nematodes on fig flowers, this study aimed to evaluate the population fluctuations of nematodes across different genotypes of caprifigs; in addition to investigate the mutual effects of fig wasp and caprifig syconium nematode populations in 43 different caprifig genotypes in Fars province.

 

Materials and Methods

In this study, the population of S. caprifici nematode and B. psenes wasp in various caprifig genotypes in Fars province (Iran) were examined. A total of 175 profichi caprifig syconium samples (categorized as early, mid-early, and late-early fruits) from 43 caprifig genotypes across the counties of Estahban, Ij, Khafr, Sarvestan, Kavar, and Shiraz in Fars province were collected during the spring of 2022 to 2023. First, the surface of the syconia was disinfected and the fruits were then cut into pieces with a scalpel. Extraction, identification, and population density determination were done according to the routine procedure in nematology laboratories. The nematode species was identified through morphometric and morphological characteristics. The number of fig wasps in each syconium of the caprifig genotypes was also counted under a stereo microscope. Relation indices between pollinator wasp and caprifig syconium nematode populations were analyzed. Factor analysis was performed based on the set of observable indices to identify unobservable combined factors affecting the correlation between these two species. Cluster analysis was used to categorize the best genotypes based on the correlation between the pollinating of wasps and nematodes.

 

Results and Discussion

 The species of all extracted nematodes was identified as S. caprifici. Data analysis showed that among the 43 caprifig genotypes, the Nok-Ghermezi, Haj Mohammad Ali, and Shah Anjiri Dane Sefid caprifig genotypes had the lowest correlation rank between the wasp population and the nematode population. Consequently, the relationship between nematodes and pollinating wasps had the least impact on pollination efficiency in these three genotypes. The level of infestation index, expected relative infestation, average population density, relative density, Okiai degree of overlap, and the Jaccard index of wasps and nematodes were calculated as 27, 50.17, 248.50, 18.17, 0.74, and 0.26, respectively. In any Fig genotype, where the overlap between the two species was higher, pollination efficiency decreases because the nematode uses the wasp as a phoretic and somewhat acts as a parasite on the pollinating wasp. Based on the results, it is likely that the relationship between the S. caprifici and the fig pollinator (B. psenes) in Fars province is a phoretic type, though this phoretic relationship imposes some cost on the wasp, affecting its lifespan.

 

Conclusion

The caprifig genotypes with a high number of B. psenes wasps and without or with a low population of S. caprifici could serve as a useful index for identifying fig genotypes with a high potential for caprification. These genotypes could be considered in fig production or breeding programs. Selecting and cultivating these genotypes in Fars province where the interaction of fig wasp and caprifig syconium nematode causes fig fruit fall, could improve pollination efficiency.

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Iranian Journal of Plant Protection Science
Volume 55, Issue 1
December 2024
Pages 99-120

  • Receive Date 07 October 2024
  • Revise Date 30 November 2024
  • Accept Date 21 January 2025