Journal of Agriculture and Rural Development in the Tropics and Subtropics Vol. 123 No. 2 (2022) 235–245 https://doi.org/10.17170/kobra-202212057193 ISSN: 2363-6033 (online); 1612-9830 (print) – website: www.jarts.info First report and population dynamics of the Tobacco Thrips, Thrips parvispinus (Karny) (Thysanoptera: Thripidae) on ridged gourd, Luffa acutangula (L.) Roxy in selected export fields in southern Ghana Ken Okwae Fening a,b,∗, Komlanvi Amouzou a, Walter Hevi c, Ethelyn Echep Forchibe a, Maxwell Kelvin Billah a,d, Francis Onono Wamonje e aARPPIS Sub-regional Centre for West Africa, University of Ghana, Accra, Ghana bSoil and Irrigation Research Centre (SIREC), University of Ghana, Accra, Ghana cCABI West Africa Centre, Accra, Ghana dDepartment of Animal Biology and Conservation Science, University of Ghana, Accra, Ghana eNational Institute of Agricultural Botany (NIAB), East Malling, United Kingdom Abstract Thrips attack several crops causing considerable economic damage. To prevent this damage, sticky traps can be used to monitor their population for the timely execution of management interventions. Ridged gourd or turia (Luffa acutangula (L.) Roxy) is an important Asian vegetable exported regularly to the European Union market from Ghana. However, this vegetable has been intercepted severally at the point of entry because of thrips infestation. The current study is aimed at identifying and monitoring thrips population on turia using blue and yellow sticky traps in six export vegetable production sites in Ghana for two consecutive seasons and three trapping periods. The results showed that Thrips parvispinus (Karny) (Thysanoptera: Thripidae) was the commonest and only species of thrips found attacking turia. The highest and lowest mean number of thrips were recorded from the blue and yellow sticky traps during the dry and the late part of the major rainy seasons, respectively. Thrips population build-up was observed to reach its peak at the flowering stage of the crop. This is the first report of T. parvispinus in Ghana. The implications of this finding on the export of turia to the EU market has been discussed. Keywords: DNA barcoding, export, intensification, seasonal pest fluctuations, sticky traps 1 Introduction Thrips belong to the order Thysanoptera and family Thrip- idae and are small, slender, soft-bodied insects with fringed wings just visible to the naked eye (Reynaud, 2010). They feed on a wide range of plants by perforating them and suck- ing up the contents of the plants’ cells (Reynaud, 2010). Many thrips species are pests of commercial crops. They feed on developing flowers, causing discolouration and physical damage resulting in reduced crop marketability (Nault, 1997). According to Mound & Teulon (1995), thrips damage includes direct feeding on leaves, flowers or fruits, transmission of viruses and contamination during or after feeding. Therefore, monitoring the population dynamics of ∗Corresponding author – kfening@ug.edu.gh thrips is important for the timely execution of control meas- ures. The data obtained could be useful in identifying areas of low and high pest prevalence (Fening et al., 2017; Fen- ing & Billah, 2019). Gillespie & Quiring (1987) reported that effective monitoring of thrips population is crucial for successful implementation of insect and vector control pro- grammes. The population of thrips increases when there are high temperatures and prolonged drought, whilst high rela- tive humidity and rainfall reduce thrips population (Hamdy & Salem, 1994). Traps are one of the most effective tools for monitoring and controlling insect pests in crop ecosystems. Traps that exploit the response of insects to colour are used in integrated pest management (IPM) programmes in diverse agricultural cropping systems (Gerling & Horowitz, 1984). Notably, blue colour sticky traps are much more attractive to Published online: 7 December 2022 – Received: 26 May 2022 – Accepted: 1 December 2022 © Author(s) 2022 – This work is distributed under the Creative Commons Attribution 4.0 License CC BY | https://creativecommons.org/licenses/by/4.0 236 K. O. Fening et al. / J. Agr. Rural Develop. Trop. Subtrop. 123 – 2 (2022) 235–245 thrips (Tian-Ye et al., 2004; Muvea et al., 2014; Maimom & Kusal, 2017). Luffa acutangula (L.) Roxy is generally known as ridged gourd or turia. Taxonomically, it belongs to the family Cu- curbitaceae, and it has varied names depending on the com- munity. Some examples include turia, angulate, sinkwa towel sponge, vegetable sponge, ridged gourd, Chinese okra, luffa, dish-cloth gourd, ribbed luffa, rilk gourd, sinqua melon, etc, (Manikandaselvi et al, 2016). Ridged gourd is a dark green, ridged vegetable having white pulp with white seeds embedded in spongy flesh. This vegetable, believed to have originated within the Arabic deserts, is consumed widely in Asian countries, and exported into the European market. All species of the ridged gourd are edible, although they must be consumed before they mature (Shaun DMello, 2022). Gourds are consumed in varied forms, i.e., soup (cu- cumber, gherkins, long melon), sweet (ash gourd, pointed gourd), pickles (gherkins) and desserts (melons) (Rathore et al., 2017). The European and Mediterranean Plant Protection Organ- ization (EPPO) listed Thrips palmi (Karny) (Thysanoptera: Thripidae) as an A1 pest recommended for regulation as a quarantine pest. A1 pests are absent from the EPPO re- gion and member countries regulate the entry of the pest by putting restrictions on trade (EPPO, 2017). From October 2015 to December 2017, the European Commission decided to prohibit the introduction of five (5) plant commodities; Capsicum (peppers), Lagenaria (bottle gourd), Luffa (ridged gourd), Momordica (bitter gourd) and Solanum (mainly egg- plant) from Ghana into the European Union (EU) market due to detection of harmful organisms (thrips, whiteflies, fruit flies and false codling moth) in vegetable shipments. As a result of the ban, the contribution of vegetable ex- ports to Ghana’s gross domestic product (GDP) decreased by USD 5 million (Yeray et al., 2016). Following the rein- statement of exports to the EU, growers and exporters of turia have adopted sustainable pest management strategies. These strategies include field monitoring of thrips species, a thorough understanding of their crop population dynamics, and sustainable management to prevent the high intercep- tions that contributed to the earlier ban. Two species of thrips of economic and quarantine im- portance that have recently spread around the world are the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) and the melon thrips, Thrips palmi (Capinera, 2000). These two thrips species pose a high quarantine risk with the potential to affect world trade and crop production (Mound & Collins, 2000). Other thrips species are important, such as the highly polyphagous tobacco thrips, Thrips parvispinus (Karny) (Thysanoptera: Thripidae)]. T. parvispinus is a major pest of Capsicum (Vos & Frinking, 1998) in Java and vegetable crops in Thailand (Bansiddhi & Poonchaisri, 1991). In Malaysia, it is a pest of papaya. The damage caused by its feeding on papaya is associated with secondary attacks by the saprophytic fungus Cladosporium oxysporum, causing bunchy and malformed tops of papaya (Lim, 1989). Exten- sive leaf damage attributed to T. parvispinus was observed on Gardenia plants in Greece (Mounds & Collins, 2000). Addi- tionally, T. parvispinus is also reported as a vector of tobacco streak ilarvirus in transmission studies (Klose et al., 1996). This pest was removed from the EPPO alert list in 2001 as doubts were expressed about the severity of damage in the EPPO region (EPPO, 2001b). However, T. parvispinus was intercepted on Solanum aethiopicum by the EU from Uganda in 2016 (EUROPHYT, 2016; EPPO, 2016). The objective of this study was to identify thrips species present on luffa and monitor their population dynamics using blue and yellow sticky traps in six export vegetable produc- tion sites in southern Ghana to establish the levels of in- festation. The baseline information obtained will be useful in ascertaining the effectiveness of pest management inter- ventions undertaken by farmers and whether producers are strictly adhering to the guidelines outlined in the roadmap for pest reduction in vegetables for export by Ghana’s Plant Protection Organisation (NPPO). 2 Materials and methods 2.1 Study sites The study was conducted from December 2017 to Au- gust 2018 to monitor thrips population in ridged gourd farms using yellow and blue sticky traps. During the study period, the dry season spanned from the first week of Decem- ber 2017 to the last week of February 2018, culminating in the onset of the major rainy season from March 2018 until the end of the season in July and part of the dry spell in August 2018. Therefore, we undertook three different trap- pings periods of approximately three months each. From 6th December 2017 to 21st February 2018 (dry season), 21st March to 23rd May 2018 (early part of the major rainy sea- son) and 4th June to 6th August (late part of the major sea- son into the early part of the dry spell in August). Six vegetable farms namely, AB Farms, AT Mahli Farms, My Farms, Dhillon Farms, Trosky Farms and Jeokopan Farms, were selected. The farms are in different localities in Greater Accra and Eastern regions of Ghana, coinciding with the semi-deciduous and Coastal Savanna agro-ecological zones of Ghana. AB Farms, My Farms, Trosky Farms, Dhilon Farms and Jeokopan Farms are located in the Nsawam area, K. O. Fening et al. / J. Agr. Rural Develop. Trop. Subtrop. 123 – 2 (2022) 235–245 237 a district in the Eastern Region of southern Ghana, a town situated on a main railway and highway to Kumasi. All these farms share the semi-deciduous forest agro ecological zone and the forest ochrosols soil type. AB Farms, My Farms and Trosky Farms are clustered around Nsawam town, while Dhillon Farms and Jeokopan Farms are located at Ade- iso and Kyekyewere, respectively, a bit away from Nsawam town. AT Mahli Farms is in the west of Accra near the Weija dam. This area is made up of coastal savanna thicket and grassland vegetation where the soils are well drained, friable, porous loam savanna ochrosols. 2.2 Land preparation, pest and crop management practices utilised by farmers An acre size plot planted with turia was adopted in each farm for monitoring. The approved roadmap or farm man- agement practices utilised by farmers involved a combin- ation of crop and pest management strategies. These in- cluded good land preparation, certified hybrid seeds, im- proved soil fertility by applying organic manure and/ or in- organic fertilisers, and supplementary irrigation. Addition- ally, pests and diseases management involving the adoption of good farm sanitation practices (timely weeding and re- moval of crop residues), use of less toxic or low persist- ence synthetic insecticides and biopesticides, and trapping of thrips using sticky traps with or without lures were used (Fening et al., 2017). Other agronomic practices for cultiv- ating ridged gourd, such as staking, were done. The farmers utilised a planting distance of 150 cm x 150 cm for turia, with two seeds per hole. 2.3 Setting up of sticky traps for monitoring thrips population Ridged gourd was grown in rows and staked as per the farmers’ protocol. The traps were placed in between rows to the height of the staked plants two weeks after planting. Eight sticky traps, i.e., four yellow and four blue, were set randomly at equidistant positions in each field. The popu- lation dynamics of adult thrips were monitored at weekly intervals by recording the number of trap catches. Sticky traps were collected from the field weekly and brought to the laboratory to count and record the number of thrips. Mon- itoring was done for a period of 10-12 weeks. In addition, flowers were randomly selected from each plot/location to collect thrips for identification. 2.4 Pesticide treatments utilised by farmers The farmers used a range of pesticides; synthetic in- secticides, Protocol® (Lambda cyhalothrin 15 g L−1 + Acet- amiprid 20 g L−1) @ 40 ml per 15 L of water, Cydim Su- per EC® (Dimethoate (400 g L−1) + Cypermethrin (36 g L−1) @ 35 ml per 15 L of water, Viper 46 EC® (Acetamiprid (16 g L−1) + Indoxacarb (30 g L−1)) @ 40 ml per 15 L of wa- ter. These were rotated biweekly until flowering stage of the crop. During flowering and fruiting stages, farmers applied either Eradicoat T GH® (Maltodextrin 282 g L−1) @ 150 ml per 15 L of water, Aqueous Neem Kernel Extract (ANKE) @ 50 g L−1 of water, neem oil (1 % Azadirachtin) @ 30 ml per 15 L of water, neem oil (0.3 % Azadirachtin) @ 60 ml per 15 L of water weekly to protect fruits against attack by thrips and others insect pests. 2.5 Molecular Identification of thrips Collected thrips specimens were preserved in 95 % (v/ v) ethanol and sent to CABI Plantwise Diagnostic and Advis- ory Service laboratory, UK for molecular analysis and iden- tification. Molecular assays were carried out on each sample using nucleic acid as a template. A proprietary formulation [microLYSIS®- PLUS (MLP), Microzone, UK] was subjec- ted to the rapid heating and cooling of a thermal cycler, to lyse cells and release deoxyribonucleic acid (DNA). Fol- lowing DNA extraction, Polymerase Chain Reaction (PCR) was employed to amplify copies of the DNA in vitro. The primers used in amplification were the universal primer pair HCO 2198 5’TAAACTTCAGGGTGCCAAAAAATCA-3’ and LCO 1490 5’-GGTCAACAAATCATAAAGATATTGG- 3’ for the cytochrome c oxidase subunit 1 (COI) – mitochon- drial gene (Former et al., 1994). The quality of the PCR product was assessed by agarose gel electrophoresis. PCR purification was performed to remove unutilised dNTPs, primers, polymerase and other PCR mixture compounds and obtain a highly purified DNA template for sequencing. Semi-automated Sanger sequencing was done using previ- ously described methods (Sanger et al., 1977; Smith et al., 1986). Following sequencing, identifications were under- taken by comparing the reverse compliment of the sequence obtained with those available from The Barcode of Life Data System (BOLD). Additionally, the sequence data was also compared to the database available from NCBI BLAST (Altschul et al., 1990). https://blast.ncbi.nlm.nih.gov/Blast. cgi?CMD=Web&PAGE_TYPE=BlastHome. 2.6 Phylogenetic analysis Relevant sequences for phylogenetic analyses were down- loaded from GenBank in FASTA format. Multiple sequence alignments were done using MUSCLE (Edgar, 2004) in Mo- lecular Evolutionary Genetics Analysis Version X. (MEGA X) (Tamura et al., 2013). The evolutionary history was in- ferred by using the Maximum Likelihood method based on 238 K. O. Fening et al. / J. Agr. Rural Develop. Trop. Subtrop. 123 – 2 (2022) 235–245 the Tamura-Nei model (Tamura and Nei, 1993). Pairwise sequence comparisons were made by aligning the sequences using MUSCLE in Species Demarcation Tool v 1.2 (SDT v. 1.2) (Muhire et al., 2014). 2.7 Data analysis The prevalence of thrips was estimated using the indices used for fruit flies, F /T /W (ISPM 30, 2008; Billah & Fen- ing, 2019; Fening & Billah, 2019). Where F= total num- ber of thrips captured, T= number of inspected traps and W= number of weeks traps were exposed in the field. A student’s t test of significance was used to compare catches from blue and yellow sticky traps (P< 0.05). 3 Results 3.1 Species of thrips identified on ridged gourd The tobacco thrips, Thrips parvispinus was the only spe- cies identified on the ridged gourd (Table 1). The samples or specimens 1, 2, 5 and 6 for identification showed 100 % similarity to each other, marching with T. parvispinus in the GenBank, Accession number KF 144125.1 from Indonesia (Chang & Ramasamy 2013), among others (Figs. 1 and 2). Sequences generated from this study have been deposited in GenBank and assigned accession numbers (see Table 1). Samples 3 and 4 did not produce significant sequences that could be analysed, thus were not used in the analysis. Table 1: Summary of results of samples of thrips sent to CABI Plantwise Diagnostic and Advisory Service Laboratory, UK. MMS Accession Sample Summary SN ref. number* details key results 1 E527001 OM761193 Thrips T. parvispinus 2 E527002 OM761194 Thrips T. parvispinus 5 E527005 OM761195 Thrips T. parvispinus 6 E527006 OM761196 Thrips T. parvispinus Note: The samples or specimens 1, 2, 5 and 6 for identification showed 100 % similarity to each other, marching with T. parvispinus in the GenBank, Accession number KF 144125.1 from Indonesia (Chang & Ramasamy 2013), among others. SN: sample number; *Sequences have been deposited to the GenBank with their accession numbers indicated. 3.2 Thrips abundance in turia flowers A total of 40 thrips were sampled in flowers during all cropping seasons in all farms and served as part of the spe- cimens used for the molecular identification. Therefore, the data used in the population dynamics study were based on sticky traps catches only, as the number of thrips sampled in Fig. 1: Molecular phylogenetic analysis by neighbour-joining method. The outgroup is the potato psyllid Bactericera cocker- elli. flowers were very few. Six thrips specimen, three each from the flowers and trap catches were sent for molecular identi- fication as they all appeared similar morphologically. 3.3 Prevalence of thrips using sticky traps The highest prevalence of thrips in the different farms across the seasons was recorded at Trosky Farms, followed by AB Farms with the blue sticky traps during the early part of the major rainy season (Table 2). However, during the late part of the major rainy season, the lowest prevalence of thrips per week was recorded from the yellow sticky traps at Trosky Farms and My Farms (Table 2). Generally, the dry season recorded high prevalence of thrips in all the farms during that period. Exceptionally, Jeokopan Farms recorded K. O. Fening et al. / J. Agr. Rural Develop. Trop. Subtrop. 123 – 2 (2022) 235–245 239 Fig. 2: Pairwise comparison for thrips species using MUSCLE in Species Demarcation Tool v 1.2 (SDT v. 1.2), showing a cluster of identified thrips species (E527001-E527006) with Thrips parvispinus low prevalence of thrips during the early and late parts of the major rainy seasons when the traps were in place. Moreover, thrips relative density or prevalence in all the farms at the end of the study (third trapping period) was much lower compared to the beginning (first trapping period) and was always higher with the blue sticky traps compared to the yel- low. Thus, the study revealed a significantly higher number of thrips catches in the blue sticky traps than the yellow traps during the dry season (t3;4 = 12.58; P = 0.001). 3.4 Population dynamics of thrips based on weekly trap catches 3.4.1 Yellow sticky traps The dry season showed Dhillon and My farms having a high population of thrips, whereas AB farms and AT Mahli farms had low thrips population (Fig. 3). Thrips population then decreased in all the farms in week 2 and 3. From week 4 to 7 (coinciding with the beginning of fruit formation), the thrips population rose and peaked on week 6 for almost all the farms. After that, thrips population build-up reduced and remained constant with slight fluctuation from week 7 to 12 in all the farms. Generally, during the late part of the major rainy season and early dry spell in August, AT Mahli and Dhilon farms had a higher population of thrips than the rest of the farms, Fig. 3: Mean number of catches of thrips by yellow sticky traps on weekly basis during the dry season at four exporters’ turia farms. while Trosky farms had the least number of thrips (Fig. 5). Probably effective pest control ensured pest population is suppressed where the incidence of thrips population was ini- tially high. Trosky farms had the highest number of catches during the dry season and the least during the major rainy season, where thrips population remained zero after the first week. In the last three weeks of monitoring thrips population build up, the number of catches was zero on all farms. The late part of the major rainy season was also marked by a low 240 K. O. Fening et al. / J. Agr. Rural Develop. Trop. Subtrop. 123 – 2 (2022) 235–245 Table 2: Comparison of relative density of thrips based on weekly trap catches. Relative density (F/T/W)* Season Trap colour AB Farms AT Mahli Farms Dhilon Farms My Farms Trosky Farms Jeokopan Farms Dry season Yellow 1.98 1.60 2.08 2.96 – – Blue 6.63 7.75 6.81 7.35 – – Early part of the major rainy season Yellow 1.75 1.38 0.48 0.80 4.14 0.16 Blue 7.81 6.60 0.83 4.33 21.48 0.48 Late part of the major rainy season Yellow 0.85 1.37 1.06 0.11 0.10 0.30 Blue 0.55 0.20 0.57 0.14 0.27 0.12 *F= total number of thrips captured, T= number of inspected traps and W= number of weeks traps were exposed in the field; –= Farm did not cultivate turia. Fig. 4: Mean number of catches of thrips by yellow sticky traps on weekly basis during the early part of the major rainy season at six exporters’ turia farms. number of catches compared to the early part of the major rainy season and the dry season. Fig. 5: Mean number of catches of thrips by yellow sticky traps on weekly basis during the late part of the major rainy season at six turia exporters’ farms. 3.4.2 Blue sticky traps During the cropping seasons, thrips population as depic- ted in catches from the blue sticky traps exhibited different peak periods. Unlike with the yellow sticky trap, the ini- tial number of catches in all farms was lower, but between weeks 5 to 7, all the farms recorded their peak, followed by a general decline in the number of thrips. Week 1 to 4 corres- ponded to the vegetative period of turia plant. From week 5, flowering and fruiting started, and the thrips were probably more attracted to the plant, which resulted in the high num- ber of catches during this period. As with the yellow sticky traps during the dry season, the highest number of thrips was recorded in My farms during week five (Fig. 6). Fig. 6: Mean number of thrips catches by blue sticky traps on weekly basis during the dry season at four exporters’ turia farms Trosky farms recorded the highest number of catches, and My farms had the lowest, just like when the yellow sticky traps were used during the early part of the major rainy sea- son (Fig. 7). The trend of thrips population build-up in all farms with the yellow or the blue sticky traps was very simi- lar with the only difference was that the blue sticky traps had a higher number of catches than the yellow traps. The num- ber of catches on the blue sticky trap during the dry season was the highest recorded in the study. Fig. 7: Mean number of thrips caught by blue sticky traps on weekly basis during the early part of the major rainy season at six exporters’ turia farms. K. O. Fening et al. / J. Agr. Rural Develop. Trop. Subtrop. 123 – 2 (2022) 235–245 241 Fig. 8: Mean number of thrips caught by blue sticky traps on weekly basis during late part of the major rainy season at six exporters’ turia farms. 4 Discussion The study aimed to correctly identify and monitor the population dynamics of thrips species common on turia in Ghana. This was necessary as turia and other vegetables ex- ported to the EU had been intercepted for the presence of thrips, mostly T. palmi, which is known to be of quarant- ine importance. This had led to export bans which were subsequently lifted. In the current study, the thrips species identified was the tobacco thrips, T. parvispinus. It is con- sidered a polyphagous species and is reported as a major pest of Capsicum in Java and vegetable crops in Thailand (EPPO, 2001a). Thrips parvispinus was removed from the EPPO pest alert list in 2001 as doubts were expressed about the severity of damage in the EPPO region (EPPO, 2001b). However, T. parvispinus was intercepted on Solanum ae- thiopicum by the EU from Uganda in 2016 (EUROPHYT, 2016; EPPO, 2016). Although, T. parvispinus is not in the current EPPO Pest Alert List (EPPO, 2020), EPPO A1, or A2 Quarantine Pest Lists (EPPO, 2019), it still has implica- tions on international trade as it was intercepted in 2016. In certain instances, the EU intercepts a commodity by identi- fying only to the genus level, e.g., Thrips sp. or the order and family only, e.g., order Thysanoptera, family Thripidae. For instance, turia or luffa from Ghana was intercepted recently for the presence of Thripidae as indicated in the Europhyt notifications (EUROPHYT, 2020). Thus, it can be inferred that the presence of thrips in an exported commodity poses a big threat to trade irrespective of the species identity. Amin (1980) stated that ridged gourd, bottle gourd, bit- ter gourd, cucumber, pumpkin and soybean can be colon- ised by large populations of thrips. This confirmed the re- sults in this study where the thrips population reached as high as 21 catches/ trap per week at Trosky Farms. As ex- pected, the results from the current study concur with the fact that thrips prefer the blue sticky traps than the yellow traps. In a similar study, thrips were attracted to blue col- oured sticky traps over the crop growth period than white, yellow and fluorescent green sticky traps (Soniya-Devi et al., 2017). Winged adult thrips are usually monitored using col- oured sticky traps, whereby the ability of a colour to attract thrips varies for different thrips species, but blue or white traps are known to be effective for trapping T. palmi, though yellow traps will also work (ISPM 27 Annex 1, 2010; 2016). Within the same period of data collection, and with the same colour of sticky trap, there is a difference in the peak period throughout the farms. Therefore, the differences in the peak activity period of the pest observed in the present studies could be attributed to the variations in the flower- ing and fruiting period, and prevailing weather at different sites since they were planted at different times by the farm- ers for export. The findings of Pickett et al. (1988) are in line with the current study, as they found that thrips population build up reach their peak during the flower developmental stage of the cotton. Similarly, Gebretsadkan (2017) reported that thrips abundance fluctuated based on plant growth stage, months, locations (altitudes), and weather factors, mainly temperature and rainfall. Generally, the late part of the major rainy season of 2018 recorded the least number of thrips partly since it coincided with the peak period of the rainfall (June-July), which may have dislodged the thrips from the crop. But that period was also the third trapping occasion, so the continuous trapping involving many traps (mass trapping) may have also led to population suppression of thrips. A very low number of thrips were found in the flowers of turia sampled from the fields. Some of the exporter farms seem to have fewer thrips catches in the traps, which sug- gests that the management interventions for thrips as pro- posed in the roadmap for pest reduction were better adhered to by some farmers than others (Fening et al., 2017). The farmers are therefore encouraged to pay more attention to implementing the control measures for thrips strictly, es- pecially during the dry and early part of the major rainy seasons, including the use of blue sticky traps for monit- oring and mass trapping (by increasing the trap density) to suppress the thrips population. Post-harvest treatment, in- volving the removal of dried floral parts attached to the turia, sorting and washing of harvested turia gently in a diluted soapy detergent solution or mineral oil are likely to dislodge most of the thrips hidden in the ridges and the dried floral parts (KO Fening Per. Comm.). Interestingly, T. parvispinus has concurrently been identi- fied as the commonest and only species of thrips found on African eggplant, S. aethiopicum and okra, Abelmoschus es- culentus, sampled during the same period in Ghana from the University of Ghana Research Farms, Kpong (K.O. Fening, Per. Comm.). Thus, it is recommended that a detailed study 242 K. O. Fening et al. / J. Agr. Rural Develop. Trop. Subtrop. 123 – 2 (2022) 235–245 of T. parvispinus distribution on different host plants (crops and wild plants) in Ghana should be undertaken to inform management decisions. The current finding is the first report of T. parvispinus in Ghana. Homology search using BLAST search option for the samples or specimens of thrips collected from turia in Ghana resulted in 100 % similarity to T. parvispinus sequences from Indonesia with the Accession number KF 144125.1 in the GenBank (Chang & Ramasamy, 2013). The potato psyl- lid, Bactericera cockerelli was used as the outgroup in the molecular phylogenetic analysis by Maximum Likelihood method. The T. parvispinus samples from Ghana (with ac- cession numbers OM761193, OM761194 and OM761196) branched with some accessions from Indonesia with over 99 % similarity. The molecular evidence verify that the spe- cimens of thrips collected from turia in Ghana represents T. parvispinus. Pairwise comparison for thrips species using MUSCLE in Species Demarcation Tool v 1.2 also revealed a similar trend of 100 % pairwise identity between T. par- vispinus collected from turia in Ghana and those from In- donesia. 5 Conclusion The population of thrips are very difficult to trace in the field due to their cryptic nature. The use of yellow and espe- cially blue sticky traps in ridged gourd production could be a useful tool to monitor the build-up of thrips population in the field and help farmers to protect their crops against thrips infestation early enough by timely execution of management interventions to avert significant damage symptoms on their crop. The results from this study and earlier studies have confirmed the distribution and population of thrips under a sustainable pest management programme is always fluctuat- ing according to different factors such as seasonality, agro- ecology, land use history and management interventions em- ployed, among other reasons (Amin, 1980; Fening et al., 2017; Soniya-Devi et al., 2017). The population of thrips decreased during the late part of the major rainy season (June and July which mostly receives more rainfall) as compared to the dry and early part of the major seasons (December to May, which receives less rain- fall). The use of sticky traps in pest monitoring should be an integral part of tailor-made IPM programme, where de- tection and monitoring of thrips population becomes an in- tegral part for decision making before pesticide applications and other control measures are employed in the field. Ac- cording to the CABI Crop Protection Compendium and the European and Mediterranean Plant Protection Organisation, T. parvispinus has not previously been recorded in Ghana and is not of quarantine importance, unlike T. palmi which is an A1 pest species that have been recorded as the cause of many interceptions of commodities from Ghana to the EU market. Therefore, this study offers a baseline for further studies to ascertain if other Thrips spp., especially T. palmi, is present in Ghana, as it has been intercepted severally in ex- ported vegetables (including turia) from Ghana into the EU market. Authors’ contribution statement All authors contributed to the study conception and design. Material preparation, data collection and analysis were per- formed by KA and EEF under the supervision of KOF, FOW and MKB. The first draft of the manuscript was written by KA and all authors commented on previous versions of the manuscript. Funding for the study was sought by WH. All authors read and approved the final manuscript. Acknowledgements This study is part of KA Master of Philosophy thesis in En- tomology at the African Regional Postgraduate Programme in Insect Science (ARPPIS), University of Ghana with fin- ancial support from the German Academic Exchange Ser- vice (DAAD). The authors are also grateful to the Centre for Agriculture and Bioscience International (CABI) West Africa for the financial and logistical support during the data collection in the field. We are also appreciative of the sup- port from the vegetable exporters (Joekopan Enterprise, My Farms, AT Mahli Farms, AB Farms, Trosky Farms and Dhi- lon Farms) who are members of the Ghana Association of Vegetable Exporters (GAVEX), for offering their farms for this study. Conflict of interest The authors declare that they have no conflict of interest. References Altschul, S. F., Gish, W., Miller, W., Myers, E. W., & Lip- man, D. J. (1990). Basic local alignment search tool. 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