In response to the threat caused by the fall armyworm to African maize farmers, we conducted a series of field release studies with the egg parasitoid Telenomus remus in Ghana. Three releases of ≈15,000 individuals each were conducted in maize plots of 0.5 ha each in the major and minor rainy seasons of 2020, and compared to no-release control plots as well as to farmer-managed plots with chemical pest control. No egg mass parasitism was observed directly before the first field release. Egg mass parasitism reached 33% in the T. remus release plot in the major rainy season, while 72–100% of egg masses were parasitized in the minor rainy season, during which pest densities were much lower. However, no significant difference in egg mass parasitism was found among the T. remus release plots, the no-release control plots and the farmer-managed plots. Similarly, no significant decrease in larval numbers or plant damage was found in the T. remus release fields compared to the no-release plots, while lower leaf and tassel damage was observed in farmer-managed plots. Larval parasitism due to other parasitoids reached 18–42% in the major rainy season but was significantly lower in the minor rainy season, with no significant differences among treatments. We did not observe significant differences in cob damage or yield among the three treatments. However, the lack of any significant differences between the release and no-release plots, which may be attributed to parasitoid dispersal during the five weeks of observation, would require further studies to confirm. Interestingly, a single application of Emamectin benzoate did not significantly affect the parasitism rates of T. remus and, thus, merits further investigation in the context of developing IPM strategies against FAW.
14 November 2019 in International Journal of Tropical Insect Science
An ecological guild of Tephritidae fruit flies exploits cucurbit vegetable fruits, tremendously reducing their production worldwide. Knowledge of the composition of the guild of infesting flies in the field and information on their natural enemy species, might improve pest management strategies. Our aim was therefore to identify Tephritidae species infesting the watermelonCitrullus lanatus(Thunb.) Matsum. & Nakai in the Republic of Benin. Morphological and molecular identification of parasitoid species present in the field collections was also done. Infested watermelons were sampled in one of the main watermelon-production areas in the country. Adult tephritid flies emerging from watermelons were identified asDacus bivittatus(Bigot), D. ciliatusLoew, D. punctatifronsKarsch,D. vertebratusBezzi, Zeugodacus cucurbitae(Coquillet), andCeratitis cosyra(Walker). In this study period,D. vertebratuswas consistently the most abundant species emerging from watermelon.Dacus ciliatuswas the second most common species followed byZ. cucurbitae.The number of emerging fruit flies per kilogram of watermelon varied with collection date and month, and was most variable forD. vertebratus. Parasitism in the fruit flies was 1.6 ± 6.4% and occurred through one wasp species that was identified asPsyttalia phaeostigmaWilkinson (Hymenoptera: Braconidae). This solitary parasitoid is closely related to other members of theP. concolorspecies complex, some of which are used in biological control. Problems associated with identifyingPsyttaliaspecies and possibility of using this wasp as a biological control agent against tephritid flies were discussed.
17 April 2024 in Bulletin of Entomological Research
The eggplant fruit and shoot borer (EFSB) is a devastating pest of eggplants (Solanum aethiopicum L. and Solanum melongena L.) in Ghana, causing significant economic losses. Although initially thought to be the Leucinodes orbonalis Guenee species found in Asia, recent European and Mediterranean Plant Protection Organization reports suggest its absence in Africa. However, eight Leucinodes species have been recently described in Africa, including two new species, Leucinodes africensis sp. n. and Leucinodes laisalis Walker, which were intercepted in eggplant fruits exported from Ghana to the United Kingdom. Despite the reported absence of L. orbonalis in Africa, it remains on the pest list of Ghana as a species known to attack eggplants. To accurately determine the identity of the EFSB complex occurring on eggplant in Southern Ghana, molecular and morphological taxonomic tools were employed, and adult male populations were monitored in on-farm conditions. Our results revealed the presence of two EFSB species, L. africensis and L. laisalis, in the shoot and fruits of eggplants, with L. africensis being the dominant species and widely distributed in Southern Ghana. Notably, L. africensis males were attracted to the pheromone lure of L. orbonalis despite the two species being biologically distinct. This study provides crucial information on correctly identifying the EFSB species attacking eggplants in Southern Ghana and has significant implications for developing management interventions against these pests and their effects on international eggplant trade.