The Science of Entomology 

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Insect Science - Research

Abstract

T. Grovéa, M.S. De Beer and P.H. Joubert

The most important mango production areas in South Africa are located in Mpumalanga and Limpopo provinces. Three fruit fly species of economic importance, namely the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), the Natal fruit fly, Ceratitis rosa Karsch and the Marula fruit fly, Ceratitis cosyra (Walker), are known to attack mangoes and other subtropical crops in South Africa. Current control strategies are based on population monitoring and preventative control by applying toxic bait and doing regular orchard sanitation. Fruit flies were monitored in mango orchards at Hoedspruit (Limpopo Province) and Nelspruit (Mpumalanga Province) with a variety of traps and lures in order to determine the efficacy of trapping and abundance of species. Fruit were also inspected for the presence of eggs and larvae throughout the fruiting period, to determine when fruit fly infestation commenced. Sensus® traps with Capilure or Questlure, McPhail-type traps with Biolure® and Three component lure and yellow Delta traps with enriched ginger oil and enriched ginger oil blend were used. Delta traps with enriched ginger oil blend attracted the highest number of C. cosyra, while McPhail-type traps with Biolure and Three component lure attracted the highest number of C. rosa. Ceratitis rosa and C. cosyra were the abundant species at both localities, while numbers of C. capitata were very low. Fruit were not infested during the early fruiting period but were markedly more prone to attack closer to harvest. Fruit that ripened on the tree and that were picked for the local market, were more prone to attack than mature but green fruit picked for export.

Abstract

A. Manrakhan, J.-H. Daneel, M. Virgilio, M. De Meyer

Enriched ginger oil (EGO) is a new male attractant for Ceratitis (Diptera: Tephritidae) species. The relative sensitivity of three Ceratitis pest species, C. capitata, C. rosa and C. cosyra, and their distance-dependent responses to EGO were determined using mark-release-recapture trials in three commercial fruit orchards
in Mpumalanga, South Africa. Mature males of the three species (9e14 days after adult emergence) marked with fluorescent pigments were released at four distances: 25m, 50m, 100m and 200m from a centrally located white Delta trap baited with EGO. Different pigment colours were used for the different distances. Two releases were conducted in each orchard with an interval of one month between the releases. Traps were checked the following day, one week, two weeks and a month after release. Specimens captured were examined under a UV light to determine pigment colour on males of C. capitata, C. rosa and C. cosyra. There were no significant differences in recapture rates of the three Ceratitis species in the EGO baited trap. Most of the recaptures of all species occurred within a 50m distance from the EGO baited trap. Most of the recaptures also occurred on the day following release. Based on the recapture rates obtained in this study, the probability of a trapping grid of 5 EGO baited traps per 2.59 km2 capturing one or more flies of C. capitata, C. rosa and C. cosyra for a population consisting of 1000 males for each species was estimated at over 95%. The EGO based trapping system would be an effective detection method for C. capitata, C. rosa and C. cosyra in pest free areas and in areas of low pest prevalence.

Abstract

A. Manrakhan, J-H. Daneel , R. Beck, C.D. Theron, C.W.Weldon, S.D. Moore, & V. Hattingh

Markets importing citrus fruit including lemons, Citrus limon (L.) Burman f., from South Africa require that the fruit be free of fruit fly pests (Diptera: Tephritidae). Historically there has been no fruit fly infestation recorded on lemons destined for export from South Africa. In this study, we assessed the host status of commercial export grade Eureka lemons, Citruslimon (L.) Burmanf. cv. Eureka, for four fruit fly pest species of economic importance in South
Africa: Ceratitis capitata (Wiedemann), Ceratitis rosa Karsch, Ceratitis quilicii De Meyer, Mwatawala & Virgilio, and Bactrocera dorsalis (Hendel). Trapping was conducted in 10 Eureka lemon orchards in two major citrus production regions over two citrus seasons between 2016 and 2017 to determine the level of fruit fly abundance in the sampled orchards. Lemons were collected at harvest over the two seasons in the same orchards where trapping was conducted. Fruit fly infestation of the sampled lemons was determined by dissection. Additionally, infestation of lemons was determined under forced exposure to mature mated
females of C. capitata and B. dorsalis. Trapping data showed the presence of adults of all four fruit fly species in the sampled lemon orchards.No fruit fly infestation was detected in 43 222 Eureka lemons sampled at harvest. There was also no infestation of lemons under forced exposure conditions. The results of this study provide evidence with 99.99 % efficacy and a 99% confidence level that South African commercial export grade Eureka lemon fruit is not a host for C. capitata, C. rosa, C. quilicii or B. dorsalis.

Abstract

Aruna Manrakhan, Peter Stephen, MC Pretorius, Tim Grout and Paul Fourie Citrus Research International (CRI)

The Asian citrus psyllid (ACP), Diaphorina citri, is an important pest of citrus in many parts of the world due to its effective ability to vector Asian Huanglongbing (HLB) caused by the phloem limited bacteria Candidatus Liberibacter asiaticus (LAS). ACP can also vector Canditatus Liberibacter africanus (LAF), which is present in certain parts of Southern Africa and causes African greening disease (or African HLB). African Greening is a serious disease, particularly in cooler production areas. However, HLB is the most serious disease of citrus worldwide because of its rapid spread, causing rapid tree decline and death and being extremely difficult to control.

Abstract

Understanding fruit fly species’ responses to lures are critically important, especially when a single lure is recommended for the purpose of trapping multiple fruit fly species in commercial fruit orchards. To date, few studies have tested the relative trapping efficiency of different lures and many commercial fruit growers assume that a general lure would attract multiple species. In addition, South African fruit industries are facing threats from the recent invasion of the Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) (initially described as Bactrocera invadens Drew, Tsuruta and White and now synonymised with B. dorsalis) into novel areas in South Africa. Here, using a multi lure comparison approach we test the relative efficiency of thirteen different trapping systems for various fruit fly species, including B. dorsalis in mango orchards in South Africa. This is the first time such a lure comparison has been done, quantifying the number of non-target organisms trapped and including B. dorsalis.  Pronounced variation in species attractiveness across the trapping systems was found. The enhanced ginger oil (EGO) PherolureTM captured 33.77% of all the Ceratitis spp. (Diptera: Tephritidae). Invader-LureTM captured 36.47% of the total number of B. dorsalis trapped. These results are important and significant for on-farm monitoring strategies as well as for invasion monitoring systems currently in place to detect the distribution of B. dorsalis in South Africa.

Abstract

A case study of a pheromone based attract-and-kill management strategy for codling moth, Cydia pomonella (L.), was conducted to examine key insect behavioral factors mitigating the possible effectiveness of this strategy. Last Call CM is a newly registered attracticide product that combines the primary component of codling moth sex pheromone with the insecticide permethrin. Studies of competition between pheromone point sources within caged trees showed individual attracticide droplets were signiÞcantly more attractive to male moths than calling females. In commercial orchard blocks, marked male moths were recaptured after visiting attracticide droplets applied at rates of 50, 100, and 200 droplets/ha, although no marked moths were recaptured in plots with 500 droplets/ha. This experiment also revealed no signiÞcant differences among 0, 50, 100, and 200 droplets/ha in suppressing total catch in female baited traps, nor were total numbers of females attracting at least one male reduced signiÞcantly. In plots with 500 droplets/ha applied, male moth catch was suppressed signiÞcantly compared with catches in untreated control plots, and the number of females attracting at least one male was reduced signiÞcantly as well. Experiments investigating sublethal physiological effects of attracticide exposure upon mating competency of male codling moths demonstrated male leg autotomy at 1, 24, 48, and 72 h after exposure. Male codling moth at 1, 24, 48, and 72 h after exposure placed near calling virgin females exhibited signiÞcant behavioral differences from sham-treated males in courtship and mating. These results clarify some of the possible mechanisms, and strengths and weaknesses of this attract-and-kill management strategy for codling moth.

 

Abstract

The field trial was conducted to test the efficacy of Last Call LFM™, an “attract and kill” product, in litchi orchards in Malelane, South Africa. The trial was followed on from the previous year on the same farm. This particular farm was selected for the second year because of the distances between separate blocks. In 2006 it was clear that Last Call LFM™ has a “spill over” effect into nearby orchards used as control blocks. The aim of this season was to evaluate the efficacy of Last Call LFM™ by making applications earlier in the season before the litchi fruit moth population could establish itself. A more elaborate fruit inspection was also employed to test the integrity of the inspection method. The litchi fruit moth numbers did not increase significantly in the control blocks of this trial. The fruit damage as a result of litchi fruit moth was extremely low at 0.1% on average.

Abstract

The males of some fruit flies (Diptera: Tephritidae) are known to be attracted to specific parapheromones. The trapping results between trimedlure (TML) and enriched ginger root oil (EGOlure) were compared at two experimental sites in Morogoro (Central Tanzania) for a period of 12 weeks co-inciding with the main citrus season. Both attractants captured a comparable diversity of fruit flies, except that EGOlure also attracted fruit flies, such as Ceratitis cosyra, not normally found in TML-baited traps. Both EGOlure and TML attracted mainly or exclusively male fruit flies, but the catches with EGOlure were equal or superior to those with TML. It is concluded that EGOlure should be considered as a suitable alternative for TML in detection, monitoring and control programs for African fruit flies of the genus Ceratitis. It has the added advantage that it combines the attractiveness with regard to species spectrum of both TML and terpinyl acetate.

Abstract

The Five Deadly Sins of Empty Plastic Pesticide Container Management.

These containers, even though triple rinsed, MAY NOT BE:

  • Buried on the farm.
  • Burned on the farm.
  • Re -used as containers.
  • Sold as containers for anything.
  • Given away as to be used as containers for any purposes

THEY MUST BE RECYCLED.

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The Science of Entomology 

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