Responses of Anastrepha suspensa, Diachasmimorpha longicaudata, and Sensitivity of Guava Production to Heterorhabditis bacteriophora in Fruit Fly Integrated Pest Management

Abstract

Caribbean fruit fly, also known as Caribfly or Anastrepha suspensa, is a major tephritid pest of guavas. A virulent entomopathogenic nematode (EPN) species was investigated to suppress the fruit-to-soil stages of Caribflies, which are also attacked by the koinobiont parasitoid Diachasmimorpha longicaudata in south Florida. The main objective was to develop a feasible and cost-effective EPN-application method for integrated pest management (IPM) of Caribfly to improve guava production. Naturally infested guavas were treated with increasing Heterorhabditis bacteriophora infective juvenile (IJ) concentration or rate (0, 25, 50, …, 1,600 IJs cm −2) in field trials to measure the optimum IJ rate and then examine sensitivity of producing guavas to inclusion of Heterorhabditis bacteriophora in Caribfly IPM plans. Relative survival of Caribfly in treatments significantly decreased with increasing IJ rate from 0 to 100 IJs cm −2. Similarly, probability of observing large numbers of parasitoid wasps (Diachasmimorpha longicaudata) in EPN treatments significantly declined with increasing IJ rate (0-100 IJs cm −2), even though the non-target effects of Heterorhabditis bacteriophora on relative survival of Diachasmimorpha longicaudata could not be determined because of few emerging parasitoid wasps. Optimum suppression (≥ 60%) of Caribfly was consistently achieved at 100 IJs cm −2 or 17,500 IJs fruit −1. Profitability analysis showed that Heterorhabditis bacteriophora can be included in Caribfly IPM tactics to produce guavas. Costs of EPNs in Caribfly IPM are minimized if Heterorhabditis bacteriophora is strategically applied by spot treatment of fruit. Repayment of costs of EPN-augmentation by spot treatments appears achievable by recovering 5.71% of the annual yield losses (≥1,963 kg ha −1 ≈ US$ 8,650 ha −1), which are largely due to Caribfly infestation. Hectare-wide EPN-augmentation (or broadcasting) method requires more fruit recovery than the total annual yield losses to repay its high costs. Profitability of guava production in south Florida will not be very sensitive to marginal costs of the spot treatment method, when compared to the field-wide broadcasting of Heterorhabditis bacteriophora.

Potential of Moroccan entomopathogenic nematodes for the control of the Mediterranean fruit fly Ceratitis capitata Wiedemann (Diptera: Tephritidae)

“…A split split plot design with soil texture or humidity level as main factors, nematode concentration as sub-factor, and EPN isolate as sub-sub-factor was implemented. Three replicates for each EPN-treatments to 10 larvae in each soil type at each moisture content were made in pots and then incubated in dark conditions at 25 °C 45,46 . The mortalities of larvae and pupae caused by EPN strains were confirmed under a microscope.…”

Overview and future research needs for development of effective biocontrol strategies for management of Bactrocera dorsalis Hendel (Diptera: Tephritidae) in sub‐Saharan Africa

“…EPN species have exhibited a remarkable biological control potential against the subterranean life stages of numerous invasive insect pests, including tephritid fruit flies 97–103 . In trials, EPN species killed and successfully multiplied in larvae, pupae and adults of fruit flies 46,99–101,104,105 .…”

“…Usually, the effectiveness of an EPN species against an insect pest varies from field to field, and prediction has been improved using repeated laboratory and field trials 71,99–101,116,121 . In previous experiments, a number of EPN species which included exotic, native or both were randomly selected and tested against fruit flies 46,47,98–112,117 . Thus, selection of EPN species for screening against tephritid fruit flies in experimental trials has largely been guided by the availability of a considerable number of EPN species rather than principles of whether the selected EPN species are commercially available or are native.…”

Opportunities and challenges of entomopathogenic nematodes as biocontrol agents in their tripartite interactions

“…Scientists should further advance biopesticides to occupy new positions. For example, IPM of Caribfly, Anastrepha suspensa, to boost guava production was established on adequate identification of conditions and practices that enhance effective application of EPNs using a costeffective technique (Heve et al 2018). Another avenue to wider utilization of EPNs is to control veterinary pests such as the gray flesh flies Parasarcophaga aegyptiaca as one of the external parasites, an important pest with wide distribution and significant role in causing serious diseases such as myiasis, which can invade various tissues of man and animals.…”