Spiroacetals in the Colonization Behaviour of the Coffee Berry Borer: A ‘Push-Pull’ System

Coffee berries are known to release several volatile organic compounds, among which is the spiroacetal, conophthorin, an attractant for the coffee berry borer Hypothenemus hampei. Elucidating the effects of other spiroacetals released by coffee berries is critical to understanding their chemo-ecological roles in the host discrimination and colonization process of the coffee berry borer, and also for their potential use in the management of this pest. Here, we show that the coffee berry spiroacetals frontalin and 1,6-dioxaspiro [4.5] decane (referred thereafter as brocain), are also used as semiochemicals by the coffee berry borer for host colonization. Bioassays and chemical analyses showed that crowding coffee berry borers from 2 to 6 females per berry, reduced borer fecundity, which appeared to correlate with a decrease in the emission rates of conophthorin and frontalin over time. In contrast, the level of brocain did not vary significantly between borer- uninfested and infested berries. Brocain was attractive at lower doses, but repellent at higher doses while frontalin alone or in a blend was critical for avoidance. Field assays with a commercial attractant comprising a mixture of ethanol and methanol (1∶1), combined with frontalin, confirmed the repellent effect of this compound by disrupting capture rates of H. hampei females by 77% in a coffee plantation. Overall, our results suggest that the levels of frontalin and conophthorin released by coffee berries determine the host colonization behaviour of H. hampei, possibly through a ‘push-pull’ system, whereby frontalin acts as the ‘push’ (repellent) and conophthorin acting as the ‘pull’ (attractant). Furthermore, our results reveal the potential use of frontalin as a repellent for management of this coffee pest.     

On the Eyes of Male Coffee Berry Borers as Rudimentary Organs

The coffee berry borer, Hypothenemus hampei, is the most damaging insect pest of coffee worldwide. Like males in other species in the genus, male coffee berry borers have a lower number of facets in the compound eyes than females. The rudimentary eyes in male coffee berry borers could be an evolutionary response to their cryptic life habit, whereby they are born inside a coffee berry and never leave the berry. The main objective of the study was to determine if the differences in the number of facets translates into differences in visual acuity. We used low-temperature scanning electron microscopy to visualize and quantify the number of facets in the compound eyes. There was a significantly lower (p<0.0001) number of facets in males (19.1±4.10) than in females (127.5±3.88). To assess visual acuity, we conducted optomotor response experiments, which indicate that females respond to movement, while males did not respond under the conditions tested. The coffee berry borer is an example of an insect whereby disuse of an organ has led to a rudimentary compound eye. This is the first study that has experimentally tested responses to movement in bark beetles.     

How Old are Colonizing Hypothenemus hampei (Ferrari) Females When They Leave the Native Coffee Fruit?

The age of colonizing Hypothenemus hampei (Ferrari) females when they leave the native coffee fruit was determined under laboratory conditions. This biological parameter might be useful for planning experiments with this species because certain physiological statuses are expressed from or until a determined age, which in turn may determine the response of individuals to different treatments. An experimental device was used to simulate the conditions inside a coffee berry and to permit the observation of the abandonment behavior of the beetles. Virgin and mated females with or without melanized cuticles were used in the experiments. On average, colonizing coffee berry borers were 15-days-old at the moment of host abandonment. Females at this age were mated, had full dark cuticles, and were able to display flight and lay viable eggs. Interestingly, H. hampei females that mated before they acquire a fully dark cuticle abandoned the host 1.7 times faster than females that mated after they reach this physiological status. Further studies into food conditions and their impacts on the pre- abandonment of H. hampei females are encouraged.     

Manipulating tropical fire ants to reduce the coffee berry borer

1. The coffee berry borer Hypothenemus hampei (Coleoptera, Curculionidae) (Ferrari) is the most important pest of coffee production worldwide. 2. The hypothesis that the tropical fire ant, Solenopsis geminata Westwood, indirectly protects the coffee berry borer by suppressing other ant species that are the coffee berry borer's primary predators was tested. 3. It was found that removing S. geminata from coffee plots significantly increased the disappearance of adult coffee berry borer beetles from coffee berries compared with control plots. An average of 6% of beetles disappeared from plots with S. geminata whereas 23% of beetles disappeared from plots from which S. geminata was removed. This pattern was observed on two shade coffee farms with marked differences in ant species composition, one in the rainforest in central Costa Rica and one in the cloudforest in northwest Costa Rica. 4. If the results of this small‐scale study can be replicated on the farm level, then S. geminata suppression may represent a new management technique for the coffee berry borer throughout Central and South America.     

Field superparasitism by Phymastichus coffea, a parasitoid of adult coffee berry borer, Hypothenemus hampei

Superparasitism by Phymastichus coffea LaSalle (Hymenoptera: Eulophidae), a parasitoid of adults of the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae), was recorded under field conditions in a coffee plantation in Colombia. Parasitoid adults were released 1, 5, and 9 days after artificial infestations of 90‐, 150‐, and 210‐day‐old coffee berries with H. hampei females. The position of the beetle inside the berry and the number of P. coffea larvae per female host were assessed 10 days after each parasitoid release. Under laboratory conditions, P. coffea usually lays two eggs per host, one female and one male. In our studies, we often recorded more than six P. coffea larvae in an individual host and mean numbers of larvae per host ranged from two to 4.45. Superparasitism by P. coffea under field conditions was influenced by the age of the coffee berries, which is the most important factor determining the speed of penetration by H. hampei, and therefore the time the beetles are exposed to a P. coffea attack. The number of parasitoid larvae in each H. hampei female gradually decreased with the age of the berry, and also linearly decreased with the time of parasitoid release. Age‐dependent effects of coffee berries that alter the ratio of available hosts to searching parasitoids by providing refuges to the herbivore, largely determine the extent of superparasitism of H. hampei by P. coffea under fields conditions in Colombia.     

Reproductive Biology ofCephalonomia hyalinipennis(Hymenoptera: Bethylidae), a Native Parasitoid of the Coffee Berry Borer,Hypothenemus hampei(Coleoptera: Scolytidae), in Chiapas, Mexico

The coffee berry borer,Hypothenemus hampei(Ferrari) (Coleoptera: Scolytidae), is the most important pest of coffee worldwide.Cephalonomia hyalinipennisAshmead (Hymenoptera: Bethylidae) was recently discovered naturally attackingH. hampeiin Mexico.C. hyalinipennisboth preys upon and parasitizesH. hampei.We report laboratory investigations on the reproductive biology ofC. hyalinipennisaimed at assessing the suitability of this parasitoid for culturing and release in biological control programs. Adult females lived up to 95 days (mean for mated females = 57 days), and risk of death increased with age. Mating status, reproductive effort, and female size influenced adult female longevity, but only weakly. The number ofH. hampeipreyed upon did not affect longevity. Rates of attack (predation plus parasitism) declined with age, but the proportion of attackedH. hampeithat were parasitized increased. Overall, about half of the attackedH. hampeiwere preyed upon and half were parasitized. Females received approximately 46 sperm per mating and 77% became sperm depleted before the end of their reproductive lives. Estimated mean lifetime fecundity was 88 eggs. Offspring survival from egg to adulthood was 60%, with batches of eggs tending to survive or die collectively; 21.2% of surviving progeny were males. These results suggest thatC. hyalinipennismay be suitable for mass rearing and release, but further work is needed to investigate interactions betweenC. hyalinipennisand other parasitoids ofH. hampei.     

Behavior and Activity Pattern of Cephalonomia stephanoderis (Hymenoptera: Bethylidae) Attacking the Coffee Berry Borer,Hypothenemus hampei (Coleoptera: Scolytidae)

We describe behavioral sequences and daily activities of pre-ovipositing and ovipositing females of Cephalonomia stephanoderis (Hymenoptera: Bethylidae), an ectoparasitoid of the coffee berry borer, Hypothenemus hampei (Coleoptera: Scolytidae). Noticeable behavioral differences among preovipositing and ovipositing females include host examination, host stinging—probing, host feeding, and the oviposition per se. The female of C. stephanoderis feeds primarily on host eggs, but pupae are also exploited, mainly by pre-ovipositing females. After the onset of the oviposition period, C. stephanoderis examines the pupae repeatedly, stings them at frequent intervals, and spends more time feeding than during the pre-oviposition period. Host paralysis is linked both to host feeding and oviposition. It induces irreversible developmental arrest, which presumably allows preservation of the host until subsequent utilization, and contributes to successful offspring development, particularly by reducing host motility. Oviposition consists in a host selection process, a prolonged period of preparation of the potential host, and the egg-laying phase itself. Under our experimental conditions, pre-ovipositing and ovipositing females are active 17% and 36% of the day, respectively. Host handling time averages 6% and 23% in pre-ovipositing and ovipositing females, respectively. All coffee berry borer developmental stages are exploited by C. stephanoderis females, either for host feeding and/or oviposition activities. Such flexible behavior is advantageous given that host availability is limited inside the coffee berries.     

Artificial diet sandwich reveals subsocial behaviour in the coffee berry borer Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae)

An artificial diet sandwich, consisting of coffee berry borer artificial diet within two glass plates, has been developed to elucidate the behaviour of the coffee berry borer, an insect that in nature spends most of its life cycle inside the coffee berry. Various types of behaviour have been observed for the first time, including gallery construction, oviposition, gallery blocking, mating and most remarkably, subsocial tasks such as maternal sanitation and tending of eggs and larvae. This observational technique is a breakthrough for studies and manipulations of the coffee berry borer's social behaviour and could be applicable to other bark beetles, consequently yielding important insights into the origin of parental care in scolytine beetles.     

Biological control of the coffee berry borer Hypothenemus hampei (Coleoptera: Curculionidae) by Phymastichus coffea (Hymenoptera: Eulophidae) in Colombia

The potential of the eulophid parasitoid Phymastichus coffea LaSalle to control coffee berry borer Hypothenemus hampei (Ferrari) populations under field conditions in Colombia was evaluated. Parasitoid adults were released one, five and nine days after artificial infestations of 90-, 150- and 210-day-old coffee berries with H. hampei females. The position of the beetle inside the berry and the parasitism levels were assessed ten days after each P. coffea release. Parasitism of H. hampei by P. coffea was significantly affected by the age of the berries at the time of infestation, and by the position of the beetle inside the berries. Highest levels of parasitism were recorded in 150-day-old berries (75-85%) and in 90-day-old berries (75%) when P. coffea were released one day after the artificial infestation with H. hampei. In 150-day-old berries, highest levels of parasitism were recorded for H. hampei found in the outer layer of the endosperm followed by beetles penetrating the exocarp. Increasing the time of P. coffea releases after the artificial infestations with H. hampei led to decreased levels of parasitism in beetles attacking 90- and 150-day-old coffee berries. Low levels of parasitism were recorded in H. hampei females infesting older coffee berries because most of the beetles had already constructed galleries deep in the endosperm of the berries, i.e. out of reach of the parasitoid. The potential of P. coffea for biological control of coffee berry borer in Colombia is discussed.     

Sterile males of Ceratitis capitata (Diptera: Tephritidae) as disseminators of Beauveria bassiana conidia for IPM strategies

Sterile Mediterranean fruit fly, Ceratitis capitata (Wied.), males were evaluated as vectors to spread Beauveria bassiana (Bals) conidia to wild C. capitata populations under field conditions. The inoculated sterile males were released by air, using the chilled adult technique over 7000 ha of coffee growing in Chimaltenango, Guatemala, Central America. The impact of releases was determined using dry traps baited with a food attractant. The effects of these releases on Apis mellifera, Linnaeus (honey bee), Hypothenemus hampei, Ferrari (coffee berry borer) and the parasitic mite Varroa destructor (Oudeman) were also evaluated. Inoculated sterile males were able to transmit fungal spores to 44% of the wild C. capitata flies captured in traps, which likely were infected through intra- and intersexual interactions during leks, mating or mating attempts. There was no transmission of the fungal spores to non-target insect species such as coffee berry borer, honey bees or varroa. We conclude that sterile males of Mediterranean fruit fly inoculated with B. bassiana can act as effective vectors of conidia to wild populations, constituting a safe, environmentally friendly and selective alternative for suppressing the medfly under a Sterile Insect Technique-based IPM approach.     

Testing ant predation on the coffee berry borer in shaded and sun coffee plantations in Colombia

Soil‐dwelling ants, many of which are generalist predators, are more diverse in shaded than in sun coffee plantations without trees. We compared ant predation on the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae) in three shaded and three sun coffee plantations in Apía, Colombia, in both the wet and the dry seasons. We found that H. hampei adults exposed to ants for 5 days suffered higher removal in shaded plantations and in the wet season. In the laboratory, we observed that ants killed 74–99% of H. hampei adults over the course of 5 days. Ants appear to be important predators of H. hampei, particularly in shaded coffee plantations and in the wet season.     

Isolation,morphological and molecular characterization of Bacillus thuringiensis strains against Hypothenemus hampei Ferrari (Coleoptera: Curculionidae: Scolytinae)

The coffee berry borer Hypothenemus hampei Ferrari, 1876 (Coleoptera: Curculionidae: Scolytinae) is considered the most serious pest of the coffee crop and is controlled primarily with the use of chemical insecticides. An alternative to this control method is the use of the entomopathogenic bacterium, Bacillus thuringiensis Berliner, 1911. Therefore, the objective of this work was to select strains of B. thuringiensis virulent against H. hampei and characterize them by morphological and molecular methods to identify possible genes for the production of genetically modified plants. To achieve this objective, 34 strains of B. thuringiensis underwent a selective bioassay to evaluate their toxicity to H. hampei first-instar larvae. Among the strains tested, 11 and the standard B. thuringiensis subspecies israelensis (IPS-82) caused mortality above 90%. Then, the median lethal concentration (LC₅₀) was estimated for these strains followed by characterization using morphological, biochemical and molecular methods. The lowest LC₅₀ was obtained for strain BR58, although this concentration did not differ significantly from that of the standard strain IPS-82 or from that of strains BR137, BR80 and BR67. The molecular characterization detected cry4A, cry4B, cry10, cry11 and cyt1 genes in 10 of the most virulent strains (BR58, BR137, BR80, BR81, BR147, BR135, BR146, BR138, BR139, BR140). Strain BR67 differed completely from the others and amplified only the cry3 gene. This strain was more virulent than BR135, BR146, BR138, BR139 and BR140, but it did not differ from BR58, BR137, BR80, BR81 and BR147. The protein profile revealed proteins of 28, 65, 70 and 130 kDa, and the morphological analysis identified spherical crystalline inclusions in all strains. The results showed that the 11 strains studied have potential for use as a gene source for insertion into coffee plants for the control H. hampei, especially the cry3, cry4A, cry4B, cry10, cry11 and cyt1 genes, that were repeated in the most virulent isolates.     

Behavioural responses of bethylid parasitoid species of the coffee Berry borer to chemicals cues from host and non-host dust/frass

The bethylid wasps Cephalonomia stephanoderis Betrem and Prorops nasuta Waterston are parasitoids of the coffee berry borer, Hypothenemus hampei (Ferrari), the most serious insect pest of coffee worldwide. Recent studies on the host location behaviour of these parasitoids have shown that females are attracted to volatile compounds released by immature stages and dust/frass of H. hampei. Also, these studies have reported that the locomotory behaviour of parasitoids is influenced by contact chemical cues from host dust/frass. In this study, we investigated the responses of females of both species to volatiles and contact cues from dust/frass from different sources. Volatiles from dust/frass from H. hampei-infested coffee and maize infested with Sitophilus sp were attractive to P. nasuta females. In contrast, C. stephanoderis females were only attracted to the volatiles from dust/frass from H. hampei-infested coffee. Volatiles from an artificial diet used for rearing H. hampei were not attractive to females of both species. The effect of methanolic extracts from dust/frass from different sources on the patch-searching time of parasitoids was analysed using the Ethovision software. P. nasuta females spent more time in the patches treated with extracts of dust/frass from H. hampei-infested berries, artificial diet, and from maize infested with Sitophilus sp than on patches treated with dry coffee extract or solvent control. C. stephanoderis females spent more time on patches treated with dust/frass extracts from H. hampei-infested berries and artificial diet than on patches treated with an extract of dust/frass from maize infested with Sitophilus sp, an extract of dry coffee, and methanol control.     

Sterility of the coffee berry borer,Hypothenemus hampei (Coleoptera: Curculionidae), caused by the nematode Metaparasitylenchus hypothenemi (Tylenchidae: Allantonematidae)

Metaparasitylenchus hypothenemi is an endoparasitic nematode that causes partial or total sterility of coffee berry borer (Hypothenemus hampei) females, although the causes are unknown. Fecundity and the average size of the common and lateral oviduct, vitellarium, and germarium in the four ovarioles (I, II, III and IV) were compared between parasitised and non-parasitised insects to determine the causes of sterility. The nematode significantly lowers the number of oocytes and 86% of parasitised insects (24 out of 28 insects) were sterile, while fecundity in the remaining 13% was non-significantly different to that in non-parasitised insects. No significant differences were recorded in the size of the common oviduct, lateral oviduct, vitellarium, and germarium between parasitised and non-parasitised insects and the nematode does not cause any apparent damage on the surface of the ovary.     

Effect of physiological status on olfactory and visual responses of female Hypothenemus hampei during host plant colonization

The response of Hypothenemus hampei (Ferr.) (Coleoptera, Scolytidae) (coffee berry borer, CBB) females to olfactory stimuli was demonstrated to be related with the physiological status; especially with age, whether they were mated or not, and whether they have already oviposited. A special behaviour, the abandonment of the native berry, was also found to play a major role. In contrast, response to visual stimuli (false coffee berries) was found to be independent of the physiological status of CBB females. Variations in behavioural responses to visual and olfactory stimuli are discussed in relation to colonization strategy.     

Cry1B and Cry3A are active against Hypothenemus hampei Ferrari (Coleoptera: Scolytidae)

Cry1B and Cry3 proteins from Bacillus thuringiensis are toxic to beetles such as the colorado potato beetle and the cottonwood leaf beetle. We report the development of a suitable rearing, bioassay method and the toxicity of these Cry proteins to coffee berry borer first instar larvae.     

Life history studies of <Emphasis Type="Italic">Prorops nasuta</Emphasis>, a parasitoid of the coffee berry borer

Life history studies were conducted in the laboratory on the African parasitoid Prorops nasuta Waterston (Hymenoptera: Bethylidae), a parasitoid of the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae). The female wasp enters an infested coffee berry, kills the adult borer and seals the entrance of the berry with the body of the borer, impeding the entry of other organisms into the berry. The preoviposition period ranges from 3 to 14 days (mean 5.42 ± 0.37 SE). During this time females feed on the immature stages and paralyse fully grown larvae and pupae of the CBB. P. nasuta is an idiobiont solitary ectoparasitoid. Eggs are laid externally on the last instar larvae and pupae. Mean development time (egg to adult) for males and females was 27.7 (±0.37 SE) and 30 (±0.12 SE) days, respectively. Median survival for wasps fed on final instar CBB larvae was 27.7 days, significantly longer than any other treatment, while for females without food it was 2.5 days. In culture, females produced an average of 4.3 (±0.39 SE) progeny during their lifetimes. Adults began emerging at 30.6 days (±0.28 SE) after cultures were started and peak production was reached at 36 days, declining thereafter. Males normally emerged from coffee beans 2–3 days before females. Males usually emerged from 07:00 to 09:00h and females from 10:00 to 14:00 h. The culture sex ratio (proportion of males) was 0.21. Virgin females produced only male offspring.     

Metaparasitylenchus hypothenemi n. sp. (Nematoda: Allantonematidae), a parasite of the coffee berry borer, Hypothenemus hampei (Curculionidae: Scolytinae)

Metaparasitylenchus hypothenemi n. sp. (Nematoda: Allantonematidae) is described from the coffee berry borer, Hypothenemus hampei (Ferrari) (Curculionidae: Scolytinae), in Chiapas, Mexico. This species differs from other members of the genus by its small size, annulated cuticle, lateral fields with 3 ridges, free-living stages with an excretory pore located between the pharyngeal gland orifices, a distinct stylet with basal swellings in free-living females, a postvulval uterine extension, a thin stylet lacking basal swellings in males, 2 separate spicules, a gubernaculum, and a peloderan bursa. Parasitic females are white, with a straight or slightly curved body and are ovoviviparous. Third-stage juveniles emerge from parasitized beetles and molt twice before reaching the adult stage. Because the coffee berry borer is the most important pest of coffee throughout the world and this parasite partially or completely sterilizes female beetles, it is worthy of further investigation as a potential biological control agent.     

The chemotaxonomy ofBeauveria bassiana (Deuteromycotina: Hyphomycetes) isolates from the coffee berry borerHypothenemus hampei (Coleoptera: Scolytidae)

A preliminary chemotaxonomic analysis was carried out on 16 isolates ofBeauveria bassiana from adults of coffee berry borer (Hypothenemus hampei) from 10 countries in Latin America, Africa, Asia and the Pacific. Thirteen formed an homogeneous group with very similar electrophoretic and physiological profiles. Two isolates differed in esterase and acid phosphatase band patterns, one of which was also deficient in chitin-degrading enzyme production, but both were still relatively similar to the major group compared with the total variability within the species. A third isolate was abnormal and may have degenerated in storage. These results suggest a distinct population of the fungus on this host. The implications for selection of pathogenic isolates for development as biological pesticides are discussed.     

Testing what we know about coffee volatiles affecting behaviour of Hypothenemus hampei

Coffee berry borer (CBB), Hypothenemus hampei (Ferrari) (Coleoptera: Scolytinae), is a major pest of coffee worldwide. CBB females use berry volatiles while searching for hosts. Coffee volatiles can be used for monitoring CBB populations. The main objective of this study was to test under laboratory and field conditions bioactive compounds for H. hampei. In the laboratory, CBB females were attracted to the methanol-ethanol blend (MEB), but not to methylcyclohexane, ethylbenzene, nonane, methyl salicylate, verbenone, α-pinene, farnesene, and frontalin compared to clean air. In contrast, CBB females preferred clean air over linalool. Females were attracted to most of the tested compounds combined with the MEB over clean air, except farnesene, α-pinene, and linalool. Females preferred clean air to α-pinene or linalool, and they showed no preference for clean air or farnesene. Females also preferred the MEB over linalool, verbenone, α-pinene, or farnesene when combined with MEB. The combination of tested compounds and the MEB did not increase the capture of CBB in the field. Interestingly, α-pinene and linalool alone, or combined, inhibited the capture of CBB females and non-target insects by trapping bait with the MEB. Thus, α-pinene or linalool can be used in a push-pull strategy considering the low impact over non-target insects.