Authors: Jihao You, Edmond Lou, Mohammad Afrouziyeh...

Identifying daily oviposition events for individual broiler breeders is important for bird management. Identifying non-laying birds in a flock that might be caused by improper nutrition or diseases can guide diet changes or disease treatments for these individuals. Oviposition depends on follicle maturation and egg formation, and follicle maturation can be variable. As such, the day and time of oviposition events of individual birds in a free-run flock can be hard to predict. Based on a precision feeding (PF) system that can record the feeding activity of individual birds, a recent study reported a machine learning model to predict daily egg-laying events of broiler breeders. However, there were 2 limitations in that study: 1) It could only be used to identify daily egg-laying events on a subsequent day; 2) The prediction outputs that were binary labels were unable to indicate more details among the outputs with the same label. To improve the previous approach, the current study aimed to predict and output the probability of daily oviposition events occurring using a specific time point in 1 day. In the current study, 706 egg-laying events recorded by nest boxes with radio frequency identification of hens and 706 randomly selected no-egg-laying events were used. The anchor point was newly defined in the current study as a specific time point in 1 day, and 26 features around the anchor point were created for all events (706 egg-laying events and 706 no-egg-laying events). A feed-forward artificial neural network (ANN) model was built for prediction. The area under the receiver operating characteristic (ROC) curve was 0.9409, indicating that the model had an outstanding classification performance. The ANN model could predict oviposition events on the current day, and the output was a probability that could be informative to indicate the likelihood of an oviposition event for an individual breeder. In situations where total egg production was known for a group, the ANN model could predict the probability of daily oviposition events occurring of all individual birds and then rank them to choose those most likely to have laid an egg.

Topics: Animal Feed; Animals; Chickens; Female; Neural Networks, Computer; Oviposition; Probability

PubMed: 34198100
DOI: 10.1016/j.psj.2021.101187

Authors: Victor S Mwingira, Leonard E G Mboera, Willem Takken...

BACKGROUND

Olfactory cues have been shown to have an important role in guiding gravid mosquito females to selected sites for egg laying. The objective of this study was to determine the influence of emanations from soil from a breeding site and the putative oviposition pheromone nonane on oviposition-site selection of natural populations of Anopheles gambiae sensu lato (s.l.) and Culex quinquefasciatus.

METHODS

This field-based study was conducted in Mvomero District in East-central Tanzania. In a dual-choice experimental set up, clay bowls were dug into the ground and filled with one of the following treatments: (i) distilled water + autoclaved soil (control), (ii) distilled water + soil from a natural mosquito breeding site, (iii) distilled water + nonane and (iv) distilled water + nonane + soil from a natural breeding site. Soil was dried and autoclaved or dried only before use. After five days of incubation, larvae were collected daily for 10 days. The median number of larvae per bowl per day was used as outcome measure.

RESULTS

Autoclaved soil had a significant attractive effect on oviposition behaviour of Cx. quinquefasciatus (median values ± s.e: 8.0 ± 1.1; P < 0.005) but no effect on An. gambiae (median value ± s.e: 0.0 ± 0.2; P = 0.18). Nonane and emanations from untreated soil significantly and positively influenced the selection of oviposition sites by both An. gambiae s.l. (median values ± s.e.: 12.0 ± 2.0 and 4.5 ± 1.5, respectively; P < 0.0001) and Cx. quinquefasciatus (median values ± s.e.: 19.0 ± 1.3 and 17.0 ± 2.0, respectively; P < 0.0001). A mixture of nonane and untreated soil caused a synergistic effect on oviposition behaviour in An. gambiae s.l. (median value ± s.e.: 23.5 ± 2.5; P < 0.0001) compared to either nonane (median values ± s.e.: 12.0 ± 2.0; P < 0.0001) or untreated soil alone (median value ± s.e.: 4.5 ± 1.5; P < 0.0001). A synergistic effect of nonane mixed with untreated soil was also found in Cx. quinquefasciatus (median value ± s.e.: 41.0 ± 2.1; P < 0.0001) compared to either nonane (median value ± s.e. 19.0 ± 1.3; P < 0.0001) or untreated soil alone (median value ± s.e.: 17.0 ± 2.0; P < 0.0001). The oviposition activity index for An. gambiae was 0.56 (P < 0.001) and for Cx. quinquefasciatus 0.59 (P < 0.0001).

CONCLUSIONS

The larval pheromone nonane and emanations from breeding-site soil both induced oviposition in wild An. gambiae s.l. and Cx. quinquefasciatus, with a synergistic effect when both stimuli were present simultaneously. This is the first study in which nonane is shown to cause oviposition under natural conditions, suggesting that this compound can potentially be exploited for the management of mosquito vectors.

Topics: Alkanes; Animals; Anopheles; Culex; Female; Larva; Mosquito Control; Mosquito Vectors; Olfactory Perception; Oviposition; Pheromones; Soil; Tanzania

PubMed: 33478526
DOI: 10.1186/s12936-020-03575-0

Authors: Dinesh Erram, Nathan Burkett-Cadena

BACKGROUND

Culicoides insignis is a confirmed vector of bluetongue virus (BTV) throughout the American tropics and a possible vector of epizootic hemorrhagic disease virus (EHDV) in Florida. Despite its importance, fundamental information on the biology and ecology of this vector species is lacking. In this study, we examined the oviposition of C. insignis under laboratory conditions, monitored the development of immature stages and attempted colonization of this species.

METHODS

Live C. insignis females were collected from the field using CDC-UV-LED traps, allowed to blood-feed on live chicken and given various natural substrates for oviposition in two-choice assays. The eggs deposited were transferred to 0.3% agar slants, and the hatched larvae were provided a diet of Panagrellus redivivus Linnaeus nematodes and the development of all immature stages was monitored.

RESULTS

Culicoides insignis females exhibited an overall oviposition preference for dishes containing mud from their larval habitat as gravid females deposited a significantly higher number of eggs on these dishes (35.3 eggs/female) than on controls (17.7 eggs/female). The ovipositing females also deposited a higher percentage of eggs on substrates with habitat mud and other organically enriched muds (≥ 75.2%) compared to controls (31.0%). The larvae developed successfully to adulthood on the nematode diet, exhibiting high overall larval survival rates (85.0%). Sex ratios of the F1 generation were male biased, approximately 3:1 (male:female). Captive mating could not be induced in the F1 adults.

CONCLUSIONS

Mud from the larval habitat and other organically enriched muds provide strong oviposition cues to C. insignis under laboratory conditions. Further studies will be needed to identify the key biotic/abiotic factors influencing midge oviposition in the field. The agar/nematode method is effective for the rearing of C. insignis larvae. However, further studies will be needed to address the issue of male-biased sex ratios in the progeny and to examine the mating habits/cues of C. insignis in nature, which may provide clues towards inducing captive mating in the F1 adults.

Topics: Animals; Bluetongue; Bluetongue virus; Ceratopogonidae; Ecosystem; Female; Insect Vectors; Laboratories; Larva; Life Cycle Stages; Life History Traits; Oviposition

PubMed: 34627349
DOI: 10.1186/s13071-021-05025-5

Authors: Márcia Cristina Bernardo de Melo Moura, Josinaldo Vidal de Oliveira, Rodrigo Moreira Pedreira...

OBJECTIVE

The objective of this study was to analyse abundance and spatial distribution of Aedes aegypti and Aedes albopictus oviposition in the city of Natal-RN, 2016 to 2018.

METHODS

Three hundred and seven oviposition traps were installed covered the whole city and were monitored weekly from January 2016 to December 2018. To verify the abundance of the vector based on its location, the formation of oviposition clusters was studied using the Kernel statistics. Egg Density Index (EDI) and Oviposition Positivity Index (OPI) values were calculated.

RESULTS

Temperature and humidity presented weak and very weak correlation, respectively, with the oviposition indicators. The median of oviposition positivity index (OPI) was 60.5%, and the egg density index (EDI) was 45.4 eggs/trap. The OPI (71.1%) was higher in the second quarter of the year. The areas with the most persistent oviposition are located in a continuous strip that extends from the extreme of the northern district and extends along the western district of the city. Also noteworthy is the proximity to the strategic points.

CONCLUSION

The spatio-temporal distribution of oviposition revealed that there is spatial segregation and marked seasonality. Therefore, this study highlights the importance of maintaining surveillance targeting and control strategies focused on these areas, especially during the most important period of the year.

Topics: Aedes; Animals; Brazil; Cities; Female; Humidity; Mosquito Vectors; Oviposition; Seasons; Spatio-Temporal Analysis; Temperature

PubMed: 32959943
DOI: 10.1111/tmi.13491

Authors: Hiroshi Jinguji, Yuki Fujiwara, Kazuhisa Ohtsu...

This study examined the effectiveness of sodium chloride (NaCl) as an oviposition repellent for Aedes albopictus females. Oviposition responses to 0.5%, 0.75%, 1.00%, 1.25%, and 1.5% solutions of pure NaCl were evaluated over 8 days using ovitraps. Gravid Ae. albopictus females showed a reduction in oviposition at all NaCl concentrations. Compared with controls, the inhibition of oviposition ranged from 84.4% to 97.0% at concentrations above 0.5% NaCl. We also show that NaCl is effective for oviposition control of gravid females when laying their overwintering eggs. Our results showed that a 0.5% NaCl solution is effective for use as an oviposition repellent against Ae. albopictus females.

Topics: Aedes; Animals; Female; Insect Repellents; Male; Mosquito Control; Oviposition; Sodium Chloride

PubMed: 33647112
DOI: 10.2987/20-6962.1

Authors: Masaharu Hasebe, Sakiko Shiga

Animals show photoperiodic responses in physiology and behavior to adapt to seasonal changes. Recent genetic analyses have demonstrated the significance of circadian clock genes in these responses. However, the importance of clock genes in photoperiodic responses at the cellular level and the physiological roles of the cellular responses are poorly understood. The bean bug shows a clear photoperiodic response in its reproduction. In the bug, the pars intercerebralis (PI) is an important brain region for promoting oviposition. Here, we analyzed the role of the photoperiodic neuronal response and its relationship with clock genes, focusing on PI neurons. Large PI neurons exhibited photoperiodic firing changes, and high firing activities were primarily found under photoperiodic conditions suitable for oviposition. RNA interference-mediated knockdown of the clock gene abolished the photoperiodic response in PI neurons, as well as the response in ovarian development. To clarify whether the photoperiodic response in the PI was dependent on ovarian development, we performed an ovariectomy experiment. Ovariectomy did not have significant effects on the firing activity of PI neurons. Finally, we identified the output molecules of the PI neurons and analyzed the relevance of the output signals in oviposition. PI neurons express multiple neuropeptides-insulin-like peptides and diuretic hormone 44-and RNA interference of these neuropeptides reduced oviposition. Our results suggest that oviposition-promoting peptidergic neurons in the PI exhibit a circadian clock-dependent photoperiodic firing response, which contributes to the photoperiodic promotion of oviposition.

Topics: Animals; Brain; Circadian Clocks; Circadian Rhythm; Female; Gene Expression Regulation; Heteroptera; Insect Proteins; Membrane Potentials; Neurons; Neuropeptides; Ovariectomy; Ovary; Oviposition; Photoperiod; Somatomedins; Sunlight

PubMed: 33622784
DOI: 10.1073/pnas.2018823118

Authors: Dannielle Kowacich, Eduardo Hatano, Coby Schal...

BACKGROUND

Gravid females assess the conditions of oviposition sites to secure the growth and survival of their offspring. Conspecific-occupied sites may signal suitable oviposition sites but may also impose risk due to competition or cannibalism at high population density or heterogeneous larval stage structure, respectively. Chemicals in the habitat, including chemicals emitted from other organisms, serve as cues for females to assess habitat conditions. Here, we investigated the attraction and oviposition preference of the Old World cutaneous leishmaniasis vector, Phlebotomus papatasi, to young and old conspecific stages, including eggs and evaluated the effect of a semiochemical associated with eggs and neonate larvae.

METHODS

Attraction and oviposition preference of Ph. papatasi to each of various life stages (eggs, first-, second-, third-, fourth-instar larvae, pupae and male and female adults) was investigated using cage and oviposition jar behavioral assays. Identification of organic chemical compounds extracted from eggs was performed using GC-MS and chemicals were tested in the same behavioral assays in a dose-response manner. Behavioral responses were statistically analyzed using logistic models.

RESULTS

Gravid Ph. papatasi females were significantly attracted to and preferred to oviposit on medium containing young life stages (eggs and first instars). This preference decreased towards older life stages. Dose effect of eggs indicated a hump-shaped response with respect to attraction but a concave-up pattern with respect to oviposition. Chemical analysis of semiochemicals from eggs and first-instar larvae revealed the presence of dodecanoic acid (DA) and isovaleric acid. Sand flies were attracted to and laid more eggs at the lowest DA dose tested followed by a negative dose-response.

CONCLUSIONS

Findings corroborated our hypothesis that gravid sand flies should prefer early colonized oviposition sites as indicators of site suitability but avoid sites containing older stages as indicators of potential competition. Findings also supported the predictions of our hump-shaped oviposition regulation (HSR) model, with attraction to conspecific eggs at low-medium densities and switching to repellence at high egg densities. This oviposition behavior is mediated by DA that was identified from surface extracts of both eggs and first-instar larvae. Isovaleric acid was also found in extracts of both stages.

Topics: Animals; Behavior, Animal; Female; Hemiterpenes; Larva; Lauric Acids; Male; Oviposition; Ovum; Pentanoic Acids; Pheromones; Phlebotomus; Pupa

PubMed: 32493498
DOI: 10.1186/s13071-020-04151-w

Authors: Johanna E Elsensohn, Marwa F K Aly, Coby Schal...

The information that female insects perceive and use during oviposition site selection is complex and varies by species and ecological niche. Even in relatively unexploited niches, females interact directly and indirectly with conspecifics at oviposition sites. These interactions can take the form of host marking and re-assessment of prior oviposition sites during the decision-making process. Considerable research has focused on the niche breadth and host preference of the polyphagous invasive pest Drosophila suzukii Matsumura (Diptera: Drosophilidae), but little information exists on how conspecific signals modulate oviposition behavior. We investigated three layers of social information that female D. suzukii may use in oviposition site selection-(1) pre-existing egg density, (2) pre-existing larval occupation, and (3) host marking by adults. We found that the presence of larvae and host marking, but not egg density, influenced oviposition behavior and that the two factors interacted over time. Adult marking appeared to deter oviposition only in the presence of an unmarked substrate. These results are the first behavioral evidence for a host marking pheromone in a species of Drosophila. These findings may also help elucidate D. suzukii infestation and preference patterns within crop fields and natural areas.

Topics: Animals; Drosophila; Female; Fruit; Larva; Oviposition; Social Behavior

PubMed: 33589670
DOI: 10.1038/s41598-021-83354-2

Authors: Victor S Mwingira, Jeroen Spitzen, Leonard E G Mboera...

In the selection of oviposition sites female mosquitoes use various cues to assess site quality to optimize survival of progeny. The presence of conspecific larvae influences this process. Interactive effects of oviposition site selection were studied in the malaria mosquito Anopheles coluzzii Coetzee & Wilkerson in dual- and no-choice assays, by exposing single gravid mosquitoes to oviposition cups containing 1) larvae of different developmental stages, 2) larvae-conditioned water (LCW), and 3) cups where visual cues of conspecific larvae were absent. Early-stage conspecific larvae had a positive effect on the oviposition response. By contrast, late stages of conspecific larvae had a negative effect. Oviposition choice was dependent on larval density. Moreover, in oviposition cups where larvae were hidden from view, late-stage larvae had a significant negative effect on oviposition suggesting the involvement of olfactory cues. LCW had no effect on oviposition response, indicating involvement of chemicals produced by larvae in vivo. It is concluded that the presence of larvae in a breeding site affects the oviposition response depending on the development stage of the larvae. These responses appear to be mediated by olfactory cues emitted by the larval habitat containing live larvae, resulting in the enhanced reproductive fitness of the females.

Topics: Animals; Anopheles; Female; Larva; Mosquito Vectors; Oviposition; Population Density

PubMed: 31630193
DOI: 10.1093/jme/tjz172

Authors: Bruce Schoelitsz, Victor Mwingira, Leonard E G Mboera...

The oviposition behavior of mosquitoes is mediated by chemical cues. In the malaria mosquito Anopheles gambiae, conspecific larvae produce infochemicals that affect this behavior. Emanations from first instar larvae proved strongly attractive to gravid females, while those from fourth instars caused oviposition deterrence, suggesting that larval developmental stage affected the oviposition choice of the female mosquito.We examined the nature of these chemicals by headspace collection of emanations of water in which larvae of different stages were developing. Four chemicals with putative effects on oviposition behavior were identified: dimethyldisulfide (DMDS) and dimethyltrisulfide (DMTS) were identified in emanations from water containing fourth instars; nonane and 2,4-pentanedione (2,4-PD) were identified in emanations from water containing both first and fourth instars. Dual-choice oviposition studies with these compounds were done in the laboratory and in semi-field experiments in Tanzania.In the laboratory, DMDS and DMTS were associated with oviposition-deterrent effects, while results with nonane and 2,4-PD were inconclusive. In further studies DMDS and DMTS evoked egg retention, while with nonane and 2,4-PD 88% and 100% of female mosquitoes, respectively, laid eggs. In dual-choice semi-field trials DMDS and DMTS caused oviposition deterrence, while nonane and 2,4-PD evoked attraction, inducing females to lay more eggs in bowls containing these compounds compared to the controls. We conclude that oviposition of An. gambiae is mediated by these four infochemicals associated with conspecific larvae, eliciting either attraction or deterrence. High levels of egg retention occurred when females were exposed to chemicals associated with fourth instar larvae.

Topics: Age Factors; Animals; Anopheles; Chemotaxis; Larva; Olfactory Perception; Oviposition; Volatile Organic Compounds

PubMed: 32240482
DOI: 10.1007/s10886-020-01175-5